From owner-laser Mon Mar 31 20:54:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26359; Mon, 31 Mar 97 20:54:27 PST Message-Id: <3340B0B9.2D98@Prodigy.Net> Date: Mon, 31 Mar 1997 22:52:41 -0800 From: kc5an Organization: Prodigy Internet X-Mailer: Mozilla 2.02 (Win16; I) Mime-Version: 1.0 To: laser reflector Subject: Greetings to all Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Greetings and many thanks to all corespondents here. I have only been interested in this laser area for about a month, now, but have learned much by reading the posts here. Yesterday I replicated the design for a light-pen transciever described by AB5Ue in the February 97 issue of QST. I use a cheap& ill-mounted 50mm refractor telescope. The solar cell is mounted where the eyepiece should be, and the 1 mW laser is in tye place where the "spotting scope" used to be. It ws a bit of a job tweaking the aim of the laser so that where you look in the scope is where the beam is hitting... but I guess you older hands are used to that alignment stuff! Anyway, the dx record to-date is about 50 ft. That is, 25 ft. out to the side reflector of my stepdaughter's car, & 25 ft. return path to the input of the telescope. Lunar echo it ain't.. but I enjoyed it heaps, and intend to go on from here. One change I have made but have not had time to check is this: I put a pot in the dc supply to the diode, to cut down the unmodulated output. Now I can visually detect changes in the beam intensity as I speak into the amplifiier used for modulation. I don't have a scope, so can't look at actual envelopes, but this just "looks" like more audio power impressed on the beam. Advice? (other than "buy a scope")? 73 John kc5an From owner-laser Tue Apr 1 07:02:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17192; Tue, 1 Apr 97 07:02:29 PST To: laser@berlioz.nsc.com Date: Tue, 1 Apr 1997 09:43:27 -0500 Subject: Combining Solid State Laser Diodes ? Message-Id: <19970401.095341.470.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,5-6,9-10,14-15,18-19,24-25,32-33,38-39,42-43, 49-50,55-56,58-59,65-66,71-76 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Combining Solid State Laser Diodes ---------------------------------------------------- I did a couple of experiments that make me wonder about the feasibility of combining the output of several solid state laser diodes to make a more powerful transmitting laser. At first I thought something like this would NOT work because the diodes would not be precisely the same frequency and phase. This would be a requirement if the receiver were a coherent system such as a superhet. However, those days aren't here yet and most of us are stuck with wide band detectors such as photodiodes and PMTs. The output of these detectors seem to be based for the most part on the number of photons hitting the detector regardless of frequency and phase. With that in mind I tried aiming 2, 3 and then 4 solid state lasers at one detector. All were modulated with identical subcarriers and were adjusted for the same exact power output. The result? Two lasers aimed at the same detector produced a gain of +3 dB and four aimed at the same detector produced a gain of +6 dB! Carrying this to an extreme I tried aiming an IR laser diode (780 nm) and a visible (650 nm) laser diode at the same detector and still noticed an increase at the detector output. However, since I am using a solid state detector it is more sensitive to the 780 nm signal with the result that the addition of the 650 nm signal didn't produce a full 3 dB increase. To compensate for this I adjusted the laser powers for the same detector output when fired separately at the detector. When these two lasers were fired simultaneously at the same detector I then noticed the same +3 dB increase even though one laser was at 650 nm and the other was at 780 nm! NOTE: You would achieve best DX by running ALL laser diodes at full power. In the above experiment I adjusted all lasers for the same power because I was trying to determine if there was a 3 dB gain when combining them. This would have been more difficult had each laser been operating at a different power level. I am giving some serious thought to the possibility of combing TEN 5 mw IR laser diodes to make a 50 mw transmitter. I doubt that going to 20 diodes (100 mw) to gain another 3 db would be worth the effort! Of course you could simply use ten separate lasers each with it's own collimation optics and mount them closely together on a board to reduce parallax problems and aim them so that they all pointed at the same spot, preferably infinity. Of course if all were pointed at infinity you would notice the separate beams when using the system at closer distances and would need to re-converge the system for the shorter distance. NOTE: The above presents some interesting possibilities for atmospheric scatter and other types of experiments. How about an array of laser diodes that are purposely misconverged so that they cover a larger area of sky? Or an array aimed at the horizon? This would allow coverage of a fairly large part of the sky without re-aiming. My goal however, is to focus the array of diodes into a single beam for L-O-N-G haul DX! I am working on a couple of ideas to combine the outputs in such a fashion that a single transmitting lens could be used. If anyone has any ideas or suggestions on things to try please let me know. You can't just mount an array of laser diodes behind one big lens because you will end up with ten spots no matter how you position the diodes since each appears as a point source coming from a different angle. NOTE: I think it MIGHT be possible to injection lock solid state lasers together in much the same way that you can lock a magnetron to a crystal reference. Fortunately my experiments seem to indicate that this will NOT be necessary when using the detectors that we have to work with today. John K3PGP@juno.com -==- From owner-laser Tue Apr 1 10:08:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23461; Tue, 1 Apr 97 10:08:24 PST Message-Id: <33414FBC.27C3@rockie.nsc.com> Date: Tue, 01 Apr 1997 10:11:09 -0800 From: Jim Moss Reply-To: jmoss@rockie.nsc.com Organization: nsc X-Mailer: Mozilla 4.0b2 (Win95; I) Mime-Version: 1.0 To: vhf@w6yx.stanford.edu, laser@berlioz.nsc.com Subject: 50 MHz and UP Group Meeting (SF Bay Area - 4/6) X-Priority: 3 (Normal) Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Sender: owner-laser@berlioz.nsc.com Precedence: bulk Next Meeting, SUNDAY, 4/6/97 at 1PM, AT NATIONAL SEMICONDUCTOR CREDIT UNION in Sunnyvale, CA. PROGRAM: VHF thru Microwave tune up clinic. Lars, AA6IW will bring test equipment to measure Noise Figure, Filters, Power, and Frequency. Note the location is National Semiconductor Federal Credit Union in Sunnyvale this month. NSFCU is located on Kifer, between Lawrence Expressway and Wolfe. Very close to HRO Sunnyvale. Kifer is located just 1 light south of Central Expressway. From 101, take Lawrence Expressway south to Kifer. Turn right on Kifer. Go past the main National Semiconductor Buildings. On the right just before a park is the Credit Union. Go around to the back entrance. Visit the 50MHz and UP Group Homepage at: http://www.nitehawk.com/rasmit/50UP.html and visit the Amateur Radio Laser Communications Homepate at: http://www.qsl.net/wb9ajz/laser/laser.htm From owner-laser Tue Apr 1 11:03:45 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25785; Tue, 1 Apr 97 11:03:45 PST Date: Tue, 1 Apr 97 11:03:41 PST From: jmoss (Jim Moss) Message-Id: <9704011903.AA25776@berlioz.nsc.com> To: laser Subject: TX power gains Sender: owner-laser@berlioz.nsc.com Precedence: bulk John, I read your plan/experiment about combining lasers with interest. I have also done similar experiments. I suggest another perhaps cheaper approach. Rather than increase the number of diodes to increase power, another option is to narrow the beam by using a beam expander. This will reduce the divergence by a factor equal to the expansion. So with 1mR laser thru a 10x expander, the divergence will reduce to .1mR. Is this significant? a 10x reduction in the diveregence results in 100x signal (since the area is PI*R^2). So you get a 20dB improvement. So what is a beam expander? "Simply a Galilean telescope." 2 lenses that will end up expanding the beam to 10x the size. New problem: aiming must now be 10x more precise. My system currently will handle .1mR steps. A zoom lens might be nice! Any more ideas on this? Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Tue Apr 1 11:38:44 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27108; Tue, 1 Apr 97 11:38:44 PST To: laser@berlioz.nsc.com Date: Tue, 1 Apr 1997 14:05:50 -0500 Subject: Wavelength Chart Showing Eye Response Curve Message-Id: <19970401.140613.17766.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-591 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk _=_ _=_ Part 001 of 001 of file Chart2.zip _=_ begin 666 Chart2.zip M4$L#!!0``@`(`"%P@2*Z-T'OY64``+IH```*````8VAAB MNQ_ZJXA\^2)4-7..''.,F:G\6/[8`GR1$I,4`X"!@0%\/C^`CW=`DIH*PW=[ M6PW-/DN_V3@Z,@/\_/A^K@&``(BP< M/!P,(CP"QL M'%P\"DHJ:AI:=@Y.+FX>WN\_1,7$)22EE%54U=0U-+6,34S-S"TLK9Q=7-W< M/3R]@H)#0L-^A4L?&!P: M'AF=G9M?6%Q:7@%M[^SN[1\<_CTZOKJ^N;V[?WA\>@8#0(#]K^?_B`?U,QYP M2$@(2)A_X@$#=__G)2HD%"D+-)J((HRA(_I7U@!8C&_QN;4]<&1L2I>81DXS M\%CD[-L45_^$])^(_C\+*/#_IXC^KX#^KW@^U@&?,_\!`B!"@'VF#0(5(`1( M'\!;OT]V+EX]NK^<8MBM`R,EBV]`WGU9D&R7+M>V3*O?U-06]338?@#M.S+)]@U--UU=XY8N3S( M9RS/U=:7^94@A4_[I[L/=?-(#CW1+0%="H3KMD%STV[(&3=3`E0RD@3/'%1< MSM@EX+);$.7X`*!G>EA"+\EJ![9-NI\A1-VMO]'J:@J%=829A,KO(DDAC-7= M+Q8MSEZ*T"BL!B9T$W7X*D\*<)?S`B/L*ZON3.M"U[?F9EC/HYQ.1YD=Q,M] M505!:GY+?M?(*CK3'(3V"BEPC-D2+WQ%]Q*X43FH0[@D3F)69X.%_'J4C7.J MQLP3$!)#,`YDF]P#UKAC*:=J=-9:ZX/9U4=N+.+HHAZK.C5\822.4QUF5AMT M776V&J)(M2\8,^)$^W;?H2<][TN3U:KM3T1*?4_)S=E MXC0TIFF3.@PDC30^&`0$!;)\`$YR51*7\21B95NOH,[N<\'::D2LJ5*S26/D M6&&?FL^6A*+-5SRRM3OFSVYCO\)6J[E)IX`D5'2<>(8>.MN]9IW3I,?IHV.Q MK5)Y=1OSM>61FM,<\<>^GH.8/0=,CK-(.AHNK^;I72V8;IR^;C"X03U)DD&^ MT4S:77K]G40_,W%XI'#UE?%UTL&RV8-?X&QJZQ\IOQ8M>IND>/PPKM)@@4D<9.4YI2N8YL!U19B08>_5,,J` ME5``?&LAY)V!KU("WM5PF!@^I@ZHWVO=B!1#65M3J+4\?;<;@8"\/X8AG)#> M(30Z)U0CI7_@!/''P\0X[O/]S M>3IWR+;[X94.9\VJ7L/:*U@K8V;$T)7=8:"1OR-"I`?*R8/<];;.H3E=G';2ZIF6?P$?"UN4=%748FZ264E[RFY_%V-76K^S)61\ROE!5 ML\F6!Z$;IDB\PZB,R[U4[5OA;F%TQ7TJJ&K%%=;0KVGK2\LA@0O/&VUA=KA= MQ:M\F;;>^(7%'+MB&\$O;88&Q$NPGM<0Y6R&-,PJ4<K?C" M%UQH=;*N3NY7-F5K]27.3G1)6T:.7SJ;D`Q>;F/1823&CQZO-\KCI^L;FPRA MMLOBCD4>\3:R;POK#8N5-"_282:F!FP9B(AXUU(1#Y),^M..YUY=$;>2C='? 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Tue, 1 Apr 97 14:22:54 PST Date: Tue, 1 Apr 97 14:22:52 PST From: jmoss (Jim Moss) Message-Id: <9704012222.AA03807@berlioz.nsc.com> To: laser Subject: Archives & Who Sender: owner-laser@berlioz.nsc.com Precedence: bulk The March Laser archives have been added to the website, along with the list of who is currently subscribed to the laser reflector. http://www.qsl.net/wb9ajz/laser/laser.htm Look in: http://www.qsl.net/wb9ajz/laser/mailarch for the archives and list of who. Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Tue Apr 1 15:03:22 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05324; Tue, 1 Apr 97 15:03:22 PST Message-Id: <199704012241.RAA21927@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 01 Apr 1997 17:41:35 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: QRO laser diodes! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone, I read John's recent message regarding combining of laser diodes in order to get a more powerfull beam. It is fairly easy to do so, as John pointed out and a 6 db (or more) increase is great (if you need the power). There is another way to get high power output from solid state lasers tho-buying multiple diodes and stacking them might be somewhat costly. You can get 300 to 500 percent MORE POWER out of a single diode by cryo cooling it. Liguid nitrogen is very inexpensive to buy in small quan's. If you cool the diode only (but leave the electronics at room temp), you will get 3 to 5 times the power just beacuse of the cooling. As a side benefit, the output freq of the diode drops 30 nm or so-a 670 nm diode that looks dim will now put out 640 nm and will be BRIGHT because it falls closer to the eyes visiblity peak. Liquid nitrogen from a well stocked welding supply shop costs about 4 dollars per liter. A liter of LN2 will last a long time in the field! So, for an occasional attempt, it might be appropriate to cryo cool instead of using multiple stacked diodes to get the extra output power. GL Art, KY1K. From owner-laser Tue Apr 1 14:57:58 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05084; Tue, 1 Apr 97 14:57:58 PST Message-Id: <199704012233.RAA21232@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 01 Apr 1997 17:33:42 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: laser diode question Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone- I'm still interested in playing airplane tag with lasers. It's ben pointed out to me that I made SEVERAL mistakes in my previous example regaring the airplane scatter communication feasability message. I'm working on a revision-more later. Right now, I'm wondering what happens to a laser in the LED mode? By this, I mean what is the actual differece between the laser diode output when opearated ABOVE or BELOW the laser threshold current? If there is a prohibition against shining a laser at a plane, I'm not sure they could object to shining an LED at a plane hi hi. I have a laser diode that has a threshold of 70 ma. Above 70 ma, I get monochromatic ligt at 670 nm. But, what happens if I operate the diode at 65 ma? I know that some different wavelenghts are present in the output (to varying degrees). I know it becomes an expensive LED. I know the output is reduced slightly. But, as far as collimation and output power, isn't a laser diode operated just under the threshold ALMOST AS GOOD as a laser diode in 'laser mode'? Comments? Drop me a line...Art... From owner-laser Tue Apr 1 14:48:53 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04664; Tue, 1 Apr 97 14:48:53 PST Date: Tue, 1 Apr 97 14:48:51 PST From: jmoss (Jim Moss) Message-Id: <9704012248.AA04650@berlioz.nsc.com> To: laser Subject: zapppppp!!! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Well, on the last day of March, I created an expensive LED! Beware, not all laser pointer modules have voltage regulators! The cheap ones from FRY's, CL2000 model, don't. I was adjusting the bias on a transistor that was tied to 12v (with the laser across the 12v line to the xstor collector, and biasing for voltage across the laser), when I exceeded 3.3V. Things didn't go dark, just dimmer. And the diode got warmer. OH WELL! So I decided to play with some HeNe tubes from a bar code scanner (these can be gotten for <$10 with supply, but no guarantee!) and tried modulating with a xsistor on the LVDC side of the HV brick. Didn't know it used AMPS! (1.2A@5v) pop, pop, pop. So 3 transistors later I figured it out! My daughter was wondering what that little LCD machine (DVM) was doing to make me keep throwing away little black 3 legged creatures! I gave up on xsitors, because I didn't have any big enough! So I tried an old 1k:8 Ohm xformer. Put 8 Ohm side on the DC leg, and put audio into the 1K side. (After thought... lucky I didn't smoke the winding, too.) But it worked. I had WWV coming thru (baseband audio from my HF RX) the laser beam into my laser RX. I'm sure someone must have a tube modulating scheme... anyone? Jim From owner-laser Tue Apr 1 17:49:44 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12215; Tue, 1 Apr 97 17:49:44 PST From: Kb8tej1@aol.com Date: Tue, 1 Apr 1997 20:27:46 -0500 (EST) Message-Id: <970401202645_-2105620777@emout04.mail.aol.com> To: k3pgp@juno.com, laser@berlioz.nsc.com Subject: Re: xenon visable laser (caveat emptor???) Sender: owner-laser@berlioz.nsc.com Precedence: bulk the B & B Caving catalog offers a "Xenon Laser Light" for cavers, this is a reputable outfit for caving gear ( have done business with them since 1977), claiming "Amazing " penetrating light?? I think this is advertising hype by the manufacturer but will drive up there and check it out. anybody ever heard of a visable xenon laser??? BTW any takers on the trade for the 6" lense?? tnx and 73 Rob From owner-laser Tue Apr 1 20:23:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17551; Tue, 1 Apr 97 20:23:51 PST Message-Id: <3341FAEF.6250@Prodigy.Net> Date: Tue, 01 Apr 1997 22:21:35 -0800 From: kc5an Organization: Prodigy Internet X-Mailer: Mozilla 2.02 (Win16; I) Mime-Version: 1.0 To: laser reflector Subject: Need help with part ID Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk This afternoon I bought what I believe is a surplus phototransistor. The plastic container says Honeywell..... Fiber Optics.... SD-3498-002 850-3498 Lot# C1184-85 Qty 1 12-10-84 The device itself has three transistor-like leads, and a normal looking emitter tab on one side. The top of the case is transparent. Can anybody tell me what I have, so that I can look for some specs for it? Thanks. John C. kc5an From owner-laser Tue Apr 1 20:49:02 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18399; Tue, 1 Apr 97 20:49:02 PST To: laser@berlioz.nsc.com Date: Tue, 1 Apr 1997 23:39:24 -0500 Subject: Modulating He-Ne Tubes ! Message-Id: <19970401.233927.3542.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-3,8-9,18-19,22-23,26-27,29-30,40-41,48-49,56-57, 59-64,66-67,69-75 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >I'm sure someone must have a tube modulating scheme... anyone? > >Jim Just make sure you have that transformer in the ground return lead of the laser tube! If you put it in the high voltage lead you stand a good chance of the transformer arcing over internally with disastrous results! Most audio transformers don't have a high enough breakdown voltage rating to be used safely in the high voltage lead! I have had very good luck with removing the diodes and filter caps out of several 12 volt switch mode laser supplies. This then runs the laser tube on high frequency AC. In my case the power supplies run around 45 KHz. I then applied audio to the base of the oscillator transistor through a small value resistor and series capacitor and ended up with great sounding FM on a 45 KHz subcarrier! Plus the laser is now 100% modulated instead of the 3 or 4 % that you can achieve using the series transformer. (The actual % you can achieve using the series transformer varies greatly from tube to tube.) Every time I mention this my mail box gets flooded with a bunch of warnings about running He-Ne tubes on AC. I don't need any more warnings - PLEASE! It all depends on who you talk to. Some say it flat out doesn't work! Others say it works great but the tube life is shortened. Others say it actually prolongs tube life! If this is the case then why don't all He-Ne lasers runs on high frequency AC? The fact is, most people want a CW carrier and most uses actually demand this! The only way to get a clean CW carrier is with well filtered DC. All I can say is, so far I haven't burnt up any He-Ne tubes running them on AC. (I wish I could say the same for solid state lasers!) It seems to work great. However, I'm sure (He-Ne tubes being as temper mental as they are) that some will work better than others and some may not work at all. If you can get at the components of the HV power supply (many are sealed in epoxy) or can build up a power supply specifically with this in mind, give it a try. If it works you end up with a really nice FM system! NOTE: Most switch mode laser power supplies are extremely sensitive as to oscillation frequency vs DC input voltage. So another way to FM them is to apply audio in series with the 12 VDC input line. (Watch out for any internal large value filter caps across the 12 volt input line!) Use a low impedance winding to do this. Something like the 3.2 or 4 ohm secondary winding of an audio output transformer MIGHT work provided it can carry the current. Another candidate is a 2.5 or 6.3 volt filament transformer secondary which WILL carry the current with no problem! And yes a 60 Hz filament transformer does a pretty decent job with voice frequencies! I used to modulate a 100 watt 829B transmitter with a filament transformer turned around backwards. The low impedance center tapped winding was connected to several high power (in those days!) PNP power transistors. I used a rectifier filament transformer which was rated for high voltage use. >So I decided to play with some He-Ne tubes from a bar code scanner (these >can be gotten for $10 with supply, but no guarantee! OK. Who has these? >Well, on the last day of March, I created an expensive LED! You need a Damark pen. 60 day no hassle return. Two year manufacturers warranty. An additional year (3 years total) costs approx. $7 extra. A friend of mine did manage to blow one up. (Hooked it to an external power supply - BACKWARDS!) They replaced it no problem! John K3PGP@juno.com -==- From owner-laser Tue Apr 1 20:49:04 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18405; Tue, 1 Apr 97 20:49:04 PST To: laser@berlioz.nsc.com Date: Tue, 1 Apr 1997 23:04:10 -0500 Subject: Combining Solid State Laser Diodes Message-Id: <19970401.233927.3542.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0,2,9-16,19-20,23-24,30-31,37-38,42-43,48-49,56-57,60-65 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >John, >I read your plan/experiment about combining lasers with interest. I have also >done similar experiments. I suggest another perhaps cheaper approach. >Rather than increase the number of diodes to increase power, another option >is to narrow the beam by using a beam expander. This will reduce the >divergence by a factor equal to the expansion. So with 1mR laser thru a 10x >expander, the divergence will reduce to .1mR. Is this significant? a 10x >reduction in the diveregence results in 100x signal (since the area is PI*R^2). >So you get a 20dB improvement. > ~~ > ~~ >Jim >WB9AJZ/6 CM87xi Sunnyvale, CA Jim: Thanks for the suggestion. The only problem is I am already doing this and have just about reached the practical limit! For what I have in mind I would like something more than the 5 mw that a single diode puts out. What brought this to mind is I came by a great deal on IR laser diodes. At the moment I'm looking at a box of 50 (yes FIFTY) of them and that's what led to the idea of trying to combine at least 10 of them. With the recent discovery that long term integration techniques can be used to successfully recover weak laser signals I am giving serious thought to the possibilities of milliwatt laser EME! If anyone would have mentioned this as little as a month ago I would have told them to forget it! However, from what I've seen lately I'm not so sure about that. Up to this point I had been working on an 800 / 1000 watt pulsed ruby rod system that I KNOW can be heard off the moon. However, it can only be pulsed something like once per second or less and it's pretty hard to use something like that for communications. It's also quite a beast to set up and keep running let alone trying to get another station on the air with a similar system so I could work them! It is my humble opinion that with good optics, sensitive detectors and long integration times a milliwatt signal could be heard off the moon. Since I already have the optics, and the receiving system is showing great promise, I'm now looking at ways to increase the transmitted power. Since the retro-reflectors are useless for any kind of DX (returned echo is only 20 km in diameter back on earth!) my only choice is to use the lunar surface as a reflector. If one were going to use the retro-reflectors then of course narrowing the transmitted beam width even more would continue to produce a stronger return signal. Although no one knows for sure, it is my opinion that the diameter of the laser beam should be between 1/2 and 1 moon diameter at the distance of the moon. (Anything over 1 moon diameter would be wasted power since it would go around the sides of the moon. / Anything much less than 1/2 diameter and you start to have other problems.) This seems feasible with the optics that I have. Beyond that we're looking at increasing transmit power as the only way to pick up any more dB. So the question remains. What's the easiest way to combine ten (or more) laser diodes so they could all be focused on the same distant target? In this case the moon? John K3PGP@juno.com -==- From owner-laser Wed Apr 2 06:10:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04833; Wed, 2 Apr 97 06:10:47 PST To: laser@berlioz.nsc.com Date: Wed, 2 Apr 1997 09:02:51 -0500 Subject: Modulating Laser Light Message-Id: <19970402.090252.15438.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-3,5-9,11-12,15-16,20-21,27-28,34-37 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >I'm sure someone must have a tube modulating scheme... anyone? > >jim I posted this sometime last year but do to the large number of new people on here I thought I would repost this: Modulating Laser Light --------------------------------- Scientific American 1970 Nov, pg 120 - A modulator is constructed for laser light. Most any library should have this. Call around. If you want it and can't find it I am willing to copy it for you. All I ask is SASE with extra postage because of the number of pages. This is a brute force method to say the least! The article describes an audio amplifier with two 6146's running with 800 volts on the plates feeding a solenoid of wire wound around a glass tube filled with liquid. The laser light is passed through the liquid. The article doesn't mention the output power that this amp produces (My guess ~100 to 150 watts) but you could do the same a LOT easier today with off the shelf solid state audio amps. The drawing shows a 0-20 amp meter (to measure the audio signal !) in series with the solenoid coil around the glass tube so apparently you really have to drive this thing with a LOT of audio! This may be more than most of us want to get into but the article presents some little known facts about what happens to laser light as it passes through various materials that are within an extremely strong magnetic field. The article is interesting reading even if you have no intention of building the device as it demonstrates just how hard it is to modulate laser light! John K3PGP@juno.com From owner-laser Wed Apr 2 07:40:59 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07441; Wed, 2 Apr 97 07:40:59 PST To: laser@berlioz.nsc.com Date: Wed, 2 Apr 1997 10:33:13 -0500 Subject: CCD Camera Head Message-Id: <19970402.103347.16926.3.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,5-6,9-10,13-14,17-18,23-24,27-36 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk CCD Camera Head --------------------------- I recently came up with a GE CID Video Camera model # TN-2500 manufactured by General Electric, OSO Electronics Park, Syracuse, N.Y. 13221 I want to mount this camera remotely (to replace an OLD vidicon system) so I can check to see that the computer is pointing the antenna correctly! Does anyone have an old catalog that they can look this up in? Anyone have a fax number for GE in Syracuse? (The voice number would also help but the fax would be better.) What I have is only the camera head. It has a C-mount lens fitting much the same as a closed circuit TV camera. There is a black cable coming out of the head with a DB-25 on it. >From tracing the circuit out so far it looks like I will need to build up a power supply and possibly some circuitry to supply horizontal and vertical drive signals. (The actual driver circuits for the CCD imaging chip are inside the box that I have. However, they appear to need external oscillators.) Any help would be appreciated, even spec's on just what this thing is capable of such as resolution, color/B&W, sensitivity, drive requirements etc. Thanks John K3PGP@juno.com -==- From owner-laser Wed Apr 2 15:20:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25688; Wed, 2 Apr 97 15:20:47 PST Date: Wed, 2 Apr 97 15:20:44 PST From: jmoss (Jim Moss) Message-Id: <9704022320.AA25682@berlioz.nsc.com> To: laser Subject: Re: Modulating He-Ne Tubes ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From jmoss Wed Apr 2 15:19:46 1997 To: k3pgp@juno.com Subject: Re: Modulating He-Ne Tubes ! Content-Length: 1540 John, I used the 8 ohm side of the 1k:8 Ohm xformer in the LV DC leg, not HV leg. I ran it for several minutes last night with no issues with heating or winding loss. I was in error in my previous post, current is about <200mA at 5v. (I really don't know what the right voltage for these supplies is, it appears to be 5-6 volts. The bar code guns are from Intermec.) The modulation was way down, had to run the radio's volume control up to 1/2 - 3/4 way out the headphone jack to hear much at all. The surplus place that has the "BAD" guns is HALTEK of Mountain View CA. <1062 Linda Vista Ave (Shoreline exit off 101), Mountain View, CA 415-969-0510 M-F 9-6, Sa 10-5 Pacific Time> Besides the 6" tube and supply, there are 2 lenses, and a 2 first surface mirrors (one on a "scanning motor"), 2 red filters (about 50nM), 2 light sensors (general on plastic), and bunch of electronics on 2 boards. Can check unopened guns for laser operation by applying voltage to 2 pins and switching a 3rd to Vcc (5v?) on the 9 pin connector. You have to pull the trigger, too. switch to +5 | v v +5v (I use 4 1.5v cells for quick check) . . . . . . . . . looking into the connector ^ground Realize that they may or may not work.. their list is $10 each, but you may be able to talk them down because of "sight unseen"? Last weekend they had about 10 left. (they've been moving very slowly.) They also have some longer tubes without supplies (<5mW) for about $75 (marked this price). Jim WB9AJZ/6 CM87xi Sunnyvale, CA. ----- End Included Message ----- From owner-laser Wed Apr 2 17:45:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01514; Wed, 2 Apr 97 17:45:21 PST From: sjnoll@ix.netcom.com Date: Wed, 2 Apr 1997 19:35:54 -0600 (CST) Message-Id: <199704030135.TAA24194@dfw-ix12.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: Need help with part ID: SD3498 To: laser@berlioz.nsc.com In-Reply-To: <3341FAEF.6250@Prodigy.Net> X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Tue, 01 Apr 1997, kc5an wrote: >This afternoon I bought what I believe is a surplus phototransistor. The >plastic container says Honeywell..... Fiber Optics.... >SD-3498-002 >850-3498 >Lot# C1184-85 >Qty 1 12-10-84 > >The device itself has three transistor-like leads, and a normal looking >emitter tab on one side. The top of the case is transparent. > >Can anybody tell me what I have, so that I can look for some specs for >it? >Thanks. >John C. >kc5an This is an IR silicon PIN photodiode. SD3498 Mfg: Honeywell Operating wavelength: 760nm - 1000nm (Don't know how they cut out the visible as you say the top of the case is transparent, silicon photodiodes normally work down to at least 400 nm. I would have expected a black-looking filter.) Responsivity: 0.4A/W @ 820nm Dark current: 5nA max. Rise time: 30nS max. Junction capacitance: 4.9 pF (don't know at what bias) Reverse bias: 50V max. Don't know the pinout... One anode, one cathode, the third lead is either the case or not connected. Don't know what the -02 designation is for. Might be obsolete. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html From owner-laser Wed Apr 2 18:48:03 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04062; Wed, 2 Apr 97 18:48:03 PST Message-Id: Date: 2 Apr 1997 18:34:18 -0800 From: "Stone Richard" Subject: Re combining SS laser diodes,etc. To: "laser" X-Mailer: Mail*Link SMTP-MS 3.0.2 Sender: owner-laser@berlioz.nsc.com Precedence: bulk John, Optical EME is a ambitious project keep at it and I wish you success. Let us know when you plan to try maybe some of us could pick you out of the noise with a PMT and FFT integrating software. As far as beam combining , I have heard of combining multiple laser beams using polarization or dichroic beam splitters (beam splitters that reflect some wavelengths and transmit others.) You can probably find some surplus polarizing cubes around but the polarization scheme can only combine 2 diodes. You will find that your laser diodes are polarized and you can rotate their mountings to get 2 orthogonal polarizations. The problem here is to figure out how to combine more than 2 laser diode beams. There was 'once upon a time' a space flight qualified laser transmitter made up that used 16ea. 100mW single frequency laser diodes all at a slightly different wavelength to get approxamately a 1 watt beam. The beam from each one was directed into the beam path by a dichroic that reflected its beam but passed through all the beams form the laser diodes upstream from it. This worked but as you can guess was an alignment nightmare. It was their backup plan if their first choice failed(it did). The main problem that I see here is finding the necessary beamsplitters at an affordable price and all the mechanical assembly necessary. Also then the wavelength ( read temperature) of each diode would have to be carefully controlled. Can you picture aligning up 50 5mW diodes in this way to get a beam of about 2 watts? Another solution may be to try to couple as many laser diodes into a optical fiber as you can letting the fiber do the beam combining for you. You would need to figure out how to position as many lasers beams as possible within the acceptance angle of the fiber and minimize the coupling loss for each one.. So that would be the limit of how many lasers could be coupled this way. One other consideration would be to select the fiber core diameter such that the output was a low order mode so you could get a relatively clean (minimum holes and side lobes) beam out the output end of the fiber. The mechanical stability needed for all the mounts and optics to do this is challenging but not impossible. I have seen systems like this that sucessfully couple 10 watts into a fiber from high power diode bars (using only 3 diode bars) These are used to pump solid state lasers. One of these would be great but the cost could be close to your house value or at least an expensive car! SDL and other manufacturers also make laser diode bar packages that are already fiber pigtailed with 10 to 15 watts (for pumping solid state lasers) The price on these is only silghtly less than a new car as well. but maybe some of these will show up on the surplus market some day. I don't feel like I have helped much with this rambling. I think I have a couple of " high power " laser diodes I'll have to find them and and there is no promise that they work. A friend gave me some reject quasi CW laser diodes that are supposed to produce about 1 watt peak power at a low duty cycle. They run at about 800 nm. They would be happy running at a khz rate as long as the pulses were short. These diodes are in "C" mounts which means that the bare diode chip is mounted on a small ( approx. 5mmX7mm) gold plated heat sink with a wire bond connection to the anode . This would have to be mounted on a much larger heat sink(or preferably a temperature controled one) and protected from the environment ( remember the bare chip is exposed). You would also need some lenses to collect, circularize, and collimate the output. If this doesn't seem too difficult and worth the effort to you let's talk further . I'd be willing to let you have one for the cause if you thought you could use it for EME. -- Richard KD6BQ From owner-laser Wed Apr 2 20:45:08 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07937; Wed, 2 Apr 97 20:45:08 PST Message-Id: <334355FA.6B5C@mnsinc.com> Date: Wed, 02 Apr 1997 23:02:18 -0800 From: Neil Spokes X-Mailer: Mozilla 2.01 (Win16; U) Mime-Version: 1.0 To: John K3PGP Cc: laser@berlioz.nsc.com Subject: Re: Combining Solid State Laser Diodes References: <19970401.233927.3542.0.K3PGP@juno.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk There's a fundamental law of physics that says that you cannot increase the brightness of a light beam by simple superposition. You can, in effect, only put them side by side. So, if your light beams are 1 mm diameter, you need to find a way to stack them side by side. Unfortunately, just stacking them side by side does nothing to decrease divergence since the sources are not coherent. You need an expander to give you the gain, but directly you add another beam, it is a little off axis and you lose any advantage that you picked up with the increased intensity. As you are probably aware, you cannot stack four exactly parallel 1mm diameter beams all within the 1mm diameter - if you could do that you would have broken the law of physics that says that water cannot run up hills, cannot accomplish perpetual motion, defy entropy and a bunch of other cute things. You CAN compress laser beams through a single 1 mm diamter hole provided they come in at an angle. That, of course give you a loss of angular resolution -- not what you want to do. One, not very good way to do what you want to do is to provide one expander telescope system per laser beam pointed to the distant location. Stack fifty of those (good luck and deep pockets) to get the desired 50 parallel beams. The circle of confusion is limited by the quality (and diameter) of each individual telescope. The supersposition is here accomplished at the far end. An alternative is to array the lasers in a circle 0.1 feet across at a distance of 1000 ft from a 1 ft diameter mirror with a 1000 ft focal length and point the emerging beam at the moon. Your lasers subtend an angle of <0.1 mR at the mirror and the mirror subtends and angle of 1 mR at the laser stack - maybe we're coming closer to practicality. Now, if you fold the light path (e.g with high quality retro-reflectors -- optical experts needed), you will be able to compress the length of the system. I will wait with interest to see what other responses you get to your very practical question. GD DX es 73 Neil AB4YK. PS Why not point at a particular crater, a good telescope should be able to single out a desirable crater? ============================================================= John K3PGP wrote: > > >John, > >I read your plan/experiment about combining lasers with interest. I have also > >done similar experiments. I suggest another perhaps cheaper approach. > >Rather than increase the number of diodes to increase power, another > option >is to narrow the beam by using a beam expander. This will > reduce the >divergence by a factor equal to the expansion. So with > 1mR laser thru a 10x >expander, the divergence will reduce to .1mR. Is > this significant? a 10x >reduction in the diveregence results in 100x > signal (since the area is PI*R^2). >So you get a 20dB improvement. > > ~~ > > ~~ > >Jim > >WB9AJZ/6 CM87xi Sunnyvale, CA > > Jim: > > Thanks for the suggestion. The only problem is I am already doing this > and have just about reached the practical limit! For what I have in mind > I would like something more than the 5 mw that a single diode puts out. > > What brought this to mind is I came by a great deal on IR laser diodes. > At the moment I'm looking at a box of 50 (yes FIFTY) of them and that's > what led to the idea of trying to combine at least 10 of them. > > With the recent discovery that long term integration techniques can be > used to successfully recover weak laser signals I am giving serious > thought to the possibilities of milliwatt laser EME! If anyone would > have mentioned this as little as a month ago I would have told them to > forget it! However, from what I've seen lately I'm not so sure about > that. > > Up to this point I had been working on an 800 / 1000 watt pulsed ruby rod > system that I KNOW can be heard off the moon. However, it can only be > pulsed something like once per second or less and it's pretty hard to use > something like that for communications. It's also quite a beast to set > up and keep running let alone trying to get another station on the air > with a similar system so I could work them! > > It is my humble opinion that with good optics, sensitive detectors and > long integration times a milliwatt signal could be heard off the moon. > Since I already have the optics, and the receiving system is showing > great promise, I'm now looking at ways to increase the transmitted power. > > Since the retro-reflectors are useless for any kind of DX (returned echo > is only 20 km in diameter back on earth!) my only choice is to use the > lunar surface as a reflector. If one were going to use the > retro-reflectors then of course narrowing the transmitted beam width even > more would continue to produce a stronger return signal. > > Although no one knows for sure, it is my opinion that the diameter of the > laser beam should be between 1/2 and 1 moon diameter at the distance of > the moon. (Anything over 1 moon diameter would be wasted power since it > would go around the sides of the moon. / Anything much less than 1/2 > diameter and you start to have other problems.) This seems feasible with > the optics that I have. Beyond that we're looking at increasing transmit > power as the only way to pick up any more dB. > > So the question remains. What's the easiest way to combine ten (or more) > laser diodes so they could all be focused on the same distant target? > In this case the moon? > > John > K3PGP@juno.com > > -==- From owner-laser Thu Apr 3 06:48:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27105; Thu, 3 Apr 97 06:48:24 PST Message-Id: <199704031445.JAA19984@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 03 Apr 1997 09:45:30 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: stacking lasers Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone... I'm not sure about stacking lasers-if we want to maintain the coherancy of the laser beam, then we need to make sure they are all on the exact same frequency. Even the HE-NE doesn't remain steady on 632.8 nm. There are some 'stabalized' lasers that are lab instruments, very expensive and out of our reach as far as cost. Melles Griot makes a line of these type of HE-NE. Obviously, if there is the slightest difference in output frequency, the beams will be non-coherant after a few miles at best. This is a problem. One should bear in mind that the coherancy of the laser beam is lost soon after it enters the atmosphere also-due to reflections, gravity and other atmospheric trauma. So, even a single HE-NE laser isn't coherant after a couple miles of atmosphere. --------------------------------------- I did see a bench setup for locking 2 solid state diodes to a variable frequency grating. The stability of the locking frequency was no better than the grating tho-within a couple tenths of a nm. And, the temperature of the grating needed to be regulated to achieve that degree of stability! This concept works, but keep in mind that the ammount of power fed back into the laser to phase lock it REDUCES the available output of the laser because the laser has to dissapate that power too. So, there is a major power penalty here. The setup I saw had diodes with the output windows removed. The energy was fed back into the diode through a short piece of optical waveguide. It is necessary to mount the end of the waveguide and splitter held VERY CLOSE to the diode. Fortunately, the acceptance angle of the diode is MUCH WIDER than the output beam, so energy can be fed into the diode without blocking its output beam. I talked the the owner of this setup at great length! He hoped to phase lock multiple diodes using a HE-NE beam as the frequency reference. He pointed out to me that such a setup has ALOT of phase noise and that this is an additional power loss and defeats the purpose of having a monochromatic laser hi hi. This was a research project on an optical test bench at an educational institution. So, COST of components wasn't a major problem. Also, the OUTPUT POWER of the beam(s) wasn't a major consideration either. This concept not be a very practical for our purposes-after all, we have losses due to the energy needed to phase lock the diodes, we also have power loss in the 'distution' of the output spectra (phase noise). We might only end up with 1 db of power gain when we should have 3... Hope this info is useful. GL..Art, KY1K. From owner-laser Thu Apr 3 07:12:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27796; Thu, 3 Apr 97 07:12:06 PST Message-Id: <199704031508.KAA22027@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 03 Apr 1997 10:08:50 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: HE-NE direct modulation? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone... After some off-list discussion with John, k3pgp, I've become a believer in the practicality of driving a HE-NE with an AC supply. Obviously, this makes modulation of the beam a snap, and we get 100 percent modulation! If we choose to modulate the beam at 30 or 100 khz, it also makes FM practical because we can easily FM those carrier frequencies. I'm wondering about the losses due to harmonic energy tho. Obviously, since the diode laser or the HE-NE tube operates in a 'contolled arc' mode, it is NOT POSSIBLE to apply a sine wave power input because the laser is either full on or full off-there is no 'in between'. Since we can only switch the laser with a square wave, there has to be a large loss due to the harmonics of the original switching frequency of the power supply. My guess is that we would have harmonics into the 5 or 10 mhz region-neatly spaced at the frequency of the switching frequency of the power supply. Does anyone have any idea of the magnitude of these losses resulting from the harmonics of the power supply switching frequency? Drop me a line..>Art... From owner-laser Thu Apr 3 07:26:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28174; Thu, 3 Apr 97 07:26:06 PST Message-Id: <199704031522.KAA23246@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 03 Apr 1997 10:23:07 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: cryo cooling of HE-NE? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone- Do to John's recent discussion of getting higher power out of our lasers, I dug out my source for cryo-cooling of laser diodes, and sent a note to the reflector regarding this topic. I've recently began to wonder about the possibility of cryo cooling HE-NE tubes also! Since HE-NE tubes are notoriously inefficient, they waste ALOT of heat, and alot of it is in the mirrors themselves! Cryo cooling the tube MIGHT provide an ENORMOUS increased power output potental! Since liquid nitrogen is nearly a perfect insulator, we should be able to power the tube with high voltage, even if it is totally immersed in LN2. Obviously, the mirrors in the tube would limit the output power because of cooling (or lack there of)-so, technically the tube could support much more power output IF we can cool both end mirrors. This scheme MIGHT require a different mix of HE-NE in the tube. It might also require a different internal gas pressure inside the tube. Obviously, with COLD PLASMA, we would need to hit it with MUCH HIGHER voltage to light the plasma initially also. Wonder if anyone has ever thought of this/heard of this or tried it? As always, keep those lasers lit...Art... From owner-laser Thu Apr 3 07:31:55 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28392; Thu, 3 Apr 97 07:31:55 PST Date: Thu, 3 Apr 1997 08:27:06 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704031527.AA01938@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: TX power gains X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk from a friend ----- Begin Included Message ----- From: Doug Music If you make a beam expander that has an adjustable focus, you have, in effect, an arbitrary beam focus. I built a pair out of, honest, sprinkler parts and lenses. (High curvature near the source.) The result is that we produced a spot less that 1 inch across at 1/3 mile. This mounts to a standard catadiopteric or Newt telescope with a PMT reciever. Pointing control is not a problem. The problem becomes locating the other unit. We have a solution to this which we would like to try out (time allowing). -Doug ----- End Included Message ----- From owner-laser Thu Apr 3 09:03:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01705; Thu, 3 Apr 97 09:03:06 PST Date: Thu, 3 Apr 97 09:03:02 PST From: jmoss (Jim Moss) Message-Id: <9704031703.AA01696@berlioz.nsc.com> To: laser Subject: CORRECTION: Bar Code Scanner info Sender: owner-laser@berlioz.nsc.com Precedence: bulk SEE CORRECTIONS IN PIN DIAGRAM! Sorry was doing it from memory yesterday. Jim ------- The surplus place that has the "BAD" guns is HALTEK of Mountain View CA. <1062 Linda Vista Ave (Shoreline exit off 101), Mountain View, CA 415-969-0510 M-F 9-6, Sa 10-5 Pacific Time> Besides the 6" tube and supply, there are 2 lenses, and a 2 first surface mirrors (one on a "scanning motor"), 2 red filters (about 50nM), 2 light sensors (general on plastic), and bunch of electronics on 2 boards. Can check unopened guns for laser operation by applying voltage to 2 pins and switching a 3rd to Vcc (5v?) on the 9 pin connector. You have to pull the trigger, too. v ground . . . . . . . . . looking into the connector ^ ^ ground | +5v or use 4 1.5v cells for quick checking. Realize that they may or may not work.. their list is $10 each, but you may be able to talk them down because of "sight unseen"? Last weekend they had about 10 left. (they've been moving very slowly.) They also have some longer tubes without supplies (<5mW) for about $75 (marked this price). Jim WB9AJZ/6 CM87xi Sunnyvale, CA. From owner-laser Thu Apr 3 09:13:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02080; Thu, 3 Apr 97 09:13:41 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 11:34:51 -0500 Subject: RE: Combining Solid State Laser Diodes Message-Id: <19970403.115546.14526.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-4,8-14 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk > I don't feel like I have helped much with this rambling. >-- Richard KD6BQ Oh, but you have! The thought of using optical fiber as a combiner did cross my mind. Now that I know it's possible I'll give it some more thought! This has the potential of being a LOT cheaper than beam splitters and may actually have less loss. John K3PGP@juno.com -==- From owner-laser Thu Apr 3 09:20:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02337; Thu, 3 Apr 97 09:20:29 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 11:55:35 -0500 Subject: RE: Combining Solid State Laser Diodes Message-Id: <19970403.115546.14526.2.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-7,10-11,14-15,22-25,28-29,33-49,51-52,56-57,61-62, 64-66,69,72-75,77-78,83-84,86-96,99-100,107-108,110-113,115-118, 120-121,126-127,134-135,141-142,147-148,154-155,161-162,165-167, 169-173,177-178,180-181,184-190 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >There's a fundamental law of physics that says that you cannot >increase the brightness of a light beam by simple superposition. >You can, in effect, only put them side by side. So, if your light >beams are 1 mm diameter, you need to find a way to stack them >side by side. > >Neil AB4YK. Yes, when two laser beams are superimposed on top of one another they don't look any brighter. I believe this is because they aren't the same exact frequency and phase. However, when I aim two lasers at a power meter or PIN diode detector I DO note a three dB increase in detected signal whether the beams are beside each other or on top of one another. Based on the above I aimed one laser at a water tower about 5 miles away. (I have no problem detecting reflections off this tower and it makes a great test signal.) When I aim two lasers at the same tower with identical modulation I end up with a three dB increase in received signal level. Four lasers and I get a +6 dB increase in the radar returns! It didn't seem to matter if I was using all IR diodes or a combination of IR (780 nm) and some 650 / 670 nm diodes. I am basing my theory of combing laser diodes on the above experiments. Yes they are NOT the same frequency, NOR the same phase. Because of this one might think that it would be impossible to do any combining at all, and it might turn out that way, but for other reasons. :-^( Based on the above experiments however, it looks to me like the detector doesn't care if there's one beam or many and whether they are side by side or on top of one another, just so they all hit the target on transmit and the active area of the detector on receive. >Unfortunately, just stacking them side by side does nothing to >decrease divergence since the sources are not coherent. You need >an expander to give you the gain, but directly you add another beam, >it is a little off axis and you lose any advantage that you picked up >with the increased intensity. >As you are probably aware, you cannot stack four exactly parallel >1mm diameter beams all within the 1mm diameter - if you could do >that you would have broken the law of physics that says that water >cannot run up hills, cannot accomplish perpetual motion, defy >entropy and a bunch of other cute things. You CAN compress >laser beams through a single 1 mm diamter hole provided they >come in at an angle. That, of course give you a loss of angular >resolution -- not what you want to do. Hmmmm...... I need to think about this one. Unless I'm mis-reading the above (most likely!) I think I've done this with beam splitters. The beam splitters are positioned in a line so that the first laser beam is passing through all of them. One additional laser beam is added with each additional beam splitter. You end up with (I think?) all the lasers superimposed on top of one another. The only problems with the above that I can see is expense (BIG PROBLEM) and the losses through the system which might cause one to loose more than 3 dB per laser negating the whole project especially since many of the lasers would need to go through multiple beam splitters. My applogies if I mis-read or didn't understand what you were trying to say! >One, not very good way to do what you want to do is to provide one >expander telescope system per laser beam pointed to the distant location. >Stack fifty of those (good luck and deep pockets) to get the desired >50 parallel beams. The circle of confusion is limited by the quality (and >diameter) of each individual telescope. The supersposition is here >accomplished at the far end. This is the system I'm using now. I'd be extremely happy if I could combine just TEN diodes this way. 5 to 50 mw = +10 dB increase in SNR!) If I had to buy the laser diodes we wound NOT be having this discussion! However, I already have FIFTY of them sitting here in a box and I'm giving serious thought to an array of TEN like mentioned above. A lot depends on what kind of optics I can come up with on the surplus market. There's no way I could afford to do this with new stuff! One nice thing about this system is that there is NO combining loss and any single failures in the system don't put the whole project on hold! >An alternative is to array the lasers in a circle 0.1 feet across at a >distance of 1000 ft from a 1 ft diameter mirror with a 1000 ft focal >length and point the emerging beam at the moon. Your lasers >subtend an angle of <0.1 mR at the mirror and the mirror subtends >and angle of 1 mR at the laser stack - maybe we're coming closer to >practicality. Now, if you fold the light path (e.g with high quality >retro-reflectors -- optical experts needed), you will be able to >compress the length of the system. Very interesting. I've seen this done (in reverse) with huge solar heating systems that used an array of mirrors all tracking the sun and focusing on one central collector. Making a 1 foot mirror (or larger) with a 1000 ft focal length is quite easy because of the very shallow curve. I've built several mirrors like this for other experiments. Leaving the lasers fixed and only moving the mirror unfortunately creates a distortion of the projected image. I'd have to sit down and brainstorm my way through this one to see how serious this might be. Moving the whole assembly (1000 foot long!) ??????...... No, I don't even want to think about it! >I will wait with interest to see what other responses you get to your very >practical question. ME TOO !!! Keep those ideas coming! I'm sure there are other people out there that might want to combine 2 or more lasers! >GD DX es 73 Neil AB4YK. >PS Why not point at a particular crater, a good telescope should be able to >single out a desirable crater? I might end up doing this. No one seems to know if I'd be better off using the entire surface as a reflector or try to focus down to as small a spot size as possible. Most commercial work to date has concentrated on using the retro-reflectors which presents a completely different problem. If I were going to use the retro-reflectors then of course the smaller the beam diameter the better with the lower limit being the physical dimensions of the retro-reflector array. As pointed out several times before these are actually too good for my use since they return a beam that is only 20 km wide when it is returned to earth. (I'd like to work a station that is more than 10 miles away after all this work and traveling a half-million miles!) Since the moon is sperical there is a problem with distortion of the returned echo. (It takes longer for a return from the limb than from the central region because the central region is closer to earth. - The moon is approx. 2160 miles in diameter.) This distortion could limit what FFT and long integration could recover from the noise. I haven't really looked into this effect yet but I intend to study this as well. Because of this I have set a practical upper limit of somewhere around 1/2 to 3/4 moon diameter for the outgoing beam. (Any power directed at the limb area or any that goes over the sides and completely misses the moon is wasted power.) The lower limit isn't as well defined as of right now. You're thoughts about using a single crater are intriguing. If the beam were that tight one could pick out a single feature (perhaps even something other than a crater - maybe a large area that is fairly flat) that is noticeably brighter than the average surface of the moon. This would also return a much cleaner waveform as the echo would be coming from a very small area - NO pulse spreading. NOTE: The most likely times for a laser EME contact are probably when the phase of the moon is less than half full. This would allow the luxury of visual tracking but allow the laser system to look at the unlit surface. Unfortunately the darkened half isn't totally dark (some sunlight is scattered from earth) but it's a LOT better target than the sunlit half since I wouldn't have to put up with sun noise! Since I intend to have a CCD camera head mounted on the laser system optical tracking will be practical and most likely will be a neccessity if I end up having to work with a very small diameter beam width. ----- Hint..... We can stop this discussion as soon as someone loans me a high power CW laser for this experiment! Hey, you can't blame me for trying! ----- I recently purchased a CD-R drive and noticed that it uses a 35 mw IR diode. That's almost +6 dB and could make a difference between success and failure! Plus you don't need any combiners at all. Anyone seen any of these or know where to get one without mortgaging the house? Too bad we can't get some laser manufacturer interested in this project to make a donation. It would make a great ad! First amateur laser EME contact and xxx optical products made it possible! If our products can go to the moon they can do anything! xxx optical products - Reaching for the stars! Today the moon. Tomorrow ??? John K3PGP@juno.com -==- From owner-laser Thu Apr 3 11:50:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08304; Thu, 3 Apr 97 11:50:17 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 14:30:47 -0500 Subject: RE: Combining Solid State Laser Diodes Message-Id: <19970403.143047.21934.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-4,6-11 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >I'm not sure about stacking lasers-if we want to maintain the >coherancy of the laser beam, then we need to make sure they >are all on the exact same frequency. >GL..Art, KY1K Fortunately this doesn't appear to be a requirement for this use. See my previous post on detector / radar experiments. John K3PGP@juno.com -==- From owner-laser Thu Apr 3 12:10:40 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09073; Thu, 3 Apr 97 12:10:40 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 14:46:29 -0500 Subject: RE: Combining Solid State Laser Diodes Message-Id: <19970403.144629.21934.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-4,6-7,12-13,15-25,28-33 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Do to John's recent discussion of getting higher power out >of our lasers, I dug out my source for cryo-cooling of laser >diodes, and sent a note to the reflector regarding this topic. >GL..Art, KY1K. Boy would I love to see that article! Can you tell us where to look this up or can you forward a copy? I tried putting a couple of diodes in the freezer (-30 F) and the power went DOWN! However, I didn't bother to adjust the current since I wasn't sure of what I was doing and just what the cold temperature was doing to the diodes. I know this isn't cryogenic but I would expect to see some effect. Maybe you need to cool them then run the current back up??? I'm willing to sacrifice a couple of diodes to see what can be done along these lines but I'd like to have a bit more info on this before starting! >I believe that the most common failure mode for the lasers is >optical damage to the front facet. There is always some optical >absorption at this part of the laser. The maximum operating >current of the laser is determined by the maximum optical >power that the front facet will take without being fractured. >--Richard KD6BQ How does cooling aleviate this problem? Let's see now, I think the local hardware store has larger faucets in stock. If I replace the fa.... OOOPppppppssss.... It's a facet. Sorry..... That sounds like a special order! :-^) John K3PGP@juno.com -==- From owner-laser Thu Apr 3 12:25:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09509; Thu, 3 Apr 97 12:25:24 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 15:00:06 -0500 Subject: RE: HE-NE direct modulation? Message-Id: <19970403.150123.18142.2.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-10,16-24 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >My guess is that we would have harmonics into the 5 or 10 mhz >region-neatly spaced at the frequency of the switching frequency >of the power supply. > >Does anyone have any idea of the magnitude of these losses >resulting from the harmonics of the power supply switching frequency? >GL..Art, KY1K. I too would like to know more about this! I'll have to dig out my old He-Ne stuff and take some measurements. However, I do know that it's not quite as bad as presented above because you have a low pass filter that's made up by the ballast resistor and the load presented by the tube. Those high frequency harmonics really hate the high impedance presented by the resistor with that huge load hanging on the other side! The higher the fundamental switching frequency the faster the harmonics disappear. PS - Let's hear from some of those people out there reading the mail! John K3PGP@juno.com -==- From owner-laser Thu Apr 3 12:47:53 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10494; Thu, 3 Apr 97 12:47:53 PST Date: Thu, 3 Apr 1997 13:33:56 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032033.AA16475@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: laser diode question X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk from a friend: ----- Begin Included Message ----- From: Doug Music Subject: Re: laser diode question >Right now, I'm wondering what happens to a laser in the LED mode? By this, I >mean what is the actual differece between the laser diode output when >opearated ABOVE or BELOW the laser threshold current? The diode in LED mode is phase incoherent and broadband. When the current is high enough to put it in strong populaiton inversion, oscillation starts and all (damn near) of the energy gets dumped into the output line (freq) with a narrow band (a few nM wide). The idea is to use band tunable mirrors as band pass filters on your receiver, thus dropping the background noise down a LONG ways. > >If there is a prohibition against shining a laser at a plane, I'm not sure >they could object to shining an LED at a plane hi hi. If I were you, I would never even joke about doing that, even in LED mode. ;-) > >But, what happens if I operate the diode at 65 ma? I know that some >different wavelenghts are present in the output (to varying degrees). I know >it becomes an expensive LED. I know the output is reduced slightly. Bandwidth opens up, the beam becomes noncoherent in phase and the pointing stability goes to pot. > >But, as far as collimation and output power, isn't a laser diode operated >just under the threshold ALMOST AS GOOD as a laser diode in 'laser mode'? Not even close... > >Comments? > >Drop me a line...Art... > > ----- End Included Message ----- From owner-laser Thu Apr 3 12:50:43 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10618; Thu, 3 Apr 97 12:50:43 PST Date: Thu, 3 Apr 1997 13:40:04 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032040.AA16627@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: Combining Solid State Laser Diodes X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk I'm beginning to think I should have my friend get on the list HIMSELF ;-) ----- Begin Included Message ----- From: Doug Music Subject: Re: Combining Solid State Laser Diodes Expensive way to combine em... use splitter cubes. Cheap way... use fibre tapers (1 per diode) to bring N lasers to close proximity. This will produce the same spread angle as the original diodes and place them in a tight array at approx. 2 wavelengths separation. You should be able to deliver a few watts this way. USE APPROPRIATE SAFETY OR DON"T TRY THIS... Remember: DON'T LOOK INTO BEAM WITH REMAINING GOOD EYE!!! (Not joke) Even beam scatter could cost you your sight for life. Period. (I know people this has happened to.) -Doug ----- End Included Message ----- From owner-laser Thu Apr 3 12:57:59 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10919; Thu, 3 Apr 97 12:57:59 PST Date: Thu, 3 Apr 1997 13:46:39 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032046.AA17014@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: Combining Solid State Laser Diodes X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: Re: Combining Solid State Laser Diodes > Use fibre tapers per my earlier email. The divergence does not change per beam, true, but they CAN be placed DAMN close together... on the order of a few wavelengths separation. At the distance to the first lens (high curve) in an expander, this is good enough to actually use. Combine this with TE cooling and impulse drive and many many watts should be available for a couple hundred dollars and some good safety goggles. -Doug > There's a fundamental law of physics that says that you cannot increase the > brightness > of a light beam by simple superposition. You can, in effect, only put them > side by side. > >----- End Included Message ----- > > > ----- End Included Message ----- From owner-laser Thu Apr 3 13:06:13 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11217; Thu, 3 Apr 97 13:06:13 PST Date: Thu, 3 Apr 1997 13:54:13 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032054.AA17695@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: Modulating He-Ne Tubes ! X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: Re: Modulating He-Ne Tubes ! Get yer cheap and working laser goodies from Meridith Instruments in Glendale AZ. Area code (602) and I am out of state so get Rusty to look up the rest of the number for us all. -Doug ----- End Included Message ----- Note that the spelling is Meredith Instruments: Meredith Instruments 5035 N 55th Ave; Glendale, AZ 85301-7500 602-934-9387 rusty From owner-laser Thu Apr 3 12:49:25 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10553; Thu, 3 Apr 97 12:49:25 PST Date: Thu, 3 Apr 1997 13:37:49 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032037.AA16589@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: xenon visable laser (caveat emptor???) X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk more forwards from my friend. ----- Begin Included Message ----- From: Doug Music Subject: Re: xenon visable laser (caveat emptor???) Xenon lasers put out several "lines" (freq or WL) of light which is bright white if not separated. These lasers are FAR brighter than HeNe's and more expensive. These are used for remote illumination and optical micro surgery on semiconductor die. -Doug At 12:59 PM 4/2/97 -0700, you wrote: > >----- Begin Included Message ----- > >the B & B Caving catalog offers a "Xenon Laser Light" for cavers, this is a >reputable outfit for caving gear ( have done business with them since 1977), >claiming "Amazing " penetrating light?? I think this is advertising hype by >the manufacturer but will drive up there and check it out. anybody ever heard >of a visable xenon laser??? > >----- End Included Message ----- ----- End Included Message ----- From owner-laser Thu Apr 3 13:42:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12751; Thu, 3 Apr 97 13:42:28 PST Date: Thu, 3 Apr 1997 14:32:07 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704032132.AA19008@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: cryo cooling of HE-NE? X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: Re: cryo cooling of HE-NE? NeNe lasers are limited by the conversion efficiency from hole/pair population to coherence capable e- population. The coherence capability is due to a binding mechanism and gain at that site greater than unity. The poor ole HeNe (like most atomic ion lasers) is simply pathetic and any improvement on pathetic is still on the order of pathetic (in this case). Duuuude... Bummer. Now, molecular lasers are a whole lot better. (Orders of magnitude kind of better.) Anyone building a free electron laser? -Doug ----- End Included Message ----- From owner-laser Thu Apr 3 15:19:13 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16396; Thu, 3 Apr 97 15:19:13 PST Date: Thu, 3 Apr 1997 15:11:54 -0800 (PST) From: Walter Miller Reply-To: Walter Miller To: "Art Allen, KY1K" Cc: laser@berlioz.nsc.com Subject: Re: stacking lasers In-Reply-To: <199704031445.JAA19984@host-04.colby.edu> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Thu, 3 Apr 1997, Art Allen, KY1K wrote: > Hi everyone... > > I'm not sure about stacking lasers-if we want to maintain the coherancy of > the laser beam, then we need to make sure they are all on the exact same > frequency. > > Even the HE-NE doesn't remain steady on 632.8 nm. There are some > 'stabalized' lasers that are lab instruments, very expensive and out of our > reach as far as cost. > > Melles Griot makes a line of these type of HE-NE. > > Obviously, if there is the slightest difference in output frequency, the > beams will be non-coherant after a few miles at best. This is a problem. > > One should bear in mind that the coherancy of the laser beam is lost soon > after it enters the atmosphere also-due to reflections, gravity and other > atmospheric trauma. So, even a single HE-NE laser isn't coherant after a > couple miles of atmosphere. This really is not an issue for the type of communication work we amateurs are doing. Our concern is basically how many photons/second are emitted by the laser (or array of lasers), and what fraction of them is collected on the surface of the detector. An important issue with stacking lasers is the relative pointing of each beam...getting them aligned is not trivial when the beamwidths are only in the milliradian range. We are detecting only the total power incident on the detector, and the lasers can be viewed as a source of streaming particles (photons).....kind of like a machine gun shooting bullets. If you can get two machine guns (lasers) with two separate trains of bullets to strike the same target, your received "power" will go up by a factor of two (3 dB). By the way, despite their reputation, lasers are notoriously non-monochromatic. It is true that their fractional bandwidth (BW/F0) is small, but the actual spectrum is almost always an array of separate lines whose spacing is related to the size of the standing wave cavity formed by the two laser mirrors (delta F=c/2L where L is the cavity length). The relative amplitude and phases (and sometimes polarizations) of these multiple lines are constantly changing as the lines compete with each other, and as the cavity length changes.Even "single frequency" lasers in which all modes except one are suppressed, are not very stable with residual jitter in the kilohertz to Megahertz range (due to effective cavity length modulation). Since most amateur optical experiments do not involve heterodyning, most of these considerations are not relevant. We are just interested in raw power. 73, Walt ------------------------------------------------------------------------ Walter Miller, AJ6T Saratoga, CA USA CM87 Reply to aj6t@slip.net From owner-laser Thu Apr 3 15:32:19 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16810; Thu, 3 Apr 97 15:32:19 PST Message-Id: <33443C81.3532@kansas.net> Date: Thu, 03 Apr 1997 17:25:53 -0600 From: "Gregory A. Cerny Sr." X-Mailer: Mozilla 2.01 (Win95; I) Mime-Version: 1.0 To: laser@berlioz.nsc.com Subject: uniphase HE-NE Gas Laser info??? Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey guys, and gals. I am a newbie to the laser stuff, but I found a local place that has several of the following tubes: manufature: Uniphase HE-NE GAS LASER The tube also has the following written on it: THIS TUBE DOES NOT COMPLY WITH 21CFR 1040. USE ONLY AS A COMPONENT. SEE INTALLATION INSTRUCTIONS. MADE IN USA. S/N 88832 P/N 50-03400--15 POWER 1.01mw the tube itself is about 5.75" in overall length, and the diameter is appox. 1". there is also a copper clad box (I assume the power supply) with several leads coming out. One is a +20kv, another is a black wire with a ring connector on it (gnd?) and then four wires coming out of a small black connector. Is this thing worth $10 for the package, or $5 for just the tube? Thanks for your time.. -- Gregory A. Cerny Sr. WQ0P EM19VF 50,144,222,432,902,1296,5760,10ghzWBFM mailto:wq0p@kansas.net http://www.kansas.net/~wq0p From owner-laser Thu Apr 3 17:22:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19814; Thu, 3 Apr 97 17:22:27 PST Date: Thu, 3 Apr 97 17:22:24 PST From: jmoss (Jim Moss) Message-Id: <9704040122.AA19808@berlioz.nsc.com> To: laser Subject: EME thoughts Sender: owner-laser@berlioz.nsc.com Precedence: bulk The Moon is about 1/2 degree in size from the Earth (8.7mR). To illuminate more, you will have to spread the beam? What dispersion is there upwards thru the atmosphere (it will be less than staying flat in altitude)? Illuminating the entire Moon may not be optimum. It would seem only illuminating the part where the RX is looking is needed. Further, based on the curvature of the Moon, you'd want to offset the beam towards one side or the other to provide best bounce (probably mostly the center anyway). Just some thoughts, Jim WB9AJZ/6 From owner-laser Thu Apr 3 17:15:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19630; Thu, 3 Apr 97 17:15:11 PST Date: Thu, 3 Apr 97 17:15:08 PST From: jmoss (Jim Moss) Message-Id: <9704040115.AA19624@berlioz.nsc.com> To: laser Subject: re: combining... Sender: owner-laser@berlioz.nsc.com Precedence: bulk I am a bit confused from all I read on this subject... Seems that at a far enough distance from an array of independent lasers, all pointed parallel at the target, that due to the divergence, the patterns will overlap. As the distance increases the distance between the source lasers becomes less important. The detector systems we are using seem to be proportional output to photons hitting them, not in-phase waves etc. Simple experiments seem to prove this out. 2 = 3dB more on a sensor. Why are we trying to get all the diodes physically close, or use splitters, etc? It seems that it is only important when the beamwidth at the RX is is small with respect to the RX detector size. Am I missing something? Jim WB9AJZ/6 CM87xi From owner-laser Thu Apr 3 17:52:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20520; Thu, 3 Apr 97 17:52:23 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 20:19:07 -0500 Subject: Re: Band Tunable Mirrors Message-Id: <19970403.201907.11846.3.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-3,6-11 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >The idea is to use band tunable mirrors as band pass filters on >your receiver, thus dropping the background noise down a LONG ways. >-Doug I've seen and used bandpass filters before but never a band tunable mirror. Can we have some details on this as well and a good place to get the parts necessary to build one? John K3PGP@juno.com -==- From owner-laser Thu Apr 3 17:39:49 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20169; Thu, 3 Apr 97 17:39:49 PST Date: Thu, 3 Apr 1997 17:56:23 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704040056.AA04775@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: mailing list speed... X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Wow. I emailed a bunch of messages to the laser list at 1:33 pm local time today. Just started getting them back right now. Its 5:54 pm! what a time warp! rusty From owner-laser Thu Apr 3 17:50:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20474; Thu, 3 Apr 97 17:50:41 PST To: laser@berlioz.nsc.com Date: Thu, 3 Apr 1997 20:13:14 -0500 Subject: RE: Combining Solid State Laser Diodes Message-Id: <19970403.201314.11846.2.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 1,3-4,6,8-12,14-15,17-18,22-23,25-26,28-29,32-33,35-41 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Use fibre tapers per my earlier email. The divergence does not change per >beam, true, but they CAN be placed DAMN close together... on the order of >a few wavelengths separation. At the distance to the first lens (high >curve) in an expander, this is good enough to actually use. Combine this >with TE cooling and impulse drive and many many watts should be available >for a couple hundred dollars and some good safety goggles. > >-Doug Exactly what is a fibre taper? Is this one strand out of an optical fiber bundle? TE cooling? Could use some help here as well! What does TE stand for and how cold is it? How much does it increase power output? Impulse drive? (How about warp drive?) I've been told you can't pulse laser diodes (above their normal operating current) because the front facet will fracture with increased drive. Tell us how to do this!!! P-L-E-A-S-E !!! >I'm beginning to think I should have my friend get on the list HIMSELF ;-) Yes, by all means! It sounds like he has a LOT of good ideas but his answers are a bit on the brief side. We're not in that big a hurry! :-^) If I can get ' WATTS ' out of this array then this is going to be a VERY interesting project when combined with weak signal integration techniques!!! CQ 780 nm DX! Only stations from W6 and W1 land please! (I'll pick up you local guys later!) John K3PGP@juno.com -==- From owner-laser Thu Apr 3 18:27:40 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21666; Thu, 3 Apr 97 18:27:40 PST Content-Length: 1563 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Thu, 03 Apr 1997 20:20:04 -0500 (EST) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi guys sorry I haven't been contributing to the group here lately but I've been lurking in the background in my few free minutes!!! I've got the Burr Brown device going but need to get a larger feedback resistor in order to get the amplification I need. I am now able to detect back scatter of of a tree at a couple of hundred feet but should be able to do much better. Art (KY1K) I meant to answer your email a while a go but better now then never. Yes I'm very familiar with Mount Equinox . You can (if I'm not mistaken) get permission to stay up at the top after they shutdown the toll road. After all there is a hotel at the top! Maybe if I can make the Hoss traders flea in New Hampshire this spring we can discuss equipment loans and the other matters related to a world record try!! Another path I've thought about is right up Lake Champlain. I haven't looked at a map for a distance but I think it might just measure out. On the aiming front I was thinking about using a surveyors transit with a laser diode mounted and aligned with it. You would sight on a navigation star just as it transits the zenith. That would be exactly south you should be able to point the laser, maybe with only a few arc seconds of error. 73 for now! Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe From owner-laser Thu Apr 3 19:32:22 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24208; Thu, 3 Apr 97 19:32:22 PST From: Kb8tej1@aol.com Date: Thu, 3 Apr 1997 22:28:32 -0500 (EST) Message-Id: <970403222721_48333644@emout10.mail.aol.com> To: c1040@azfms.com, laser@berlioz.nsc.com Subject: Re: xenon visable laser (caveat emptor???) Sender: owner-laser@berlioz.nsc.com Precedence: bulk TU all for the feedback. Seems this is just a hype-bright low voltage light for illuminating fine work, not coherent ( damn damn damn!). 73 Rob From owner-laser Thu Apr 3 22:17:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29872; Thu, 3 Apr 97 22:17:27 PST Message-Id: Date: 3 Apr 1997 19:03:04 -0800 From: "Stone Richard" Subject: RE: Combining Solid State Laser Diodes To: "Neil Spokes" Cc: "laser" X-Mailer: Mail*Link SMTP-MS 3.0.2 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I think that there is a slight misunderstanding here of this fundamental law of physics. I believe that the law of conservation of brightness (related to conservation of energy) or conservation of entendu is what you are refering to . I believe it has to do with the conservation of brightness of single source with optical transformations ( you can always loose energy but you cant gain it without adding it in from somewhere) but does not specifcally prohibit the combination of sources. I'm not sure so give me some time to look it up. Or maybe someone else can help here. There are various ways to combine (or separate) beams of light all based on what make them different. Different frequency,different polarization, or different spatial properties. Maybe someone else can help us out here. --Richard KD6BQ _______________________________________________________________________________ From: Neil Spokes on Thu, Apr 3, 1997 12:27 AM Subject: Re: Combining Solid State Laser Diodes To: John K3PGP Cc: laser@berlioz.nsc.com There's a fundamental law of physics that says that you cannot increase the brightness of a light beam by simple superposition. You can, in effect, only put them side by side. So, if your light beams are 1 mm diameter, you need to find a way to stack them side by side. Unfortunately, just stacking them side by side does nothing to decrease divergence since the sources are not coherent. You need an expander to give you the gain, but directly you add another beam, it is a little off axis and you lose any advantage that you picked up with the increased intensity. As you are probably aware, you cannot stack four exactly parallel 1mm diameter beams all within the 1mm diameter - if you could do that you would have broken the law of physics that says that water cannot run up hills, cannot accomplish perpetual motion, defy entropy and a bunch of other cute things. You CAN compress laser beams through a single 1 mm diamter hole provided they come in at an angle. That, of course give you a loss of angular resolution -- not what you want to do. One, not very good way to do what you want to do is to provide one expander telescope system per laser beam pointed to the distant location. Stack fifty of those (good luck and deep pockets) to get the desired 50 parallel beams. The circle of confusion is limited by the quality (and diameter) of each individual telescope. The supersposition is here accomplished at the far end. An alternative is to array the lasers in a circle 0.1 feet across at a distance of 1000 ft from a 1 ft diameter mirror with a 1000 ft focal length and point the emerging beam at the moon. Your lasers subtend an angle of <0.1 mR at the mirror and the mirror subtends and angle of 1 mR at the laser stack - maybe we're coming closer to practicality. Now, if you fold the light path (e.g with high quality retro-reflectors -- optical experts needed), you will be able to compress the length of the system. I will wait with interest to see what other responses you get to your very practical question. GD DX es 73 Neil AB4YK. PS Why not point at a particular crater, a good telescope should be able to single out a desirable crater? ============================================================= John K3PGP wrote: > > >John, > >I read your plan/experiment about combining lasers with interest. I have also > >done similar experiments. I suggest another perhaps cheaper approach. > >Rather than increase the number of diodes to increase power, another > option >is to narrow the beam by using a beam expander. This will > reduce the >divergence by a factor equal to the expansion. So with > 1mR laser thru a 10x >expander, the divergence will reduce to .1mR. Is > this significant? a 10x >reduction in the diveregence results in 100x > signal (since the area is PI*R^2). >So you get a 20dB improvement. > > ~~ > > ~~ > >Jim > >WB9AJZ/6 CM87xi Sunnyvale, CA > > Jim: > > Thanks for the suggestion. The only problem is I am already doing this > and have just about reached the practical limit! For what I have in mind > I would like something more than the 5 mw that a single diode puts out. > > What brought this to mind is I came by a great deal on IR laser diodes. > At the moment I'm looking at a box of 50 (yes FIFTY) of them and that's > what led to the idea of trying to combine at least 10 of them. > > With the recent discovery that long term integration techniques can be > used to successfully recover weak laser signals I am giving serious > thought to the possibilities of milliwatt laser EME! If anyone would > have mentioned this as little as a month ago I would have told them to > forget it! However, from what I've seen lately I'm not so sure about > that. > > Up to this point I had been working on an 800 / 1000 watt pulsed ruby rod > system that I KNOW can be heard off the moon. However, it can only be > pulsed something like once per second or less and it's pretty hard to use > something like that for communications. It's also quite a beast to set > up and keep running let alone trying to get another station on the air > with a similar system so I could work them! > > It is my humble opinion that with good optics, sensitive detectors and > long integration times a milliwatt signal could be heard off the moon. > Since I already have the optics, and the receiving system is showing > great promise, I'm now looking at ways to increase the transmitted power. > > Since the retro-reflectors are useless for any kind of DX (returned echo > is only 20 km in diameter back on earth!) my only choice is to use the > lunar surface as a reflector. If one were going to use the > retro-reflectors then of course narrowing the transmitted beam width even > more would continue to produce a stronger return signal. > > Although no one knows for sure, it is my opinion that the diameter of the > laser beam should be between 1/2 and 1 moon diameter at the distance of > the moon. (Anything over 1 moon diameter would be wasted power since it > would go around the sides of the moon. / Anything much less than 1/2 > diameter and you start to have other problems.) This seems feasible with > the optics that I have. Beyond that we're looking at increasing transmit > power as the only way to pick up any more dB. > > So the question remains. What's the easiest way to combine ten (or more) > laser diodes so they could all be focused on the same distant target? > In this case the moon? > > John > K3PGP@juno.com > > -==- ------------------ RFC822 Header Follows ------------------ Received: by mm.rdd.lmsc.lockheed.com with SMTP;3 Apr 1997 00:26:57 -0800 Received: from natsemi-bh.nsc.com by eagle.lmsc.lockheed.com (8.6.11/DEC-Ultrix/4.3) id AAA17288; Thu, 3 Apr 1997 00:25:16 -0800 Received: (from uucp@localhost) by natsemi-bh.nsc.com (8.6.12/8.6.11) id AAA05124; Thu, 3 Apr 1997 00:18:49 -0800 Received: from nsc.nsc.com by natsemi-bh.nsc.com via smap (V3.1.1) id xma004758; Thu, 3 Apr 97 00:18:02 -0800 Received: from berlioz.nsc.com by nsc.nsc.com (5.65/1.34) with SMTP id AA11461 for Ken_R_Mason@ccm.fm.intel.com; Thu, 3 Apr 97 00:22:22 -0800 Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07937; Wed, 2 Apr 97 20:45:08 PST Message-Id: <334355FA.6B5C@mnsinc.com> Date: Wed, 02 Apr 1997 23:02:18 -0800 From: Neil Spokes X-Mailer: Mozilla 2.01 (Win16; U) Mime-Version: 1.0 To: John K3PGP Cc: laser@berlioz.nsc.com Subject: Re: Combining Solid State Laser Diodes References: <19970401.233927.3542.0.K3PGP@juno.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk From owner-laser Fri Apr 4 04:22:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06413; Fri, 4 Apr 97 04:22:20 PST Message-Id: <199704041220.HAA17369@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 04 Apr 1997 07:20:14 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: mailing list speed... Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >Wow. I emailed a bunch of messages to the laser list at 1:33 pm local time >today. > >Just started getting them back right now. Its 5:54 pm! what a time warp! > Hey, The list is free and made available to us with no strngs. The host is a comm'l enterprise. We get priority AFTER their needs are met. GL...Art... From owner-laser Fri Apr 4 06:57:07 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11073; Fri, 4 Apr 97 06:57:07 PST Date: Fri, 4 Apr 1997 07:53:10 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704041453.AA25060@fmsserv99.azfms.com> To: music@san-jose.ate.slb.com, laser@berlioz.nsc.com Subject: Fiber optic joining of lasers. X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk I've got a fiber bundle at home that was designed to illuminate the holes in punched cards as they pass through a card reader, and thought it might make a great laser joiner. So this morning before work I ran my laser pen through it to see what sort of beam I got out the other end. It turned a small spot from the laser into a wide beam, but I did not notice any interference patterns. It looks like, if one was able to align the 'x' lasers into the linear side, you could get 3 nice outputs (it converts a linear thing, about 8" long, into 3 round bundles). If I had a bunch of laser diodes I could say more ;-) Shucks, if I had a detector set up and ready for making amplitude comparisons I could say more also... Maybe someday. rusty From owner-laser Fri Apr 4 07:23:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11858; Fri, 4 Apr 97 07:23:28 PST Message-Id: <199704041521.KAA00551@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 04 Apr 1997 10:21:37 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: timeline module? Sender: owner-laser@berlioz.nsc.com Precedence: bulk hi everyone... I just got my timeline module yesterday-it seems like a good deal. It's built like a brick outhouse. I was going to reverse engineer the driver pcb but thought I would check with the GROUP first. Has anyone done this before? Incidently, BEWARE! Despite the fact that they advertise it as a 5 mw module, the diode supplied is only 3 mw! Also, the diode should come with factory specs for each individual diode, so they can be set up properly. These specs are NOT GIVEN-but there is a general spec sheet for the diode type (LT022). Is that driver board worth reverse engineering for our purposes? GL...Art... FIRST From owner-laser Fri Apr 4 07:26:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11933; Fri, 4 Apr 97 07:26:21 PST Message-Id: <199704041525.KAA00792@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 04 Apr 1997 10:25:25 -0500 To: c1040@azfms.com (Rusty Carruth) From: "Art Allen, KY1K" Subject: Re: TX power gains Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Rusty, I have a pair of .07 milliradiain lasers-that's 7 cm at a distance of 1 km! At 100 km, its only 7 meters wide! If I could use them, I would be thrilled as pie! But, due to the tightness of the beam, they are useless for general purpose communications! When I run the range figures for such a system, I find that they are capable of working the world-literally..if I could find a line of sight path hi hi. Aiming a laser of this divergence is easier said than done-just building a stable platform is very tough! I would be very interested in hearing from anyone who has an aiming system capable of aiming these beasts! GL..Art, KY1K. At 08:27 AM 04/03/1997 -0700, you wrote: > >from a friend > >----- Begin Included Message ----- > >From: Doug Music > > If you make a beam expander that has an adjustable focus, you have, in > effect, an arbitrary beam focus. I built a pair out of, honest, sprinkler > parts and lenses. (High curvature near the source.) The result is that > we produced a spot less that 1 inch across at 1/3 mile. This mounts to > a standard catadiopteric or Newt telescope with a PMT reciever. Pointing > control is not a problem. The problem becomes locating the other unit. > We have a solution to this which we would like to try out (time allowing). > > -Doug > >----- End Included Message ----- > > > From owner-laser Fri Apr 4 07:43:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12532; Fri, 4 Apr 97 07:43:06 PST From: daveaa1a@ssih.com Date: Fri, 4 Apr 1997 10:39:24 -0500 Message-Id: <199704041539.KAA05177@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: RE: Combining Solid State Laser Diodes To: "Stone Richard" , "Neil Spokes" Cc: "laser" In-Reply-To: X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Thanks for the BRAINSTORMING.. Geez, now a few things are making sense.. For long time since TRW flea market I picked up a flat plate with 6 micro lenses with finite aiming controls, a real engineering wonder.. It all connects to a 1/4" cord thence to a round brass plug type connector with a light detector at the tip.. If I shine a 75w watt lamp into the detector, I get get 6 re-productions at a very finite small angle leaving each of 6 output lenses. A beam splitter?? It's a passive device.. (seems like low mrads.) What am I?? tnx.. you guys are HOT.. 73 de Dave Riley From owner-laser Fri Apr 4 07:57:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13019; Fri, 4 Apr 97 07:57:47 PST Message-Id: From: Willson Flor To: "'laser@berlioz.nsc.com'" Subject: RE: Combining Solid State Laser Diodes Date: Fri, 4 Apr 1997 09:55:02 -0600 X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.993.5 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk >K3PGP wrote: > > >>I believe that the most common failure mode for the lasers is > >>optical damage to the front facet. There is always some optical > >>absorption at this part of the laser. The maximum operating > >>current of the laser is determined by the maximum optical > >>power that the front facet will take without being fractured. > >>--Richard KD6BQ >> >>How does cooling aleviate this problem? > The problem is that the front facet is heated due to the absorption, and eventually cracks under thermally-induced stress. Cooling alleviates this problem by helping keep the facet cool enough that the stress doesn't develop to the degree necessary to cause failure. This is a SWAG, but I think it's correct. -Will KB9JTT > From owner-laser Fri Apr 4 09:09:18 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA15307; Fri, 4 Apr 97 09:09:18 PST Date: Fri, 4 Apr 97 09:09:16 PST From: jmoss (Jim Moss) Message-Id: <9704041709.AA15301@berlioz.nsc.com> To: laser Subject: SLOW but mostly SURE Sender: owner-laser@berlioz.nsc.com Precedence: bulk Sorry to all about the "slowish" response of the server, I've talked to the administrator, but she tells me nothing has changed in the way the system is set up. A number of factors can affect the "propagation" of email. I am the first one on the list (well what do you expect), and I have noticed that mails take a few hours to show up. So I suspect that the major delay is in the server itself. My expectation for "light speed" on the "laser reflector" is like most of yours, the faster the better... but like Art said, we are free loaders here. I have considered moving the reflector to the QSL.NET system. Does anyone have any experience with their response times? Jim WB9AJZ/6 From owner-laser Fri Apr 4 09:21:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA15776; Fri, 4 Apr 97 09:21:34 PST Date: Fri, 4 Apr 97 09:21:31 PST From: jmoss (Jim Moss) Message-Id: <9704041721.AA15769@berlioz.nsc.com> To: laser Subject: FM mod/demod Sender: owner-laser@berlioz.nsc.com Precedence: bulk I forget who mentioned using the 4046 PLL for FM demod... Can he/she ID... or shed some more light here. I spent last night playing on the bench setting up a 70KHz subcarrier system (the frequency was random, based on R's and C's I had). I used a CMOS 555 in Astable mode and varied voltage on (pin 5?) to create what the data book calls pulse position modulation (looks like FM to me). Then ran the output thru a pot... wiper thru a .01 cap to the 4046 input. The issue is, what R's and C's to pick for the 4046. I fumbled around and fell into a set that seems to work. But, from the info in my NSC databook, R1 and C set the center frequency (that worked) and R2 sets the "offset". (I didn't know what that meant, seems to be maximum deviation and it varies directly with R2 value.) Then there is R and C for the loop filter, with no info given at all. I just picked some R/C that was close to "audio" and it seems to work. But I want to understand. (and optimize). It also appears that the 4046 wants TTL type input signals to the input. I skirted this by AC coupling, but the PLL seems to want about 100mV p-p to lock. (I expect it is just crossing threshold with this AC coupling.) My plan is to use full on/off switching on the laser, and decode using the baseband rx fed into the demod. I'll likely move to a lower frequency subcarrier, too. Jim WB9AJZ/6 From owner-laser Fri Apr 4 10:05:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17443; Fri, 4 Apr 97 10:05:51 PST To: laser@berlioz.nsc.com Date: Fri, 4 Apr 1997 12:21:33 -0500 Subject: Re: uniphase HE-NE Gas Laser info??? Message-Id: <19970404.122134.4590.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-27,32-33,36-37,40-41,43-44,47-50,53-54,59-60,66-72 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Manufature: Uniphase >HE-NE GAS LASER > >MADE IN USA. > >S/N 88832 > >P/N 50-03400--15 > >POWER 1.01mw > >the tube itself is about 5.75" in overall length, and the diameter >is appox. 1". >there is also a copper clad box (I assume the power supply) >with several leads coming out. One is a +20kv, another is a black >wire with a ring connector on it (gnd?) and then four wires coming >out of a small black connector. > >Is this thing worth $10 for the package, or $5 for just the >tube? Thanks for your time.. >-- >Gregory A. Cerny Sr. WQ0P >EM19VF 50,144,222,432,902,1296,5760,10ghzWBFM >mailto:wq0p@kansas.net >http://www.kansas.net/~wq0p Greg: I didn't bother to rip the case off what I have to check part numbers, but what you describe sounds very similar to several hand held bar code scanners that I picked up last fall at a local hamfest. I paid $5.00 apiece for the completely assembled hand held scanners. They look like a small gun complete with a red pistol grip! On the outside of the case, (which apparently isn't part of this deal!) it says Symbol Technologies, Inc. Bohemia, N.Y. Model no. LS-7000 II-I000A, Class II, September, 1987. Inside is an assembly much like you describe and I think the tube had Uniphase stamped on it. The power levels are marked in by hand and seem to vary from 1.01 mw to 1.6 mw on the ones that I have. If the stuff works, I say grab it. He-Ne laser tubes seem to be disappearing, having been replaced with solid state lasers. If the tube is bad, you might still end up with a good power supply. If it works it's probably worth $10 by itself. (I've paid more than this for just the supply!) If both are bad, you have a nice decoration for the shack! If it ends up being the same assembly I can give you pinouts for the power supply. If you need this get back to me and I'll open one up and compare notes to be sure we're talking about the same assembly! If you're not sure on this don't hook it up as the power supply can be damaged beyond repair (sealed unit!) with reverse polarity! If you're going to probe around at least hook a light bulb in series with the power supply as a current limiter till you get it going! A bulb that pulls 200 to 400 ma at 12 VDC is about right. When I first got these I managed to hook the power supply up with reverse polarity a couple of times while trying to figure out the connector. The light bulb just lit up brighter indicating something was wrong. NO damage was done. Had the bulb not been there I would have let the smoke out of the power supply. Once that happens, it's very hard to put it back in! :-^) John K3PGP@juno.com -==- From owner-laser Fri Apr 4 12:07:16 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA22457; Fri, 4 Apr 97 12:07:16 PST Date: Fri, 4 Apr 1997 12:49:56 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704041949.AA26447@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: mailing list speed... X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk > Hey, > > The list is free and made available to us with no strngs. > > The host is a comm'l enterprise. We get priority AFTER their needs are met. > > GL...Art... > > Sorry if I sounded whiny or complainy (complainy???), not intended so. But it was sort of surprising to have the mail take 6 hours to turn around. Guess its been too long since i've been a uucp hop from the internet! I suppose part of the point is to let everyone know that the mailing list can be pretty slow, at least for us near the end, so if you have time-critical giveaways ... well.. whatever :-) rusty From owner-laser Fri Apr 4 13:41:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25620; Fri, 4 Apr 97 13:41:17 PST Date: Fri, 4 Apr 97 13:41:15 PST From: jmoss (Jim Moss) Message-Id: <9704042141.AA25612@berlioz.nsc.com> To: laser Subject: sub mR aiming Sender: owner-laser@berlioz.nsc.com Precedence: bulk Art, I'm pretty sure we could build something that could control your .07mR beams. I was shooting for .5mR and have achieved .1mR so far. I think I can beat that with some micro stepping on my motors. I haven't gone into microstepping as I haven't needed more than 1/2 steps so far. Still have no time trials on how fast the raster blaster can align to target. Hope to try it BEFORE June! Jim WB9AJZ/6 ----- Begin Included Message ----- From owner-laser Fri Apr 4 11:00:54 1997 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 04 Apr 1997 10:25:25 -0500 To: c1040@azfms.com (Rusty Carruth) From: "Art Allen, KY1K" Subject: Re: TX power gains Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Content-Length: 1378 Hey Rusty, I have a pair of .07 milliradiain lasers-that's 7 cm at a distance of 1 km! At 100 km, its only 7 meters wide! If I could use them, I would be thrilled as pie! But, due to the tightness of the beam, they are useless for general purpose communications! When I run the range figures for such a system, I find that they are capable of working the world-literally..if I could find a line of sight path hi hi. Aiming a laser of this divergence is easier said than done-just building a stable platform is very tough! I would be very interested in hearing from anyone who has an aiming system capable of aiming these beasts! GL..Art, KY1K. At 08:27 AM 04/03/1997 -0700, you wrote: > >from a friend > >----- Begin Included Message ----- > >From: Doug Music > > If you make a beam expander that has an adjustable focus, you have, in > effect, an arbitrary beam focus. I built a pair out of, honest, sprinkler > parts and lenses. (High curvature near the source.) The result is that > we produced a spot less that 1 inch across at 1/3 mile. This mounts to > a standard catadiopteric or Newt telescope with a PMT reciever. Pointing > control is not a problem. The problem becomes locating the other unit. > We have a solution to this which we would like to try out (time allowing). > > -Doug > >----- End Included Message ----- > > > ----- End Included Message ----- From owner-laser Fri Apr 4 15:58:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01182; Fri, 4 Apr 97 15:58:54 PST Message-Id: <3345BC77.2455@mnsinc.com> Date: Fri, 04 Apr 1997 18:44:07 -0800 From: Neil Spokes X-Mailer: Mozilla 2.01 (Win16; U) Mime-Version: 1.0 To: Richard Stone , "John, K3PGP" Cc: Laser Subject: Re: Combining Solid State Laser Diodes References: Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Mime-Autoconverted: from 8bit to quoted-printable by news2.mnsinc.com id SAA24818 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I can probably throw a little more info into the maelstrom - Neil, AB4YK: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Stone Richard wrote: >=20 > I think that there is a slight misunderstanding here of this fundamenta= l law of > physics. I believe that the law of conservation of brightness ........ > has to do with the conservation of brightness of single source > with optical transformations ( you can always loose energy but you cant= gain it > without adding it in from somewhere) but does not specifcally prohibit = the > combination of sources. I'm not sure so give me some time to look it up= . Or > maybe someone else can help here. There are various ways to combine (or > separate) beams of light all based on what make them different. Differe= nt > frequency,different polarization, or different spatial properties. Mayb= e someone > else can help us out here. --Richard KD6BQ =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Brightness e.g. of a black body, is measured in watts per m=B2 of source,= per nm at the=20 specific frequency per steradian. If the light intensity of the original= laser=20 corresponds to an equivalent black body "temperature" T kelvin then, unle= ss you put an=20 amplifier in line with the source or add power from another frequency you= are limited to=20 the effective temperature Tmax of the hottest laser. A dichroic mirror c= an be used to=20 add power but at another frequency, -- most of the dichroics that I have = seen have a=20 transition band between high and low transmission of tens of nm, although= probably you=20 can do better if you pay enough but then you would have to be able to con= trol your laser=20 freq. I don't know anything about optical transformation - sounds like bl= ack magic=20 unless you have coherent light, but that's not in the hopper of options. Basically, if you try to combine light of two unpolarized lasers at the s= ame frequency=20 using a 50 % reflecting mirror (or any other device) you throw away 50 % = of the light of=20 laser 1 and 50 % of the light of laser 2 so that you have zero gain (at b= est). Maybe, if=20 you could control the polarization of a pair of lasers you could get a fa= ctor of two=20 power increase by combining them with a simple combiner. My understanding= is that the=20 polarization of cheap solid state lasers is random, however. NS. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > _______________________________________________________________________= ________ > From: Neil Spokes on Thu, Apr 3, 1997 12:27 AM > Subject: Re: Combining Solid State Laser Diodes > To: John K3PGP > Cc: laser@berlioz.nsc.com >=20 > There's a fundamental law of physics that says that you cannot increase= the > brightness etc....... =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BTW, for the cluster concept in which there is a bunch of lasers in a 1" = dia circular=20 disk 1000 ft from a 1000 ft focal length mirror, while the lasers all hav= e to be within=20 a half inch of the axis of the far distant mirror, they would not all hav= e to be exactly=20 at the focal distance point of the system. There is some tolerance for l= ongitudinal=20 offset probably measured in feet along the axis if the focal length were = 1000 feet. That=20 would ease construction potentially. A 6" dia plane mirror at 500 feet could reflect the light beam back to a = 1 ft dia., =20 1000 ft focal length paraboloid conveniently near to the operating locati= on. That would=20 give local control back to the operator. =20 If one really wanted to irradiate half the moon's disk (5 mR beam), then = I would not see=20 any advantage to such a big expander. For this a 1 inch cluster of laser= s could be at a=20 distance of just 200" from an expander mirror of focal length 200" and di= ameter 1 inch.=20 Or with the folded path, described above, use a one inch dia. plane mirro= r 100" away and=20 reflect the light back to a 1" paraboloid of focal length 200" at the ope= rating=20 position. However, by irradiating the whole moon's disk, one would have = significantly=20 increased the noise signal into a receiver from scattered earth light. Be= tter, I think=20 would be blanketing the moon with a raster which would give some modulati= on which the Rx=20 might be able to work with. NS. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3Dend=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From owner-laser Sat Apr 5 14:43:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10190; Sat, 5 Apr 97 14:43:26 PST Message-Id: <199704052241.RAA03422@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 05 Apr 1997 17:41:53 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: grating? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I'm getting ready to publish a written report on the timeline module. Despite the fact that is is misrepresented as a 5 mw module, it is probably well worth the 20 dollar asking price IF the power supply could be used (needs reverse engineeering). Anyway, in the sparse docs, they mention one of the optical components is called a 'grating'. This grating is located on the output side of the module. So, its laser diode, collimator, then grating. The grating has similar dimensions to the collimator and is mounted about the same way. Anyway, what the heck is this optical component used for? Is it possible that the collimator makes the beam parallel, and the additional 'grating assy' is used to actually focus the beam to a small point at a few cm distance? I do know that the module is used in a XEROX laser printer, and it seems likely that they would need a focused beam and NOT a collimated one. Does anyone really know WHAT the grating is? Stand by for full tech report on the timeline IR module, including some reverse engineering on the very nice gain guided controller. I am hopefull that it can be used to power the laser diode. GL...Art, KY1K. From owner-laser Sat Apr 5 14:52:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10486; Sat, 5 Apr 97 14:52:06 PST Message-Id: <199704052251.RAA03852@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 05 Apr 1997 17:51:44 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: diodes in laser vs led mode? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone- Its me (again). Hey, I posted a message earlier asking what the difference was between a laser diode operated in led mode was? It wasn't very clear and some commented, but I didn't get the needed info... Since the relationship between laser threshold current and max current is generally just a few milliamps, and since each diode has its own specific ratings, I was wondering how we set the power supply up IF we had a bunch of unknown diodes? Obviously, we operate the power supply at a low current, then ramp it up slowly till the diode changes from led mode to laser mode. This should be a visible change (I hope). I'm wondering what we actually see IF we are looking at the diode reflection as we pass the threshold current? Anyone have any practical experience here? Thanks, Art... From owner-laser Sat Apr 5 15:10:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11052; Sat, 5 Apr 97 15:10:57 PST Message-Id: <199704052309.SAA04742@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 05 Apr 1997 18:09:19 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: laser radar? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I know a few of you are running your HE-NE's on multi-khz AC supplies. Also, some are pulsing solid state diodes at multi-khz rates... I also know a few have actually bounced signals off of reflectors in the multi-mile range, and either heard their own reflections, or have been able to work others by using a reflector. It seems that laser radar would be VERY EASY to implement! If we used a wide band receiver and a 1 khz (+/-) pulse rate, we could actually have an active optical radar... If we had a fast scope, we could set the scope to trigger on the falling edge of the output of the laser power supply. If we monitored the rx output, we should be able to see a return signal on the scope. If it bounces off something close, it would be close to the left hand side of the scope trace. If it bounces off something farther away, it would be in the middle or the right hand side of the screen. You probably should have a wide band RX for best results. Wonder if anyone has ever tried to actually quantify the distance to a particular target by usung this method? Might be possible to track airborne objects too (notice I DIDN'T say 'airplanes'). As usual, drop a line to the reflector. GL..Art, KY1K. From owner-laser Sat Apr 5 16:07:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12051; Sat, 5 Apr 97 16:07:28 PST Message-Id: <199704052333.SAA05920@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 05 Apr 1997 18:33:53 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: timeline reverse engineering report Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I ordered a Timeline module and I'm very pleased with the quality of the thing. I would like to use the EXISTING power module tho, but it has no docs with it. The timeline module is a 20 dollar laser module available from timeline. It is an IR laser diode, collimator and power contrl unit for gain guided laser diodes. It is advertised as a '5 mw' power output, but it contains an LT022 diode, which is 3 mw max. It comes in a very heavy duty cast aluminum box which is solidly shielded and has a 10 wire ribbon conductor input cable. It says it is made for a XEROX laser printer. The only numbers on it are XEROX house numbers. The mounting block is detachable from the box and the collimator is plastic lens type. The box is triangular and odd shaped. The pcb containing the controller unit is also triangular shaped. I would like to be able to use the controller to power the diode, but no schematic or hookup info is given with the thing. So, I sat down and traced out all the etches and made a diagram. Having the diagram didn't help much! Even looking at the diagram, its not clear which wires are power supply inputs and which are signal inputs. There are 2 small variable resistors on the pcb, but their function is not labelled. It has a 28 pin inline chip which powers the diode and senses the PD output to keep the thing operating at the proper output. There is also a single small transistor, which looks like it might be a sub mini voltage reference supply rather than a transistor. I was able to identify the 'ground' trace on the pcb. It should be noted that the PCB and the diode holder are both FLOATING from the aluminum chasis, so they are playing games with the power supply inputs maybe. The sub mini 3 lead transistor appearing device (probably a voltage reference supply) appears to be a negative voltage input and output with respect to the ground etch because it has electrolytic caps that a positive to ground. I have a hand drawn schematic and I'd be happy to ship it via email to anyone who thinks they can make sense of it. Anyone care to take a shot at guessing how to power this sucker? GL...Art... From owner-laser Sun Apr 6 08:16:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02978; Sun, 6 Apr 97 08:16:26 PDT Content-Length: 920 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Sun, 06 Apr 1997 10:49:52 -0400 (EDT) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Hey you guys using the Burr Brown devices I could use some advice! When I first tried it the opt202 with just the internal 1 meg feed back resistor I didn't have any problems with hum etc. Next I tried 20 megohm external feedback resistor and I had some hum (60 cycle) but by adding an additional ground I fixed that problem. Now I'm at 100 meg feedback and I just can't seem to eliminate the 60 cycle hum! Now I'm running everything off of battery's so there is no ac connected. I've shielded every thing I can. Any suggestions ? How do you guys have the device configured? Thanks Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe From owner-laser Sun Apr 6 12:47:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10127; Sun, 6 Apr 97 12:47:15 PDT From: sjnoll@ix.netcom.com Date: Sun, 6 Apr 1997 14:43:00 -0500 (CDT) Message-Id: <199704061943.OAA13899@dfw-ix12.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: 60 cycle hum & OPT202 To: laser@berlioz.nsc.com In-Reply-To: X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Sun, 06 Apr 1997, wayne hilliard wrote: >Hello >Hey you guys using the Burr Brown devices I could use some advice! >When I first tried it the opt202 with just the internal 1 meg feed back resistor >I didn't have any problems with hum etc. Next I tried 20 megohm external >feedback resistor and I had some hum (60 cycle) but by adding an additional >ground I fixed that problem. Now I'm at 100 meg feedback and I just can't seem >to eliminate the 60 cycle hum!............ Just a quick comment... As you add feedback resistance you increase gain AND lower bandwidth, so it's becoming better & better at amplifying 60 Hz! I built my last photodiode/op amp receivers on a round circuit board with lots of ground plane, then soldered steel Coffee-Mate jar metal lids to the front & back of the circuit board for EM shielding. Punched hole in one of the lids for the photodiode to look thru. No significant hum problems. Steel gives good magnetic field shielding, as well as electric field shielding. BTW: in my instance, 50 Meg-ohm gave optimum S/N. Your milage may vary. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html From owner-laser Sun Apr 6 21:55:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24030; Sun, 6 Apr 97 21:55:31 PDT Date: Sun, 6 Apr 97 21:55:29 PDT From: jmoss (Jim Moss) Message-Id: <9704070455.AA24024@berlioz.nsc.com> To: laser Subject: Article in MTTS? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Heard there was an article this/last? month in MTTS about modifying a laser pen for use with data/voice etc!? Anyone see it? I don't get that magazine, and will have to search into our company library. Jim WB9AJZ/6 From owner-laser Sun Apr 6 21:47:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23807; Sun, 6 Apr 97 21:47:34 PDT Date: Sun, 6 Apr 97 21:47:32 PDT From: jmoss (Jim Moss) Message-Id: <9704070447.AA23798@berlioz.nsc.com> To: laser Subject: Burr Brown cct. Sender: owner-laser@berlioz.nsc.com Precedence: bulk Wayne, I used only 15 M Ohm feedback. Note that BB suggests no resistors greater than 5 M be used as an independent component. That means that I run 3 - 5M resistors in series. Further is says to keep the leads short and mount the resistors at board level (near ground plane). Do you have your device completely in a black box when testing for the noise? If not, you are likely picking up noise from 60 Hz lighting. If your RX is good, this is almost guaranteed to happen where there is any lighting! You should also completely shield the RX (except for the light input), and AF gain section. Jim WB9AJZ/6 CM87xi Sunnyvale, CA. From owner-laser Mon Apr 7 04:03:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04212; Mon, 7 Apr 97 04:03:35 PDT Date: Mon, 7 Apr 1997 07:00:50 -0400 (EDT) Message-Id: <2.2.16.19970407062037.26af9174@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Measuring received signal strength Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello All. I was wonder if anyone is doing any measuring relative or absolute, oft he signal strentgh that they receive on any given signal path. This info maybe interesting on something less than a LOS path. Thanks for any interest 73's PaulC KB1RP From owner-laser Mon Apr 7 08:01:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10473; Mon, 7 Apr 97 08:01:51 PDT Date: Mon, 7 Apr 1997 08:01:03 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071501.AA11436@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: re: combining... X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: re: combining... >Why are we trying to get all the diodes physically close, or use splitters, >etc? It seems that it is only important when the beamwidth at the RX is small >with respect to the RX detector size. > >Am I missing something? > >Jim >WB9AJZ/6 CM87xi You've got it. By the way, there are ways of bringing diode outputs close together (as measured in wavelengths) but they are of questionable value. The pointing problem is why you would want them close AND aligned. This makes using simple optics possible for trying to hit a specific flea on the moon. Otherwise, yea... not much use. -Doug ----- End Included Message ----- From owner-laser Mon Apr 7 08:06:05 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10586; Mon, 7 Apr 97 08:06:05 PDT Date: Mon, 7 Apr 1997 08:05:30 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071505.AA11453@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: timeline module? X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: Re: timeline module? >Incidently, BEWARE! > >Despite the fact that they advertise it as a 5 mw module, the diode supplied >is only 3 mw! Laser ratings are NOT the power output. They are the power level the device is guaranteed NOT to exceed. -Doug ----- End Included Message ----- From owner-laser Mon Apr 7 08:04:38 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10522; Mon, 7 Apr 97 08:04:38 PDT Date: Mon, 7 Apr 1997 08:03:57 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071503.AA11447@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: RE: Combining Solid State Laser Diodes X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: Doug Music Subject: RE: Combining Solid State Laser Diodes Sorry about being brief. Dragons about and all that rot. Actually I jam these things in during breaks in otherwise fatally boring meetings. > >Exactly what is a fibre taper? Is this one strand out of an optical >fiber bundle? A taper is made by heating and stretching a fibre line (glass only) just the same way that capillary tubes are made. In a fibre bundle, you fuse one end together and then stretch it under heat. This tapers all of the fibre line exactly the same. You will want to beleive that this makes a fibre lens. Fibre lenses are a different process. The light entry and exit angles will remain exactly the same (assuming the ends are ground flat). This process can produce exit appertures 632nM across. This is why you can use these to bring a zillion diodes to bear. > >TE cooling? Could use some help here as well! What does TE stand for >and how cold is it? How much does it increase power output? > You are right in that the diode is going to die a mean death BUT... you can give it longer life by #1) buying IMPULSE diodes and #2) freezing the heck out of them. Cambion makes TE (thermo-electric) coolers which can pump heat. These will drive the diode temp to near -90 degrees C. These are differentially doped semiconductor stacks and they are cheap. About $60 for frostbite. These take 12 or so volts at 10 amps and ya gotta cool the back side with heatsink/fans or liquid cooling. >Impulse drive? (How about warp drive?) I've been told you can't pulse >laser diodes (above their normal operating current) because the front >facet will fracture with increased drive. Tell us how to do this!!! >P-L-E-A-S-E !!! This is true for most diodes. If you cool them, they can take more abuse. If you fish about a bit, you can find diodes that take pulses really well. The trick is to put the diode into LED mode about 2 mA below laser threshold and pump it in a 1 to 3% duty cycle at a pile of current. Even if you cool them, they can't take much more RMS power than maybe 1.5 maximum rated power so you have to fish about for them. > >>I'm beginning to think I should have my friend get on the list HIMSELF >;-) > >Yes, by all means! It sounds like he has a LOT of good ideas but his >answers are a bit on the brief side. We're not in that big a hurry! :-^) > >If I can get ' WATTS ' out of this array then this is going to be a VERY >interesting project when combined with weak signal integration >techniques!!! If you find a pulse diode and cool it, you must VERY SERIOUSLY pay your safety dues. If you guys decide to goof with anything over 5mW, you have been warned here and now that laser damage is instant and forever. (We know people who will regret not heeding this for the rest of their lives.) >John >K3PGP@juno.com > Doug ----- End Included Message ----- From owner-laser Mon Apr 7 07:58:10 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10303; Mon, 7 Apr 97 07:58:10 PDT Date: Mon, 7 Apr 1997 07:57:27 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071457.AA11405@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: more laser comments X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Yeah, I was there, and this actually happened. ----- Begin Included Message ----- From: Doug Music Subject: Re: more laser comments Get this... We aim our receiver at the lower half of the side wall in the garage. We open the attic door and have someone shine a laser into the back part of the attic. The person's pulse puts micro variations on the laser pointing. We can hear the pulse in our receiver. I'd call that a nice front end, hmmmm? :-) :-) -Doug From owner-laser Mon Apr 7 07:59:59 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10368; Mon, 7 Apr 97 07:59:59 PDT Date: Mon, 7 Apr 1997 07:59:48 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071459.AA11416@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: Band Tunable Mirrors X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk I have a feeling that, if everyone on the list wants one of these Doug will have to ask a small fee to cover his cost... ----- Begin Included Message ----- From: Doug Music Subject: Re: Band Tunable Mirrors > > >The idea is to use band tunable mirrors as band pass filters on > >your receiver, thus dropping the background noise down a LONG ways. > >-Doug > >I've seen and used bandpass filters before but never a band tunable >mirror. Can we have some details on this as well and a good place to get >the parts necessary to build one? > >John >K3PGP@juno.com > These are called "cold" mirrors, or "hot" mirrors in the trades and Meredith Instruments just may have em for $5 each or so. You need to cut em up with a glass cutter into smaller sizes. The surface has dielectric coatings on it that are pretty thick. Viewed straight on, you see a mirror. As you pitch the mirror to an angle, you begin to see through it, but only in ONE color. You can tune in any line (color or freq) you like by simply changing the angle. These can have bandwidths of 10-20nM (typ) and make your front end as selective as you think it's going to. (I assume you are a Ham.) These are real neat and if you simply can't locate one, I'll cut one into 25mm squares and mail you one of em. -Doug ----- End Included Message ----- From owner-laser Mon Apr 7 07:58:16 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10309; Mon, 7 Apr 97 07:58:16 PDT Date: Mon, 7 Apr 1997 07:54:56 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704071454.AA11363@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: RE: HE-NE direct modulation? X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk >From my friend: ----- Begin Included Message ----- Date: Sun, 06 Apr 1997 19:35:10 -0700 From: Doug Music Subject: RE: HE-NE direct modulation? The harmonics are related to the speed of the edge unless the frequency nears the band pass (to ground) and all that. The reason the ballast resistor is there is to stop tube oscillations as well as limit the instantanious current. One VERY cheap way to modulate a HeNe at 100% but sloppy duty cycle is to put a SMALL but high voltage cap directly across the tube. The tube will set up relaxation oscillations and all that crud. Noisy, but what the heck, it's a signal. -Doug > >----- Begin Included Message ----- > >From: k3pgp@juno.com (John K3PGP) > > >My guess is that we would have harmonics into the 5 or 10 mhz > >region-neatly spaced at the frequency of the switching frequency > >of the power supply. > > > >Does anyone have any idea of the magnitude of these losses > >resulting from the harmonics of the power supply switching frequency? > >GL..Art, KY1K. > >I too would like to know more about this! > ... > >PS - Let's hear from some of those people out there reading the mail! > > >John >K3PGP@juno.com > >----- End Included Message ----- ----- End Included Message ----- From owner-laser Mon Apr 7 09:28:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13284; Mon, 7 Apr 97 09:28:34 PDT Date: Mon, 7 Apr 97 09:28:31 PDT From: jmoss (Jim Moss) Message-Id: <9704071628.AA13278@berlioz.nsc.com> To: laser Subject: Measuring received signal strength Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul, I did not include S-meters in my RX! Maybe I should. At 20 miles my "best RX" (unknown photo diode with large active area), could just barely hear a 800Hz tone from a 4mW laser. No optics were used, only a cheap plastic red filter from a RadioShack IR box. With a 8" mirror as a reflector, signals were 599 with QSB. None of my other RX's could hear it. I have done some measurements at home, with a scope after running thru 2 stages of amplification. Using a 2mW emitter, and a RS phototransistor, with 10M pull up thru 2 stages of amplification, (I don't know the gains off hand) a 2 foot distance to a semigloss white painted door and back was >> 1 volt. 20 foot to a flat white wall and pack was at the noise level, about 10mV. (These were not done in total darkness, and misc lights were on.) Is there a lot of interest in collecting quantitative results on signal strength? Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Mon Apr 7 18:49:59 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02638; Mon, 7 Apr 97 18:49:59 PDT Message-Id: <199704080143.VAA17767@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 07 Apr 1997 21:44:10 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: quadrature driver chip? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I am looking at the inclinomators on the US Digital homepage. They would make a fairly nice elevation readout. They are a little pricey but they are ruggeed as HELL and VERY small and compact. They have a quadrature output though. They do sell a quadrature chip which is US Digital only-but that chip is expensive and doesn't come built in the encoder! To make matters even worse, the custom chip DOESN'T EVEN have a built in up/down counter, so an additional chip is necessary just to keep track of the elevation count. To make matters even worse, there is no less than/more than/equal to output, so I thaink that means a third chip (ALU chip). So, the overhead in the stuff that has to be fabricated in order to support the original device is MAJOR. Does anyone know if there are other chips that decode quadrature outputs? Drop me a line...Art... From owner-laser Mon Apr 7 19:00:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02972; Mon, 7 Apr 97 19:00:17 PDT Content-Length: 4112 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 In-Reply-To: <199704062029.QAA20220@host-04.colby.edu> Date: Mon, 07 Apr 1997 21:06:31 -0400 (EDT) From: wayne hilliard To: Laser Messages Subject: Re: Sender: owner-laser@berlioz.nsc.com Precedence: bulk Thanks all for replying. I have solved the hum problem by adding a separate ground from the ground of the device to the metal tube of my telescope. I noticed that my body would alter the hum as I moved away from and then nearer the tube. So on a whim I attached a clip lead from ground on the board to the telescope tube and presto chango no more hum. I have the device built into a copper box with all components mounted right on the ic socket i used. I heard a beacon on top of a small broadcast tower about two miles away last night with it. By the way the op202 chip is rated for 100 meg +. Also I have bypass caps right on the socket between + and - volts going to ground. Does anybody on this reflector know what the laws are regarding the power of broadcast tower beacons? I know I might be able to look up the relevant part of the FCC rules but I just thought I'd ask. Would it be possible to use them as a sort of standard noise source? On 06-Apr-97 Art Allen, KY1K wrote: >Hi Wayne, > >I'm wondering HOW you went from 10 meg to 20 meg? Did you add an additional >10 meg resistor in series? If so, you might be picking up ac from the >atmosphere because the length of the resistor string is acting as an >antenna! You gotta keep all the component leads at the absolute minimum! > >Some other things you might want to look at are ps decoupling and the max >value that BB allows for the feedback resistor? > >I'm not sure they spec that device for 100 meg ohms! At that value, it takes >a very highly stable chip because the gain is so high. It's possible that >the 60 hz you hear is due to OSCILLATION of the device itself and is >agravated by the 60 hz pickup electrical fields. > >Make sure you bypass the supply. I used .01 uf feedthrough caps and .1 >surface mount caps just to make sure I had a low impedance bypass. It made a >big difference. > >I operate with 1000 meg ohm resistor, and it works FB! At this extreme >amplification level, the circuit has to be properly bypassed (supply leads) >and the layout has to use absolute minimum length component leads-I used smt >components. > >At 1000 meg, the entire circuit must be TOTALLY shielded-I built mine inside >a metal box, then soldered the box closed. Part of this is due to microvolt >static charges induced because of moving air-so the box provides electrical >shielding as well as preventing noise caused by random air flow. > >I'm wondering whether the 60 hz noise occurrs all the time, or just when the >detector sees light? > >If there is any light from manmade sources falling on the detector, then the >60 hz noise is normal-remember, you are running that thing at EXTREMELY high >gain! > >For a quickie test, wrap the detector in aluminum foil and see if the 60 hz >noise goes down. > >Drop me a line...Art... > > >At 10:49 AM 04/06/1997 -0400, you wrote: >>Hello >>Hey you guys using the Burr Brown devices I could use some advice! >>When I first tried it the opt202 with just the internal 1 meg feed back >resistor >>I didn't have any problems with hum etc. Next I tried 20 megohm external >>feedback resistor and I had some hum (60 cycle) but by adding an additional >>ground I fixed that problem. Now I'm at 100 meg feedback and I just can't seem >>to eliminate the 60 cycle hum! >>Now I'm running everything off of battery's so there is no ac connected. >>I've shielded every thing I can. >>Any suggestions ? How do you guys have the device configured? >> >> >>Thanks >> >>Wayne Hilliard >> "If computers are making the world a global >>village, >>KA1CXD and I can't figure out how to use one, does that >>woody@sover.net make me the global village idiot ?" >> Shoe >> >> >> > > Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe From owner-laser Mon Apr 7 22:37:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09384; Mon, 7 Apr 97 22:37:41 PDT Message-Id: <3349DEDF.4E9D@mnsinc.com> Date: Mon, 07 Apr 1997 22:59:59 -0700 From: Neil Spokes X-Mailer: Mozilla 2.01 (Win16; U) Mime-Version: 1.0 To: Jim Moss Cc: laser@berlioz.nsc.com Subject: Re: Burr Brown cct. References: <9704070447.AA23798@berlioz.nsc.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk It's difficult to tell whether this is relevant to the thread but, Fwiw, my company had a lot of trouble with >2M feedback resistors in gain circuitry some years back. Prototypes were fine but when we went to production, a vendor used "environmentally friendly" solder flux. The problem was that the flux could not be 100 % washed off the PCB and, since the residual flux attracted moisture, this led to variable gain in the feedback circuit. We now prohibit these environmentally friendly fluxes from being used in our PC board systems. Neil, AB4YK. =================================== Jim Moss wrote: > > Wayne, > I used only 15 M Ohm feedback. > > Note that BB suggests no resistors greater than 5 M be used as an > independent component. That means that I run 3 - 5M resistors in > series. Further is says to keep the leads short and mount the > resistors at board level (near ground plane). > > Do you have your device completely in a black box when testing for > the noise? If not, you are likely picking up noise from 60 Hz lighting. > If your RX is good, this is almost guaranteed to happen where there is > any lighting! > > You should also completely shield the RX (except for the light input), and > AF gain section. > > Jim > WB9AJZ/6 CM87xi Sunnyvale, CA. From owner-laser Tue Apr 8 22:58:10 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20686; Tue, 8 Apr 97 22:58:10 PDT Message-Id: <9704090554.AA05119@omnigroup.com> Content-Type: text/plain Mime-Version: 1.0 (NeXT Mail 4.1mach v148) In-Reply-To: <199704080143.VAA17767@host-04.colby.edu> X-Nextstep-Mailer: Mail 3.3 (Enhance 1.3) From: William Lewis Date: Tue, 8 Apr 97 22:55:02 -0700 To: "Art Allen, KY1K" Subject: Re: quadrature driver chip? Cc: laser@berlioz.nsc.com References: <199704080143.VAA17767@host-04.colby.edu> Sender: owner-laser@berlioz.nsc.com Precedence: bulk > Does anyone know if there are other chips that decode quadrature outputs? This sounds like an ideal application for a PIC --- it should be well within its capabilities to decode the quadrature outputs, maintain a count, compare against a reference, drive indicators for too high/too low, etc. A PIC (apologies if you already know about them) is a very minimal microcontroller; the most hobbyist-friendly version (the 16C84) comes in an 18-pin DIP and only needs a couple of external components. Most of those 18 pins are available for I/O. It's a very nice chip. (Of course, you still have to write the software...) From owner-laser Wed Apr 9 08:23:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03551; Wed, 9 Apr 97 08:23:00 PDT To: laser@berlioz.nsc.com Date: Wed, 9 Apr 1997 11:16:43 -0400 Subject: Solar Storm May Hit Power Message-Id: <19970409.111655.12902.4.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-5,7,9-10,12-13,15-22 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Reuters Hourly News Summary Solar Storm May Hit Power NASA says a big storm on the surface of the sun will hit Earth's magnetic field today with the potential to disrupt communications satellites and power grids. A NASA official described the solar storm as a ``big event'' in which matter blown off the face of the sun would strike a "glancing blow'' to the magnetic field that shields the Earth more than 100 miles from its surface. Operators of sensitive satellites and power grids have been warned to take precautions. Scientists still are calculating the precise arrival time of the solar impact, which is likely to produce a shimmering curtain of multi-colored light called an aurora over the North and South poles. John K3PGP@juno.com -==- From owner-laser Wed Apr 9 12:54:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12868; Wed, 9 Apr 97 12:54:50 PDT Date: Wed, 9 Apr 1997 12:51:15 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704091951.AA00781@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re: quadrature driver chip? Cc: aballen@colby.edu X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Doug had the same solution, a PIC (or similar). Here's his comment: ----- Begin Included Message ----- From: music@Tempe.ate.slb.com (Doug Music) Subject: Re: quadrature driver chip? > Does anyone know if there are other chips that decode quadrature outputs? Sure. Use a Motorola 68HC11 micro controller to read the quad data. You can accept input from your inclinomator and handle a keypad and readout all from this single chip. It even has several channels of A/D and D/A on board. -Doug ----- End Included Message ----- From owner-laser Wed Apr 9 15:58:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18994; Wed, 9 Apr 97 15:58:29 PDT Date: Wed, 9 Apr 97 15:58:27 PDT From: jmoss (Jim Moss) Message-Id: <9704092258.AA18988@berlioz.nsc.com> To: laser Subject: collimation lens Sender: owner-laser@berlioz.nsc.com Precedence: bulk DON'T SAY "H*E*L*P!" From: k3pgp@juno.com (John K3PGP) H*e*l*p with Collimation Lens ! ---------------------------------------- Please excuse my absence the past week or so. I've been extremely busy testing PMT tubes plus working on a scheme to combine TEN 780 nm laser diodes to make a 30 to 50 mw transmitter! Which brings me to the following: Anyone have any experience using various lens for collimation? I have to come up with ten of these and I think I located what I need at a price that I can afford. However, I need to draw on the knowledge of those who visit here before I make a mistake and order something that I can't use! I've played around with some junk box lens and just about any type of PCV (plano-convex) or DCX (double-convex) short focal length lens that I've tried seems to work. The only thing that seems to be somewhat critical is the lens diameter vs focal length. If I use a small diameter lens with too long a focal length then some of the radiated energy coming out of the laser diode ends up going around the lens with a corresponding reduction of power in the collimated beam. If the focal length is too short, I sometimes can't get the lens close enough to the source of radiation to bring the beam into focus because the beam appears to come from the back of the laser diode and not the front. So there is also a minimum focal length that will work. I've read in an article somewhere that the best lens to use is an f 2.8. That is the focal length should be 2.8 times the diameter. (I'm sure this varies a bit from laser to laser depending on exactly what the beam width of the radiation coming out of the laser is.) Also, there's no way for me to determine if this is good advice or not! Using the above for a 1 cm diameter lens the following would be true: 1 cm diameter / divided by 2.8 cm focal length = f 2.8 A lens of approx. these characteristics pulled from the junk box seems to work. However, I seem to get a bit more power out of an f 1.3 lens (1 cm diameter with a focal length of 1.3 cm). I assume this means that with the f 2.8 lens some of the energy is going around the lens since the diameter is too small for the focal length when used with this particular brand of laser diode. NOTE: There isn't much difference here. However, it IS detectable. Either lens would be satisfactory. I think anything above f 2.8 though and the power would start to fall off severely.) I KNOW that there are lens made specifically for solid state laser collimation. However I only have two of these and buying 8 more new ones would be cost prohibitive since I need at least ten of them. In both long range and short range tests I see very little difference between the 1 cm junk box lens and the proper collimation lens made for the laser. In fact when looking at the beam close up after being projected several hundred feet the 1 cm lens actually seem to produce a bit cleaner beam! This may be because the real laser collimation lens are plastic and the 1 cm lens are high quality optical glass. I'm trying to come up with a reasonable substitute for the real McCoy. I've found a source of small diameter lens in the f 1.3 to f 2.8 range. Based on the above I'm thinking of ordering ten of the f 1.3 lens. (1 cm lens with a focal length of 1.3 cm) As mentioned above this may not be the ideal situation but it seems to work. Any comments or suggestions before I make a purchase? Any one have any sources for lens that perhaps I don't know about? NOTE: Unfortunately, I've found out that many of the PMTs that I have will NOT work at all at 780 nm! The response isn't down, there isn't any! I can't even detect a 780 nm beam by shining it right into the PMT! (This is NOT recommended procedure but I had to find out! - It was done with a junk box tube!) However, these same tubes respond just like new up in the green part of the spectrum where they are EXTREMELY sensitive. Apparently they have some type of IR filter built in. They DO respond to 630 nm but again the response is down quite a bit as expected. Fortunately I've found several PMTs (of a different type) that I THINK are going to work well enough at 780 nm. (At least they blow my solid state detector away!) More info to follow and some details on a simple PMT preamp that I've designed that seems to work well. Just give me some time, as things are happening (and changing!) too fast to document at the moment! I'll post the results here as usual when it's ready. I think I'm suffering from withdrawal symptoms and I must get back to the soldering iron! :-^) John K3PGP@juno.com -==- ----- End Included Message ----- ----- End Included Message ----- From owner-laser Wed Apr 9 16:40:46 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20305; Wed, 9 Apr 97 16:40:46 PDT Date: Wed, 9 Apr 1997 19:37:40 -0400 (EDT) Message-Id: <2.2.16.19970409185659.2d5fa532@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Looking for 40 - 50 mw IR diode Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks I am looking for a 40 to 50 mw IR laser diode of anyone has one they wish to part with or knows where 1 can be had Thanks 73's PaulC KB1RP From owner-laser Wed Apr 9 17:19:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21653; Wed, 9 Apr 97 17:19:37 PDT Message-Id: <9704100016.AA20208@omnigroup.com> Content-Type: text/plain Mime-Version: 1.0 (NeXT Mail 4.1mach v148) In-Reply-To: <199704091553.LAA03945@host-04.colby.edu> X-Nextstep-Mailer: Mail 3.3 (Enhance 1.3) From: William Lewis Date: Wed, 9 Apr 97 17:16:38 -0700 To: laser@berlioz.nsc.com Subject: Re: quadrature driver chip? References: <199704091553.LAA03945@host-04.colby.edu> Sender: owner-laser@berlioz.nsc.com Precedence: bulk Well, PICs aren't too expensive to use if you're willing to get your hands dirty. Digi-Key sells the EEPROM (reprogrammable) versions for $7 in singles. (One-time-programmable versions are cheaper.) If you have a PC, you can build a programmer that attaches to your parallel port (or your serial port) out of a handful of discretes and some 7400 and 4000 series logic. Half the cost of the one I built was the ZIF socket, which isn't strictly necessary of course. If your PC runs either DOS or Linux, you can get freeware programmer-drivers and assemblers off the net. There might even be a tiny-C compiler for them now. Not "professional quality" perhaps but quite usable. About the same applies to 68HC11s. 'HC11s are "bigger" chips: more memory, more complicated instruction set, lots more on-chip peripherals (A/Ds, timers, PWM outputs, and so forth.) They're very popular for hobbyist robotics. There's a reasonable amount of information on the net about both; I can point people in the right direction if they're interested. Wim. From owner-laser Wed Apr 9 20:53:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27634; Wed, 9 Apr 97 20:53:26 PDT To: laser@berlioz.nsc.com Date: Wed, 9 Apr 1997 23:38:53 -0400 Subject: Re: Looking for 40 - 50 mw IR diode Message-Id: <19970409.233853.12758.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-12,19-20,28-31,37-38,40-46 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Hello Folks > >I am looking for a 40 to 50 mw IR laser diode of anyone has >one they wish to part with or knows where 1 can be had > >Thanks > > >73's >PaulC KB1RP Find me one of these and I'll work you off the moon tomorrow night! Seriously, these should be available. The CD-R system that I bought a couple of months ago has a 35 mw IR diode in it and it does a pretty good job of marking up disks! I would think since these are now in mass production that the price of 35 mw IR diodes should have come down quit a bit and be readily available but so far I've come up with nothing. That's why I'm spending all this time trying to combine 10 smaller diodes. However, having the diodes helps also! :-^) The only thing that scares me a just a bit is just how fragile laser diodes are. I've had my share of them quit for no apparent reason. (I think the phase of the moon had something to do with it!) I'd hate to put all my money in one big diode and have it go the way of some of my 5 mw diodes. At least with a bank of ten of them it's unlikely that they'd all fail at the same time especially since the system I'm building up has seperate regulators for each diode. And even if all ten did fail I have enough spares to replace them all! While we're on the subject: Looking for B-I-G IR laser diode. 1 KW or larger. Will consider something smaller like 35 or 40 mw. (That's milliwatt not MEGAwatt!) Will trade ten or more smaller diodes, power combiner, collimation optics, 1 year's worth of sweat, burnt out laser diodes and other small parts. I'll even through in a box of photomultiplier tubes that don't work at 780 nm! Sorrry. Just having a little fun. I've been spending way too much time on this project lately !!! John K3PGP@juno.com -==- From owner-laser Sat Apr 12 13:06:19 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14525; Sat, 12 Apr 97 13:06:19 PDT From: daveaa1a@ssih.com Date: Sat, 12 Apr 1997 16:07:40 -0400 Message-Id: <199704122007.QAA28892@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Barcode Scanner To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I see in Electronic Goldmine a new arrival of a BarCode Reader by burr-brown with light pen and control box for 14.95... www.goldmine-elec.com 73 de daveaa1a From owner-laser Mon Apr 14 15:01:48 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16892; Mon, 14 Apr 97 15:01:48 PDT Content-Length: 341 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Mon, 14 Apr 1997 17:41:29 -0400 (EDT) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk Any life on the reflector?? test message!!! Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe From owner-laser Mon Apr 14 16:09:22 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18838; Mon, 14 Apr 97 16:09:22 PDT From: daveaa1a@ssih.com Date: Mon, 14 Apr 1997 19:10:52 -0400 Message-Id: <199704142310.TAA01586@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: LOWFER-LASER Transverter To: laser@berlioz.nsc.com Cc: bill@ietc.ca, microwave@wa1mba.org, cjr@wavefront.com, k0lr@emily.net, cbuttsch@slonet.org, wlake@silcom.com, rcal@ziplink.net X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Where did everyone go?? I was just sleeping it off from the last flurry of activity here on the reflector when a project hit me.. Am currently building a basic universal RF switched transverter for the IC-706 with dual Balanced Modulators that will supply 0-500khz at 1mw. in any mode for transmit and likewise receive down into the noise... This is all similar to the last set-up explained in previous messages to the list only full duplex... If the LOWFER head is plugged into the switcher than I can receive and transmit 160-190khz any mode with 1 watt output.. An E-Probe on the receive channel and a loaded wire or flat-top for transmit antenna makes portable work easier.. If the LASER head is plugged in then I receive light from baseband up to 500 khz++ and transmit with 3mw coherent diode with any mode from the Icom.. With Coherent/BPSK in mind for adding to the above, one can truly say that the Icom-706 covers DC to light with a few SMALL transverters.. I am planning to use the L.O. out of the Icom so that 'netting on Coherent' will be a reality.. With the optional Txo, things stay nice and stable for Coherent.. Even the stock unit is good once the offset is known.. Thanks to VE2IQ for the neat software and ideas.. You can get his version 6.0 Coherent BPSK software and other neat helper programs from his site: www.ietc.ca/home/bill/bbs.htm He also has some pre-made S-D boards to make life real easy as far as interfacing your radio to PC.. Anybody else doing a rig like this?? QRU-QRV from FN51/41/42 Lowfer through Light.. 73 de Dave Riley AA1A.. From owner-laser Tue Apr 15 09:41:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14400; Tue, 15 Apr 97 09:41:30 PDT Date: Tue, 15 Apr 97 09:41:27 PDT From: jmoss (Jim Moss) Message-Id: <9704151641.AA14394@berlioz.nsc.com> To: laser Subject: LOWFER-LASER Transverter Sender: owner-laser@berlioz.nsc.com Precedence: bulk Dave, Will you have any trouble copying FM'ed (full on/off) with that setup? I know it was intended for when the laser is operated in the "linear" region. I haven't said much lately,as I have been building up a 30KHz subcarrier system. Used a 555 modulated on pin 5. And on RX demod, used a 74HCT4046. (Why? It was at Radio Shack!) But I think a CD4046 would be better. The input to the HCT4046 needs 100-200mV to cross the threshold. On a qualitative basis the S/N looks to have to be much higher for the PLL to demodulate, than using 700Hz to the ear. I can hear stuff I can't see on the scope, but the PLL needs signal noticably above the noise. But it sure sounds good (fidelity). And it allows my daughter to enjoy the stuff more than MCW! I'll be presenting a laser demo at a local club Wednesday night. I hoped to finish the mod/demod system by then, but right now its on a proto board. Jim WB9AJZ/6 cm87xi ----- Begin Included Message ----- From owner-laser Mon Apr 14 19:41:17 1997 From: daveaa1a@ssih.com Date: Mon, 14 Apr 1997 19:10:52 -0400 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: LOWFER-LASER Transverter To: laser@berlioz.nsc.com Cc: bill@ietc.ca, microwave@wa1mba.org, cjr@wavefront.com, k0lr@emily.net, cbuttsch@slonet.org, wlake@silcom.com, rcal@ziplink.net X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Content-Length: 1589 Where did everyone go?? I was just sleeping it off from the last flurry of activity here on the reflector when a project hit me.. Am currently building a basic universal RF switched transverter for the IC-706 with dual Balanced Modulators that will supply 0-500khz at 1mw. in any mode for transmit and likewise receive down into the noise... This is all similar to the last set-up explained in previous messages to the list only full duplex... If the LOWFER head is plugged into the switcher than I can receive and transmit 160-190khz any mode with 1 watt output.. An E-Probe on the receive channel and a loaded wire or flat-top for transmit antenna makes portable work easier.. If the LASER head is plugged in then I receive light from baseband up to 500 khz++ and transmit with 3mw coherent diode with any mode from the Icom.. With Coherent/BPSK in mind for adding to the above, one can truly say that the Icom-706 covers DC to light with a few SMALL transverters.. I am planning to use the L.O. out of the Icom so that 'netting on Coherent' will be a reality.. With the optional Txo, things stay nice and stable for Coherent.. Even the stock unit is good once the offset is known.. Thanks to VE2IQ for the neat software and ideas.. You can get his version 6.0 Coherent BPSK software and other neat helper programs from his site: www.ietc.ca/home/bill/bbs.htm He also has some pre-made S-D boards to make life real easy as far as interfacing your radio to PC.. Anybody else doing a rig like this?? QRU-QRV from FN51/41/42 Lowfer through Light.. 73 de Dave Riley AA1A.. ----- End Included Message ----- From owner-laser Wed Apr 16 11:26:14 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11778; Wed, 16 Apr 97 11:26:14 PDT To: laser@berlioz.nsc.com Date: Wed, 16 Apr 1997 14:22:40 -0400 Subject: RCA PMT Specs ? Message-Id: <19970416.142242.8742.3.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-1,5-6,8-11,13-18 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk To ALL: Please excuse my absence. I've been trying to spend more time on the project and less time on the computer! I'll post an update when I'm a little further along as things are happening and changing too fast at the moment to document anything! Can anyone offer any specs (or cross this to another tube) for the following: RCA PMT 8852 The tube has an RCA factory chart on it with calibration figures for 8600 Angstroms so this appears to be a pretty rare IR beast! John K3PGP@juno.com -==- From owner-laser Wed Apr 16 17:37:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AB23210; Wed, 16 Apr 97 17:37:00 PDT From: sjnoll@ix.netcom.com Date: Wed, 16 Apr 1997 19:32:20 -0500 (CDT) Message-Id: <199704170032.TAA19688@dfw-ix14.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: RCA PMT 8852 To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hamamatsu says their R1017 is an exact replacement... Head-on 2" dia. Red Enhanced multialkali photocathode. 300-900 nm spectral response. 640 nm peak response. 1500V max anode to cathode, 1000V typical. 0.01 mA max average anode current. 250V max last dynode. 200 uA/lm typical cathode sensitivity. 2 nA typical anode dark current. 2.8E4 A/W typical anode radient sensitivity @ 632.8 nm. 7.0E3 A/W typical anode radiant sensitivity @ 852 nm. 2.8E4 A/W maximum anode radiant sensitivity. 7.5E5 typical current amplification. 7.8E-16 W ENI. 12 nS typical rise time. Pretty nice PMT. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html From owner-laser Thu Apr 17 01:48:38 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06566; Thu, 17 Apr 97 01:48:38 PDT To: laser@berlioz.nsc.com Date: Thu, 17 Apr 1997 04:47:32 -0400 Subject: PMT Info... Message-Id: <19970417.044739.10822.4.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-1,4-5,7-8,11-12,16-22,24-130 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Steve: I always post questions like this to the reflector so that others can benefit. I want to thank you for all the fine info that you have posted here in the past. I agree, this seems to be an extremely nice PMT. (R-1017) I can't wait to fire it up. Can you give me pinouts for this tube? I find it interesting that there are ratings right on the tube for 8600 A. The IR response on this tube must go way down into the IR before the tube finally quits. PS - Where can I get a data book like you are using to cross these tubes and come up with specs? I presently have several PMTs running, but I'm trying to get some of the other ones that I have up and running and I'm having trouble locating data. I also need the following: ----- Hamamatsu Hamamatsu R331-05 (*** Need Specs & Pinout ***) Hamamatsu R647-01 (*** Need Pinout only! ***) You alread y posted specs for this tube on the reflector! - Thanks! Hamamatsu R1017 (*** Need Pinout only! ***) ----- RCA 8852 > >Hamamatsu says their R1017 is an exact replacement... > >Head-on 2" dia. >Red Enhanced multialkali photocathode. >300-900 nm spectral response. >640 nm peak response. >1500V max anode to cathode, 1000V typical. >0.01 mA max average anode current. >250V max last dynode. >200 uA/lm typical cathode sensitivity. >2 nA typical anode dark current. >2.8E4 A/W typical anode radient sensitivity @ 632.8 nm. >7.0E3 A/W typical anode radiant sensitivity @ 852 nm. >2.8E4 A/W maximum anode radiant sensitivity. >7.5E5 typical current amplification. >7.8E-16 W ENI. >12 nS typical rise time. > >Pretty nice PMT. > >73, > >Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html > >R647-01 > >1/2" dia head-on >Selected for scintillation counting. >10-stage bialkali photocathode >300nm - 650nm, 420 nm peak >Anode-Cathode 1250V max. >Anode-Last dynode 250V max. >0.1 mA avg anode current max. >Cathode sensitivity: 90 uA/lm typ., 85 mA/W typ. >Anode sensitivity: 90 A/lm typ., 8.5 x 10^4 A/W typ. >Current amplification: 1 x 10^6 typ. >Anode dark current: 1 nA typ. >Rise time: 2.3 nS typ. > >Looks great at blue, pretty crappy at 670 nm. > >73, > >Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html ----- > >R928 PMT > >1 1/8" dia side-on type. >Extended red high sensitivity multialkali photocathode. >185nm - 930nm, 400 nm peak. >UV glass window. >9 stages. >1250V max, anode-cathode. >250V max, anode-last dynode. >0.1 mA max average anode current. >140 uA/lm min luminous sensitivity. >200 uA/lm typical luminous sensitivity. >6.8 x 10^5 A/W anode radiant sensitivity. >2000 A/lm typical anode luminous sensitivity. >1 x 10^7 typcial current amplification. >2.2 nS typical rise time. > >Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html ----- Dumont 6292 PMT > >Hamamatsu says their 7696 is a substitute for this. > >7696 >2" dia head-on type with plastic base. >S-11 response, general purpose. >300nm-650nm, 440 nm peak. >10 dynodes. >1500V max anode-cathode. >250V max anode-last dynode. >0.1 mA max average anode current. >40 uA/lm min luminous sensitivity. >80 uA/lm typical luminous sensitivity. >64 mA/W typical radiant cathode sensitivity. >4 x 10^4 A/W typical radiant anode sensitivity. >50 A/lm typical anode luminous sensitivity. >6.3 x 10^5 typical current amplification. >14 nS rise time. > >Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html ----- John K3PGP@juno.com -==- From owner-laser Thu Apr 17 16:09:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29683; Thu, 17 Apr 97 16:09:00 PDT Date: Thu, 17 Apr 97 16:08:57 PDT From: jmoss (Jim Moss) Message-Id: <9704172308.AA29677@berlioz.nsc.com> To: laser Subject: Article in MTTS? Sender: owner-laser@berlioz.nsc.com Precedence: bulk It should have read... NTMS - North Texas Microwave Society. Apparently K3PGP's article! ----- Begin Included Message ----- From jmoss Sun Apr 6 21:55:29 1997 To: laser Subject: Article in MTTS? Content-Length: 218 Heard there was an article this/last? month in MTTS about modifying a laser pen for use with data/voice etc!? Anyone see it? I don't get that magazine, and will have to search into our company library. Jim WB9AJZ/6 ----- End Included Message ----- From owner-laser Thu Apr 17 23:07:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09774; Thu, 17 Apr 97 23:07:31 PDT To: laser@berlioz.nsc.com Date: Fri, 18 Apr 1997 01:04:51 -0400 Subject: Article in MTTS? Message-Id: <19970418.020703.4630.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-19,22-23,26-31 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >It should have read... >NTMS - North Texas Microwave Society. >Apparently K3PGP's article! > >----- Begin Included Message ----- > >From jmoss Sun Apr 6 21:55:29 1997 >To: laser >Subject: Article in MTTS? >Content-Length: 218= > >Heard there was an article this/last? month in MTTS about >modifying a laser pen for use with data/voice etc!? > >Anyone see it? I don't get that magazine, and will have to search >into our company library. > >Jim >WB9AJZ/6 >From the Email that I've received on this it is apparent that something got lost in the editing. I understand it was based on what was posted here. Since I never saw the article I can't comment. I was promised a copy but never got it. If anyone has a copy I wouldn't mind seeing it. It's pretty hard to repond to questions when one doesn't even know what was printed! John K3PGP@juno.com -==- From owner-laser Fri Apr 18 06:28:13 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13954; Fri, 18 Apr 97 06:28:13 PDT From: sjnoll@ix.netcom.com Date: Fri, 18 Apr 1997 08:24:15 -0500 (CDT) Message-Id: <199704181324.IAA20023@dfw-ix10.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: PMT info, R331-05 To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hamamatsu R331-05 2" dia head-on. For liquid scintillation counting. spherical window. 300 nm - 650 nm range. 420 nm peak. 2500V max anode-cathode 500V max anode-last dynode. 0.2 mA max average anode current. 80 uA/lm typ luminous cathode sensitivity. 80 mA/W typ radiant cathode sensitivity. 120 A/lm typ luminous anode sensitivity. 1.2E5 A/W typ radiant anode sensitivity. 1.5E6 typ current amplification. 2.6 nS typ rise time. The radiant sensitivity drops to about 10% of its peak at 620-630 nm, at about 660-670 nm it is at about 1% of its peak. 1 DY1 2 DY3 3 DY5 4 DY7 5 DY9 6 DY11 7 P (Plate) 8 DY12 (Dynode 12) 9 IC (Internal Connection) 10 SH (Shield) 11 IC 12 DY10 13 DY8 14 DY6 15 DY4 16 DY2 17 G (Grid - focusing electrode) 18 IC 19 IC 20 IC 21 K (Photocathode) 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html From owner-laser Fri Apr 18 09:18:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18567; Fri, 18 Apr 97 09:18:20 PDT To: laser@berlioz.nsc.com Date: Fri, 18 Apr 1997 12:16:53 -0400 Subject: QSL.NET system Message-Id: <19970418.121653.4350.3.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,4,6-8,12-18 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: >My expectation for "light speed" on the "laser reflector" is like most >of yours, the faster the better... but like Art said, we are free loaders here. >I have considered moving the reflector to the QSL.NET system. Does anyone >have any experience with their response times? Typical response time is a matter of minutes. I just posted something there and had it echoed back while I was still online! Roundtrip time was approx. 3 minutes. However, this could change as the service becomes more poplular. It might pay to do some experimenting there! John K3PGP@juno.com -==- From owner-laser Fri Apr 18 09:54:14 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19348; Fri, 18 Apr 97 09:54:14 PDT Date: Fri, 18 Apr 1997 09:45:08 -0700 (PDT) From: Clifford Buttschardt To: daveaa1a@ssih.com Cc: laser@berlioz.nsc.com, bill@ietc.ca, microwave@wa1mba.org, cjr@wavefront.com, k0lr@emily.net, wlake@silcom.com, rcal@ziplink.net Subject: Re: LOWFER-LASER Transverter In-Reply-To: <199704142310.TAA01586@ssih.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi All.... Just a VERY short note as I just got home from sea. The call to return will happen once again in a few days. Nice working some of you on CW (3591). It certainly would be nice to have a laptop and IC 706 along but this would just be too much to lug up a Jacobs ladder on a tanker! I'll try and join you either tonight or Saturday night for a quick QSO---that is if Mother Chevron will allow! 73 Cliff K7RR From owner-laser Sat Apr 19 17:25:53 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00813; Sat, 19 Apr 97 17:25:53 PDT Date: Sat, 19 Apr 1997 20:23:15 -0400 (EDT) Message-Id: <2.2.16.19970419194052.2847af26@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: What makes a good detector? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, I just received a OPT 210 from Burr-Brown. I set this up inside 1 of my rx lens assemblies. I could not believe how much better it was than the opt 202. I set it up with a 120 meg feedback resistor that should yield a NEP of about 10 to -12.5 or so I don't have the docs here in front of me. I am using this in a reflective path. Using a barn(gray) as a reflector. I have a 5mw 670 SS diode as a Xmitter. The barn is 200 ' away. with the OPT 210 in a 4" RX the reflected signal seems to almost saturate the RX. As I attenuate the Xmitter power by blocking the beam slightly the intensity begins to drop to the point where I can no longer see it. The signal is still very strong into the RX. I will further attn. the signal to the point where it starts to become weak in the RX. With binoculars and only after my eyes have adjusted to the dark I can see the dot on the side of the barn. Change to the 6" Rx and the signal is strong again. I build all my RX's inside of aluminum tubing, for 3 reasons. 1 it shields the RX very well and 2 it allows easy comparison of the 2 RX units very quickly. 3 it allows adjustment of the focal point for initial acquisition of the signal. A little more attn. and the dot disappears from sight. I have also had my wife look for it as well as my 9 year old son. No one can see it. The RX can still hear it. This is still using the binoculars. My question is around the active area of the device itself. What spec makes a good detector? How can one compare the OPT 210 to a bare RX diode ? The BB device has a relatively large active area. Would the same device with a smaller active are be a quieter RX? Also how much of the gain of a PMT is due to the large active are? I don't' think I need this kind of sensitivity for an LOS shot but I am trying for a NON-LOS shot. Any good red PMT's out there? 1 other question I have is when does the ambient light on a moonless night become the dominant factor in a NON-LOS shot ....? Any ideas are all welcome Thanks for all the interesting info everyone!!!! 73's PaulC KB1RP From owner-laser Mon Apr 21 08:32:38 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14867; Mon, 21 Apr 97 08:32:38 PDT Message-Id: <199704211530.LAA12183@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 21 Apr 1997 11:30:35 -0500 To: "Paul A. Cianciolo" From: "Art Allen, KY1K" Subject: Re: What makes a good detector? Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >My question is around the active area of the device itself. What spec makes >a good detector? The ultimate rating is the NEP. A larger diode will make more noise internally-that's the laws of physics. Use the smallest active area that your rx can handle. Selecting the 'best diode' for the job is slightly more complicated. To do this, you need to consider more factors than just the NEP. For instance, a large frensel lens is NOT likely to focus all the captured light on a small active area device-lots of 'loss'. On the other hand, with a large high quality glass lens, you can use the small active area device to its best advantage. > >How can one compare the OPT 210 to a bare RX diode ? The BB device has a >relatively large active area. Would the same device with a smaller active >are be a quieter RX? > YES! >Also how much of the gain of a PMT is due to the large active are? > Gain from the PMT comes from the number of dynode stages. A small active area PMT with 10 dynodes will give the same performance as a large active area pmt with the same dynode structure. None of the gain comes from the large active area. Different active area tubes are made for different applications-fortunately, for our purposes, we can use just about any type of pmt as long as it is sensitive at the wavelengths we are running. >I don't' think I need this kind of sensitivity for an LOS shot but I am >trying for a NON-LOS shot. If you have clear air, you can work almost any LOS path with ss rx's and medium size rx optics. But, add a little fog, a wx front moving across the area or wood smoke from forest fires miles away, and you will be glad you had the extra RX sensitivity! >Any good red PMT's out there? > Red enhanced PMT's are available. Fortunately, HE-NE is widely used in the scientific community and therefore, red pmt's are made. I have priced Hamamatsu pmt's only, but, their 'red enhanced' photocathode units run about 200 dollars more than the standard types. None of them are cheap to buy NEW hi hi! Used pmt's are possibly abused-either by the original purchaser, or by the hammerheads that take the equipment apart without realizing what they are doing. Also, surplus places don't give a rats hoot about special handling needed to preserve the usefullness of the pmt. My opinion is that used pmt's are worth about 2 dollars each-read in the standard disclaimer... >1 other question I have is when does the ambient light on a moonless night >become the dominant factor in a NON-LOS shot ....? Any ideas are all welcome > ANY ambient light will create electron flow in the active device. Any electron flow is 'noise'. The bigger the lens, the more of a problem this is. For very very very weak signal reception, the answer is to minimize the stray light pickup from the stars. This probably isn't necessary unless you have a HUGH rx lens. Ambient light from nearby cities and stuff like that is much more likely to be a problem-if the atmospheric conditions aren't clear, then alot of this light can pollute because the light gets reflected by the atmosphere (ever notice the 'halo's over the cities). Again, the answer is to minimize stray light pickup and to use 60/120 hz active filters in the rx. Keep those lasers lit. and have fun.. Art, KY1K. From owner-laser Mon Apr 21 09:24:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16167; Mon, 21 Apr 97 09:24:41 PDT Date: Mon, 21 Apr 97 09:24:37 PDT From: jmoss (Jim Moss) Message-Id: <9704211624.AA16159@berlioz.nsc.com> To: laser Subject: OPT210 more Sender: owner-laser@berlioz.nsc.com Precedence: bulk To any 210 users... what are you using for feedback resistors? The highest value resistors I can find are 22M Ohm. I built up a 210 over the weekend with 6 x 18M. It's excellent. Got a good return off the top of a tree (in the leaves) about 200 ft over and 100 ft up with 2mW and NO lens. I tried using one of my PMT's and had much more noise. (still have some work on the PMT cct to do) Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Mon Apr 21 15:12:56 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25695; Mon, 21 Apr 97 15:12:56 PDT Date: Mon, 21 Apr 97 15:08:33 PDT From: jmoss (Jim Moss) Message-Id: <9704212208.AA25534@berlioz.nsc.com> To: flip@greene.xtn.net Subject: Re: schematic Cc: laser Sender: owner-laser@berlioz.nsc.com Precedence: bulk Philip, Thanks for the work... I put the schematic on the laser web under graphics and called it 555mod.gif Everyone. Philip transcribed the CHEAPO laser schematic (for the TX) for us. It is now on the laser page in subdirectory graphics file name 555mod.gif Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Mon Apr 21 15:38:42 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26631; Mon, 21 Apr 97 15:38:42 PDT Date: Mon, 21 Apr 97 15:38:37 PDT From: jmoss (Jim Moss) Message-Id: <9704212238.AA26624@berlioz.nsc.com> To: PaulC@snet.net Subject: Re: OPT210 more + PMT Cc: laser Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul, Only noticed flutter when I moved the laser across the tree. What are you using for feedback resistors (value & number). The PMT has an experimental I to V opamp, I suspect it is running away. I have: PMT OUT ------------/\/\/\/\/\/\/\/\/------------- | 1.5M | | |\ | | | \ | -----| \ | | \--------------------------------- -----| / gnd | / | / LM6365 |/ had to put a 200 pF cap across the resistor to make it quiet. Was oscillating at about 10MHz or so. Seems to work better with "slower opamps". Anyone have any good PMT interface designs? Jim WB9AJZ/6 From owner-laser Mon Apr 21 16:51:05 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28871; Mon, 21 Apr 97 16:51:05 PDT Date: Mon, 21 Apr 97 16:51:01 PDT From: jmoss (Jim Moss) Message-Id: <9704212351.AA28862@berlioz.nsc.com> To: laser Subject: Re: OPT210 more + PMT Cc: PaulC@snet.net Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul, where did you find such big resistors? Alan mentioned he can get 1 Gig resistors but they cost like $3. The OPT 211 is supposed to be better than the 210 for leakage. But I don't expect a large difference. Signal did peak somewhat (but very broadly) when moving the angle of the 210. Laser used is about 1.5-2 mR (not measured) but definitely more than my 1mR (measured) one. I was not running thru my DSP. I was just hand holding the RX and feeding into a cheep RadioShack pocket amp, and into headphones. Signal and noise were both quite low. Sky was quite bright with Sodium Vapor lamp and other lights to surface of clouds. (didn't get a signal on cloud bounce) But I did find out that the 210 would pick up backscatter from side lobes(?) of the laser (fringe?) when the beam was within 6" of another object (invisible to me). This can give some surprises if you don't watch out. (think you have a signal when you don't!) I will try again with another PMT (the one I was using is unknown response, and unknown quality). Another I have is red shifted and "box kept". Jim WB9AJZ ----- Begin Included Message ----- From PaulC@snet.net Mon Apr 21 16:07:05 1997 Date: Mon, 21 Apr 1997 19:03:48 -0400 (EDT) X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: jmoss@berlioz.nsc.com (Jim Moss) From: "Paul A. Cianciolo" Subject: Re: OPT210 more + PMT Content-Length: 1779 Hello Jim, I am using 2 in series 56 meg resistors 2%... I could not find better tolerance . How strong was the signal? Could you have angled the detector slightly and still heard the signal? Also what divergence was the laser... this end is 1.5 mr I am going to try a 1400 round trip shot tonight. The target will be a birch tree. I have no leaves here yet!!! This is where knowing the headroom in SNR of the RZ system would be helpful. I am using a audio filter after the opt 210 and before the audio amp. This is a military surplus LC filter. The thing works great. Centered around 900 hz. My Xmitter is at 900 hz. PS I thought the PMT would have blown away the OPT 210 in this test. Will you try it again when the oscillation is taken care of? PS I wonder if the OPT 210 is the quietest thing on the market today? At 03:38 PM 4/21/97 PDT, you wrote: >Paul, > >Only noticed flutter when I moved the laser across the tree. > >What are you using for feedback resistors (value & number). > >The PMT has an experimental I to V opamp, I suspect it is running away. >I have: > >PMT OUT ------------/\/\/\/\/\/\/\/\/------------- > | 1.5M | > | |\ | > | | \ | > -----| \ | > | \--------------------------------- > -----| / > gnd | / > | / LM6365 > |/ > >had to put a 200 pF cap across the resistor to make it quiet. >Was oscillating at about 10MHz or so. > >Seems to work better with "slower opamps". > >Anyone have any good PMT interface designs? > >Jim >WB9AJZ/6 > > 73's PaulC KB1RP ----- End Included Message ----- From owner-laser Mon Apr 21 17:58:48 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01124; Mon, 21 Apr 97 17:58:48 PDT Date: Mon, 21 Apr 1997 20:55:14 -0400 (EDT) Message-Id: <2.2.16.19970421201229.12b73ea8@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Re: OPT210 more Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Jim, Just got dark enough here to use the OPT210 RX. I aimed at a birch tree about 700' away. 1400' round trip approx. The tree is about25 feet tall. I would guess it is about 2" or so in dia. at the point I was using for a target. I got very good returns so strong I covered about 80% of the lens and could still hear it fine. I need to go somewhere to achieve a greater distance than this since that was my longest LOS to an object within reason. I am very excited. Sure gave me an opportunity to optimize the focal point of the RX. Also it is not all that clear here tonight. >Date: Mon, 21 Apr 1997 17:44:19 >To: jmoss@berlioz.nsc.com (Jim Moss) >From: "Paul A. Cianciolo" >Subject: Re: OPT210 more > >Hello Jim, > >What freq were you using when you while you had the 108 meg feedback? > >Did the leave cause a flutter on the return signal? > > >At 09:24 AM 4/21/97 PDT, you wrote: >> >>To any 210 users... >>what are you using for feedback resistors? >>The highest value resistors I can find are 22M Ohm. >> >>I built up a 210 over the weekend with 6 x 18M. It's excellent. >>Got a good return off the top of a tree (in the leaves) >>about 200 ft over and 100 ft up with 2mW and NO lens. >> >>I tried using one of my PMT's and had much more noise. (still have some work >>on the PMT cct to do) >> >>Jim >>WB9AJZ/6 CM87xi Sunnyvale, CA >> >> > 73's PaulC KB1RP From owner-laser Mon Apr 21 20:23:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04035; Mon, 21 Apr 97 20:23:47 PDT Message-Id: <335C217D.49F2@lan.nsc.com> Date: Mon, 21 Apr 1997 19:25:01 -0700 From: Dave Fifield Organization: National Semiconductor Corp. X-Mailer: Mozilla 3.01 (Win95; I) Mime-Version: 1.0 To: laser@berlioz Subject: Cheapo TX Circuit References: <9704212208.AA25534@berlioz.nsc.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim et al, I built the 555 cheapo TX circuit yesterday and found that it had problems, at least with my laser. I'm assuming that the original circuit intended to keep the laser pointer's batteries in circuit and that the output from the cheapo TX goes to a third wire (switch input of some sort) on your laser. My laser did not have this arrangement at all. The switch in my pointer was directly in the battery (3V) line and there are just two wires on the laser (red and black). Is this unusual? I reasoned that if I put the laser from the collector of the transistor up to +9V it might work. Well, it did, but only weakly. The transistor just couldn't supply enough current to run the laser properly. I figured that an average of 4.5V shouldn't kill the laser too quickly (does anyone know if it will kill the laser faster in the long run?). Also, looking at the drive waveform on my 'scope, I found the duty cycle was all wrong. Anyway TCALSS, I changed the 555 circuit to the one that generates a 50% duty cycle output (in all the old National Semiconductor databooks) and changed the driver transistor to a 2N7000 MOSFET. This can deliver plenty of current for my laser. It now works just great. I put it all in a little Al box with switches and a key jack - looks nice. If anyone wants it, I'll draw up a circuit of what I ended up with and post it. Sent off for some OPT210's today also.....can't let you guys have better receivers than me! When I've got the whole set up going properly I'll be looking for skeds, stay tuned. Dave, AD6AY From owner-laser Tue Apr 22 09:54:58 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23339; Tue, 22 Apr 97 09:54:58 PDT To: laser@berlioz.nsc.com Date: Tue, 22 Apr 1997 12:42:18 -0400 Subject: Optimizing PMT and Other Laser Receive Front Ends Message-Id: <19970422.124220.6406.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-1,4-7,10-11,13-18,22-23,27-38,40-41,43,45-56, 59-63,65-70,72-76,79-84,88-89,95-96,101-102,105-106,109-113, 119-120,128-129,135-136,141-142,146,149-150,152-153,157-158, 160-161,168-169,171-172,176-177,184-185,188-189,194-195,198-199, 201-204,210-213,217-218,221-222,225-226,229-230,233-237,239-240, 246-247,250-251,256-257,261-262,264-271,273-274,277-282,286-287, 291-294,297-298,302-305,310-311,315-324,326-327,334-335,337-338,341-349 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk To all: I wasn't quite ready to publish this, but since others are apparently having trouble getting PMTs up and running, here are some notes on the difficulties that I had and some observations. I was under the impression that only I was having these difficulties! I will be revising this very shortly. This is only a rough draft of the info that I've accumulated so far. I will post the revised copy later on complete with graphics. I have tried to convert some of the graphics to text drawings. I hope they are readable. --------------------------------------------- A few notes on PMT front ends: --------------------------------------------- There is nothing wrong with using an op-amp I / V converter. However, since we are working with weak signals we don't need wide dynamic range nor laboratory linearity and can get by with something a LOT simpler using readily available parts. (Radio Shack :-^) !!! Keep in mind that you are dealing with an ACTIVE device that has a LOT of gain and for this reason it doesn't require as much attention (for typical laser communication use!) to front end design as an INactive device such as a PIN diode. I have had excellent results with a simple MPF-102 RC coupled preamp! ----------------------------------------- MPF-102 PREAMP ---------------------------- 10 Meg |--/\/\/\/\/\/----GND | | MPF-102 drain Coax .01 uf | gate |---------------------->Out PMT >----|-----| |------------|-------------------| 2.2 k | |--------/\/\/\/\/\---- GND | |------||---------GND | + 10 uf | |-/\/\/\/\/\------/\/\/\/\/\------GND 100 K | 10 K |------------------> Protection circuit ---- + (Strong Light) ---- 10 uf (Over Current, etc.) | | GND When wiring and powering this be extremely careful to avoid ground loops. You are dealing with extremely high gain and meticulous attention must be paid to proper grounding techniques and shielding! ----------------------------------------- NOTE: The above preamp is designed to be REMOTE powered. Of course you can change this if you like. Here's the remote power setup: MPF-102 >----------------||------------------> To receiver front end Preamp | .1 uf Assumes high impedance! | | 10 k 1 k |-----/\/\/\/\/\/-----------/\/\/\/\/\------- + 12 vdc | |----------||-----------GND + 100 uf Just remember to properly decouple it from the 12 vdc power supply. (1 K and 100 uf cap to ground.) Even if you think your supply is quiet you will most likely still need this! ----------------------------------------- THE PROTECTION CIRCUIT ----------------------------------------- As most of us are painfully aware, a PMT can be damaged by too much light. Because of this my present system has a shutter mounted in front of the tube. It is held open with a solenoid. A small DC motor could also be used. In series with the signal electrode load resistor is a 10 k resistor in parallel with a capacitor to ground. This connects to a voltage sensing circuit. (The voltage will be close to zero with a good tube and go negative with increasing light. If you see any kind of voltage here (even a couple of millivolts) with zero light and the high voltage on your tube may be damaged from a previous exposure to high light levels!) My circuit is set to trip at 1 volt. (This is NOT a lot of light folks! - In fact I can't see this so it may be safe to increase this a bit. For now I'm playing it safe!) When the trip point is reached an RS flip flop is toggled removing power from the solenoid and the shutter snaps closed! It remains closed until manually reset. NOTE: Power MUST be applied to open the shutter. This is a failsafe system to prevent accidental exposure to high light levels even when powered down! This might seem like a lot of extra work but since it took me two years to find what I assume is a good PMT I'm not taking any chances with it! Finding ones that work at 780 nm is even more difficult! OPERATION & TESTING ------------------------------------ Applying power to the FET (with the PMT high voltage off !) brings the noise up on the system approx. +20 dB. If you don't see a noise increase you need to work on the system following the FET. The actual amount of noise increase isn't important, just so you have enough gain that the FET is establishing the noise figure of the system. Much the same as a weak signal VHF/UHF receiving setup. Applying high voltage to the PMT should cause another large increase in noise output from the system. Mine comes up approx. +10 dB with a good tube. This increase in noise means that the PMT is establishing the noise figure of the system. If you are seeing this then any further improvements in the preamp will be useless as the only thing you will achieve will be more or less gain with NO change in signal to noise ratio. In the above case the SNR is being established by the PMT and NOT the preamp. This is as it should be. A tube that has been exposed to too much light will cause an even larger increase in noise, and a dead tube may not cause any increase at all, so this noise test doesn't mean that things are working correctly and 10 dB isn't a magic number. It depends on the tube and the only important thing is that you are seeing a noise increase when the high voltage is turned on. Some tubes have more gain, some have a higher dark current, etc. No two tubes are alike. Not even two with the same number when new! The amount of high voltage will GREATLY influence this also! One of my tubes that was accidently exposed to too much light causes an increase of +45 dB. Needless to say it's now useless! When making this test make sure the PMT is in TOTAL darkness. It's more sensitive than your eyes are. If you place a piece of dark paper or aluminum foil around the PMT and the noise floor drops you have too much stray light! Watchout for the not so obvious things like CRTs, (including the TV set in the next room!), LED and blue flourescent displays on test equipment as well as neon bulb power indicators! Remember to cover the back of the PMT as well as the front. Light coming into the sides of the PMT will also bring the noise floor up. The PMT should be hooked up with ANODE grounded and cathode at -1000 to -1500 volts. (Most tubes will still work fine with 700 to 800 volts. You get less gain but usually the weak signal performance (signal to noise ratio) remains the same.) If the tube has a gate electrode you will need to bias this so that it is on all the time. If you need help with this drop me a note. Most PMTs have a falling response at the red end of the spectrum. A few of mine are excellent at 330 nm but won't detect anything at all at 780 nm, even if the laser is fired directly into the PMT window! (I didn't think a response curve like this was achievable but apparently these tubes have some kind of IR / red filter on them that won't allow any red through at all! This in combination with the falling red response of the PMT produces ZERO response!) If the PMT isn't 30 to 50 dB better than your best solid state detector something is seriously wrong! (For those of you thinking about world records, etc. you can tack on another 30 to 40 dB sensitivity increase using FFT techiniques. A front end like this makes the typical solid state detector setup look like a spark gap and crystal set! More on this shortly!) The tube could have been exposed to too much light. The tube could have a response curve that makes it useless at 670 nm. Remember to put a load resistor between the signal electrode and ground! You could be having power supply problems. The supply MUST be as stable as a rock. Any variation will be multiplied exponentially by the PMT making for an extremely noisey and unstable front end! I wasted several days using a bad power supply! Most PMTs have a falling response at the red end of the spectrum. A few of mine are excellent at 330 nm but won't detect anything at all at 780 nm, even if the laser is fired directly into the PMT window! The PMT must be shielded especially if it is of the larger 2 inch by 6 inch variety but this also applies to the miniature variety as well. The internal structure of the PMT acts like an antenna (capacitive probe) hooked to the high gain high impedance preamp and will pick up all surrounding electric fields including radio signals! A readily available shield that seems to work well is aluminum foil. However, anything placed against the glass of the tube MUST be at cathode potential, otherwise you will RAISE the noise floor! If you are using the grounded anode circuit, this means the shield will be at -1000 to -1500 volts, a very dangerous situation to say the least! Two solutions: # 1 - Wrap an insulator around the tube. Black paper works well but I'm not sure what might happen on a damp summer night! (This won't damage the tube, however the noise will become unbearable!) The aluminum foil is wrapped around the insulating layer and connected to ground potential (anode!). For a connecting wire, wrap some of the foil around a piece of copper wire and tape it. Use the copper wire as the ground strap. # 2 - More work but probably a better setup! Wrap a piece of aluminum foil around the glass envelope. Make the length such that it ends approx 1/4 to 1/2 inch from the front of the tube. Include a copper wire ground strap and connect this to the cathode. (should be at -1000 volts or so!) Wrap a second layer around tube but this time use a good insulator. (One that can't absorb moisture!) The insulator should overlap the front and back edges of the foil by 1/4 to 1/2 inch or so. At this point you can tape everything up with electrical tape and call it good. However, since I tend to handle my PMTs a lot on the bench I prefer to have a ' safety ' shield! For the safety shield I use another layer of aluminum foil complete with copper wire ground strap. However, this ground strap is connected to the anode which is at 0 volts (ground). If you do this correctly it will be possible to slip the shield off the tube! I use a setup like this for testing PMTs on the bench and have been using the same shield now for a couple of months. SIGNAL SOURCES ---------------------------- If you are going to work on laser receiving front ends, do yourself a BIG favor and build up a weak signal source! I have had very good luck with an LED hooked in series with a high value pot. Don't make the mistake of using a low value pot like 1 K or so and a low value series resistor to the LED. This will cause the LED to have a very small dynamic range. (It wants to go full on or off at a well defined current.) PS - I talking about standard LEDs here and NOT laser diodes but this comment applies to BOTH! If you can see the LED lighting you have way too much current going through the LED to serve as a weak signal source unless of course you are working with a dead front end! If you are working with a 630 to 670 nm system use a standard red LED. If you are working with an IR system use an IR LED. However, if you are working with a 780 nm system like I am you may run into difficulty trying to come up with a 780 nm LED! The typival 820 to 904 nm IR diodes are too far down the response curve of most PMTs to be of much use. In this case I used a 780 nm laser diode operating way BELOW threshold. True it's output isn't any more spectrally pure than a simple LED, but we don't need this to test front ends! The output is still close enough to 780 nm to be useful. NOTE: You will only be putting a couple of microamps through the LED or laser diode for use as a weak signal source. ------------------------------ 10 K 100 K ten turn pot 5 VDC >------/\/\/\/\/---------/\/\/\/\/\/\/\/\/-------------GND Can be modulated! ^ | 10 K --/\/\/\/-----LED-------GND Mount the LED in a flat black cardboard tube that slips over the PMT or whatever detector you are using. Read the signal level from the calibrated turns counter on the ten turn pot. ------------------------------- NOTE: If you are working with PMTs, you will need to change the 10 K resistor (from the 5 volt line) to something like 1 megohm or more to get the ten turn pot off the stop! This should give you some idea as to the sensitivity of a GOOD PMT! Of course you can also increase the value of the 10 k resistor to the LED. Doing either however, will limit the maximum signa level that the test signal can put out. What you end up with will depend on whether you are using solid state front ends or PMTs. ----- I'm developing a CALIBRATED weak signal source, complete with homebrew optical attenuators. Please don't ask for info on this. I have nothing to send at this time !!! I will post the info when it's available. However, you don't need absolute calibration to compare two front ends. All you need is an AC voltmeter calibrated in dB and a relative signal source that is adjustable. I think you will find the above circuit more than you need to compare and optimize front ends. ----- You should also have a good AC voltmeter calibrated in dB. Something like an old HP-403B with scales from -60 dB to +50 dB is very nice. The companion attenuator setup (Model 353A Patch Panel) has a calibrated attenuator that goes in 1 dB steps from 0 to 100 dB and is also very helpful! If you don't have something like this, keep your eyes open this summer at hamfests, flea markets, etc. I picked up the attenuator set for $10 and the voltmeter for free! (The internal nicad batteries shorted making the unit inoperable!) This concludes Chapter one on laser receiving front ends. Stay tuned to 780 nm for info and late breaking news! ----- And now a few comments from the editorial staff: Lets all join in and do what we can to stop this crazy light pollution that is going to ruin our hobby and all astronomical observations! Pointing a good PMT into the typical night sky that we have today will cause the noise floor to come up +20 dB or so and this is a sky that appears black (other than starlight) to the naked eye! Analysis of the resulting noise floor indicates hamonics of 60 Hz up through the 13 th at 780 Hz, indicative of mercury and sodium vapor street lighting being scattered back from the upper atmosphere! I'm working on filters to reduce this. (If you have a street light across the street you can FORGET IT! Take up stamp collecting!) It's a shame to have this kind of sensitivity and not be able to use all of it because of a city twenty miles away causing the sky to glow because of improperly installed lighting fixtures! Keep those lasers lit and the skies dark! John K3PGP@juno.com -==- From owner-laser Tue Apr 22 12:35:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27541; Tue, 22 Apr 97 12:35:11 PDT Date: Tue, 22 Apr 97 12:35:09 PDT From: jmoss (Jim Moss) Message-Id: <9704221935.AA27535@berlioz.nsc.com> To: laser Subject: Cheapo TX Circuit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Dave, Don't put higher voltage on your diode system. They are quite fragile. The way the cct was designed was to have 2 independent voltage sources, One for the laser and one for the oscillator. The laser (many have a buffered switch, especially if they have BLINK mode) so current is minimal thru the xistor. for others, it may be necessary to set up as a darlington pair. The goal is to do as you expected, act as a short between the laser batteries and the laser. Since the voltage sources are independent, you can close either the ground side or the hot side, but have to be sure the collector is to the more positive side. Each laser is a bit different and caution should be the name of the game when opening them up and deciding what to connect where. 50% duty cycle and 600-800 Hz is the goal of the 555 design. Jim WB9AJZ/6 ----- Begin Included Message ----- From owner-laser Mon Apr 21 23:51:35 1997 Date: Mon, 21 Apr 1997 19:25:01 -0700 From: Dave Fifield Organization: National Semiconductor Corp. X-Mailer: Mozilla 3.01 (Win95; I) Mime-Version: 1.0 To: laser@berlioz Subject: Cheapo TX Circuit Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Content-Length: 1553 Jim et al, I built the 555 cheapo TX circuit yesterday and found that it had problems, at least with my laser. I'm assuming that the original circuit intended to keep the laser pointer's batteries in circuit and that the output from the cheapo TX goes to a third wire (switch input of some sort) on your laser. My laser did not have this arrangement at all. The switch in my pointer was directly in the battery (3V) line and there are just two wires on the laser (red and black). Is this unusual? I reasoned that if I put the laser from the collector of the transistor up to +9V it might work. Well, it did, but only weakly. The transistor just couldn't supply enough current to run the laser properly. I figured that an average of 4.5V shouldn't kill the laser too quickly (does anyone know if it will kill the laser faster in the long run?). Also, looking at the drive waveform on my 'scope, I found the duty cycle was all wrong. Anyway TCALSS, I changed the 555 circuit to the one that generates a 50% duty cycle output (in all the old National Semiconductor databooks) and changed the driver transistor to a 2N7000 MOSFET. This can deliver plenty of current for my laser. It now works just great. I put it all in a little Al box with switches and a key jack - looks nice. If anyone wants it, I'll draw up a circuit of what I ended up with and post it. Sent off for some OPT210's today also.....can't let you guys have better receivers than me! When I've got the whole set up going properly I'll be looking for skeds, stay tuned. Dave, AD6AY ----- End Included Message ----- From owner-laser Tue Apr 22 12:43:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27840; Tue, 22 Apr 97 12:43:06 PDT Date: Tue, 22 Apr 97 12:43:04 PDT From: jmoss (Jim Moss) Message-Id: <9704221943.AA27833@berlioz.nsc.com> To: laser Subject: opt210 and PMT's Sender: owner-laser@berlioz.nsc.com Precedence: bulk Fixed my PMT issues last night. Rebuild the I-V converter and added a small feedback cap (200pF). Seemed to work fine with the other PMT. one is a -05 marking and was "unknown", the other a -08 and was box kept. Anyway, with the box kept one... I couldn't even lower the gain enough to prevent saturation! Had to cover the opening partially! (it was overcast, and we had a full moon shining in, and reflected light off the bottoms of the clouds from the city... very bright to a dark adapted eye). So I put a 650 +/-20 nM filter in place (50% in pass band) and was able to play around a bit (also reduced opening by 60%). Since conditions were different than the other night (no clouds then); I repeated trying the OPT210 vs PMT. The added background light level reduced the 210 to a barely perceptible signal at 200ft off the tree trunk. The PMT was Q5. This was all done with about 2mW 2mR 670nM and NO LENSES on either RX. Found significant improvement by shielding light with my hands... Obviously adding a lens or a tube to restrict light outside the desired location will have significant positive effects! Jim WB9AJZ/6 From owner-laser Tue Apr 22 16:47:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04907; Tue, 22 Apr 97 16:47:57 PDT Date: Tue, 22 Apr 1997 16:39:55 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704222339.AA15955@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: regenerating BROKEN PMT's, maybe. Cc: k3pgp@juno.com X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From: music@Tempe.ate.slb.com (Doug Music) Subject: Re: Optimizing PMT and Other Laser Receive Front Ends John, DON'T THROW AWAY THAT PMT!!! [unless you want to throw it to me ;-) - rusty] If your interested, try this trick. Put the light zapped PMT in your oven and bring it to 250 F. Wait 10 minutes and bring it to 350 F. Wait 10 minutes and bring it to 425 F. Wait 4-8 hours and turn it off. LEAVE THE TUBE IN THERE TILL BELOW 150 F. Give the tube a try again. This ONLY works for bakeproofed tubes (thermoset as opposed to thermo plastic bases). If your tube has thermo plastic it will melt. If it has thermoset plastic, it will not. Your call. This trick works a lot of imaging tubes and can be used to drive the sensitivity way up. This also CREAMS A LOT OF TUBES so don't do this to a known good tube. Oh... do this in dark conditions...NO light AT ALL while hot. -Doug From owner-laser Wed Apr 23 02:25:18 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18238; Wed, 23 Apr 97 02:25:18 PDT To: laser@berlioz.nsc.com Date: Wed, 23 Apr 1997 05:27:29 -0400 Subject: PMT High Voltage vs SNR Message-Id: <19970423.052729.8742.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,4-5,11-12,20-21,26-27,30-31,35-36,42-43,51-52, 61-64,68-69,75-81 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk PMT High Voltage vs SNR -------------------------------------- I ran across an interesting thing this evening while playing around with some PMTs that I thought were light damaged. What I am calling a good tube normally puts outs a noise floor of round (-43) dbm with NO light. (This is a relative reading and can be set to any number simply by adjusting the gain.) A weak test signal at 780 nm was injected into the front of the PMT and read approx. (-19) dbm making the SNR somewhere around +24 dB. (-43) - (-19) = +24. This tube was running at -905 volts as were all the tubes that I tested up til now! I was going to do some playing around with the system so I took out my ' good ' tube. I replaced it with one that I assumed was light damaged because it always displayed an elevated noise floor. When the HV was turned on the noise floor was at -16 dbm and the signal was now at +1 dbm making the SNR approx. +15 db, exactly the same as the last time I tested this tube! Even when running in this severely degraded mode this tube is still a LOT better than any solid state detector and that's why I never tossed the tube in the junk! While playing around with the system I accidently dropped the high voltage to 800 volts. The noise floor was now (-25) dbm, signal (-4) dbm and SNR +21 db! I continued to drop the voltage until the SNR peaked and then started to drop again. Returning to the point of highest SNR I measured everything. Voltage = 563 volts. Noise floor = (-47) Signal = (-23) SNR = +24 db !!! And this was out of a tube that I had previously put in the junk box because it I thought it was damaged !!! After seeing this I am now going to restest ALL my tubes and adjust the HV for optimum SNR. I'm very curious to find out what happens to my ' good ' tube when I optimize the HV. I don't know if it will be possible to get more than +24 SNR out of it or not. If you are playing around with PMTs and are NOT optimizing the HV for best SNR you could be missing a good thing! I don't know exactly what all this means just yet, but I find it most interesting. Up till now I just assumed that the more voltage you put on a tube the more gain it produced. I didn't know that there was an optimum voltage to produce the best SNR. If you are going to attempt this you will need a very stable weak signal source. Aiming across the yard or across the basement probably isn't a good idea as there are too many variables and it's extremely hard to duplicate measurements from night to night. You will need a light tight fixture for the PMT with an LED of the appropriate wavelength in front of the PMT. I modulate my weak signal LED source with a 50% duty cycle 800 Hz square wave so that I can use a HP AC voltmeter for the output indicator. By the way my latest PMT housing is a couple of tomato puree cans soldered together and LINED WITH BLACK PAPER. (< This is IMPORTANT!!!) All electrical connections come out the back. This produces a light tight housing and provides all the necessary shielding without having to tape anything to the glass envelope of the PMT itself. There is about an inch spacing between the glass and the metal can when using a big 2 inch diameter PMT that is approx. 6 inches long. (Can approx. 4 inches in diameter.) Black foam rubber or crumpled black paper can be stuffed around the PMT for shock mounting. One note of caution! I did have trouble with light leaking in around the coax connector in the back of the can. I couldn't see how this was possible as it appeared the can was being pulled up against the connector with the four mounting screws. I ended up putting a black piece of paper in the back of the can to block any leakage from the rear. Before I did this, turning on the lights in the room would bring the noise floor up approx. 20 dB and this was through a hole BEHIND the PMT that I couldn't even find by visual inspection. (The front end of the can was covered and was NOT leaking any light.) The sensitivity of these tubes never ceases to amaze me! John K3PGP@juno.com -==- From owner-laser Wed Apr 23 06:24:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA22924; Wed, 23 Apr 97 06:24:06 PDT Message-Id: <199704231322.JAA25406@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 23 Apr 1997 09:22:27 -0500 To: c1040@azfms.com (Rusty Carruth) From: "Art Allen, KY1K" Subject: Re: regenerating BROKEN PMT's, maybe. Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 04:39 PM 04/22/1997 -0700, you wrote: > >----- Begin Included Message ----- > >From: music@Tempe.ate.slb.com (Doug Music) >Subject: Re: Optimizing PMT and Other Laser Receive Front Ends > > >John, > >DON'T THROW AWAY THAT PMT!!! > > >[unless you want to throw it to me ;-) - rusty] > >If your interested, try this trick. Put the light zapped PMT in your >oven and bring it to 250 F. Wait 10 minutes and bring it to 350 F. >Wait 10 minutes and bring it to 425 F. Wait 4-8 hours and turn it off. >LEAVE THE TUBE IN THERE TILL BELOW 150 F. > >Give the tube a try again. > >This ONLY works for bakeproofed tubes (thermoset as opposed to thermo plastic >bases). If your tube has thermo plastic it will melt. If it has thermoset >plastic, it will not. Your call. > >This trick works a lot of imaging tubes and can be used to drive >the sensitivity way up. This also CREAMS A LOT OF TUBES so don't do this to >a known good tube. > >Oh... do this in dark conditions...NO light AT ALL while hot. > > >-Doug > > Incidently, hi vacuum is a nearly perfect insulator-the 4 to 8 hour bake times mentioned above indicate that this process requires heating of the guts of the tube, not just the outer glass envelope. Along the lines of heating glass and maintaining vacuum seals.. I might be able to contribute. I used to work with plasma systems and high vacuum systems at Fairchild semi. 'Thermo plastic????' The ONLY insulator that is suitable for vacuum tubes is glass (maybe I'm behind the times on this topic). This is because the tube envelope cannot be allowed to outgass as it is heated-if it does the tube becomes noisey. The envelope must be heated in order to seal the tube WHILE it is exposed to high vacuum-this is a tall order hi hi. Also, glass is a real good insulator. Absolute electrical insulation necessary to maintian the near zero leakage currents (which is why we have a low noise PMT). The envelopes are made with a small outlet through which a vacuum is applied to the interior of the tube. Then, this outlet is heated (while still applying the vacuum). This causes the outlet to collapse, which seals the tube. You can see these little 'nubs' on most vacuum tubes. I'm guessing that plastic has not been developed that can perform like this, so damaging the PMT vacuum seal to the outside world will probably not happen at oven temps. Any plastic used in PMT's would have to be an extremely low outgassing type, and would have to be an extremely good electrical insulator! The internal interelement spacings within the PMT are VERY CRITICAL however-and these dimensions MIGHT be maintained by plastic parts-again, this probably ISN'T likely as plastics will degass and destroy the high vacuum within the tube. The hi tech plastic type materials which are suitable for hi vacuum enviornments do not outgass (much), but teflon, delrin and other similar solids will not be damaged by home oven temps either..... We should bear in mind that the PMT must have an extremely high vacuum level within the envelope in order to be low noise. Towards this end, the envelope and all the internal guts of the tube are heated during the manufacturing process anyway! This helps to remove the last trace of gas in the tube (which is a single molecule thickness layer which sticks like glue to all the internal surfaces). The idea is to heat the tube while applying the high vacuum from the cryo pump/turbo pump. I don't know what temperature they actually heat these tubes to during manufacturing, but I would guess 200 to 300 c (minimum). So, I'm not quite sure where the damage comes from when we heat the tube to 450 degrees in the home oven. My guess is that it does not come from any melting of plastic in the tube envelope or in the internal supporting structure of the interelements. My guess is that there might be a gas trap built into the tube to catch misc small ammount of left over gas molecules. This 'trap' is the silvered surface visible through the glass envelope of the PMT. By heating the tube once the gas trap is already saturated, we might release this trapped gas into the tube. Perhaps this is why some oven heated tubes become unusable? Or, maybe the the heating of the interelements releases the trapped mono-layer gas, which is then sucked up and trapped by the internal gas trap? If this is the case, then we need to be real careful to apply just the right ammount of heat and not to over do it. Any idea what the actual repair process is here? How does this heating actually improve the performance? Is this home oven method applicable to a permanently damaged PMT, or is it just applicable to a PMT that has been exposed to a slight overload and is 'temporarily' noisey for a few days (till it gets better on its own)? Inquiring minds want to know! Drop a line to the reflector. Keep them lasers lit and good dx!!!!! Art... Hey, let's get Doug on the laserlist hi hi! From owner-laser Wed Apr 23 06:45:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23414; Wed, 23 Apr 97 06:45:11 PDT Message-Id: <199704231343.JAA27316@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 23 Apr 1997 09:43:45 -0500 To: k3pgp@JUNO.COM (John K3PGP) From: "Art Allen, KY1K" Subject: Re: Optimizing PMT and Other Laser Receive Front Ends Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >I wasn't quite ready to publish this, but since others are apparently >having trouble getting PMTs up and running, here are some notes on the >difficulties that I had and some observations. > >I was under the impression that only I was having these difficulties! > >I will be revising this very shortly. This is only a rough draft of the >info that I've accumulated so far. I will post the revised copy later on >complete with graphics. When in doubt 'publish'. And please accept my thanks for taking the time to put this together John! > >However, anything placed against the glass of the tube MUST be at cathode >potential, otherwise you will RAISE the noise floor! > >If you are using the grounded anode circuit, this means the shield will >be at -1000 to -1500 volts, a very dangerous situation to say the least! > >Two solutions: > The Hamamatsu catalog mentions this as being caused by random molecular motion within the glass envelope of the tube. They cure it by having the tube coated (HA coating) ie 'aguadag'. They also downplay the importance of this-they talk about it like this is only a concern for the most pickey applications. For the average user, they seem to say 'don't worry about this'. John, I know you are busy-but, I'd very much apprecaite an estimate of how much noise this actually contributes??? I had pretty much decided to build up my pmt without considering this as a major noise contributing factor. Is this a mistake to assume this is a minor qrm source? This condition could be aggrivated by improper handling of the pmt also. PMT's should be handled with gloved hands only and the only cleaning solution Hamamatsu sanctions is isopropanol. GL...Art... From owner-laser Wed Apr 23 07:13:48 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24021; Wed, 23 Apr 97 07:13:48 PDT Message-Id: <9704231409.AA28899@is.ups.com> From: "Guy Hamblen" To: "Laser" Subject: Ordering Info on OPT210 or OPT211? Date: Wed, 23 Apr 1997 10:09:00 -0400 X-Msmail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello all: Have been following the BB-OPT210 optical sensor thread.....I may have missed specific ordering or source vendor information for this device. I called DigiKey but they only carry the OPT211 for $8.25ea plus a 5.00 handling fee plus shipping charges for orders less than $25. Are there other sources without the minimums? What are the differences between the 210 and 211? DigiKey didn't have the App Notes available either...where can I get them...is there a website? Thanks in advance for any information. Background: I was catalyzed by the Feb QST article...quickly built up a system to get my feet wet and learned how inefficient it was. Migrated to the LM555 transmitter; now I want to improve the receive side. Since I am living in NNJ, I've got some potential "high sites" to coordinate tests with other southern New Englanders. BTW, this reflector is a breath of new air in comparison to others. Keep up the good, open communication. Regards, Guy H. N7UN/2 (ex AA7QZ/2) From owner-laser Wed Apr 23 10:22:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29274; Wed, 23 Apr 97 10:22:30 PDT Date: Wed, 23 Apr 1997 10:17:08 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704231717.AA02758@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: PMT repairs and HV adjustments X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- >From music@Tempe.ate.slb.com Wed Apr 23 10:00 MST 1997 From: music@Tempe.ate.slb.com (Doug Music) Date: Wed, 23 Apr 1997 10:06:25 -0700 (MST) Subject: PMT repairs and HV adjustments To: c1040@azfms.com Mime-Version: 1.0 SWAG at the repair mechanism: The surface of the photocathode is EXTREMELY sensitive to having a layer of unwanted atoms on it. The silver on the inside of the glass is often a RESULT of the "getter" firing. The internal thermal mass of the tube is damned tiny. Ok, here goes the story. Normally, as has been reported, the tube is stinkin hot when sealed. This degasses the surfaces. You'd think that just firing the getter again would do, but the problem isn't free atoms in the vacuum, it's more likely atoms stuck on the photocathode and dynodes. So... We heat up the tube to a few hundred degrees and the atoms are teased off the surface and the still active chemistry in the getter and on the silver surface deposit grab hold of these atoms when they happen by. The reason we heat for so long is that we want to use the minimum heat and chemistry runs forward based on heat, concentration, time, etc. The reaction to the getter material is two way but the low heat radically prefers the silver over the photocathode and/or dynodes. Also, temp is an average of the molecular energy and we are playing on the 2 and 3 sigma part that imparts thousand degree+ temps on single molecules from time to time. You exponentially drive this forward as you increase the temp. The trick is knowing when your beginning to drive atoms back off the silver and other good stuff from the getter. That's why 450 degrees over time is better than 600 over a short time. HV adjustments: Yes, PMT's do behave with certain "personalities" in regard to the voltage and SNR. They also do this for voltage vs sensitivity. The bummer is that the highly sensitive domain is also noisy as all get out. Use of a ferrous metal container is important because these PMT's make great receivers. You need to block all sources of light, heat, magnetics and RF. Your food can idea is right on target. Cool... Oh yeah, if you want to see noise go down, use a TE cooler on the tube and chill it down. As you push toward max sensitivity, thermal noise gets real bad. -Doug Douglas E. Music Voice: (602) 345-3625 FAX: (602) 345-8793 Pager: (888) 710-1508 Pager email: 905071@pagenet.net Email: music@san-jose.ate.slb.com __o _`\<,_ _______(*)/_(*)__________ ----- End Included Message ----- From owner-laser Wed Apr 23 10:22:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29276; Wed, 23 Apr 97 10:22:31 PDT Date: Wed, 23 Apr 1997 10:16:50 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704231716.AA02757@fmsserv99.azfms.com> To: laser@berlioz.nsc.com Subject: Re[2]: regenerating BROKEN PMT's, maybe. X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- >From music@Tempe.ate.slb.com Wed Apr 23 09:36 MST 1997 From: music@Tempe.ate.slb.com (Doug Music) Date: Wed, 23 Apr 1997 09:41:01 -0700 (MST) Subject: Re[2]: regenerating BROKEN PMT's, maybe. To: c1040@azfms.com Mime-Version: 1.0 Of course external plastic. Some PMT's have a glass base so nooo problem. The way tubes get creamed (and why you should NOT try this on a good tube you can't afford to cream) is when the internal "getter" boils off and deposits crud on things it shouldn't. You want to SLOWLY activate the getter just a little. That scrubs the vacuum. But it can also do the big nasty to the photocathode surface and dynodes. This is why baking IR tubes is soooo tricky. I've been able to take totally dead IR tubes and PMTs and get them to outperform spec. This is where the PMT's that Rusty and I have goofed with came from. But I must admit to having learned the tricks the expensive way. I totally creamed a fair number of marginal devices. (blush) Oh well... -Doug > > > I used to work with plasma systems and high vacuum systems at Fairchild > > semi. 'Thermo plastic????' The ONLY insulator that is suitable for vacuum > > tubes is glass (maybe I'm behind the times on this topic). > > I think Doug is talking about the external tube base, not anything > internal... > Douglas E. Music Voice: (602) 345-3625 FAX: (602) 345-8793 Pager: (888) 710-1508 Pager email: 905071@pagenet.net Email: music@san-jose.ate.slb.com __o _`\<,_ _______(*)/_(*)__________ ----- End Included Message ----- From owner-laser Wed Apr 23 11:09:44 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00668; Wed, 23 Apr 97 11:09:44 PDT Date: Wed, 23 Apr 97 11:09:40 PDT From: jmoss (Jim Moss) Message-Id: <9704231809.AA00662@berlioz.nsc.com> To: laser Subject: Re: OPT210 more Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- From aballen@colby.edu Mon Apr 21 13:23:36 1997 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 21 Apr 1997 16:21:55 -0500 To: jmoss@berlioz.nsc.com (Jim Moss) From: "Art Allen, KY1K" Subject: Re: OPT210 more Content-Length: 1429 At 09:24 AM 04/21/1997 PDT, you wrote: > >To any 210 users... >what are you using for feedback resistors? >The highest value resistors I can find are 22M Ohm. > Hi Jim, I bought noise rated mil spec 1 gig ohm resistors. They are specialty items and cost me 3 dollars each, but were well worth it! You can get them from any resistor manufacturer, but you need to ask-not all of them can make them and some won't do small orders. I'd be interested in a group order, any other takers? >I built up a 210 over the weekend with 6 x 18M. It's excellent. >Got a good return off the top of a tree (in the leaves) >about 200 ft over and 100 ft up with 2mW and NO lens. > OK, the area around the feedback resistor is the heart of the detector, long leads and extranneous coupling should be avoided for best results. I think you would see improved performance if you had a single 100 meg resistor in that same location. >I tried using one of my PMT's and had much more noise. (still have some work >on the PMT cct to do) > The pmt SHOULD ABSOLUTELY blow the ss detector away! Wonder if you had noise as a result of stray light pickup from other sources, or was it just additional white noise? Hey, one last thing about the list-I saw Johns comments.... I have never written anything so time critical that it couldnt stand a few hours delay. I'd leave the list right where it is. IMHO hi hi. GL and keep them lasers lit...Art... ----- End Included Message ----- From owner-laser Wed Apr 23 11:12:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00736; Wed, 23 Apr 97 11:12:23 PDT Date: Wed, 23 Apr 97 11:08:04 PDT From: jmoss (Jim Moss) Message-Id: <9704231808.AA00593@berlioz.nsc.com> To: laser Subject: opt210/211 Cc: tel1gah@is.ups.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk Guy, the 211 is supposed to be a bit better for dark current leakage and is recommended by BB for use with high value resistors. Check out the specs at BB or in the laser web section /data. You'll find the data sheets there. The BB website is also in the Jim's list of laser stuff on the laser web site. http://www.qsl.net/wb9ajz/laser/laser.htm leave off the laser.htm to see the directories. I got my OPT210 by asking BB who my local distributer was. They sent me 2 for about $8, and FedExed them (no extra fees) next day. Jim From owner-laser Wed Apr 23 11:27:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01317; Wed, 23 Apr 97 11:27:54 PDT Message-Id: <335E46E3.6FF4@lan.nsc.com> Date: Wed, 23 Apr 1997 10:29:07 -0700 From: Dave Fifield Organization: National Semiconductor Corp. X-Mailer: Mozilla 3.01 (Win95; I) Mime-Version: 1.0 To: Guy Hamblen Cc: Laser Subject: Re: Ordering Info on OPT210 or OPT211? References: <9704231409.AA28899@is.ups.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Guy, I just ordered some OPT210W devices from Sager yesterday. These are the SIP packaged ones, I figured they'd be easier to mount. They have the other packages too. They are all $8.25 each plus a hefty $15 minimum for shipping, but they have them in stock. Sager is at 1-800-SAGER-800 or on the web at http://www.sager.com Good luck, let us know how you get on. Dave AD6AY From owner-laser Wed Apr 23 13:00:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03916; Wed, 23 Apr 97 13:00:29 PDT From: n7stu@psnw.com Date: Wed, 23 Apr 1997 12:57:04 -0700 (PDT) Message-Id: <1.5.4.16.19970423130248.3ecf3a48@mail.psnw.com> X-Sender: n7stu@mail.psnw.com X-Mailer: Windows Eudora Light Version 1.5.4 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: "Guy Hamblen" , "Laser" Subject: Re: Ordering Info on OPT210 or OPT211? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Guy, I don't have the catalog handy to see if they stock the OPTs, but Mouser had no minimum order last time I ordered (2 months ago). >may have missed specific ordering or source vendor information for this >device. I called DigiKey but they only carry the OPT211 for $8.25ea plus a >5.00 handling fee plus shipping charges for orders less than $25. Are >there other sources without the minimums? What are the differences between 73, Robert N7STU/YB2ARO, DM07aa/OI52ee n7stu@psnw.com http://www.psnw.com/~n7stu (Norcal WSWSS activities & N7STU/YB2ARO homepages) http://www.qsl.net/n7stu (1997 WSWSS Technical Conference Information Page) wswss@qsl.net (WSWSS email reflector) From owner-laser Wed Apr 23 16:38:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09765; Wed, 23 Apr 97 16:38:52 PDT Date: Wed, 23 Apr 1997 19:35:32 -0400 (EDT) Message-Id: <2.2.16.19970423185224.26c7d4fc@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: The next shot Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Jim and the group, ' Since I have gotten such strong returns from the 1400' round trip reflective shot I have decide to go mobile in search of longer path. One of my friends who is has a place at the local Airport said I could come and test at the airport any time I want. So tonight I wil attempt a 1600' (3200') round trip path. Targets will be a tree trunk, a 8x10 inch sheet of white paper, and a common red plastic retroreflector. This is where I wish I had a way of measuring SNR... I guess I could build a cheep S meter with a BPF ahead of it. I am loading up the vehicle now I will try to report in after the attempt. The runnway is 3500' long so 7000' round trip i possible.. Small peanut compared to the stuff John is talking about, but ya gotta start somewhere. 73's PaulC KB1RP From owner-laser Wed Apr 23 18:31:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12713; Wed, 23 Apr 97 18:31:37 PDT Date: Wed, 23 Apr 1997 21:28:21 -0400 (EDT) Message-Id: <2.2.16.19970423204510.25870204@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: The Long shot Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, Just got back from the airport test site. Conditions: Some humidity in the air, not excellent visibility Lots of ambient light from runway lights and large fluorescent fuel sign 20 degrees of axis of the shot. Constant buzz in the RX except when lens is covered so no light gets into RX chip. Runway too wet and muddy to get out to tree and fence targets. Target 1 The tree, Maple dark gray bark, distance 1600' Signal strong!! very easy to locate. Cover lens with paper till only roughly 1/2 " was exposed till SNR was to poor to copy. This just gave me an idea.... could I just make covers to fit over the lens with calibrated holes in them like 1 sq. " 2sq." and so on to determine the excess SNR in the system?? HMMM Move Xmitter to fence. fence a lighter color signal much stronger Due to the terrain I could not get out to set up the white paper target or retro. Too muddy The next shot was to the end of the runway to a dense group of pine trees 3400' away. The return was good enough to copy some flutter maybe due to the porous surface of the bank of trees. Or wind blowing trees. tried to cover the lens.. could only cover about 50 % before signal would drop off so SNR was too poor to copy remember that there was always plenty of 60 HZ buzz so if I had a quiet local I am sure that I could do 2miles round trip. Especially if I had a good solid light colored target. Any comments welcome Thanks for listening 73's PaulC KB1RP From owner-laser Wed Apr 23 23:25:13 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19800; Wed, 23 Apr 97 23:25:13 PDT Date: Wed, 23 Apr 97 23:25:10 PDT From: jmoss (Jim Moss) Message-Id: <9704240625.AA19794@berlioz.nsc.com> To: laser Subject: round trip tries Sender: owner-laser@berlioz.nsc.com Precedence: bulk Sounds like a successful airport trip! What RX was this again? and what kind of lens? I played tonight also. Moon was full, cloudless night, heavy winds. Attached my OPT210 to an eyepiece cover (fits my binos and spotting scope). Got excellent returns off tree 300 ft away (in the leaves), can hear the fluttering of the leaves in the wind. Moon was VERY strong, almost blocking, it took out all the 60Hz noise from streetlights. This was all done with the 210 attached to my Celestron 8x56 binos. Aimed with one eye and had the 210 in the other. Looks like eyepiece covers may make a good way to mount these things to existing stuff. May try it on my small PMT as well. Need to find some covers! Jim WB9AJZ/6 CM87xi Sunnyvale, CA From owner-laser Thu Apr 24 02:02:01 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24060; Thu, 24 Apr 97 02:02:01 PDT To: laser@berlioz.nsc.com Date: Thu, 24 Apr 1997 04:54:26 -0400 Subject: PMT Notes # 3 Message-Id: <19970424.050117.15718.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-4,8-9,14-15,21-22,26-27,31-72,77-78,82,85-86, 90-96,98-99,106-107,111-112,116-117,122-146,148-149,152-160 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk PMT Notes # 3 --------------------- I came up with some improvements to the FET preamp circuit. The preamp is now DC coupled allowing the FET to become part of the protection circuit. The new circuit allows the shutter control circuit to sense a positive going voltage (with more light) instead of having to deal with a negative going voltage. The 100k load has been removed from the signal electrode of the PMT. This resulted in improved signal to noise ratio & higher gain. Of course the bandwidth is now also a LOT less. Since I am optimizing this circuit for weak signal use at 800 Hz (for use with the FFT / BPSK computer program) this is NOT a problem. For use at higher frequencies, such as a 20 or 30 Khz subcarrier, simply decrease the 10 megohm gate resistor to something like 100 k or so. This will increase bandwidth at the expense of gain much the same as the feedback resistor does in an op-amp design. Commercial designs use a 50 ohm load resistor on the PMT to reproduce very short pulse widths so you can go quite low here without hurting anything other than gain. I originally used a circuit like this when I started out had trouble with it due to poor shielding on the PMT. Mounting the PMT inside the tomato puree cans made a tremendous difference and allows me to increase the gain. PS - If this schematic is unreadable, try loading it into Notepad. (Assuming you are using WinDOZE. If you are using Windows 95, Wordpad does an even better job as it properly displays the text and schematic simultaneously. |------------------------------------------- | Improved DC coupled PMT FET Preamp |------------------------------------------- | PMT Preamp | MPF-102 | Coax | |--------------> Out | |--------------| 2.2 k | | |---/\/\/\--| | | | + 10 uf | | | |---||----| | | 10 Meg | | PMT >-|------/\/\/\/\/\----------|--> Gnd | |------------------------------------------- | Remote Power | | Coax 0.1 uf | >-|----------||-----------> Signal out | | | | 10 k 1 k | |---/\/\/\-|-/\/\/\-----<+ 12 vdc | | | Preamp Power | | | (Up coax) | | | + 100 uf | | |---||-------> Gnd | | | | 100 k + 1 uf | |--/\/\/\/--|--||-------> Gnd | | | |-----------> To DC voltage | comparator | shutter protection | control | |------------------------------------------- More on HV optimization ------------------------------------ As noted in an earlier post I discovered that one of my PMTs could be optimized for best SNR by adjusting the high voltage. This does NOT appear to be unique to that particular tube. Every tube tested so far displays this characteristic, some to a greater or lesser degree than others. My best tube is now approx. 10 dB better! Tubes that I had previously rejected were retested and after the HV was optimized they are pretty darn good performers. In fact many of them are just as good as my best tube! Each tube has a sweet spot that is different than all the other tubes and best SNR is achieved at a particular voltage somewhere between 500 and 1200 volts. I think these effects were there all the time but weren't as noticeable because they were being masked by the poor shielding. Getting the PMT inside a tin can did wonders for it's performance and I'm now able to detect minute changes in performance. Cooling Experiments ------------------------------ I tried cooling a PMT to -15 degrees C. (Approx. 1.4 degrees F) The noise floor dropped 7 dB! The only problem is the signal also dropped precisely 7 dB. Net improvement in SNR, 0 dB. Even though the system was being used indoors on the workbench where it is EXTREMELY dry this time of year, I was having trouble with water vapor condensing on the tube and dripping out of the tin can. I don't know about you, but I don't particularly like to see water dripping out of an assembly that has over a thousand volts on it! I'd hate to see what would happen when trying to run something like this outdoors on a humid summer night! I have worked with PMTs in the past that were being cooled by liquid nitrogen. However, that's a LONG way from -15 C. I assumed that ANY cooling would lower the noise floor, which is does. However, at -15 C no improvement was detected in SNR. For now I've given up on cooling the PMT. When the present system is taken outdoors and aimed up into a black sky the noise comes up so much that it's obvious that any further increase in sensitivity would be useless. Tomorrow I intend to try heating the assembly to find out how hot it has to get before the SNR is degraded. If I find that it degrades rapidly then I will again consider some type of cooling system. The objective here is what will happen to the present system on a 90 degree summer night? If the sky is still the limiting factor then my work is done! ----- Can anyone help me with an Hamamatsu R-1017 PMT? Here are the pin outs: 1 DY1 2 DY3 3 DY5 4 DY7 5 DY9 6 DY11 7 Plate 8 DY12 9,10,11,18,19,20 Internal Connection 12 DY10 13 DY8 14 DY6 15 DY4 16 DY2 17 Focusing Grid 21 Cathode What exactly is the purpose of the ' Focusing Grid ' and what voltage should I apply to this pin (17 above)? I've seen gate electrodes before and I think I have them pretty well figured out but this is the first time I've run into a Focusing Grid on a PMT and I'm not sure what to do with it! Tnx! John K3PGP@juno.com -==- From owner-laser Thu Apr 24 04:08:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26674; Thu, 24 Apr 97 04:08:51 PDT Date: Thu, 24 Apr 1997 07:05:11 -0400 (EDT) Message-Id: <2.2.16.19970424062156.27a70786@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: round trip tries Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Jim and the group, The RX is a 5 1/2" lens for antenna. The tube is a PVC sewer pipe. The active device is a BB OPT210 with a 120 meg feedback resistor. The lens was part of a projection lens assembly that I traded for a few years ago. I was always happy with the performance of the assembly till I took it apart and found that is contained 6 discrete lens elements! I Removed all but the 1 I am using and gained a very significant increase in signal level. assume due to the loss in all the other glass (5) elements. Your idea on the dual (multitasking) of the bino,s is cool!! Yes the moon can easily block a receiver with a large feedback resistor! This is all great fun. I got an offer from my friend at the airport. Jay Rusgrove W1VD offered to put a system on his tower and aim at my house 3-4 miles away for experiments. He says all this talk reminds him of the early pioneer days of 10 Ghz. It's getting better by the minute!!!! >Sounds like a successful airport trip! >What RX was this again? and what kind of lens? > >I played tonight also. Moon was full, cloudless night, heavy winds. >Attached my OPT210 to an eyepiece cover (fits my binos and spotting scope). >Got excellent returns off tree 300 ft away (in the leaves), can hear the >fluttering of the leaves in the wind. Moon was VERY strong, almost blocking, >it took out all the 60Hz noise from streetlights. This was all done with >the 210 attached to my Celestron 8x56 binos. Aimed with one eye and >had the 210 in the other. > >Looks like eyepiece covers may make a good way to mount these things to >existing stuff. May try it on my small PMT as well. Need to find some >covers! > >Jim >WB9AJZ/6 CM87xi Sunnyvale, CA > > 73's PaulC KB1RP From owner-laser Thu Apr 24 08:33:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02900; Thu, 24 Apr 97 08:33:15 PDT To: laser@berlioz.nsc.com Date: Thu, 24 Apr 1997 11:32:55 -0400 Subject: PMT Notes # 4 Message-Id: <19970424.113258.15542.0.K3PGP@juno.com> References: <199704231343.JAA27316@host-04.colby.edu> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 1-36,38-39,41-42,48-49,54-55,60-61,67-68,72-73, 78-79,82-83,88-89,94-95,100-101,104-105,110-111,116-120,126-127, 131-132,140-141,144-145,147-162 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Wed, 23 Apr 1997 09:43:45 -0500 "Art Allen, KY1K" writes: >> >>However, anything placed against the glass of the tube >>MUST be at cathode potential, otherwise you will RAISE >>the noise floor! >> >>If you are using the grounded anode circuit, this means >>the shield will be at -1000 to -1500 volts, a very dangerous >>situation to say the least! >> >>Two solutions: >> >> > >> >>John >>K3PGP@juno.com >> >>-==- > > >The Hamamatsu catalog mentions this as being caused >by random molecular motion within the glass envelope of >the tube. They cure it by having the tube coated (HA coating) >ie 'aguadag'. They also downplay the importance of this-they >talk about it like this is only a concern for the most pickey >applications. For the average user, they seem to say 'don't worry >about this'. > >John, I know you are busy-but, I'd very much apprecaite an >estimate of how much noise this actually contributes??? >I had pretty much decided to build up my pmt without considering >this as a major noise contributing factor. Is this a mistake to >assume this is a minor qrm source? > First off every tube is different, even two with the same number and date code even when new! There are also at least two different types of tubes that I have run into. The ones with an 'aquadag' or other type of conductive coating can be recognized because they usually have an insulator wrapped around the glass envelope of the tube, usually some type of black plastic. If you look closely you will usually see one or two very fine copper wires coming from under the plastic coating that connect to the cathode pin on the back of the tube. Examples of this type of construction are Hamamatsu R-1017 and R331-05. Tubes of this type can be mounted just about any way that you want as contact with the glass is prevented by the conductive coating and plastic insulator. (Note: This is electrical shielding only. You may still have to provide some type of magnetic shielding.) If you have a PMT where there is no visible coating covering the glass you may want to take precautions as to what if anything you allow to come into contact with the glass envelope while the tube is in operation. (You will most likely have to provide some type of shielding otherwise you will end up picking up a LOT of undesired electrical interference.) When I first played around with PMTs many years ago, I always grounded the cathode and used a conventional positive (with respect to ground) power supply. The glass envelope of the tube was wrapped with aluminum foil and taped. A copper ground wire in contact with the aluminum foil was connected to the cathode. Since the cathode was at ground potential this eliminated any shock potential. I was happy and so was the PMT! In this most recent adventure with PMTs however, I decided to invert the power system to make it easier to interface the tube to solid state electronics. This would also allow DC coupling necessary for the tube protection circuitry. This meant that the anode was now connected to ground and a MINUS 1000 volts or so was applied to the cathode. This all worked very fine. However, having approx. 1000 volts on a metal sleeve wrapped around the tube made me extremely nervous since I was doing a LOT of close work on the PMT. That's when I decided to disconnect the aluminum foil shield that was in contact with the glass envelope and connect it to ground which was now the anode! When the tube was first fired up all appeared normal. However, several minutes later a very annoying arcing sound was heard coming from the speaker. Turning the volume down and listening to the PMT itself produced nothing detectable. Turning the speaker back up and the lights off I looked for any signs of arcing. None could be seen. The arcing sound grew in intensity. At times it started to sound like eggs frying! Other times it would completely disappear only to return again several minutes later. The noise floor on this system was normally around -45 dbm but the arcing noise was up around -3 dbm making the system totally useless! I disconnected the ground wire on the aluminum foil shield and left it float. The arcing sound disappeared! However, several minutes later it was back but now it was only producing a couple of pops every second or so at it's peak. Other times 10 or 15 seconds would elapse before it would pop again. At least now I knew the source of the problem. The ground wire was returned to the cathode of the tube. An insulator was made up out of black paper and slipped over the aluminum foil. (The foil was now at -1000 volts!) The tube fired back up. All was quiet. Getting hit with 1000 volts while trying to optimize a PMT isn't my idea of fun. Fortunately the current is pretty low and there isn't a whole lot of energy storage in a .01 ufd cap at 1000 volts. I KNOW because I got to test this several times before installing the second grounded shield! A second aluminum foil shield was wrapped around the black paper and connected to ground. This had no effect on the tube which is as it should be. It was installed strictly as a safety precaution against fingers coming into contact with the shield that was at -1000 volts potential! Why all this fuss about shielding? ------------------------------------------------ If you don't shield the PMT it will act as a capacitive voltage probe antenna hooked to a very high gain high impedance preamp. To make a long story short, it will pick up any kind of electrical disturbance in the area including the horizontal oscillator of the TV set, 60 Hz power grid, all the AM broadcast stations and a good number of short wave stations thrown in for good measure! The aluminum foil shield serves the same purpose as the aquadag coating mentioned above. If your tube has this built in then your tube is already electrically shielded. However, you may still have problems with other types of interference. (magnetic, etc.) Although I was happy with the aluminum foil shielding setup for quite some time it was recently replaced with a 4 inch diameter tin can. (I'm using BIG PMTs which are approx. 2 inches in diameter by about 6 inches long.) The tin can allows the PMT to run without anything at all in contact with the glass envelope. It provides a light tight housing, electrical shielding, and a fair amount of magnetic shielding. It also makes changing tubes extremely easy since all the aluminum foil shields are now unnecessary. Although the inside of the tin can is lined with black paper I still slip a cylinder of black paper around the glass envelope of the PMT as an extra precaution against light bouncing around inside the can. Since going to the tin can shield I have observed things with the PMT setup that were previously masked by noise! John K3PGP@juno.com -==- >This condition could be aggravated by improper handling of >the pmt also. PMT's should be handled with gloved hands >only and the only cleaning solution Hamamatsu sanctions >is isopropanol. > >GL...Art... > From owner-laser Thu Apr 24 08:56:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03377; Thu, 24 Apr 97 08:56:11 PDT Message-Id: <199704241554.LAA13240@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 24 Apr 1997 11:54:23 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: PMT noise reduction tactics needed? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Paul and list users, Paul's and Johns recent comments are very interesting and very helpfull. When I first started thinking about PMT's (quite a few years ago), I always realized that the additional sensitivity of the pmt would be largely useless unless some means was taken to reduce extranneous light pickup. I had planned on a 'slot' placed in front of the pmt in order to limit its field of vision (hence its ability to pick up qrm). I originally hoped that a .5 degree field vertically and a 2 degree field azmith would provide a reasonable balance between ease of aiming the rx, and qrm rejection. I always knew I would need flocking paper to keep reflections from inside the telescope tube from bouncing around. Flat black paint looks great UNTIL you actually begin to MEASURE how much light gets reflected hi hi! Narrow passband filters (optical) were something I hoped I would never have to get into.... I hoped I would never need a 60/120 hz electronic reject filter.... BUT, my thinking has been modified quite a bit by recent revalations, thanks to the laser list and its contributors. Now, I'm thinking along the lines of a .2 degree (el) and .5 degree (az) slot with a 60/120 hz reject filter. Additionlly, I think a 3 db insertion loss optical bandpass filter would provide a great deal of qrm rejection from manmade light. Keep in mind that voilet, green, yellow etc are very easily scattered by the atmosphere, which means these are the primary components of the light pollution we see from nearby cities. Unfortunately, these other colors (green/yellow/blue) are also where most pmt's are most sensitive!! Red is not so easily refracted/absorbed/scattered, so there is alot to be gained by having the rx look at red only! With the tight beam rx and the single frequency response of the rx, I'm wondering if I should just build the rx and tx up, then assemble them on the same platform, and then rotate them as an assembly? There may not ever be any need to point them in a different directions, and since the aiming of the rx is now somewhat critical, they might as well be built as a single assembly!? I have ABSOLUTE black sky here in Central Maine, so I might not have it so bad as some others...but, as soon as I go to any hilltop, the light pollution is there. So, I don't think there are many users who can escape manmade qrm. GL and keep them lasers lit... Art... At 07:05 AM 04/24/1997 -0400, you wrote: >Hello Jim and the group, > >The RX is a 5 1/2" lens for antenna. The tube is a PVC sewer pipe. >The active device is a BB OPT210 with a 120 meg feedback resistor. > >The lens was part of a projection lens assembly that I traded for a few >years ago. I was always happy with the performance of the assembly till I >took it apart and found that is contained 6 discrete lens elements! I >Removed all but the 1 I am using and gained a very significant increase in >signal level. assume due to the loss in all the other glass (5) elements. > > >Your idea on the dual (multitasking) of the bino,s is cool!! > > >Yes the moon can easily block a receiver with a large feedback resistor! > >This is all great fun. I got an offer from my friend at the airport. > >Jay Rusgrove W1VD offered to put a system on his tower and aim at my house >3-4 miles away for experiments. He says all this talk reminds him of the >early pioneer days of 10 Ghz. > >It's getting better by the minute!!!! > > > > > > > >>Sounds like a successful airport trip! >>What RX was this again? and what kind of lens? >> >>I played tonight also. Moon was full, cloudless night, heavy winds. >>Attached my OPT210 to an eyepiece cover (fits my binos and spotting scope). >>Got excellent returns off tree 300 ft away (in the leaves), can hear the >>fluttering of the leaves in the wind. Moon was VERY strong, almost blocking, >>it took out all the 60Hz noise from streetlights. This was all done with >>the 210 attached to my Celestron 8x56 binos. Aimed with one eye and >>had the 210 in the other. >> >>Looks like eyepiece covers may make a good way to mount these things to >>existing stuff. May try it on my small PMT as well. Need to find some >>covers! >> >>Jim >>WB9AJZ/6 CM87xi Sunnyvale, CA >> >> > > >73's >PaulC KB1RP > > > From owner-laser Thu Apr 24 09:56:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04973; Thu, 24 Apr 97 09:56:39 PDT To: laser@berlioz.nsc.com Date: Thu, 24 Apr 1997 12:52:38 -0400 Subject: Temperature Typo in PMT Note # 3 ! Message-Id: <19970424.125248.12054.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-10 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Cooling Experiments >------------------------------ > >I tried cooling a PMT to -15 degrees C. (Approx. 1.4 degrees F) Change all occurrences of -15 degrees C to -17 degrees C !!! John K3PGP@juno.com -==- From owner-laser Thu Apr 24 12:33:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10434; Thu, 24 Apr 97 12:33:21 PDT Message-Id: <199704241931.PAA03784@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 24 Apr 1997 15:31:48 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: dark current vs temp. Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone-me again.... The Hamamatsu catalog shows some graps for different dark currents vs temp for some of their different types of pmt's. Its interesting to note that the graps are (again) bi-sloped. There is a very slight improvement in the dark current below -20 c, suggesting diminishing returns. But, the difference between -20 c and + 20 c is (1000 times) difference. A head oin multialkali tube shows 10e-10 amps dark current at -20 c, and shows almost 10e-7 amps at 20 c. It is almost linear betwen those points. Again, everything they write says that the dark current determines the 'detectivity' of the tube. A cold tube is esp'ly important in scintillation counting, where min eni is necessary. According to them, a reduced dark current should give a better eni. Im sure all this raises more questions than it answers, sorry. GL and good dx to you all. Art, KY1K. From owner-laser Thu Apr 24 12:09:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09245; Thu, 24 Apr 97 12:09:09 PDT Message-Id: <199704241907.PAA01379@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 24 Apr 1997 15:07:36 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: pmt snr vs ps voltage Sender: owner-laser@berlioz.nsc.com Precedence: bulk OK, just had a chance to review the hamamatsu catalog. There is a graph there for dark current vs supply voltage. The graph basically has 2 slopes..a nice gentile slope running from 400 to 700 volts. Above that, there is a much steeper slope which is nearly linear, running up past 1300 volts. Dark current is the no signal curent that flows in the tube. Interesting that John notes that this is where some/most of his pmt's are the best performers.... More on snr later... Art... From owner-laser Thu Apr 24 12:21:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09840; Thu, 24 Apr 97 12:21:30 PDT Message-Id: <199704241919.PAA02693@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 24 Apr 1997 15:19:33 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: pmt snr.. Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone.... regarding the snr vs applied voltage question... Hamamatsu has a formula for eni (equiv noise input). It sounds the same as NEP to me, but they call it ENI. Looking at the formula they give, there are constants, most of the formula deals with constants. But, 2 factors in the formula appear to be directly related to the eni. They are current amplification and dark current. To determine actual figures (relative) based on the formula, you would need to have actual numbers to plug in for these 2 variables. To come up with actaul values, you would need to have the above parameters, AND the anode radiant sensitivity at the frequency of interest and thge bandwidth of the receiving system. The product of the current amplification and the dark current are raised to the 1/2 power. So, if the square root of that product increases as the supply voltage is raised, then the snr should also be better. Throught all the techno-babble in their catlaog, they seem to infer that higher applied voltage produces a better snr tho. Hope this helps. GL..>Art... From owner-laser Thu Apr 24 12:29:05 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10281; Thu, 24 Apr 97 12:29:05 PDT Message-Id: <9704241928.AA28678@is.ups.com> From: "Guy Hamblen" To: "Laser" Subject: Fw: What makes a good detector? Date: Thu, 24 Apr 1997 15:28:04 -0400 X-Msmail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul: Are you using a lense for your 6" Rx system? If so, whose? Do you have sourcing name and numbers available? Thanks for the info...Guy, N7UN/2 ---------- > From: Paul A. Cianciolo > To: laser@berlioz.nsc.com > Subject: What makes a good detector? > Date: Saturday, April 19, 1997 8:23 PM > > > Change to the 6" Rx and the signal is strong again. I build all my RX's > inside of aluminum tubing, for 3 reasons. > > 73's > PaulC KB1RP > From owner-laser Thu Apr 24 14:28:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14517; Thu, 24 Apr 97 14:28:32 PDT Content-Length: 383 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Thu, 24 Apr 1997 17:08:10 -0400 (EDT) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk Quick question!! Where is the best place to locate pmt's ? See I said quick!!!!! 73 Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe From owner-laser Thu Apr 24 16:34:36 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18340; Thu, 24 Apr 97 16:34:36 PDT Date: Thu, 24 Apr 97 16:34:32 PDT From: jmoss (Jim Moss) Message-Id: <9704242334.AA18332@berlioz.nsc.com> To: laser Subject: 60Hz noises vs wavelength, experiences Sender: owner-laser@berlioz.nsc.com Precedence: bulk I do have some filters that I've been playing with. I have 2 types, one is 648nM +/- 20nM (50% pass in band, "heavy" reject out, just misses for 670), the other is about 630-680 pass. The later is from a barcode scanner gun, composed of a red plastic filter and a dichroic filter. There is noticible reduction in 60Hz signal pickup by inserting the filter, and un-noticible signal reduction... net improvement in S/N. (Sorry no numbers) I've tried this with PMT, 210, PIN, and Phototransistors. A narrower passband is possible. Li band filters are 670+/-2nM, but cost $36 from Edmund Sci, and will exclude 650 and 633 xmtrs.... There are filters for those frequencies too. Jim WB9AJZ From owner-laser Thu Apr 24 17:05:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19319; Thu, 24 Apr 97 17:05:26 PDT Date: Thu, 24 Apr 97 17:05:22 PDT From: jmoss (Jim Moss) Message-Id: <9704250005.AA19305@berlioz.nsc.com> To: laser Subject: need for sensitivity, experience Sender: owner-laser@berlioz.nsc.com Precedence: bulk Let's not go overboard on how much sensitivity we need! (Oh well, guess it's OK) Signals off tree trunks and leaves are WAY WEAKER than a laser 20 miles or more away! Consider exceptionally clear conditions, most of the loss is in the divergence and is an area ratio of the RX window area to the beam area at the RX point. I'm simplifying, but from experience and using my eye's to observe... a signal 20 miles away pointed at me (2-4mW, 1mR) is WAY stronger than any light in the same vacinity. And the signal from a fence at 50 ft is WAY WAY weaker than the laser signal from 20 miles. So if your objective is < 20 miles OPT210 with a small lens is more than enough. Now for record trys (>100 miles)... I've talked to Jim (WB2ODH/6) who is the current record claimer... (he hasn't confirmed that the claim was accepted) there was no problem seeing (with eyes) his <5mW laser at about 120 miles. Now let's consider quantitative input.... OPT210 is about 0.5A per w, with an area of 5.2 mm2 my PMT is over 1000A per w, area ?? Then the PMT is 10LOG(1000/.5)=33dB better assume the diameter of the RX lens to be 6" ... 2*PI*3 = 28.3 in2 or 182 cm2 1mr divergence at 100 miles = .1 miles diam... 203 x 10^6 cm2 Thats a dB loss of 10 log (203x10^6 / 182) = -60.5dB (I'll ignore losses thru air for now.... cause I don't have the figures with me) So if you start with 2 mW... there will be 2mW less 60.5 dB at the RX 2 mW = 3dBm.... so we get -57dBmW at the RX or 2x10^-6 mW = 2 nW so the 210 would provide output of 2nW * .5A/W = 1 nA .... probably in noise so the PMT would provide output of 2nW * 1000A/W = 2mA . .. way strong So ... what's the point here... There's likely lots of signal present at LONG distance for PMT... the main issue will be narrowing the RX beam to look mainly at the signal desired in both direction and wavelength. We can afford to use up gain from the PMT in the use of filters and lenses. The 210 can do better too... need to get bigger lenses. as diam doubles we get 6dB more each time... so the 12" mirror I have will get 6dB better! Some one want to make these calc's more precise with losses? Jim WB9AJZ From owner-laser Fri Apr 25 03:50:36 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00172; Fri, 25 Apr 97 03:50:36 PDT Date: Fri, 25 Apr 1997 06:47:27 -0400 (EDT) Message-Id: <2.2.16.19970425060401.18c7ea84@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Re: need for sensitivity, experience Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Jim and the group I agree and I also disagree. I think you are correct that all the sensitivity is NOT needed for a LOS shot of 20 to 40 miles. But for someone who cannot find a partner for an LOS path, I have resigned myself to the fact that if I want to comm. with someone over laser, or LED or other light, I need to find a path that is NON-LOS and be able to provide equipment for doing this. Cloud bounce, reflective path's etc. This is why I have been working on this reflective path scenario. Ideally I would like to set up a system on my tower to be able comm on light to another "laserhead" and keep the path running. BTW I have received an offer from a local ham to do just this. Only 3 miles away but still a good start. I will probably try this shot with a LED and a lens at first, since aiming on a tower may be a problem at first Thanks for the input Jim... All comments are always welcome At 05:05 PM 4/24/97 PDT, you wrote: > >Let's not go overboard on how much sensitivity we need! (Oh well, guess it's OK) >Signals off tree trunks and leaves are WAY WEAKER than a laser 20 miles or more >away! > >Consider exceptionally clear conditions, most of the loss is in the divergence >and is an area ratio of the RX window area to the beam area at the RX point. > >I'm simplifying, but from experience and using my eye's to observe... >a signal 20 miles away pointed at me (2-4mW, 1mR) is WAY stronger than any light >in the same vacinity. And the signal from a fence at 50 ft is WAY WAY weaker >than the laser signal from 20 miles. > >So if your objective is < 20 miles OPT210 with a small lens is more than enough. > >Now for record trys (>100 miles)... I've talked to Jim (WB2ODH/6) who is the >current record claimer... (he hasn't confirmed that the claim was accepted) >there was no problem seeing (with eyes) his <5mW laser at about 120 miles. > >Now let's consider quantitative input.... >OPT210 is about 0.5A per w, with an area of 5.2 mm2 >my PMT is over 1000A per w, area ?? > >Then the PMT is 10LOG(1000/.5)=33dB better > >assume the diameter of the RX lens to be 6" ... 2*PI*3 = 28.3 in2 or 182 cm2 > >1mr divergence at 100 miles = .1 miles diam... 203 x 10^6 cm2 > >Thats a dB loss of 10 log (203x10^6 / 182) = -60.5dB > >(I'll ignore losses thru air for now.... cause I don't have the figures with me) > >So if you start with 2 mW... there will be 2mW less 60.5 dB at the RX >2 mW = 3dBm.... so we get -57dBmW at the RX or 2x10^-6 mW = 2 nW >so the 210 would provide output of 2nW * .5A/W = 1 nA .... probably in noise >so the PMT would provide output of 2nW * 1000A/W = 2mA . .. way strong > >So ... what's the point here... > >There's likely lots of signal present at LONG distance for PMT... >the main issue will be narrowing the RX beam to look mainly at the signal >desired in both direction and wavelength. We can afford to use up gain >from the PMT in the use of filters and lenses. > >The 210 can do better too... need to get bigger lenses. as diam doubles we >get 6dB more each time... so the 12" mirror I have will get 6dB better! > >Some one want to make these calc's more precise with losses? > >Jim >WB9AJZ > > 73's PaulC KB1RP From owner-laser Fri Apr 25 10:05:49 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09417; Fri, 25 Apr 97 10:05:49 PDT To: laser@berlioz.nsc.com Date: Fri, 25 Apr 1997 12:46:27 -0400 Subject: Scatter Signals Detected ??? Message-Id: <19970425.124627.12470.1.K3PGP@juno.com> References: <2.2.16.19970425060401.18c7ea84@mail.snet.net> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0,2-18,20-21,29-30,41-42,48-49,54-55,63-64,68-69, 75-76,85-86,96-97,102-103,109-116 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Fri, 25 Apr 1997 06:47:27 -0400 (EDT) "Paul A. Cianciolo" writes: >Hello Jim and the group > >I agree and I also disagree. I think you are correct that all the >sensitivity is NOT needed for a LOS shot of 20 to 40 miles. > >But for someone who cannot find a partner for an LOS path, >I have resigned myself to the fact that if I want to comm. with >someone over laser, or LED or other light, I need to find a path >that is NON-LOS and be able to provide equipment for doing this. >Cloud bounce, reflective path's etc. > >This is why I have been working on this reflective path scenario. > EXACTLY! I have the same problem since the only other laser station that was active in the area moved to St. Louis. I live in the foothills of the Allegheny Mountains. Because of this the terrain is all over the place. If you happen to live on one of the hilltops and have a buddy that also lives on a hilltop and there are no other higher hilltops in between you're extremely lucky. This was the case before my friend moved. He was located approx. 5 miles line of sight to the Southeast. My horizon in that direction runs all the way to Allegheny Mountains, approx. 50 miles away so we could work each other just be pointing out the window without even going outside! Since his departure my only communications has been by building two stations and loaning one out. The only useable paths found are by using some target as a reflector. One path in particular that has worked well for us is a communications tower with 6 radomes on the top of it. It's about 3 miles from me and about 2 miles from the other station. The only problem is, you can't find it at night since it has no lights on it and the surrounding hilltop is totally black. This means you have to either have very good readouts on the pointing system or line up on it before sunset. Fortunately both of us are able to get radar returns off of it so it's possible to get lined up by running the system as a radar during initial alignment. All of this was with solid state detectors. Since going to the PMT system I am now able to detect the horizon land / sky transition where the peaks of the Allegheny Mountains meet the sky. As I said before this about 50 miles away making the total round trip approx. 100 miles. Since I only have one PMT setup at the moment there hasn't been any communications via this path other than the radar studies. The other night I was out in the back yard doing some tests with the PMT system. After doing some tests using the Allegheny Mountains as a reflector, I elevated the system to approx. 45 degrees above the horizon. (In case you're wondering my laser and receiver are mounted on a board and point as one assembly making radar studies extremely easy!) As soon as the beam left the mountains and was pointed at empty sky all audible traces of the signal disappeared. I then fired up the computer and ran the FFT program. After approx 30 seconds of integration there was a weak signal detected! It had QSB (fading) on it. Several times during the observation period the signal came up to approx. 0 dB SNR and became quite audible in the speaker. It was very hollow sounding and reminded me of long haul VHF/UHF tropo signals that had multi-path distortion on them. The weather on this particular evening was cold (approx. 30 degrees) and extremely clear, so this was NOT could bounce. The moon fortunately was behind me so it wasn't a noise source other than what was being scattered in the atmosphere. The presence of this weak signal surprised me. I knew if I had enough sensitivity it should be there, but I also knew that red light (in this case IR 780 nm) wasn't scattered as much as shorter wavelength light. (I heard it said that Blue light scatters 16 times as much as red light.) I'm sure this backscattered signal would depend on things like pollution, air temp, etc. By the way, I blocked the lens of the receiver with a black piece of paper and both the 780 Hz (13 th harmonic of 60 Hz man made light backscattered from the atmosphere) and the 800 Hz laser signal went away. Covering the laser caused only the 800 Hz signal to go away with the 780 Hz signal remaining. I blocked the laser path instead of turning it off to test for the possibility of any 800 Hz leaking into the receiver via other means such as power supply coupling etc. If this were the case some or all of the 800 Hz signal would have still been present with the laser blocked. The only remaining question in my mind is how far away is this signal coming from? I'm thinking of suitable modulation schemes to allow me to measure the round trip time delay of these signals. Normally I would just pulse the laser with a very short pulse and trigger the time base of an oscilloscope and measure the delay. However, the signals that I am working with are BELOW the noise floor and can only be detected by long term integration. Unfortunately this also means that the bandwidth of the system is extremely narrow ruling out the possibility of using any type of short duty cycle pulse on the transmitter. (Shorter pulses require more receiver bandwidth.) I might be able to use the phase delay associated with distance to get some idea of the length of this path. This is similar to what VE2IQ does with his software to measure propagation delay. It's my guess that the returns are coming from multiple reflections coming from many different distances. This would account for the hollow sounding return signal. I will be writing up a description of the VE2IQ software and interface shortly as it applies to laser research. It has the ability to measure propagation delay and to recover signals buried in the noise. However, it only measures propagation delay in increments of 1.25 ms (period of 800 Hz modulation tone) so in it's present form would NOT be suitable for measuring short distances. John K3PGP@juno.com -==- From owner-laser Fri Apr 25 10:56:58 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10828; Fri, 25 Apr 97 10:56:58 PDT Message-Id: <199704251755.NAA22449@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 25 Apr 1997 13:55:19 -0500 To: jmoss@berlioz.nsc.com (Jim Moss), laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: 60Hz noises vs wavelength, experiences Sender: owner-laser@berlioz.nsc.com Precedence: bulk I had no idea that high quality tight bandpass filters were so cheap. If a 2 nm bandpass filter can be purchased for 36 bucks (new and quaranteed), then it is a way big bargain for those who REALLY need it (pmt users with big lens). It probably offers 30 to 50 db reject of out of band signals, for 36 bucks, this is definately the most bang for the buck. Note that those using solid state diodes CANNOT use 2 nm bandpass filters. Your laser output varies in frequency with ambient temp and can move 5 or more nm depending on operating conditions. Even laser diodes from the same batch/production run can be on different frequency's. Those using HE-NE lasers can definately take advantage of the narrow bandpass filters tho. Good luck and good dx...Art... At 04:34 PM 04/24/1997 PDT, you wrote: >I do have some filters that I've been playing with. > >I have 2 types, one is 648nM +/- 20nM (50% pass in band, "heavy" reject out, >just misses for 670), the other is about 630-680 pass. The later is from a >barcode scanner gun, composed of a red plastic filter and a dichroic filter. > >There is noticible reduction in 60Hz signal pickup by inserting the filter, >and un-noticible signal reduction... net improvement in S/N. (Sorry no numbers) >I've tried this with PMT, 210, PIN, and Phototransistors. > >A narrower passband is possible. Li band filters are 670+/-2nM, but cost $36 >from Edmund Sci, and will exclude 650 and 633 xmtrs.... There are filters for >those frequencies too. > >Jim >WB9AJZ > > From owner-laser Fri Apr 25 10:45:03 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AB10598; Fri, 25 Apr 97 10:45:03 PDT Message-Id: <199704251742.NAA21476@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 25 Apr 1997 13:43:10 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: pmt comments Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 05:08 PM 04/24/1997 -0400, you wrote: >Quick question!! > >Where is the best place to locate pmt's ? > >See I said quick!!!!! > >73 > Wayne, Jim made valid points recently regarding the sensitivity of inexpensive solid state RX(s) and modest sized lens. When you can buy a diode and op amp combo that gives e-12 watts sensitivity for 9 bucks, you gotta be outta your mind to use a pmt! The pd/amp combo runs on 9 volt transistor batts too-that just doesnt happen for pmts! The only exception is IF YOU REALLY need the additional sensitivity. You do not need the additional sensitivity unless you are looking for absolute world record long range qso's, or unles you are doing airplane scatter/cloud scatter/ducting (non-los) experiments. Pmt's require 1000 volt dc supplies that are very highly regulated. If you accidently expose one to even the slightest light overload, they are noisey for days (until they recover). If you expose them to bright sunlight, they are perm'ly damaged. I do not recommend that any user uses pmt's, unless that user absolutely needs the additional sensitivity! Regarding where to get them-they can be cheap. A pmt with an unknown history might be junk, keep this in mind when purchasing from a surplus supplier. Also, bear in mind that you need a power supply and that you need need a socket. New sockets from Hamamatsu start at 75 bucks (bare socket), and then get more expensive from there... A 20 dollar unknown quality pmt without a socket is NOT a bargain (IMHO)! They are very often sold at Deerfield and other swap meets. You never know what will turn up there hi hi. If you really want a pmt after reading all of this, probably the best thing to do is to ASK on the list, its a real good group of guys. You will probably get a pmt that is atleast tested/known good by sticking to the list for pmt procurement. GL and good dx. Bye the way, will anyone be on Mt Washington overnight for the June contest? I'd like to try a qso (100 miles). Art... From owner-laser Sat Apr 26 00:53:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03235; Sat, 26 Apr 97 00:53:27 PDT To: laser@berlioz.nsc.com Date: Sat, 26 Apr 1997 03:08:42 -0400 Subject: Filters Message-Id: <19970426.035638.17198.0.K3PGP@juno.com> References: <9704242334.AA18332@berlioz.nsc.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-11,13-15,17-29,35-36,41-47 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Thu, 24 Apr 97 16:34:32 PDT jmoss@berlioz.nsc.com (Jim Moss) writes: >A narrower passband is possible. Li band filters are 670+/-2nM, >but cost $36 from Edmund Sci, and will exclude 650 and 633 >xmtrs.... There are filters for those frequencies too. > >Jim >WB9AJZ > Do you have a part number for these? This is the second time I've seen reference to this but I've never been able to locate them. Here's what I have in my Edmund Sci. Catalog: $52.50 $52.50 $88.00 H.B.W. nm 1/2x1 3/4x3/4 25mm nm %Trans Laser ---------- ------------ ------------ ------------ ---------- ---------- ---------- 457.9 A30,900 A30,903 A30,906 6.8 45 Cadmium 488.0 A30,692 A30,708 A30,907 7.2 45 Argon 514.5 A30,694 A30,710 A30,908 8.0 50 Argon 532.0 A30,901 A30,904 A30,909 8.6 50 YAG 632.8 A30,701 A30,717 A30,910 11.1 45 He-Ne 694.3 A30,739 A30,745 A30,911 12.4 45 Ruby $88.00 $88.00 $143.35 ---------- ------------ ------------ ------------ ---------- ---------- ---------- 1064 A30,902 A30,905 A30,912 15.2 45 YAG I have some filters with sufficient bandwidth to allow for the frequency drift of the typical laser diode that were removed from commercial equipment. However, the ones above are the only ones I can find in my Edmund Sci. Catalog. I couldn't find any for $36.00. Either I have the wrong catalog, (they put out more than one type) or I am not looking in the wrong place. So far I can't find any filters for 780 nm, 820 or 880 nm. About the only suitable filter I can locate is a LPF (low pass filter) that cuts off at 600 nm. (95% transmission 600 nm down through IR. Everything above 590 nm or so gets blocked. - Just about infinite attenuation!) Price $15 to $21 depending on diameter. John K3PGP@juno.com -==- From owner-laser Sat Apr 26 00:53:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03229; Sat, 26 Apr 97 00:53:21 PDT To: laser@berlioz.nsc.com Date: Sat, 26 Apr 1997 03:38:43 -0400 Subject: Laser Reflector at the Speed of Light ? Message-Id: <19970426.035638.17198.2.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 5-6,14-15,21-22,26-27,29-30,41-47 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk The present speed of the laser reflector is OK for what we're doing right now. However, if weak signal work continues to progress I can see the day coming when we are going to be experimenting with either tropo scatter or using some object beyond the earth's atmosphere for tests. When that day arrives the speed of this reflector is going to be a real handicap. There are several other reflectors running over at qsl.net that are used for things like meteor scatter skeds, etc. I can post to any of these reflectors and get a response in a matter of minutes. Same with Moon-Net and Mars-Net. These particular two are NOT a fair test though because they are not on qsl.net. However, all of the above demonstrate how a reflector with a fast throughput can be used to co-ordinate skeds and tests. It's possible to set up skeds for later the same day or even within the hour! When I post something to this reflector the average turnaround time can be 12 hours or more depending on when I send my data to it. This simply won't work for setting up skeds or co-ordinating long haul laser experiments. At times the turnaround is so slow I just give up and Email direct. True I could set up my own group Email list but isn't that supposed to be what the reflector is for? Right now I have a couple of pieces of mail that I sent to this reflector more than 15 hours ago. So far none has shown up. When stuff like this happens I never know whether to resend them or just forget it. Sometimes a re-send isn't possible if the outgoing Email bin was cleaned out. I'd be happy to set up a reflector at qsl.net for test purposes if anyone is interested in comparing how it works. (???) However, since this is Jim's baby I don't want to steal his thunder and any decisions along this line is up to him (as well as the other users here). As pointed out before, we are freeloaders here and have no right to complain and we all owe Jim a B-I-G thank you for getting this thing started in the first place. (I can remember when months would go by without a single post!) I'm just looking a bit into the future and I can see some problems ahead. When the solution is at hand why not go for it? (Or at least give it a try by setting up the new reflector while retaining this one for backup a while. Once we decide which is better then the old one could be dropped. I would have no problem with posting to both for a month or so to test them out.) John K3PGP@juno.com -==- From owner-laser Sat Apr 26 13:34:07 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17715; Sat, 26 Apr 97 13:34:07 PDT Date: Sat, 26 Apr 97 13:34:04 PDT From: jmoss (Jim Moss) Message-Id: <9704262034.AA17709@berlioz.nsc.com> To: laser Subject: Filters Sender: owner-laser@berlioz.nsc.com Precedence: bulk John, Chck page 76 of Edmund Sci Industrial Optics Div Cat N971B 11.80mm Dia 632 nM A43081 $43 11.80mm Dia 780 nM A43093 $71 880 nM A43098 $71 They are +/- 2nm accuracy, 10 nM HBW 40% in band transmittance Jim ----- Begin Included Message ----- From owner-laser Sat Apr 26 04:25:54 1997 To: laser@berlioz.nsc.com Date: Sat, 26 Apr 1997 03:08:42 -0400 Subject: Filters X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-11,13-15,17-29,35-36,41-47 From: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Content-Length: 1742 On Thu, 24 Apr 97 16:34:32 PDT jmoss@berlioz.nsc.com (Jim Moss) writes: >A narrower passband is possible. Li band filters are 670+/-2nM, >but cost $36 from Edmund Sci, and will exclude 650 and 633 >xmtrs.... There are filters for those frequencies too. > >Jim >WB9AJZ > Do you have a part number for these? This is the second time I've seen reference to this but I've never been able to locate them. Here's what I have in my Edmund Sci. Catalog: $52.50 $52.50 $88.00 H.B.W. nm 1/2x1 3/4x3/4 25mm nm %Trans Laser ---------- ------------ ------------ ------------ ---------- ---------- ---------- 457.9 A30,900 A30,903 A30,906 6.8 45 Cadmium 488.0 A30,692 A30,708 A30,907 7.2 45 Argon 514.5 A30,694 A30,710 A30,908 8.0 50 Argon 532.0 A30,901 A30,904 A30,909 8.6 50 YAG 632.8 A30,701 A30,717 A30,910 11.1 45 He-Ne 694.3 A30,739 A30,745 A30,911 12.4 45 Ruby $88.00 $88.00 $143.35 ---------- ------------ ------------ ------------ ---------- ---------- ---------- 1064 A30,902 A30,905 A30,912 15.2 45 YAG I have some filters with sufficient bandwidth to allow for the frequency drift of the typical laser diode that were removed from commercial equipment. However, the ones above are the only ones I can find in my Edmund Sci. Catalog. I couldn't find any for $36.00. Either I have the wrong catalog, (they put out more than one type) or I am not looking in the wrong place. So far I can't find any filters for 780 nm, 820 or 880 nm. About the only suitable filter I can locate is a LPF (low pass filter) that cuts off at 600 nm. (95% transmission 600 nm down through IR. Everything above 590 nm or so gets blocked. - Just about infinite attenuation!) Price $15 to $21 depending on diameter. John K3PGP@juno.com -==- ----- End Included Message ----- From owner-laser Sat Apr 26 16:53:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21338; Sat, 26 Apr 97 16:53:21 PDT Date: Sat, 26 Apr 1997 19:50:21 -0400 (EDT) Message-Id: <2.2.16.19970426190640.27f70ee6@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Do we need laser diodes? !!!!!!!! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks With all the about scattering going on the reflector I got to wondering. 1) Why do we need a laser diode for the transmitter ? 2) does the narrow spectral width help us in DX as opposed to a IR diode lets say. 3) could we not achieve 1 mr divergence using a LED ? Using big enough lens? If we could achieve that there are companies making diodes that can be pulsed to 10 amps for 1 microsecond pulses. This same diode,( I have one) has a 4 degree half power beamwidth, with a small 1.5" lens I can get that down to 1.5" and I have a lager lens that has a fitting /fd to work efficiently with this diode. Am I missing something here? Could not we achieve more power density than 1 - 5 mw laser diode? Any ideas welcome 73's PaulC KB1RP From owner-laser Sat Apr 26 20:14:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25109; Sat, 26 Apr 97 20:14:39 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Message-Id: <3362B8CB.360E97@qsl.net> Date: Sat, 26 Apr 1997 22:24:11 -0400 From: K3TKJ Organization: http://www.qsl.net X-Mailer: Mozilla 3.01Gold (X11; I; Linux 2.0.28 i486) Mime-Version: 1.0 To: laser@qsl.net Subject: [LASER] another test Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Reply-To: K3TKJ Sender: owner-laser@berlioz.nsc.com Precedence: bulk test please ingore From owner-laser Sat Apr 26 20:06:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24936; Sat, 26 Apr 97 20:06:15 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Message-Id: <3362B6D1.35B0B0EA@qsl.net> Date: Sat, 26 Apr 1997 22:15:45 -0400 From: K3TKJ Organization: http://www.qsl.net X-Mailer: Mozilla 3.01Gold (X11; I; Linux 2.0.28 i486) Mime-Version: 1.0 To: laser@qsl.net Subject: [WSVHF] test message Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Reply-To: K3TKJ Sender: owner-laser@berlioz.nsc.com Precedence: bulk This is a test please ignore From owner-laser Sat Apr 26 21:20:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26617; Sat, 26 Apr 97 21:20:52 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Sat, 26 Apr 97 21:16:05 PDT From: jmoss@berlioz.nsc.com (Jim Moss) Message-Id: <9704270416.AA26573@berlioz.nsc.com> To: laser@qsl.net Subject: [LASER] test - ignore! Reply-To: jmoss@berlioz.nsc.com (Jim Moss) Sender: owner-laser@berlioz.nsc.com Precedence: bulk ......................................................................... ------------------------------------------ ................................................................................................... flash! From owner-laser Sun Apr 27 02:05:12 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01122; Sun, 27 Apr 97 02:05:12 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Sun, 27 Apr 1997 05:04:46 -0400 Subject: Re: [LASER] Test via qsl.net - ignore! Message-Id: <19970427.050447.6374.0.K3PGP@juno.com> References: <19970427.043606.14430.4.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-13 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Received @juno.com 04:58 EDST (22 minutes later) On Sun, 27 Apr 1997 04:36:06 -0400 k3pgp@juno.com (John K3PGP) writes: >This is being posted to qsl.net at 4:36 am EDST. > >If it shows up at laser@berlioz.nsc.com then all is well! > >We'll see what the response time is! > > >John >K3PGP@juno.com > >-==- From owner-laser Sun Apr 27 02:00:36 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01094; Sun, 27 Apr 97 02:00:36 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Sun, 27 Apr 1997 04:36:06 -0400 Subject: [LASER] Test via qsl.net Message-Id: <19970427.043606.14430.4.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-10 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk This is being posted to qsl.net at 4:36 am EDST. If it shows up at laser@berlioz.nsc.com then all is well! We'll see what the response time is! John K3PGP@juno.com -==- From owner-laser Sun Apr 27 07:05:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05319; Sun, 27 Apr 97 07:05:50 PDT Message-Id: <199704271403.KAA25631@smtp2.erols.com> From: "Tyler Stewart" To: , "Paul A. Cianciolo" Subject: Re: Do we need laser diodes? !!!!!!!! Date: Sun, 27 Apr 1997 14:02:45 +0100 X-Msmail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1161 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk For one thing, if you plan on operating light in an ARRL contest, the light involved must be COHERENT light, not a flashlight, regular LED, etc. 73, Tyler K3MM ---------- > From: Paul A. Cianciolo > To: laser@berlioz.nsc.com > Subject: Do we need laser diodes? !!!!!!!! > Date: Sunday, April 27, 1997 12:50 AM > > Hello Folks > > With all the about scattering going on the reflector I got to wondering. > > 1) Why do we need a laser diode for the transmitter ? > > 2) does the narrow spectral width help us in DX as opposed to a IR diode > lets say. > > 3) could we not achieve 1 mr divergence using a LED ? Using big enough lens? > > If we could achieve that there are companies making diodes that can be > pulsed to 10 amps for 1 microsecond pulses. > > This same diode,( I have one) has a 4 degree half power beamwidth, with a > small 1.5" lens I can get that down to 1.5" and I have a lager lens that has > a fitting /fd to work efficiently with this diode. > > Am I missing something here? > > Could not we achieve more power density than 1 - 5 mw laser diode? > > Any ideas welcome > > > 73's > PaulC KB1RP > From owner-laser Sun Apr 27 10:15:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08433; Sun, 27 Apr 97 10:15:54 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Sun, 27 Apr 1997 13:09:53 -0400 Subject: [LASER] Re: Filters Message-Id: <19970427.130954.13806.1.K3PGP@juno.com> References: <9704262034.AA17709@berlioz.nsc.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-3,5-6,9-18,22-23,26-48 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: Thanks! I looked at that page many times but never flipped the page over. The filter I was looking for was on the back side of that page! They get a little on the expensive side in the IR range and the insertion loss is a little higher than I would like but I'm glad to know that they are available as I may end up with one of these. I'm going to give the 600 LPF a try for now. Page 71. # A52,527 12.5 mm dia. $14.75 # A52,528 25.0 mm dia $19.95 # A52,529 50.00 mm dia $21.15. It should work with ALL laser diodes, (approx. 95% transmission 630 nm and down through the IR range) but of course will let a little more interference through as well. I'm hoping it will eliminate most of the problems with man made light. These filters can also be used for color seperation (by ordering the set / one for red, one for blue and one for green) for astrophotograpy using a CCD camera. John K3PGP@juno.com On Sat, 26 Apr 97 13:34:04 PDT jmoss@berlioz.nsc.com (Jim Moss) writes: >John, >Chck page 76 of Edmund Sci Industrial Optics Div >Cat N971B > >11.80mm Dia 632 nM A43081 $43 >11.80mm Dia 780 nM A43093 $71 > 880 nM A43098 $71 > >They are +/- 2nm accuracy, >10 nM HBW >40% in band transmittance > >Jim -==- From owner-laser Mon Apr 28 08:08:19 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04127; Mon, 28 Apr 97 08:08:19 PDT Date: Mon, 28 Apr 1997 08:01:16 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9704281501.AA07660@fmsserv99.azfms.com> To: laser@berlioz.nsc.com, PaulC@snet.net, k3mm@erols.com Subject: Re: Do we need laser diodes? !!!!!!!! X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk > > From: Paul A. Cianciolo > > > > With all the about scattering going on the reflector I got to wondering. > > > > 1) Why do we need a laser diode for the transmitter ? > > > For one thing, if you plan on operating light in an ARRL contest, the light > involved must be COHERENT light, not a flashlight, regular LED, etc. > > 73, Tyler K3MM Does it have to be coherent for ANY contact to count for ANY award? Or just for contests? (I suppose a scan of the ARRL web site might answer that question... Hmm) rusty From owner-laser Mon Apr 28 08:59:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05364; Mon, 28 Apr 97 08:59:39 PDT Date: Mon, 28 Apr 97 08:59:36 PDT From: jmoss (Jim Moss) Message-Id: <9704281559.AA05355@berlioz.nsc.com> To: laser Subject: filters, and closed list. Sender: owner-laser@berlioz.nsc.com Precedence: bulk Looks like laser@qsl.net is a closed list right now.... only those subscribed there can post through it. Will look into it.. See note below from Neil on filters: From: Neil Spokes X-Mailer: Mozilla 2.01 (Win16; U) MIME-Version: 1.0 To: John K3PGP CC: laser@qsl.net Subject: Re: [LASER] Re: Filters - blocking info References: <9704262034.AA17709@berlioz.nsc.com> <19970427.130954.13806.1.K3PGP@juno.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit When using filters you need to be sure that your out of band blocking of the full range of your detector is kept to low levels. In our white light system we use 10 nm half width filters at work and we specify out of band blocking at the 10exp(-5) level. This assures that the signal is not swamped by big out of band signals that accumulatively contribute to the total detected. Our supplier routinely blocks at the 10exp(-6) level to assure that our 10exp(-5) specification is met. The best filters will have excellent blocking. The worst filters suffer from pinholes that bypass the filter. If interested you can tune the filters some 10s of nm by rotating them so that the normal is off axis. Performance deteriorates as you angle the filter. I do not recall the equation off hand but it involves the dielectric constant of the filter materials. If any one wants it I can get it but I'm sure that one of the laser reflector membership has it to hand, if needed. BTW, tiny filters only 1/4" in diameter will work just as well as a big one if you use them at the laser location. Note that many interference filters have a limited life. Our company specifies a two year life. If used in high humidity environments and high temperatures life is shorter. -- And we have an epoxy coating to protect the filter edge. Neil, AB4YK. ==================================== John K3PGP and others wrote about using interference filters. ----- End Included Message ----- From owner-laser Mon Apr 28 17:42:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA22876; Mon, 28 Apr 97 17:42:29 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Mon, 28 Apr 1997 20:35:48 -0400 Subject: [LASER] Hamamatsu R647 vs R647-01 PMT Message-Id: <19970428.203548.14382.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 1-2,4-9 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Can anyone tell me what the difference is between a Hamamatsu R647 and an R647-01 PMT is? I am running tests on a several of these here and all I can find are specs for the R647. I was wondering what the -01 meant ??? John K3PGP@juno.com -==- From owner-laser Mon Apr 28 18:02:14 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23493; Mon, 28 Apr 97 18:02:14 PDT Date: Mon, 28 Apr 1997 20:51:44 -0400 (EDT) Message-Id: <2.2.16.19970428200744.1d378426@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Do we need laser diodes?!!! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, Sorry I was not clear enough on my last post on this topic. My question involves the typical power level available in laser modules as being 1-5 mw at 1mr. The question is cannot a high power LED be collimated to the same extent as a laser diode or close to 1 mr depending on the lens arrangement we put in front of it. I do not care at this point about ARRL rules, ( but thanks for the data on the legal contact), but merely power density. I have a IR diode that can be run at .5 amp continuous duty current , if collimated properly could it not provide a distant echo stronger than that of a 1-5 mw laser diode. I am just looking for a way to increase the output power/density beyond the currently availaable 1-5 mw Any ideas? 73's PaulC KB1RP From owner-laser Mon Apr 28 18:22:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23927; Mon, 28 Apr 97 18:22:41 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Mon, 28 Apr 1997 21:18:50 -0400 Subject: [LASER] Scatter Signals Message-Id: <19970428.211853.14382.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 1-5,7-12,17-18,22-23,31-32,37-38,44-45,51-52,58-59, 61-62,69-70,75-80 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Sat, 26 Apr 1997 18:37:08 -0400 (EDT) "Paul A. Cianciolo" writes: >John, > >How big is the antenna (lens) in this experiment?? > >Also can you see the signal in real time on the computor? How di you know >there was QSB could you see it on the computer > >73's >PaulC KB1RP The receive optics consists of a 10 inch diameter PCV (plano-convex) glass lens with an approx. 14 inch focal length. (The lens alone weighs around 8 pounds!) At the focal point is a pin hole in front of a red filter then a big photo-multiplier tube with a 2 inch face on it which was optimized for best SNR at 905 volts. This feeds an MPF-102 preamp into an op-amp, an op-amp narrow band filter, then a third op-amp used for gain only. The output of this feeds a D/A converter into the computer and a VLF converter into a communications receiver. The transmit laser is mounted slightly behind the receive optics with a flat black piece of paper between them to prevent any coupling. Both the laser and the receiver are mounted to a single board so they can be pointed as a system much the same as a conventional radar. The system has been tested for crosstalk between the receiver and transmitter and none can be found even when running the FFT program for several hours. There is no detectable signal unless something in front of the laser causes a reflection. The FFT program had to be run anywhere from a couple of seconds to 30 seconds to find the signal, depending on the strength at the moment. At it's strongest point it was plainly audible in the speaker and that's when I noticed that it sounded extremely hollow, like a multi-path tropo scatter signal. I'm NOT jumping to any conclusions at the moment as to exactly what this signal is and where it's coming from. Although it sounds like I would expect a scatter signal to sound, this is an unknown area and I want to proceed with caution from this point on. I have no way of knowing if the reflected signal is coming from 50 feet in front of the laser or 50 miles. My guess is it's coming from multiple reflection points along the way and this could account for the distortion of the signal making it hollow sounding. The type of distortion that I'm hearing would seem to indicate that the signal traveled a fair distance before coming back but was mixed with other shorter delayed signals causing the multi-path sounding distortion. Once I can confirm the distances involved and verify that it isn't some type of local phenomena, I will then take a receiver to another location and attempt to find the signal on backscatter. Only then will I believe that this is really backscatter. If it is then I see no reason why this form of propagation couldn't be used to cover some pretty astounding distances as far a laser communications is concerned. PS - This was a cold, clear, cloudless night. We can rule out anything like cloud bounce, etc. You and I both know that this signal should be there. However, I also know that most of the scattering in the atmosphere occurs higher up in the spectrum around 450 - 475 nm (blue). At red and below scattering is almost nil. That's why I was surprised to find this signal. I know it should be there but building something sensitive enough to find it is a real challenge. It is undetectable with any other type of laser setup that I've tried in the past. Right now I'm busy working on the system so any further tests won't be for a couple of weeks. I'm trying to come up with some filters to reduce the pollution from man made lighting that is also being scattered back to the receiver. The present system is so sensitive that it can be easily overloaded by signals that the eye can't even begin to see. John K3PGP@juno.com -==- From owner-laser Mon Apr 28 19:08:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25381; Mon, 28 Apr 97 19:08:09 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Mon, 28 Apr 1997 21:53:35 -0400 (EDT) Message-Id: <2.2.16.19970428210934.1bef1304@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@qsl.net From: "Paul A. Cianciolo" Subject: [LASER] Address for really big lens's cheap! Reply-To: "Paul A. Cianciolo" Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Date: Mon, 28 Apr 1997 21:05:46 >To: laserlist @qsl.net >From: "Paul A. Cianciolo" >Subject: Address for really big lens's cheap! > >Try this one out guys. I am thinking abiut getting the 8" dia and 10"fl > >Good luck > 73's PaulC KB1RP From owner-laser Mon Apr 28 19:08:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25382; Mon, 28 Apr 97 19:08:11 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Mon, 28 Apr 1997 21:58:00 -0400 (EDT) Message-Id: <2.2.16.19970428211400.33d7b7f4@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@qsl.net From: "Paul A. Cianciolo" Subject: [LASER] repeat. big lenses cheap Reply-To: "Paul A. Cianciolo" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, lets try this again.. Try this address for big lenses cheap http://www.surplusshack.com/index.htm#LENSES, PRISMS, & MIRRORS There.... Thats better! 73's PaulC KB1RP From owner-laser Mon Apr 28 22:02:02 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29507; Mon, 28 Apr 97 22:02:02 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Tue, 29 Apr 1997 00:04:37 -0400 Subject: [LASER] Samples from Surplus Shack Message-Id: <19970429.000441.12662.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-11,20-23,26-33,36-39,41-44,46-49,55-58,61-68,72-81 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Samples from www.surplusshack.com Surplus Shack 407 U.S. Route 222 Blandon, PA 19510 610-926-9226 ----- LENSES, PRISMS, & MIRRORS RETROREFLECTORS Precision 3 mirror type. Retroreflectors are designed to reflect any ray or beam entering , regardless of the orientation of the retroreflector, back onto itself. Ideal where precision alignment is difficult or time consuming.. These are said to be accurate to 1.5 arc seconds, but we have no way to test them (this is reflected in our bargain price). They are mounted on a 2-1/4" diameter tube, 1" long. The front has a flange with 3 mounting holes. Edmund sells a 38mm, 2 second for $346.50, and a 1 second for $593.25. Their 63mm, 3 mirror retroreflector is $409.50 for 2 seconds and $666.75 for 1 second. Unused. Boxed. #L1159 $ 35.00 8" DIAMETER CONDENSER LENS Large, heavy, glass condenser lens. Good for focusing light or experiments. Not good for image work. Looks like about 10" focal length. Plano convex. #L1128 $ 12.00 ----- FILTERS 8-1/2" ORANGE FILTER Type 3 orange filter, 8-1/2" diameter by 1/2" thick. Unused, in original packaging. Made to be used with the K22 Fairchild Aerial Camera. Unmounted. #M8005 $25.00 3-3/8" DIAMETER INFRA RED FILTER Mounted IR filter. Made to fit on an aerial camera lens. 3-3/8" clear diameter. Bayonet type mount is 4-1/4" diameter. #M1102 $ 5.00 4" DIAMETER INFRA RED FILTER Mounter IR filter. Made to fit on an aerial camera lens. 4" clear diameter. Bayonet type mount is 4-3/4" diameter #M1103 $ 7.00 CIRCULAR VARIABLE DENSITY FILTER 4-1/2" diameter with 1/16" center hole and 3/4" mount. Provides linear attenuation of incident light by rotating the filter in a clockwise or counter clockwise direction. The transmitted intensity is varied as a function of the optical density range. This is silvered so it can be used to vary reflection intensity as well. Edmund sells unsilvered 4" variable filters for $290.00 #M8006 $ 45.00 CIRCULAR VARIABLE DENSITY FILTER Similar to #M8006 above, but 51mm diameter. Small hole in center with 31mm diameter gear mounted on one side. Edmund's has similar filter without the gear for $260.00. #M9005 $ 25.00 ----- MISCELLANEOUS CALIBRATED LIGHT SOURCE Solid state, calibrated, stabalized light output of 1600 Foot-Candles through a 3" diameter window. Has circuit board with ICs etc. Includes a photo Cell and (4) GE 311 lamps. Requires 115VAC, 400HZ. 9" X 6" X 4". Includes block and wiring diagrams. Unused. #M7009 $ 10.00 ----- John K3PGP@juno.com -==- From owner-laser Tue Apr 29 07:32:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13596; Tue, 29 Apr 97 07:32:34 PDT Message-Id: <9704291341.AA27068@is.ups.com> From: "Guy Hamblen" To: "Laser" Subject: Feedback resistors for OPT211/Op-amp..... Date: Tue, 29 Apr 1997 09:41:50 -0400 X-Msmail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Ok...now that I've cajoled two "engineering samples" for the OPT211 to skirt the $100 minimum order requirement from Sager on these items, I'm looking for sources and availability for a minimum of 4@56 megohm or 2@100 megohm resistors. Can anybody steer me to distributor/vendor? If necessary, I'll cover a minimum order qty then offer the reistors for resale to others. I know Art, KY1K, has offered the same for the 1 gigohm resistors....but maybe we all can get started with the smaller resistors. Thanks in advance for your suggestions... 73, Guy N7UN/2 From owner-laser Tue Apr 29 07:06:40 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12571; Tue, 29 Apr 97 07:06:40 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Tue, 29 Apr 1997 08:51:41 -0400 (EDT) Message-Id: <2.2.16.19970429080735.18c7e9ae@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@qsl.net From: "Paul A. Cianciolo" Subject: [LASER] toll free # for surplus shack Reply-To: "Paul A. Cianciolo" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks Here is the toll free number for surlpus shack 1-888-88shack any one know what a condensor lens was used for? 73's PaulC KB1RP From owner-laser Tue Apr 29 07:27:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13431; Tue, 29 Apr 97 07:27:09 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Tue, 29 Apr 1997 09:53:47 -0400 Subject: [LASER] PCV Lens Message-Id: <19970429.095355.13318.1.K3PGP@juno.com> References: <2.2.16.19970429080735.18c7e9ae@mail.snet.net> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0,2-17,20-21,27-30,36-37,40-41,47-48,54-55,59-60, 64-65,73-74,77-78,81-82,87-88,93-94,99-104 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Tue, 29 Apr 1997 08:51:41 -0400 (EDT) "Paul A. Cianciolo" writes: >Hello Folks > >Here is the toll free number for surlpus shack > >1-888-88shack > >any one know what a condensor lens was used for? > > >73's >PaulC KB1RP > > Paul: A condenser lens is usually used in projection setups such as film projectors but I have also seen them used in the large follow spot used in stage work. In a film projector they are used between the light source and the film and are NOT part of the projection lens setup. The purpose is to produce a flat illumination (equal intensity) across the entire frame of film from a point source (light bulb). Without the condenser lens the center of the picture would be brighter than the edge because the center is closer to the light source. >From Quick Tips for Projector Design, Techspec Bulletin: "Condenser lens systems collect light from divergent illumination sources and redirect - ' condense ' - the light to flood the projector lens system. The classical condenser lens system consists of two plano-convex (PCX) elements mounted convex sides together. The first lens collects the divergent light cone from the illumination; the second lens outputs the light as a convergent cone." They are ' NOT good for image work ' (such as the projection lens which goes in FRONT of the filmstrip, microscopes and telescopes) because of the fact that they have chromatic distortion. Lens focus light by refracting or bending the light rays to cause them to focus to a point. The problem is the refraction coefficient is frequency dependent meaning that higher frequency (blue) light is refracted more than lower frequency (red) light. This causes color fringing effects when you try to use them for critical image work such as telescopes, microscopes, photography, etc. When the focus is adjusted the lens will appear to have a shorter focal length for blue light than it does for red light. It will be impossible to find a focal length where ALL colors are in focus at the same time. The refractive index of the glass vs frequency is the same effect that takes place when using a prism to break white light into it's color components. The solution is to use an ' achromat ' lens. This type of lens is color corrected by using two lens cemented together, usually a positive low-index (crown) element and a negative high index (flint) element. Needless to say these are more expensive! Any simple PCV (plano-convex) lens will have chromatic distortion. My 10 inch lens has this problem as well. However, in our case we are only interested in bringing one very narrow wavelength of light into focus and don't really care about what happens to the other colors. By using a pin hole in front of the detector you can use this chromatic distortion to your advantage since the red or IR energy will have the longest focal length. All you have to do is place a pinhole in front of the detector and adjust the focus so that most of the red or IR energy goes through the pin hole. The higher frequency light will be focused in front of the pin hole causing it to have a larger diameter and as a result only SOME of it will make it through the pin hole. You will have to play with the diameter of the pinhole depending on your exact setup. This is NO substitute for a good narrow band filter since SOME of the higher frequency light will also make it through the pin hole but it DOES help. Keep in mind that a fresnel lens will produces even more chromatic distortion. Most people rule out using fresnel lens because of the severe color distortion. However, for laser work I think they are ideal. You can get an 11 inch square fresnel from Edmund Scientific for approx. $12 to $13 depending on focal length. They come in 8.85, 13 and 16 inch length focal lengths. The more you bend the light the more chromatic distortion you will have meaning that the 8.85 inch focal length fresnel will produce the greatest color separation effect. I'll look up the part number if you want to try one of these as well. It should outperform the 8 inch glass lens and be a LOT lighter. I'd pick up the glass lens if I were you as any type of lens much larger than 5 or 6 inches is extremely hard to come by but I'd also get one of the fresnels from Edmund Sci. and compare them. Keep in mind that the active surface area of your detector will enter into the equation as well. A lot of people rule out using a fresnel with a very narrow active area detector because of the ' fuzz ball ' focusing effect of fresnels. They seem to completely miss the chromatic distortion effect, but now you know how to use this to your advantage! John K3PGP@juno.com -==- From owner-laser Tue Apr 29 07:18:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13072; Tue, 29 Apr 97 07:18:41 PDT Message-Id: <199704291244.IAA08907@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 29 Apr 1997 08:44:42 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: ?? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey, did I miss something? Im getting posts from the OTHER laser list. Seems i was signed up automatically for the other list? Is the .nsc list dead? Hello? Art... From owner-laser Tue Apr 29 07:50:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14153; Tue, 29 Apr 97 07:50:26 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Tue, 29 Apr 1997 10:42:43 -0400 Subject: [LASER] Homebrew Haze Sensor Message-Id: <19970429.104246.13798.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 2-3,6-7,10-26,34-35,42-43,49-50,57-58,68-70,77-78, 86-87,93-94,102-103,108-109,117-119,126-127,133-136,144-277 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk I ran across an article that shows how to measure ' haze ' in the atmosphere. I went to the trouble to scan it in because I thought it would be of interest to the people who visit here. I am also using this post to test the new path that I am using to access the laser reflector. I want to make sure that graphics makes it through as well as text! If you need any of the other graphics let me know. However, if you are really interested in this pick up the current issue of Scientific American (May, 1997) which is on news stands now. John K3PGP@juno.com ----- >From this months Amateur Scientist (May '97) Scientific American HAZE SENSOR When Hazy Skies Are Rising by Shawn Carlson Haze is a vital indicator of our atmosphere's health. Most haze is natural; it is created by water vapor, wind-borne dust, forest fires and volcanic eruptions. Unfortunately, a lot of what humans do also ends up in the atmosphere--smog is the best-known example of artificial haze. Although many cities monitor the clarity of their local atmosphere, surprisingly little is known about how the amount of haze is changing globally because no one is coordinating haze observations over widely dispersed areas. That may change with the latest design from Forrest M. Mims III. (Mims may be familiar to readers from his columns in this section in 1990.) He has invented an atmospheric haze sensor that costs less than $20 and is so simple to construct that even the most hardened technophobe can put it together in under an hour. Mims's instrument could revolutionize this important area of study by opening the field to all comers, that is, to amateur scientists. The Visible Haze Sensor exploits the fact that sun is an ideal probe for measuring haze. The intensity of sunlight striking the top of the earth's atmosphere is essentially constant. As a result, by measuring the intensity of the sunlight at the ground and knowing the thickness of the atmosphere it has passed through, we can determine how much light has been scattered or absorbed and hence how much haze there is. There is one complication. Air molecules themselves scatter light, in a phenomenon known as Rayleigh scattering. Although Rayleigh scattering creates beautiful blue skies and brilliant sunsets, it also complicates measurements of haze. Because the efficiency with which air molecules scatter light depends on wavelength, scientists restrict their measurements to a narrow sliver of the solar spectrum so that the effects of Rayleigh scattering can be easily corrected for. Most professional haze instruments employ a broad-spectrum photodetector, coupled with an expensive narrow-band filter to achieve the necessary selectivity. Mims realized that a narrow-band detector would serve the same purpose. The perfect device for the amateur scientist is a light-emitting diode (LED), which generates light of a sharply defined color when a current passes through it. But this process is easily reversed: light falling on the LED creates a small current that can be readily detected. Furthermore, just as LED emissions appear only in a narrow wavelength band, the diode generates current only when stimulated by light within a small range of colors. SENSOR CIRCUIT is simple to assemble. Mims's device uses a green LED (Radio Shack 276-022A), which emits light at around 555 nanometers and detects light at around 525 nanometers. It costs less than a dollar. The rest of the circuit consists of one resistor, an operational amplifier, two nine-volt batteries and a voltmeter. Mims houses his instrument inside a plastic VHS videocassette case with a hole drilled in one end to admit sunlight [see illustration right]. Two angle brackets on the side of the case let you align the instrument directly with the sun. (If possible, attach them with a hot-glue gun to make a rigid connection.) Place a small piece of white tape over the bottom bracket. Open the case and point the instrument toward the sun. Move it around until the bright sun spot is centered on the LED. If the outside brackets on the side are approximately aligned, a second image of the sun should appear somewhere on the tape. Lightly mark its center in pencil. The case may flex slightly when closed, so you may need to adjust your mark. Close the case and align the instrument to the sun using the outside brackets. Then tilt the instrument slightly in different directions while watching the voltmeter and find the orientation that produces the largest voltage. Make a permanent mark at the center of the sun's image, and you're ready to go. Although you can begin collecting data right away, you will eventually need to calibrate your photometer. To do that, you'll have to set aside half a day (either early morning to solar noon or solar noon to early evening) when the sky is clear blue and there are few or no clouds. First, you'll need to record the dark signal, that is, the voltage produced when no light strikes the detector. Cover the sun port and record the voltage. You'll need to subtract this number from every measurement you make. Measure the voltage every 20 minutes when the sun is high overhead and every seven minutes when it is low on the horizon. Always record the time, the sky condition near the sun, and the angle of the sun above the horizon. (Keep your data reliable by recalibrating your instrument at least once a year.) To complete the calibration, you'll need to plot your data. First, calculate the air mass for each measurement. The air mass is the depth of the air column between you and the sun; by convention it is 1.0 when the sun is straight overhead (a sun angle of 90 degrees) and infinite as the sun sets. The formula is 1/sin(sun angle). After compensating for the dark voltage, plot the natural logarithm of your photodetector measurements against the air mass. The result is called a Langley plot and should be a straight line out to an air mass value of about 10. MEASURING HAZE If you project that line back to an air mass of zero [see upper illustration in sidebar, Measuring Haze], the result will be the logarithm of the voltage that your instrument would read if you could use it to measure the sun's brightness just above the atmosphere--the so-called extraterrestrial constant, or ET. This constant is the starting point for calculations of aerosol optical thickness, which quantifies haze. I can't think of a better way for students and adults alike to become more aware of their environment than to get involved in monitoring it. Committing to a regular program of measurements teaches young people responsibility as well as science. You can even become part of a worldwide network of haze observers by submitting observations via the Internet. Visit the TERC site for detailed instructions. ------------------------------------------------------------------------ The Visible Haze Sensor photometer was developed through a grant from the National Science Foundation to the Global Lab program at TERC in Cambridge, Mass. TERC has set up a haze monitoring site on the World Wide Web. For more information about this project, check out the Society for Amateur Scientists's World Wide Web site. The SAS can be reached at 4951D Clairemont Square, Suite 179, San Diego, CA 92117 or at (619) 239-8807 or (800) 873-8767. I gratefully acknowledge informative conversations with Forrest Mims. ----- _=_ _=_ Part 001 of 001 of file Circuit.zip _=_ begin 666 Circuit.zip M4$L#!!0``@`(`'10G2(QBQ][7!0``'(4```+````0VER8W5I="YG:6:5E^..WN[.R.SD#@CG#M[=$:RNT-*2;:4<5:(RM[*SJKLG#5N4 M'+*BG+33[][W_1/>Y]OSZ?G\F)J;$+1I"X`&P!`;P&:S#PX./GSX,#(RTM;6 M5E55E9V=G9"0$!P<[.7E96=GIZVMK::F)BPLC$:C`?]_<+_!'```&Z#\?_)_ M34,(FRE]W]OWX96ZIWY[?0'*;UKA[V\^/8@\8#-*`\R412.@IB3<6P@R"7"* M?H7`JQOK24L'FIN2B.E,17XP<%W-"0L`#8.(!)[U^_VQML(P(`(9SHFR-25# M_('`$$XP`7+?UH6+"P2`<4&2BK6`$$^(AQ;($_I`%UP*S=/AJ(-"K0VH)390 M'G<.C@38Y72>=M+UG.&1$20/F`<)\H?` MS);2"KT<(C!R\'>F.'>\]C$3IDIG2`"`A8J0`.LA?>A?L:) MWO:8#O&:!J_ED^:5C1Y'`I-'^#^#(DNV$FG40`X3<=A^CCG@P000Q4X!#K;.Q@GZKKY^ MWO/S@'EQ/((E5!>6-WQ=PO3+S$\EZ$06/EG35^GO7_+L!AN#.A&Z-WE(?,#= M]_DR-NB/1&5X>ZQF!WBG#*!J/Y#8J>#F1Q"'11"&H!40=^=IY@,K M1`8U:Q\"W\S6V[\RF>7@4[N9:TH=KS*%)2B8"OV+,C\//**UF5GZA"UY%1F8 MF4U4HY](UN\W&\OTB%P$J,HFZJ.HM%FV8%ZQ;5(; MY\=UL8>NY+W[0,9#/D-\*KWRDUL/!OW*_U-O)D/.^B'71>.$KB1P@#.K;%CL M?@I#.9JGJ0E'B+`C"U"LUCO-1)8QZB/X:!6C9*E4Y%1:6.QU+7K2\O5^=RM@ MS[XV.;N\@]P+L@JV.[A#>FF$ESCNG#TW%7Q1T+1GVR%+^><4"8U;%F=%`<,$5* MFEU2CK'XYWB*'LE\ZLVI4=0"2#UNQKX!,(BQ7K)58QCSP1L:;V,M\;><<-CJ[P1X"L+6GQ)'8LP<_K][K>S@4557RQTT=EJ#)K[!;) MNDM2^I-JG\LNKHZT:-"_^3(`XZ"*%;(_DC!@1)[_)(=6<0S'_VYX>;W=@N\< M4=;D*35G[I7>Y<\*[UB@5>:^B^^@CCUHRL1%0F4(.&JM4L3.C"P3U)1*N6\XYEDN9/3R39I>/[';\F*ZH'@&S>-#'=&N:6^LE(; MO^*+D:4`MMF]\7,@PUFE,"^25\HAC`4"7W*R M;_7TB%2;'+[&`:4X.`JM.1F5/NO\)8/4,O5?`;\8]'\ZIIU)#C/3)81J*!_*C#?S6N/]\2.X2! 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MZBB%Z]DNJH#3S!#+2>_-02ZTMHO3[C$G8I\3#I,Y>2/%!K2N?)U_UM/M]FH^ MB&[*5*$=?NX^*EFM[\7@L8O8U^1D9YHSR4X"8K MX]<3>3[<1M!2!;XPGZ*CN4@KQB5KV#X1E3YE=<[>\AAG[*[3>5 M>V2A3.8,B;`Q$,*;L5[#LN5EO.(V>JT,=*+,$Y?M):FQC;W5O6*7`<]+V^3+ M^GM-[*%>9VP\4SYX?:$)8QK-%@9\RAM7<_Q7SW2^7[#X,O!>U'Q6DPBD^B6< M?;U8Y[Z>]CHN];\=FLR[S`_3!C=W\Q_N%MK$XP``W?\!4$L!`C(+%``"``@` M=%"=(C&+'WM<%```=- From owner-laser Tue Apr 29 11:44:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21944; Tue, 29 Apr 97 11:44:57 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Tue, 29 Apr 97 11:42:32 PDT From: jmoss@rockie.nsc.com (Jim Moss) Message-Id: <9704291842.AA17770@rockie.nsc.com> To: laser@qsl.net Subject: [LASER] test Reply-To: jmoss@rockie.nsc.com (Jim Moss) Sender: owner-laser@berlioz.nsc.com Precedence: bulk test From owner-laser Tue Apr 29 14:22:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26677; Tue, 29 Apr 97 14:22:54 PDT Message-Id: <199704292120.RAA22920@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 29 Apr 1997 17:20:08 -0500 To: k3pgp@JUNO.COM (John K3PGP) From: "Art Allen, KY1K" Subject: Re: [LASER] PCV Lens Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Keep in mind that a fresnel lens will produces even more chromatic >distortion. Most people rule out using fresnel lens because of the >severe color distortion. However, for laser work I think they are ideal. > > >Keep in mind that the active surface area of your detector will enter >into the equation as well. A lot of people rule out using a fresnel with >a very narrow active area detector because of the ' fuzz ball ' focusing >effect of fresnels. They seem to completely miss the chromatic >distortion effect, but now you know how to use this to your advantage! > Obviously, those 'in the know' are going to take advantage of the chromatic splitting that takes place in all lens(s). Using a frensel lens, you take advatage of this by very careful planning of the pin hole in relation to the active area of the device. BUT, I have done experiments with fresnels vs glass lens (mono-frequency light sources). In the early days of my laser career, I set up a 500 or 700 foot test range and a he-ne light source. I illuminated the entire surface area of a 6 by 8 inch fresnel and a 1.125 inch glass lens. At this range, the source is a pinpoint, literally. The glass lens made a pinpoint spot at its focal length-tight, no fringe scattering, no nothing. The frensel is a different story. It made a dot that was 1/8 inch in diameter. There was a ring around this dot, perhaps a little more than 1/8 inch in diameter, all the way around and noticably dimmer. This is massive loss, my guess is way over 3 db, maybe 5 or 6 db. I wish I had the equipment to quantify this loss, the best I can do is a guess. But, it is definately a MAJOR loss. It might be that the frensel loss is acceptable when one considers the lighter weight and the (probably) enhanced out of band spectra rejection char's. But, don't be fooled into thinking that a frensels 'fuzzy' focus is caused by its chromatic splitting. Keep them lasers lit and good dx...Art... From owner-laser Tue Apr 29 16:00:33 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29565; Tue, 29 Apr 97 16:00:33 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Tue, 29 Apr 97 15:50:16 PDT From: jmoss@berlioz.nsc.com (Jim Moss) Message-Id: <9704292250.AA29245@berlioz.nsc.com> To: laser@qsl.net Subject: Re: [LASER] PCV Lens Reply-To: jmoss@berlioz.nsc.com (Jim Moss) Sender: owner-laser@berlioz.nsc.com Precedence: bulk All, I ordered 2 of the 8" lenses to play with! Any one have a source for 8" cardboard tubes? Jim From owner-laser Tue Apr 29 16:01:12 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29599; Tue, 29 Apr 97 16:01:12 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f Date: Tue, 29 Apr 97 15:59:32 PDT From: jmoss@berlioz.nsc.com (Jim Moss) Message-Id: <9704292259.AA29534@berlioz.nsc.com> To: laser@qsl.net Subject: [LASER] LIST INFO!!! READ THIS. Reply-To: jmoss@berlioz.nsc.com (Jim Moss) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Well, We've added more capability to our laser reflector. Now we have "2". Some of you may have noticed that it appears that laser-owner@qsl.net is sending you some mail! Well.... We've added one at "qsl.net" to provide potentially faster delivery. You don't have to move over there if you don't want to. laser@qsl.net automatically sends to laser@berlioz.nsc.com. SO... Please post all your listings to "laser@qsl.net", and they will go to everyone on both "laser reflectors". I suppose if we add another reflector we could become a corner cube! If you prefer to subscribe to the laser@qsl.net reflector, send a message to: majordomo@qsl.net and type subscribe laser in the body. Then be sure to UNSUBSCRIBE from berlioz.nsc.com, or you will get 2 copies! to unsubscribe from laser@berlioz.nsc.com, send an email to: majordomo@berlioz.nsc.com and type unsubscribe laser in the body. I'll be watching! If you need any help let me know! Jim WB9AJZ/6 CM87xi Sunnyvale CA From owner-laser Tue Apr 29 16:19:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00357; Tue, 29 Apr 97 16:19:34 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Tue, 29 Apr 1997 19:12:16 -0400 Subject: Re: [LASER] PCV Lens Message-Id: <19970429.191219.-31738.0.K3PGP@juno.com> References: <199704292120.RAA22920@host-04.colby.edu> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0,2-6,8,10-15,18-19,23-24,29-30,34-52 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Tue, 29 Apr 1997 17:20:08 -0500 "Art Allen, KY1K" writes: >The frensel is a different story. It made a dot that was 1/8 inch in >diameter. There was a ring around this dot, perhaps a little more than >1/8 inch in diameter, all the way around and noticably dimmer. This is >massive loss, my guess is way over 3 db, maybe 5 or 6 db. I wish I had the >equipment to quantify this loss, the best I can do is a guess. But, it is >definately a MAJOR loss. > I pretty much expected this response. - Hi ! As long as the detector has an active surface area of 1/4 inch (in the example above) there will be NO loss! The detector doesn't care if the light is in focus or not. All it's counting are photons. You can verify this by purposely defocusing a glass lens and measuring the received power or signal strength. You will measure NO loss until the diameter of the focused light is such that some of it starts to miss the active area of the detector. Obviously the use of a fresnel presents some problems when using a solid state detector with a very small active area. However, I was refering to the use of fresnels with a PMT. In my case I have a detector (PMT) with a 2 inch active area so by using a pin hole I can make the active area anything I want. In this case it's adjusted to match the fresnel in use. By using the chromatic distortion of the fresnel (which is a LOT more than my glass lens) to advantage I have been able to get a higher SNR compared to the same size glass lens. >But, don't be fooled into thinking that a frensels 'fuzzy' focus >is caused by its chromatic splitting. I wasn't aware that I said that. John K3PGP@juno.com -==- > >Keep them lasers lit and good dx...Art... > > > > From owner-laser Tue Apr 29 17:07:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01583; Tue, 29 Apr 97 17:07:57 PDT X-Authentication-Warning: ns1.qsl.net: majordom set sender to owner-laser@qsl.net using -f To: laser@qsl.net Date: Tue, 29 Apr 1997 20:03:19 -0400 Subject: [LASER] Re: Feedback resistors for OPT211/Op-amp..... Message-Id: <19970429.200323.-31738.4.K3PGP@juno.com> References: <9704291341.AA27068@is.ups.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0,2-10,13-14,18-24 From: k3pgp@juno.com (John K3PGP) Reply-To: k3pgp@juno.com (John K3PGP) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Tue, 29 Apr 1997 09:41:50 -0400 "Guy Hamblen" writes: >Ok...now that I've cajoled two "engineering samples" for the OPT211 to >skirt the $100 minimum order requirement from Sager on these items, > >73, Guy N7UN/2 > Sorry about that Guy! In case anyone else is having problems fulfilling minimum order requirements, Digi-key now stocks the OPT-211 as well as several other variations of this chip. The OPT-211 is $8.25 in single quantities. Orders from $0.00 to $24.99 are charged a $5.00 handling charge. $25.00 and up there is NO extra charge. So you need to order three chips plus a resistor to make a $25 order or pay the $5.00 ! John K3PGP@juno.com -==- From owner-laser Wed Apr 30 10:03:08 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05453; Wed, 30 Apr 97 10:03:08 PDT Message-Id: <199704301701.NAA26029@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 30 Apr 1997 13:01:14 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: cryo cooling, laser diodes Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, Last month I posted a message regarding cryo cooling of laser diodes and the potental for mega db power gain. Someone requested further info on this cryo cooling concept and I've been searching for my archives for this information ever since. Well, I had 2 sources, one was public domain and was easy to find. The more important source was a long email from a lab type researcher at a .edu domain. I have not been able to locate this message-I'm sorry. I will do my best to remember the contents and repeat them below. The source that I can locate is an example of cryo cooling on a regular LED, with measurements taken on a relative power meter. It's in Laser Cookbook, by Mc Comb. The email message with alot of details is the problem.... I can't locate it. But, it was from a researcher who had plotted power output and laser threshold current as the diode was cooled (he had a cryo refrigeration unit). As the temperature got lower, so did the voltage drop across the diode. The current soared and so did the output. He continued adjusting the operating current of the diode as the temperature dropped (in order to maintain laser threshold current, which was constantly changing). The last things he wrote about were attempts to directly cool the front facet by removal of the clear protective cover, and by directing a cooled stream of pre-dried air directly to the front facet of the diode (which prevented water vapor from collecting). I don't remember the numbers he quoted, but it was a way large power increase at temperatures which weren't that cold. I wish I could find the message, at the time I received it, I thought the guy was being pretty extreme. Now, I realize I was the one who wasn't very receptive to a new idea. GL and good dx...Art.