mahaun@sactoh0.UUCP (Mark A. Haun) (12/20/89)
Does anybody know of a source for visible red laser diodes? I recall reading in some electronics magazine several months ago that their availability at cheap prices was imminent. By cheap, I guess I mean ~$15 or less for single quantity prices. I don't really expect to find these goodies for a buck apiece... I could think of a thousand neat uses for these things right off the bat -- it sure would be fun to play around with a few! Thanks for any info you might have! -- ( Mark A. Haun KJ6PC )( UUCP: ...ames!pacbell!sactoh0!mahaun ) ( Sac-Unix, Sacramento CA )( AMPRNET: kj6pc@kj6pc.ampr.org ) ( IP: [44.2.0.56] 144.93 Mhz )( PACKET: kj6pc@wa6nwe.#nocal.ca.usa.na ) ( INTERNET: mmsac!sactoh0!mahaun@sacto.West.Sun.COM )
adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) (12/20/89)
mahaun@sactoh0.UUCP (Mark A. Haun) writes: > Does anybody know of a source for visible red laser diodes? A local surplus store is selling them for $19 each. They have laser diodes from 7 to 25 watts. Since I know almost nothing about lasers, let me quote them: "These Gallium-Arsenide injection diodes emit coherent infra-red radiation. The diode is built in a hetero-junction structure, consisting of 3 distinct layers: N-type, P-type gallium asenide [sic] and P-type gallium aluminum arsenide. Specs: 7 to 25 watts, lfm 40A, Lth 1A, typical peak forward coltage @ Lfm 8 volts, @ 50 ma 1.2 volts." They're $19 each or 3 for $49. Let me know if you want an address/more info/etc... > I could think of a thousand neat uses for these things right off > the bat -- it sure would be fun to play around with a few! Pardon my ignorance, but what neat things can you do with these low-power lasers? Adam -- Adam Glass, ex-"hacker" at the Media Lab \ "Something is going to happen... Email to: adam@media-lab.media.mit.edu \ ...something wonderful."
dleblanc@joplin.mpr.ca (David LeBlanc) (12/21/89)
>mahaun@sactoh0.UUCP (Mark A. Haun) writes: >> Does anybody know of a source for visible red laser diodes? > In article <1237@mit-amt.MEDIA.MIT.EDU> adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) replies: >A local surplus store is selling them for $19 each. They have laser diodes >from 7 to 25 watts. Since I know almost nothing about lasers, let me quote >them: > "These Gallium-Arsenide injection diodes emit coherent infra-red > radiation. The diode is built in a hetero-junction structure, > consisting of 3 distinct layers: N-type, P-type gallium asenide [sic] > and P-type gallium aluminum arsenide. Specs: 7 to 25 watts, lfm 40A, > Lth 1A, typical peak forward coltage @ Lfm 8 volts, @ 50 ma 1.2 volts." > No flames intended, but 7 to 25 watts sounds a little high (like a few orders of magnitude) for a laser diode. The laser diodes used in telecommunications launch (best case) somewhere around 0 dBm (1 mW) into a single mode fiber. My guess is that the spec sheet was wrong and they meant milliwatts (eg. 7 to 25 mW). Note that 7 to 25 Watts is not "low power" when you consider that the energy is coherent and concentrated in a narrow beam. Please tell me if I'm out in left field on this - I could think of a lot of really neat uses for a device like this. Dave LeBlanc dleblanc@joplin.mpr.ca
maddog@Athena.MIT.EDU (Matthew J Marjanovic) (12/21/89)
About 7 to 25 *watts* looking like a misprint: There are laser diodes in the watt range, however they have very short, pulsed beams, unlike the continuous output types usually found in CD players and the like. As the posted specs said, these have a threshold current of 1 amp, and some kind of peak current of 8 amps: they are powered by a high current pulse. (Trying to lengthen the pulse beyond the few microseconds recommended by the manufacturer would probably cause the diode to overheat.) ***********no signature; my name's at the top^************
dleblanc@joplin.mpr.ca (David LeBlanc) (12/21/89)
In article <1989Dec20.201756.13059@athena.mit.edu> maddog@Athena.MIT.EDU (Matthew J Marjanovic) writes: > > There are laser diodes in the watt range, however they have > very short, pulsed beams, unlike the continuous output types > usually found in CD players and the like. > My mistake - I feel *real* silly. Looking through the "Laser Focus World 1990 Buyer's Guide" I found the following visible semiconductor laser diodes : @ 0.67 um, Antel Optronics Inc. model#PL-670 with a rep-rate of 200kHz, pulse width of 0.12 ns (FAST!!!) and pulse energy of 8.4E-6 joules (corresponds to 7E+4 Watts "peak" or 1.68 Watts average). again @ 0.67 um but for CW operation, Holo-Spectra, Spindler&Hoyer, Melles-Griot, NEC and LiCONiX make various laser systems. Some of these are turn-key systems and CW power varies from 2 to 80 mW. My guess is that none of the above lasers come anywhere close to only $19 per unit. Note re. the posting in which I made my silly mistake, the Laser diode was emitting in the IR (not the original request). If the original poster wants addresses, phone numbers I would be happy to oblige. Humble apologies again, Dave LeBlanc dleblanc@joplin.mpr.ca
agn@unh.cs.cmu.edu (Andreas Nowatzyk) (12/21/89)
>Mark A. Haun asks for cheap, VISIBLE laser diodes >Adam Glass gives source for a 7-25W IR laser diode >David LeBlanc is puzzled by the 25W spec 25W IR laser diods are for real, and if you read through the rest of the posted specs, you'll find that the other data (lasing current and voltage drop) are in line. The 25W part is not a typo. In fact, you can buy IR laser diode arrays with more than 1KW output. Such devices are not used in fiber optic communications or CD players (obviously). Applications for high power laser diods include range finders, pump lasers (to drive another laser), SHG's (double the frequency to get visible light lasers), active night vision systems, WORM disk drives,... However, IR lasers are not visible. There are visible red diode lasers, but they are a quite recent development and therefore costly. Chances to find them in a surplus store are small and they are much less fun then a HeNe laser tube because the beam is very wide: 30-40 degree are typical. So you need some good optics to make a nice beam and coherence length isn't up there either (hence you see less interference patterns, have more trouble with making good holograms, etc.). Also, diode lasers are very sensitive to electrostatic discharges and are easily destroyed. HeNe tubes are much more robust (electrically). Finally, 7-25W lasers are downright dangerous, especially since you don't see the beam (actually cone in this case: due to their small size, diode lasers don't produce low divergence beams without external optics). -- -- Andreas Nowatzyk (DC5ZV) Carnegie-Mellon University agn@unh.cs.cmu.edu Computer Science Department (412) 268-3617
mmm@cup.portal.com (Mark Robert Thorson) (12/21/89)
I once got some poorly-translated data sheets on laser diodes from Sharp, of Japan. These were made primarily for CD players. What turned me off about them was that they were four-terminal devices. They include a phototransistor. I guess you're supposed to adjust the power in response to the emitted light level. They didn't include any application notes, so I wasn't sure how I was supposed to use these things. For all I know, just putting a battery across one of these things might put it into a positive feedback loop, where its resistance drops to zero and it blows itself out. (I'm not saying that's what happens. It's because I didn't know how to handle these things that I was afraid to buy one.) So my question is: how do you use these things? All I want to do is build a small laser, so I can throw a red spot on a far wall. Who makes the most powerful device, and what does it cost?
mahaun@sactoh0.UUCP (Mark A. Haun) (12/23/89)
In article <1237@mit-amt.MEDIA.MIT.EDU>, adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes: > mahaun@sactoh0.UUCP (Mark A. Haun) writes: > > Does anybody know of a source for visible red laser diodes? > > A local surplus store is selling them for $19 each. They have laser diodes > from 7 to 25 watts. Since I know almost nothing about lasers, let me quote > them: > "These Gallium-Arsenide injection diodes emit coherent infra-red ^^^^^^^ > radiation. The diode is built in a hetero-junction structure, > consisting of 3 distinct layers: N-type, P-type gallium asenide [sic] > and P-type gallium aluminum arsenide. Specs: 7 to 25 watts, lfm 40A, > Lth 1A, typical peak forward coltage @ Lfm 8 volts, @ 50 ma 1.2 volts." I guess I should have made myself a bit more clear in my original posting... I'm looking for VISIBLE RED laser diodes that you can actually see! These infrared laser diodes have been around for a long time (by the way, the 7-25W power spec must be a misprint -- maybe milliwatts?). > Pardon my ignorance, but what neat things can you do with these > low-power lasers? > Well, how about these: 1) cheap laser light show (bounce beam off mirror on speaker cone). 2) spotting device for any instrument that needs to be accurately aimed or alligned. 3) special effects (sweeping beams through artificial fog, etc.). 4) cheap, battery-powered pointer (for lectures or other presentations). 5) small light beam for optical experiments of all sorts. Give me an hour, and I could think of 50 more! So does anybody know if these goodies are available yet? I remember the magazine article I read about them in... it was Don Lancaster's Hardware Hacker column in Radio Electronics, but I don't remember the issue it was in. -- ( Mark A. Haun KJ6PC )( UUCP: ...ames!pacbell!sactoh0!mahaun ) ( Sac-Unix, Sacramento CA )( AMPRNET: kj6pc@kj6pc.ampr.org ) ( IP: [44.2.0.56] 144.93 Mhz )( PACKET: kj6pc@wa6nwe.#nocal.ca.usa.na ) ( INTERNET: mmsac!sactoh0!mahaun@sacto.West.Sun.COM )
siegman@sierra.Stanford.EDU (Anthony E. Siegman) (12/23/89)
Commercially available visible (red) diode lasers are just coming on the market. They are being intensively developed by Toshiba, NEC, Hitachi, Mitsubishi, Sony and Sharp -- all in Japan (naturally). Toshiba is said to be the only firm making and selling production quantities at this point. The wavelength of these diode lasers is around 670 nm (6700 Angstroms), which is readily visible though getting pretty far down on the red side of the sensitivity curve for the human eye. The wavelength of the helium-neon (He-Ne) gas laser is 633 nm (6328 Angstroms), where the eye is considerably more sensitive. The original pulsed ruby laser was at 694 nm (6943 Angstroms), still further in the red. It will probably be difficult to push diode lasers to shorter wavelengths than around 670 nm. Several small U.S. companies are packaging and selling these visible diode lasers for a few hundred dollars, presumably the Toshiba models though I don't know that for sure. I've seen an ad for a diode and power supply assembly from D. O. Industries in Rochester, NY, 1-800-828-6778 or 716-359-4000. Another source is LaserMax, Inc., Rochester NY, 716-328-2178. I have one of the latter units in front of me as I write. It costs $295.00 complete and has the diode packaged in a hand-held cylinder about 3/4" in diameter and 2-1/2" long with a built-in collimating lens for the output beam. Power output is 4 mW, and it looks plenty bright. Beam collimation is reasonably good -- you can point the beam into a tree several hundred feet away at night and readily see the spot reflecting off leaves and twigs. The kit includes a small battery pack (4 AA batteries -- probably an hour or two operating time) which will drive the diode head directly and also a 110 VAC to 6 VDC power supply. Operating current is 75 to 85 mA. Spec sheet life is >50,000 hours at 3 mW output, >5,000 hours at 4.9 mW output. Whether you can buy diodes direct from Toshiba I don't know. I'd expect to see packaged units from Edmund Scientific very soon. In general, GaAs diode lasers operating at around 800 to 880 nm in the near IR can be operated either cw at milliwatt power levels, or operated pulsed with 1 to 10 nanosecond pulses, low duty cycle, with 1 to 10 Watt peak powers and about the same average powers. Life-limiting mechanisms are partly overheating, which depends mostly on the average power, not the peak power; and partly facet damage and internal diffusion, which do depend on peak current and peak power. Whether these particular visible lasers, which use a GaAlP (gallium-aluminum-phosphide) alloy can be operated in the high-power, low-duty-cyle pulsed mode I don't know. It's not mentioned in the spec sheet.
kenmoore@unix.cis.pitt.edu (Kenneth L Moore) (01/03/90)
In article <1237@mit-amt.MEDIA.MIT.EDU> adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes: >mahaun@sactoh0.UUCP (Mark A. Haun) writes: ==>==> I could think of a thousand neat uses for these things right off ==>==> the bat -- it sure would be fun to play around with a few! ==> ==>Pardon my ignorance, but what neat things can you do with these ==>low-power lasers? ==> ==>Adam ==>-- ==>Adam Glass A guy around here has one in a Mountain Dew can on his desk. It blinks every second or so. It is a real conversation-piece/decoration. (I turn it to the wall whenever he is not looking because it annoys me)
ron@vicorp.UUCP (Ron Peterson) (01/09/90)
If you look in the latest Edmund Scientific catalog (the consumer version, not the industrial one) they have two different models of hand-held laser pointers that are based on visible, continuous, battery powered laser diodes. They are selling them for $400.00 so I suspect the diodes themselves cost on the order of $100-$200 each. Seems like it won't be long before lasers are going to be real cheap.