eric@spies.UUCP (eric) (12/01/88)
Does anybody have any information regarding lower powered lasers? I am looking for a laser in the range of about 1-3 watts. I would like to build the laser as a physics project and need a kit or instructions and would like to get an idea of the materials, cost etc. Thanks in advance... Eric Steimel -- Spies in the wire PUBLIC ACCES UNIX, Scarborough, NY (914) 762-7365
ellert@argos.uucp (Leigh Ellert) (12/03/88)
I have bought several from Meredith Instruments (602) 934-9387. Prices start at about $60 for 1 mw glass HeNe tubes and go up to about $125 for 7 mw units. HeNe heads (glass laser tube aligned and potted along with a ballast resistor inside an aluminum tube) go for $125 for 5 mw heads and go up to $300 for the 9-11mw heads. Power supplies are of the switched-mode variety and sell for $75 new. These units are physically quite small (1.0 X 1.5 X 3.75 inches for the adjustable output item) and can be supplied for use with various input voltages (9 VDC, 12 VDC, 120 VAC) All that is needed is a tube, power supply, ballast resistor (~ 80K @ 5 watt), suitable enclosure, and a source of input voltage. Those guys work fast! My goodies arrived UPS (AZ to TX) on the Tuesday after I mailed my order (with postal money order) on Wednesday. Twice! They also have onesies and twosies of higher power argon and other more exotic lasers as well as night vision items from time to time. Another supplier is M. J. Neal Co. in Orient, OH (I think). Prices are comparable, but I have not bought anything from them. Happy laseing leigh signature line is still backordered...
paul@hpldola.HP.COM (Paul Bame) (12/13/88)
>Does anybody have any information regarding lower powered lasers? I am >looking for a laser in the range of about 1-3 watts. I would like to 1-3 watts isn't really low-powered - maybe .5 to 10 mW. >build the laser as a physics project and need a kit or instructions and >would like to get an idea of the materials, cost etc. >Thanks in advance... Check out the "Amazing Electronics Products" catalog available from the back of many mags like Pop. Sci. It's a sleezy-looking ad but they have lots of laser stuff (which I've never ordered) including plans for CO2, YAG, Ruby (AlxOx?), and other lasers. There are also some books out which give plans for some of their products by Robert Iannani (mispelled). -Paul Bame
bmaraldo@watmath.waterloo.edu (Commander Brett Maraldo) (12/15/88)
I think a discussion about lasers would be incomplete without a little theory. This is derived from Einstein's Quantum Theory of Radiation. It has been simplified and I haven't bothered going through the derivations step by step. All you need is a little first year calculus to get the jist of it. If you want a more rigorous explanation I'd suggest books on Thermodynamics (all the Boltzman stuff) and a little Quantum Mechanics. For now, just keep in mind that d(something)/dt means 'the rate of change of (something) with respect to time'. Also, if d(something)/dt vanishes (=0) then the (something) is a constant. Other than that the rest id straight forward. The final conclusions are what matter, the math just backs them up. We have for spontaneous emission: d N2 (1) ------ = -A21 N2 ----> sol'n: N2(t) = N20 e^(-A21 t) dt ... for stimulated emission: d N2 (2) ------ = -B21 N2 p(f) dt where: p(f) = photon density as func'n of frequency ... and for absorption: d N1 (3) ------ = -B21 N1 p(f). dt Pictorally, for two quantum states E1 and E2 there are corresponding populations, N1 and N2. Thus: N2 (E2) --------------------------------------------- | | ^ | | | A21 N2 B21 N2 p(f) B12 N1 p(f) | | | v v | N1 (E1) --------------------------------------------- spont emmit absorb stim emmit A21, B21, and B12 are the Einstein coefficeints (The Quantum Theory of Radiation, 1916). Einstein assumed that the distribution of N1 and N2 at E1 and E2 followed the Boltzman distribution (at a blackbody temp T for the spectral density p(f)). He also assumed that (1) and (2) vanished. This means: p(f) = R [e^(hf/kT) - 1] ^ -1 ... assumes quantum thermo- dynamic equilibrium N2/N1 = e^-(hf/kT) ... Boltzman distribution and all this leads to: A21/B21 = R ( = 8 pi h f^3 / c^3)... one of those freaky constants. f= frequency But note that A21/B21 is proportional to the cube of the frequency. B12 = B21 Now, you can see the importance here: All the coefficeints are dependent on each other, stim emmit and absorption are negatively equal, for N2 > N1 (look at (2) and (3)) we have amplification and this state is population inversion, and as f increases the smaller B21 gets compared to A21 and because B21 contributes to amplification more than A21 the more difficult it is to amplify the field (ie. xray lasers are damned hard to make and you need to pump them with killer densities to stimulate emmision - see the latest Scientific American (... no I don't read it.)). Note this theory was know in 1916. It took until the 1960 to actually apply and come up with the laser. Also note that the acronym LASER makes a hell of a lot of sence... I think its one of the best acronyms we've come up with. Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" bmaraldo@watmath.waterloo.edu {uunet!clyde!utai}!watmath!bmaraldo
tomb@hplsla.HP.COM (Tom Bruhns) (12/17/88)
>... >If you're talking about the same article I remember, it wasn't a >CO2 laser, but a pulsed "organic dye" laser. I don't remember the >power it would put out, nor the wavelength (although I think I remember >that the wavelength was tuneable within limits). >... >-- >Mike Young >Software Development Technologies, Inc., Sudbury MA Tel: +1 508 443 5779 >Internet: mjy@sdti.sdti.com UUCP: {harvard,mit-eddie}!sdti!mjy >---------- And I recall yet another (in Amateur Scientist) dealing with building a really simple nitrogen laser that put out "broomstick sized pulses of UV" or something like that. It was simplicity itself: a large, triangular piece of double-sided printed circuit board, with a spark gap along the whole of one edge. The details get fuzzy at this point, but it was a single-pass laser, so no mirrors were used. And it would run (the author claimed, as I recall) in air -- though a 99+% nitrogen atmosphere was better (?). (So what do you _DO_ with broomstick-sized pulses of UV??) Tom Bruhns tomb%hplsla@hplabs.hp.com
jim@trsvax.UUCP (12/22/88)
hplsla.UUCP!tomb writes:
" (So what do you _DO_ with broomstick-sized pulses of UV??)
Erase EPROMS really quickly? 8{)
James T. Wyatt UUCP:decvax!microsoft!trsvax!rwsys!jim (817)451-5719etxbrfa@kklm01.ericsson.se (12/29/88)
Hi every visible wavelength laser user. It's new years eve' on saturday.
Have you prepared yourself to set up a lightshow??. Great! It will be a
good complement to the ordinary fireworks.
Happy new year folks!
_________________________________________________________________
SNAIL: Bjoern Fahller Vox humana: (+46) 8 - 719 62 52 \
ERICSSON TELECOM Fax machina: (+46) 8 - 740 28 34 /
KK/ETX/TT/MLG ,/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
S-126 25 STOCKHOLM ,/ "Inside every problem, there are
SWEDEN / at least two other problems
~~~~~~~~~~~~~~~~~~~~~~~~~~~ struggling to get out"i8d311v@auc.dk (Morten Tolboel) (01/05/89)
A few questions about lasers :
- As I'm new in this field, could anyone tell me how powerfull
ligthshow-lasers really are (mW or perhaps W)?
- In the Oct. or Nov. issue of EPN (electronics product news)
I have seen an advert from Toshiba showing a semiconductor
laser emiting visible (red) light, will this do the job?
- Does anyone have informations on the Toshiba laser?
(Price, data, where to buy etc.)
-----------------------------------!--------------------------
Kind regards ! JUB TVJOJA MAJD
Morten Tolboel ! all you ruskies !
Institute for electronic systems !
University of Aalborg ! Mixnimoxboxfox
Denmark (not a suburb of Sweden!) !
!
Mail: i8d311v@aud.dk !
or i8d311v@aud.uucp !
or uunet!mcvax!dkuug!aud!i8d311v!
-----------------------------------!--------------------------dave@VAX1.CC.UAKRON.EDU (David Stoutamire) (02/22/89)
I am posting this for a friend who will be selling laser power supply kits at the Dayton, OH Hamfest next month. He would like to purchase laser tubes and talk to anybody with an interest in lasers. Sooo... If anyone has laser tubes to get rid of, or wants a power supply... -= David Stoutamire =-
Azoth@cup.portal.com (Victor cthulhu Gibbs) (02/24/89)
i have an old metrological HeNe, with a bad tube and working power supply. If anyone knows where i can pick a working tube, i would be very gratefull. Also if anyone has any use for a non-working tube. When you power it up, it glows pretty pink/purple, but wont lase, make an offer, or even better tell me where to send it to get it fixed. Azoth@cup.portal.com
dtroup@carroll1.UUCP (David C. Troup - Skunk Works : 2600hz) (10/17/89)
Being a recent buyer of a 3mw helium-neon laser, I have a few questions
about the operation of the laser.
oWhy when viewing the lasers red 'dot' on a wall, does it appear to
have little 'dot's in the illuminated area? It looks kinda 3-d
(no flames about this being a 3-d world! :-) )
o What will happen if I go from 12v dc to 24v dc? What will happen to
the power in the beam?
o How can I defeat difraction on the beam over long distances?
o anyone have any interesting projects for something like this?
thanks!
--
"We got computers, we're tapping phone lines, knowin' that ain't allowed"__ _______ _______________ |David C. Troup / Surf Rat
_______)(______ | |dtroup@carroll1.cc.edu : mail
________________________________|414-524-6809______________________________siegman@sierra.Stanford.EDU (Anthony E. Siegman) (10/17/89)
In article <749@carroll1.UUCP> dtroup@carroll1.UUCP (David C. Troup - Skunk Works : 2600hz) writes: > > Being a recent buyer of a 3mw helium-neon laser, I have a few questions > about the operation of the laser. > > oWhy when viewing the lasers red 'dot' on a wall, does it appear to > have little 'dot's in the illuminated area? It looks kinda 3-d > (no flames about this being a 3-d world! :-) ) This is called "speckle". It's a diffraction effect which results because the wavefront hitting the rough wall is extremely "coherent", meaning in this situation "highly planar". The light coming off the illuminated spot in the wall is in the form of narrow "needles", or "antenna lobes", which your eye inteprets as bright spots. Try moving your eye and see which way the "dots" move; one way means you're slightly near-sighted, the other means you're slightly far-sighted. Ordinary light does exactly the same thing, except the "needles" are different for every wavelength in the ordinary light, and for every direction of arrival of the ordinary light, and so the "dots" are all averaged out and you don't see them. Try blowing up the spot on the wall to an inch or so in diameter with a simple lens, and put some printed material in the spot. Look at it, holding your head very still. After a second or so the print will go out of focus, because your eye involuntarily tries to focus on the speckle. Jiggle your head slightly, or jiggle the paper slightly; the print will come back in focus. Put the spot not on a white wall, but on the side of a flat glass container containing milk; there should be no speckle, because the "roughness" of the milk is moving. > > o What will happen if I go from 12v dc to 24v dc? What will happen to > the power in the beam? > You'll probably blow up the power supply. The power supply is probably optimized for optimum current through the laser tube at 12 volts input; increasing the tube current will NOT increase the power output. (In technical terms, increased current pumps atoms out of the upper level of the laser transition to still higher levels faster than it pumps atoms into the upper level.) > o How can I defeat difraction on the beam over long distances? > There is NO way to defeat diffraction -- NONE. Putting the beam through a good telescope and expanding its diameter at the output of the telescope will mean it will have a smaller angular spread in the far field; this is the same as using a big dish antenna instead of a small dish antenna on your microwave radar transmitter; you get a narrower beam angle. But nothing "difeats diffraction". > o anyone have any interesting projects for something like this? > > thanks! > > >-- >"We got computers, we're tapping phone lines, knowin' that ain't allowed"__ _______ _______________ |David C. Troup / Surf Rat > _______)(______ | |dtroup@carroll1.cc.edu : mail >________________________________|414-524-6809______________________________
irwin@m.cs.uiuc.edu (09/13/90)
/* Written 4:38 pm Sep 11, 1990 by DAVE@ORION.BITNET in m.cs.uiuc.edu:sci.electronics */ >Our elevators on campus are always quite busy, and we are looking to modify >them with a 'remote control' to allow authorized personnel immediate access >to a car when nessecary. We hope to do this by placing radio-controlled >switches in parallel with the inspection key switches, and certain floor >buttons. Can someone please give us some advice and schematics for INEXPENSIVE >circuits that can control at least 5 switches independantly. I would like one >or two of them to be 'permanent toggle' controlled, ie: a button is pressed >on the transmitter, causing the switch to be closed, untill the button is >pressed again, upon which point the switch will be opened. I need other >switches to be momentary, closing the circuit only while the transmiting >button is pressed. My knowlege of electronics is not great (obviously) and >I would like the RC circuit to finally control a relay - which I can connect >across the switch terminals. If my objectives are not clear, please email me >and I can explain them further. If NOTHING ELSE, I would like the schematic >for a single xmitter/reciever to control ONE relay - momentary contact. > thanx, dave michaels dave@mercury.njit.edu /* End of text from m.cs.uiuc.edu:sci.electronics */ Might I suggest for a single contact control, that you consider the home garage door opener as a possibility. The garage door opener that I have in my home was bought in the 1960s, and though the opener mechanizm worked fine, the radio link left something to be desired. Aircraft overhead, police cars and other things could cause it to open. Also, it was an obsolete design using tubes, which would get weak and need replacement. I purchased a radio system from Sears, which is solid state, and has a program switch in the receiver/transmitter, that sets the code that the unit will recognize. Now, I never find my door open unless I want it to be open. The thing is, you can purchase the receiver, and as many transmitters as you like, program the code of all to be the same, and they will be unique to your needs. The receiver would be installed at the elevator control head, not in the car, to activate the necessary circuit in the control assembly. An antenna could be attached to the receiver that would pick up the transmitters when they were activated. This would only provide you with a single contact, but would be simple to implement. Al Irwin irwin@cs.uiuc.edu
gumby@ucrmath.ucr.edu (john donahue) (11/09/90)
Hi all,
I was talking with my Dad about a device he wants to create that involves
lasers. They would have to be fairly small (running off AA batteries or
something like that -- it doesn't have to run for hours at a time), and
be "visible" so both the endpoint of the light *and* the "line of light"
can be seen.
Are such devices made? Can they be purchased through mail order or can you
go to some electronic store and pick them up these days? What do they
cost and what other variables are there to consider? We saw one in a
"Sharper Image" catalog, but it was too big, and they wanted something
like $250 for it -- but it was the closest thing we'd seen yet.
He's an electrical engineer and knows about some of this stuff, but
I'm pretty clueless (I'm just a computer geek at heart) and perhaps we
both could use a general introduction to how lasers work and what the
technology has to offer these days.
Any and all help is appreciated!
-- John
--
INET: gumby@ucrmath.ucr.edu
UUCP: {ucsd, uci, ucdavis}!ucrmath!gumby
"Consequences, schmonsequences, as long as I'm rich" -- Daffy DuckJeff.Miller@samba.acs.unc.edu (Jeff Miller) (11/09/90)
I am not sure if you were wondering about this per se, but: You cannot see the "beam" of any laser save for unimaginably powerfull ones best not mentioned unless the beam passes through smoke or fog or something else to bounce off and scatter through. This is true to the extent that air is transparent to the beam, which is usually for all practical purposes. (if life in this newsgroup has taught me one thing it is to qualify my statemnets to the point where they say nothing) If smoke or dust is in the plan, I recoomend a tube of at least 10 mW, these and power supplies that run off batteries, well, you can't buy them at the grocery store yet, but if you hang around the surplus market for any length of time there comes a point where you can't get away from them! For casual classroom pointing something of less power would likely be in order, there are in fact regulations for such things. Price on tubes varies with power, quality, and history, I have seen little tubes assured to work sell for $19. Tubes around 5 mW hover near $100. I see here a 10mW tube and AC PS for $200... Battery op'd power supplies are a bit costly because everyone wants them, $100 or $125 for a surplus commercial unit that is flexible and powerfull, less for wierd stuff. -cornhead
dll@teda.UUCP (Dan Liddell) (11/09/90)
In article <1571@beguine.UUCP> Jeff.Miller@samba.acs.unc.edu (Jeff Miller) writes: >For casual classroom pointing something of less power would likely be in > order, there are in fact regulations for such things. For "casual" use lasers (classroom, grocery store scanners) it looks like the limit is 1 milliwatt (this from reading the warnings on ads for various devices). The warning on lasers of less than a milliwatt is "Don't stare stupidly into this bright light". Anything above that carries a warning of that indicates that it should not be pointed into people's eyes at all. This is for helium-neon reddish lasers. I don't know if laser damage to the human eye is strongly correlated to frequency. -- Dan Liddell UUCP decwrl!teda!dll TELEPHONE 4089805200 USA curb your dogma. The opinions and views expressed are Dan's.
barton@latcs1.oz.au (DoomsDay) (11/10/90)
One interesting thing I've done with a fairly powerful ruby laser is to put a lens (magnifying glass) of focal length about 3cm in the beam, and fire a pulse through it. The beam converges on one spot in the air and the concentrated energy is so high that it ionises the air molecules - resulting in a fireball/ball lightning at the focal point of the mirror. Very dramatic.
johne@ex.heurikon.com (John Eckrich) (11/22/90)
(john donahue) writes: >I was talking with my Dad about a device he wants to create that involves >lasers. >..... >Are such devices made? Edmunton (sp?) Scientific sells quite a few compact battery powered lasers. Also I've seen them advertised in catalogs (Gander Mountain) that sell hunting equipment; one puts them on his/her gun to use in sighting the target. Also, The lasest issue of Radio Electronics (Nov.?) has an article on building your own NiCad laser device; Looks real neat. -- ------------------------------------------- johne@heurikon.heurikon.com N1000M Madison, WI Stinson 108-3