[sci.electronics] LASER info needed

erics@bucsb.UUCP (Michael L. Ardai) (03/29/89)

(I am posting this for a friend without netnews access...)

I just bought a green HeNe laser.  In addition to the usual Alden
connector for the HV, it has a 1/8" phone plug labled 'electro-magnet'.
There appears to be a coil wound around the output mirror of the tube.
Any ideas what this could be for and how to drive it?  

/mike

(Michael L. Ardai,  ...!decwrl!sequent!sybil!ardai)-- 
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tmm00603@uxa.cso.uiuc.edu (02/24/90)

I need to acquire a quantity of small lasers.
Emission should be in the visible red range. The
dimensions required are penlight sized and no longer
than 7.5 cm. I am not particularly knowledgeable on this
subject and would appreciate information on small lasers
(power requirements,intensity,safety measures etc...)
and sources from which they may be ordered.

I can be reached at tmm00603@uxa.cso.uiuc.edu

Many thanks for your time. 

amichiel@rodan.acs.syr.edu (Allen J Michielsen) (02/27/90)

Two of us were discussing the following.
1. You have a high power laser cutting machine.  It is used for cutting
    up to 1/2" thick plates of metals (steel, alum,...) into rough cut
    parts for machining.  Some may even be finished products, but are rather
    course  (it doesn't matter).
2. The cutter is reported to be a 24 hr a day automated continuous production
    machine.  It cuts at about a rate of 4 inches per minute for 1/2" plate
    stainless steel.
3. How would & what is the best way/method of containing the laser beam, after
   it penatrates the material, OR if the beam is running & there isn't any 
   material to penatrate.

Several other semi-informed people claimed that anything could be used, even
steel or alum or wood, just so long as it was painted with paint that had
pigmented (colored) of the same frequency as the laser beam.
I seem to recall that this is commonly done with SMALL lasers, but I somehow
doubt that this could possibly dissipate the amount of energy required to
terminate a laser of this size.
  Does anyone have any experience or opinions ?

Inquiring minds want to know.
(p.s. Did anyone buy/read the article about a WW2 bomber located,
hidden on the moon.).
al

dleblanc@joplin.mpr.ca (David LeBlanc) (02/28/90)

Re: absorbing all that nasty coherent energy from a cutting laser ...

I don't know what they do in real life, but what about using a tank
filled with a liquid dye absorptive at the lasing frequency and
recirculate it through a heat exchanger, or 

Expand the beam with high powered optics to the point where the power
density is not all that high, use a water cooled solid absorptive
target.

 just more half-baked ideas ..

Dave LeBlanc
dleblanc@joplin.mpr.ca

siegman@sierra.Stanford.EDU (Anthony E. Siegman) (02/28/90)

>1. You have a high power laser cutting machine.  It is used for cutting
>    up to 1/2" thick plates of metals (steel, alum,...) into rough cut


>3. How would & what is the best way/method of containing the laser beam, after
>   it penatrates the material, OR if the beam is running & there isn't any 
>   material to penatrate.

If you are talking about a real system here, the laser is almost
certainly a CO2 laser with a wavelength near 10 microns in the middle
infrared, and the cw power output level from the laser is somewhere
between 300 Watts and 3 kilowatts CW.  This is not too horrendous a
machine, because the efficiency of CO2 lasers from electrical power
supply input to laser beam output is at least 10%, and might be a
factor of two or three better than this.  Such a laser might cost a
few hundred thousand dollars, including power supply, controls, and
some of the material handling equipment -- in other words, comparable
to what a high-performance machine tool of any other kind costs.

As to what you do with the beam when you're not cutting with it?
(besides just turn the laser off).  Well, laser beam like this focused
into a tiny spot with a lens will do horrendous cutting, melting,
vaporizing of the material in that small spot (analogous to but
considerably more powerful than the heating effects you can do when
you focus sunlight with a small hand lens) But suppose you let the
beam expand back up again to, say, several inches in diameter and then
catch it inside a heavy metal can, perhaps lined with carbon black,
and cooled with flowing water.  OK -- you are putting somewhere
between a few hundred watts and a few kilowatts of power into that
"beam catcher" -- no worse than if you had somewhere between 3 and 30
hnundred-watt light bulbs inside the can and were trying to carry away
the heat.  A little water cooling will do it.  Also, you probably
bounce the beam around inside the can, letting it hit various cooling
fins, so that the heat gets absorbed over a large surface area instead
of being focused into one spot.