Newsgroups: comp.robotics
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From: browen@lyapunov.aoc.nrao.edu (Bruce Rowen)
Subject: Re: laser diode safety
In-Reply-To: cs911225@ariel.yorku.ca's message of Thu, 26 Aug 1993 15: 18:05 GMT
Message-ID: <BROWEN.93Aug26113134@lyapunov.aoc.nrao.edu>
Sender: news@nrao.edu
Organization: National Radio Astronomy Observatory, Socorro NM
References: <1993Aug26.084151.2444@hemlock.cray.com>
	<1993Aug26.151805.28818@newshub.ariel.yorku.ca>
Date: Thu, 26 Aug 1993 17:31:34 GMT
Lines: 35


   >From: browen@lyapunov.aoc.nrao.edu (Bruce Rowen)
   >Subject: Re: Q: IR - beacon

   >I found a Laser diode once and pondered using it as a transmitter that
   >would be so powerful, you could flash it in a room and the reflections
   >could be received *anywhere*. (did you ever look at a IR led with a
   >CCD camera with no IR filter? Damn bright!). Well (as R. Reagen would
   >say), I dug the diode out from my junk collection a while back (these
   >can be bought for about $5) and set up a power FET driver that would
   >send 10 amp pulses through the thing at a 1% duty cycle. The receiver
   >was a fat photo diode and low noise op amp circuit to test for the
   >signal.......



   Geez, I'd be a little concerned about *eye safety* in the vicinity
   of the transmitter, wouldn't you?

	   -Ken Willmott


The diode in question does not produce a "focused" beam. It has a beam
spread of about 30 degrees. It is nowhere near the power level of
those semiconductor lasers. (it's just a IR transmitter that can
handle huge power pulses for a fraction of a second!)


--
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Bruce Rowen 				National Radio Astronomy Observatory
Scientific Programmer				Array Operations Center
browen@aoc.nrao.edu			  P.O. Box O  Socorro, NM   87801
(505)385-7329					     (505)385-7000
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