Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site fortune.UUCP
Path: utzoo!watmath!clyde!floyd!harpo!ulysses!mhuxl!ihnp4!fortune!rpw3
From: rpw3@fortune.UUCP
Newsgroups: net.arch
Subject: Re: Re: seeking information on lasers an - (nf)
Message-ID: <2964@fortune.UUCP>
Date: Thu, 5-Apr-84 04:07:01 EST
Article-I.D.: fortune.2964
Posted: Thu Apr  5 04:07:01 1984
Date-Received: Sat, 7-Apr-84 02:17:50 EST
Sender: notes@fortune.UUCP
Organization: Fortune Systems, Redwood City, CA
Lines: 37

#R:infopro:-5000:fortune:16500007:000:1435
fortune!rpw3    Apr  5 00:30:00 1984

Yes, be VERY careful with lasers. There are a lot of "gotcha's" that aren't
obvious:

1. The recommended maximum direct viewing power (looking down the beam)
   is well under ONE MILLIWATT! (Ref. some Gov't Std. or other)

2. One milliwatt is not very much when scattered around the room by
   a set of music-driven mirrors, so people get tempted to use higher-power
   rigs so folks can "see it in the smoke". (Isn't there ALWAYS "smoke"
   at a concert? ;-} )

3. Should the music stop for JUST AN INSTANT while someone is looking the
   wrong way, bye bye eyes.

4. The "wrong way" is not only facing the laser platform, but could be
   anywhere in the room that has what is called a "specular reflector"
   (translation: mirror, bright metal, or ANYTHING that reflects the light
   coherently, such as tinsel on a Christmas tree or jewelry or even clear
   glass, at a shallow angle).

Moral: make sure your equipment is rated for it's intended use, and has
been certified safe for that use. (Some systems detect lack of music drive
and switch to a diffuse scan pattern when than happens.)

Homebrew jury-rigs made out of laboratory lasers bought from equipment
supply houses (and speakers with mirrors on them and guitar amps) might
not be exactly safe.

Rob Warnock

UUCP:	{ihnp4,ucbvax!amd70,hpda,harpo,sri-unix,allegra}!fortune!rpw3
DDD:	(415)595-8444
USPS:	Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065