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From: robink@aus.hp.com (Robin Kenny)
Subject: Re: Broken CD Rom drives
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Message-ID: <1994Sep29.055324.7924@hparc0.aus.hp.com>
Date: Thu, 29 Sep 1994 05:53:24 GMT
References: <35sr1e$gco@handler.Eng.Sun.COM> <STEVE.94Sep24185011@susie.vigra.com>
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Steve Haehnichen (steve@vigra.com) wrote:
: >Class I laser product: No known biological hazard. The light is
: So I guess the question is, are CD players Class I because of
: interlocks, or because they have whimpy lasers?

: I wouldn't gaze into the lit LED needlessly, but I really doubt an
: occasional glance could do much eye damage with a CD player's laser.
: -Steve "The other eye is a spare" Haehnichen

: Steve Haehnichen                 Vigra, Inc.  San Diego, CA
: steve@vigra.com                  (619) 597-7080 x116   Fax: (619) 597-7094


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The human eye can be damaged by an IR laser of any power, the nature of
the damage is different for different power levels. 
You risk destruction of the retina and selective blindness - 
                   NEVER BE CASUAL WITH LASERS!
The most damage will result when your eyes are focused on infinity.
Obviously a bright red light will make you focus close.

The original researcher in Japan who worked on the early laser printer 
technology is reportedly blind to near-horizontal lines; he gazed into a 
scanning beam. (Somebody back this up with a citation, please)

Another way to check the laser output is a strip of phosphorescent paper
in the beam. Ordinary paper will do for visible light lasers.

While I would be happier to go home and check my references, I feel better
for throwing this warning message onto the net now.
If anyone would like to confirm or correct, please feel free to do so.

Robin Kenny - robink@hparc0.aus.hp.com           
(everything in this message is PERSONAL OPINION ONLY and has no connection
with my work or my employer, the Hewlett-Packard Company Australia)
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For the record, if you wear contact lenses near an electric arc, (say a
high power knife switch breaking circuit) the soft x-rays produced have
been known to WELD THE CONTACT LENS TO THE EYE. This is independant of
the power involved and seems to be related to the frequency of the x-rays.

