Subject:
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RE: laser Safety and cats
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 17 Dec 1999 18:32:00 GMT
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Original-From:
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Jim Thomas <JIM.THOMAS@TRW.COMstopspam>
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Viewed:
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2460 times
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Here is a link for "Sam's Laser FAQ" which might be of use to anyone who is
using a laser pointer in their projects.
http://repairfaq.physik.tu-berlin.de/sam/laserfaq.htm
in particular be sure to check out this section which covers laser safety
http://repairfaq.physik.tu-berlin.de/sam/laserfaq.htm#faqsaf
and if you really just want to read the bare minimum, this section on laser
pointer safety
http://repairfaq.physik.tu-berlin.de/sam/laserfaq.htm#faqsaf
From a casual skimming it looked like what Sam had to say was on target. To
clarify on a point I had made earlier but did not have the data with me, the
older (or bad) red laser pointers used a 670nm which I would strongly
suggest be taken out of operation. These are more likely to cause eye
damage because it is really more powerful than it looks. Newer 635nm 1 Watt
are probably OK for use by a cautious adult for *play*. For use on a robot
I would try to go for the lowest possible power, and never operate
unattended. If you are running a laser from an RCX output I would not
recommend running it below max output. The output power from the RCX is PWM
so even though the laser will look dimmer to us, the beam is still full
power when it is on. 1ms pulses may not be short enough to prevent damage
accumulation.
JT
> -----Original Message-----
> From: Tony Pugatschew [mailto:support@intellecta.net]
> Sent: Thursday, December 16, 1999 2:11 PM
> To: lego-robotics@crynwr.com
> Subject: laser Safety and cats
>
>
> There have been several discussions concerning diode lasers
> (laser pointers)
> and the potential of harm to cats. It is useful to keep in
> mind several things.
> The laser safety standards that classify lasers are worked
> out for the human
> eye. The calculations assume a certain diameter of the
> pupil/iris in the eye
> and this is typically 7-9mm diameter. The permissible laser
> power is about a
> mW. The power density is 25W/square metre.
> Cat eyes have a different entrance aperture and have higher
> sensitivity to
> light. Direct exposure to laser light will not "fry" the
> eyeball etc but will
> produce a long lived after image that can confuse the cat and
> it may hurt
> itself as a consequence of the exposure.
>
> The laser standards take into account the blink reflex as a
> main aversion to
> damage.
> I think cats love chasing the spot but shining the laser
> directly in the eye is
> dangerous and cruel.
>
> The laser safety standards are well known and available from
> government
> authorities. Most modern hospitals use lasers and the laser
> safety officers are
> responsible for laser safety.
>
> If in doubt - don't do it!!!
> Thanks
> Tony Pugatschew
>
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