Subject: Re: Deflecting laser beam 90°
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Date: Mon, 30 Sep 2002 07:21:49 GMT
NNTP-Posting-Date: Mon, 30 Sep 2002 00:21:49 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
There could be a hazard to the eyes, over time. This is because laser light
is literally "dazzling" and can make even smart and trained experts want to
stare at it, dead on. I know.
There is a thing known as the human aversion response. Laser Safety
Officers include it when they assess hazards. A child's aversion might be
assessed differently, so a laser might not really be the hottest idea, for
any conservative safety minded parent. Besides, the beam would actually
need to be deflected more, such as to form the shape of cross work (up and
down as well as side to side), to really protect an area. And then, the
alignment would go haywire so easily that even an experienced laser optics
tech such as me would loose their lunch.
I have had to align ring dye lasers. It ain't easy, it can take hours and
as temperatures change, alignments must be redone. If you have, say 4
mirrors involved, well... Each time that the first one is off you will have
to do all of them again. UP and Down and Side to Side each, and you don't
have optics bench mirror adjustors, I take it? Do you know how a lever can
be used to lift a heavy load by taking a long hand movement to lift a short
object movement? Well each mirror leverages on top of the previous one, and
do you know how little a movement it takes to make a beam sweep a great
swath? Very little.
When using mirrors to deflect a laser beam a lot more than meets the eye is
involved, and will complicate things. Your mirrors are 2 surface mirrors.
This affects the actual angles and how many beams actually result (the front
glass surface will reflect 4% of the laser light). Then another thing: At
every substance interface (air to glass and visa versa) R.A.T.S occurs
(reflection, absorption, transmission, and scattering) and that means you
end up with more than one beam coming out of each darned mirror. This is
because the fronts of your mirrors are mirror surfaces that reflect 4% of
the beam each. What a mess it will be!
You would need a beam expander/collimator to make your project more safe to
the eyes of a child. Laser light (even the very low hazard class # IV) is
not only dangerous in the common sense of what most people thing of
brightness as. You see, laser light is ultra pure in color (generally), so
it can over populate a certain type of energy into one's eyes to a greater
degree than is self evident. Think of it like you might think of the effect
of a smaller amount of a more refined perfume getting the man, but in this
case it is bad effect on the eyes. On top of that, all of the light's waves
are in synch, and this further amplifies the effect of the light. It is
Using a laser is often not a practical solutions. A regular light beam can
be better, believe it or not. An IR motion device, or RF device will serve
you better and with less misery!
Anyway, if you still want to do it (and it really *is* a neat idea in the
sense that it uses a laser in a novel way) then check out this book: _The
Laser Cookbook_ by Gordon McComb.
http://www.amazon.com/exec/obidos/ASIN/0830693904/002-7267938-8658457 it is
a great book, explains lots of optics and laser fundamentals in a fun way,
and offers a lot of cool projects.
If you want to go to the best associate grade tech school in the world for
lasers, optics, vacuums, semi-conductors, and electronics, check this out:
Sorry about this.
"KILOWATT" wrote in message
> Hi everyones. It's to protect a very small area
> with the beam of an ordinary laser pointer.
> I need a way to deflect it's beam by 90° but cannot
> figure how since my knowledge in optics is limited.
> With a small piece of mirror it's easy to bring back
> the beam to toward the laser source...(at or near 180°)
> but at the angle of 90°...hmmmmm..????????????????
> Alain (alias:Kilowatt) Montreal Quebec
> P.S: Excuse me for some errors or omissions,since
> I'm a «pure» French Canadian :-)
> If replying also by e-mail,remove"no spam"
> (with the quotes) from my adress...thanks!
> Come to visit me @: http://kilowatt.camarades.com