### Re: Can you take 2 lasers, not visible, and cross them to get 1 point of light?

Date: Sun Sep 24 13:17:49 2000
Posted By: Karl Kolbus, Staff, Data processing, Mequon Consulting Corp.
Area of science: Engineering
ID: 969123069.Eg
Message:
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Hello Jake,

That's a very interesting question!

Let's use the visible "additive" colors as an example - red, green, and
blue. Each one has a different wavelength, but varying the amounts shown
upon a surface of any two or more of them can produce any other color.
Just as three pebbles thrown into a pond, each representing one of those
colors, the wavefronts will at some point, meet and create another, very
different ripple. This new ripple will have a different wavelength than
any of the individual ripples; depending on how often (or the frequency at
which) the individual ripples meet each other. So it is with light waves
which intersect. At the point of intersection, the individual light rays
will re-inforce, and then negate each other causing an entirely new
frequency (wavelength) to be produced.

Laser beams are no different - except that they are a "pure" form of
emmission, producing only one fundamental frequency or wavelength.
Therefore, it certainly is possible to produce visible light from two or
more invisible laser beams. What the eye will see is the new frequency
produced by the reinforcement and negation of the intersecting beams.

A simple experiment with sound will prove this theory. If you send a high
frequency, somewhere above the range of human hearing (like 30KHz), to one
loudspeaker and another high frequency to second loadspeaker, by varying
the frequency of one of them, a third audible tone will be produced,
provided the two frequencies "beat" together within the audible range. Try
it!

Without going through the math, you should be able to take one Infrared
laser (around 1000nm wavelength) and a Ultraviolet laser (<400nm) and
produce something in the visible range. Try it! - BUT MAKE SURE YOU USE
PROTECTIVE EYEWARE! Remember, what you can't see CAN hurt you!

If you need any more help, you can contact me directly at:
KarlKolbus@ameritech.net.

Karl

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