RE: Melanoma cancer/UV info

["Neil, David M" <neildm@id.doe.gov>]

Fluorescent lights produce UV initially, this is converted to visible
frequency peaks by the phosphors coating the tube; hence the name
_fluorescent_.   I'm less than totally sure that the plastic is intended
primarily as a filter - it's mostly for esthetics, but that it does absorb
some UV is obvious from the yellowing and embrittlement of the plastic
diffusers.

The crystal in a ruby laser is not a filter, it is the lasing substance.
The atoms of the crystal are energized by a flash of light from an external
source, in a fluorescence process. The coherence comes about from a cascade
effect, where photons stimulate more atoms to emit more photons. This is
reflected in the name: laser is an acronym for Light Amplification by
Stimulated Emission of Radiation.

Dave Neil		neildm@id.doe.gov

		If at first you don't succeed, destroy all evidence that you
tried.

> -----Original Message-----
> From:	Wright, Will (DHS-PSB) [SMTP:WWright2@dhs.ca.gov]
> Sent:	Thursday, August 10, 2000 2:31 PM
> To:	Multiple recipients of list
> Subject:	RE: Melanoma cancer/UV info
> 
> Visible light from fluorescent lamps produce UV in addition to the total
> spectrum of visible light waves as well which combined appear as
> white(heterochromatic) and very dispersed.  Fluorescent lights are
> filtered
> with the plastic cover to reduce the UV levels.  Lasers produce
> monochromatic light either red or green and can concentrate the beam, I am
> not sure these beams are pure since the rubies etc used act as filters
> only?
> 
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