RE: Melanoma cancer/UV info

["Wright, Will (DHS-PSB)" <WWright2@dhs.ca.gov>]

There was a study on such lamps in the late 80's before which time fluor
lamps did not have the "diffusers" and depending on the type, will remove
some of uvA and most of the uvb.  You are right about where the phosphoring
takes place. Thanks for the clarification of the laser.

		-----Original Message-----
		From:	Neil, David M [mailto:neildm@id.doe.gov]
		Sent:	Thursday, August 10, 2000 2:00 PM
		To:	Multiple recipients of list
		Subject:	RE: Melanoma cancer/UV info

		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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