RE: UV-exposure units/ UV LEDs:diagrams

A good starting place/reference site:
 http://ledmuseum.home.att.net/leduv.htm

Also has an excellent safety warning..
andy

-----Original Message-----
From: owner-pinhole-discussion@spitbite.org
[mailto:owner-pinhole-discussion@spitbite.org] On Behalf Of Murray Leshner
Sent: Saturday, November 04, 2006 10:33 PM
To: pinhole-discussion@spitbite.org
Subject: RE: [pinhole-discussion] UV-exposure units/ UV LEDs:diagrams

Hello Earl, etc:
   
  The other unpleasant thing about high strength lights you can't see is the
potential for eye injury. Not being aware of it because it's outside your
sensory range doesn't mean it still isn't hazardous (analogous to IR lasers
in CD players etc).
   
  There is a German company (Roither? Roither LaserTechnik?) that makes
laser and led diodes in more diverse wavelengths than I see in the US.
   
  They have some 420 nm LED's, deep deep blue, still enough to see, that
about nails the spectral peak (typ. 425 nm) for graded 'silver gelatin'
paper. Some alt-processes work with blue, some don't.
   
  I haven't worked with blue light for focussing yet, but some people say
it's almost disturbingly unnatural to look at...to each his/her own I guess.
   
  I think you're probably already aware if you get too far into UV range
most glass attenuates it. I think falloff is roughly 56% (44% transmission)
at 380 nm for non-UV-filtering window/picture framing glass. Of course,
optical glasses are all different recipes.
   
  And remember (if it matters), LED wavelength isn't monochromatic like
lasers...it'll be a bell-shaped curve covering a narrow bandwidth (LED mfr
website probably has data).
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Received on Sat Nov 4 20:11:29 2006