RE: UV point source


David J. Romano (romano@agfa.com)
Mon, 29 Nov 1999 11:48:08 -0800


Eric,
As for light sources, heat is usually a problem. There is only one that
I'm aware of that might work without producing heat, but it's pretty
exotic and expensive. Nichia Chemical sells a UV LED which has a narrow
spectral bandwidth centered on 370 nm and outputs 1 milliwatt of UV
energy. You'd need a few hundred of them to illuminate a negative though

and the cost would be over $1000. And, I don't know if 1 milliwatt is
enough anyway.

I'm using a metal halide bulb. It does produce alot of heat, but I've
dealt with it by building a special lamp housing. It's taken me a while
to build the housing and to locate the parts I need, but it will be
tested soon. I've got a very strong fan which will evacuate the hot air
from the lamp housing a couple of hundred times a minutes and heat
resistant heat blocking optics. I'm waiting for some of those parts this

week. I don't think I'll have to worry about overheating the negative.

The spectral transmission characteristics of lenses can be hard to come
by, and they do vary a bit. Schneider's web page has this info, but not
Rodenstock's. I can't even find A Nikon web page that has their enlarger

lenses or large format camera lenses. I didn't try looking for Leica.
Special quartz lenses can also be had for under $800 from
http://universekogaku.com/index.html

I don't know what Starphire glass is, but it hints at being Sapphire
glass. However, a large sheet of Sapphire is probably way too expensive.

"White glass" probably refers to Schott B-270 crown glass which is
excellent for transmitting UV down to 330 nm or so. I don't have a
spectral curve handy.



This archive was generated by hypermail 2.0b3 on Sun Dec 05 1999 - 17:09:24