Re: Liquid optic or cooling element ?


<per.corell@xxxxxxxxx> wrote in message
news:a76103a6-99c2-412e-8f73-f551d319e358@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Guess it's not here I can find any explanation about why to use water
in a condensor lens, --- true water are a great filter, but I don't
think this can be the whole issue, as a glass filter will be so much
better .

Don't forget that, when this was made (early 1930's I would say), thin film
filters were in their infancy. Also, IR absorbing glass filters have a
greenish color that they may have been trying to avoid.

Pure water also lets pass more UV than practically any IR filter available
even today. This illuminator may have been used in the printing industry to
expose printing plates that were covered with photoresist which is sensitive
to UV or blue light. Look up gravure printing.

--
Adam Norton

Norton Engineered Optics
Optical design and systems engineering for Silicon Valley and beyond.
www.nortonoptics.com

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