The Planted Tank Forum - View Single Post - Convert Lux meter to PAR meter?
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post #22 of (permalink) Old 06-14-2012, 06:27 AM
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Originally Posted by mistergreen View Post
Yeah, it does leave a residue but I also saw bits of the photo layer degrading like a burnt out LCD pixel. Maybe it reacts but not corrode.
Ooo, that's weird. The active elements of the photodiode are usually well encapsulated. Are you sure it was that? Is it possible it had a thin-film external IR filter layer which was reacting with the glue?

Originally Posted by mistergreen View Post
Shouldn't it be a green gel to deflect green out? Like chlorophyll.
You specified a "green light gel". Filter gels work by absorbing certain colors rather than by deflection, so a gel that's green in appearance is absorbing red and blue; which would be counterproductive. So I assumed you really meant "a gel that filters out green"; which by absorbing green and transmitting red/blue would appear purple. I may have assumed too much.

Now if you'd specified a dichroic filter, which does work by deflecting certain colors instead of absorption, then the correct filter would appear green.
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