The Planted Tank Forum - View Single Post - Convert Lux meter to PAR meter?
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post #5 of (permalink) Old 06-13-2012, 06:32 PM Thread Starter
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Join Date: Dec 2005
Location: Sacramento, CA
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Originally Posted by mistergreen View Post
Can you find the name of that photodiode? Maybe we can look it up to find the spectrals for it.
I notice they use a ultraviolet filter on top of the photodiode.
I can't see the actual diode for the filter and a case below it. Here is another photo:

It looks like it would be pretty easy to remove the whole sensor assembly to put it into a different, and waterproof case. I think the white plastic dome, the cosine filter? - has to be the only optical thing between the light and the sensor, so I couldn't have that part inside the watertight case. Is that correct? The only effect I can figure out from having a layer of acrylic covering the dome is reflection off the flat layer, but there is reflection off the dome too, so I can't understand why that does much harm.

The 60.6 conversion factor could change if there is acrylic over the dome, I think, but that's not a problem either. And, if the conversion factor is accurate to +/- 5% that would be outstanding.

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