Quote:
Originally Posted by DirtyCoconuts
okay, so i have a really stupid person question. is there is simple way to calculate the power of the lamp at a given distance for every light source?
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Because you put the word “simple” in your query, the answer is unequivocally “no”.
If you have the initial outlet of a point-source of light, the intensity does simply decrease as the inverse-square of the distance.
However, when you start accounting for a liner arrays of “infinite” point sources (fluorescent tubes) or multiple emitters like LEDs, where the light beams can overlap and reinforce each other, PLUS the effects of reflectors and shades, it gets pretty damned complex.
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Shifting gears a bit.
I really think one needs to know the PPF
and the spectrum to really know what’s going on, as the spectrum can affect growth if it considerably askew.
PPF tells you the sum of the intensity of the light with wavelengths from 400 to 700 nm, meaning that it is possible that an array of blue LEDs and an array of red LEDs can have identical PPF output, but will give drastically different growth, neither of which is good compared to a white, “plant light” LED of the same intensity.
Jeff White (theorchidhobbyist.com) spent about $1200 on a combo PPF/spectrometer so he could evaluate both in the designs for his LED lamps. As far as I can see, that’s about the only way to really know what you’re getting.