Originally Posted by samamorgan
LEDs don't emit a broad, even spectrum. They emit fairly spiky spectrums, and only emit visible wavelengths. this is unlike MH and flourescent, which emit lots of ultraviolet and infrared.
LED spectrum analysis is fairly well documented in post #2, click the link in there to see.
Your post is what got me thinking about this. If we could filter out/block light in the 550 nm to 625 nm range, we might get more interesting information. Of course, this would mean that we would actually have to have the lights being tested, as well as a PAR meter, and some form of filtering to block that range of wavelengths.