I’ve been researching how to measure photosynthetic photon flux with equipment that can handle LEDs rather than just broad spectrum light sources like incandescent or fluorescent lamps. From what I can tell, you need a spectroradiometer to do it properly. Tonight I came across a company that sells a hand-held unit that can measure PPFD. It costs $1,399. Not cheap, but compared to lots of lab grade test equipment, it’s relatively affordable.
This is the International Light Technologies ILT350 Spectroradiometer:
The problem with old-school PAR meters and LEDs is that the older PAR meters use sensors that make lots of assumptions about the light spectrum they will be measuring. That generally worked well with traditional incandescent and fluorescent grow lights. But, combinations of narrow spectrum LEDs confuse the old meters. A spectroradiometer doesn’t have that problem.
Does anybody know of other spectroradiometers that can measure PPFD?