Enderman
February 11, 2019, 4:41pm
572
LouieAtienza:
Well, the lux meter can be 30deg. to either side of the central axis of the LED and still read 90% luminous intensity of dead center. I found a calculator online and found the surface area of a parabolic reflector for a front-facing LED whose diameter is the approximately the same as the distance from opening to focal point about four times that of the surface area of the opening. But even though the surface area is four times as large, the light intensity I would estimate to be about 2/3 that of the light emitted from a 30deg. to 0. And the efficacy of an electroformed parabolic reflector surface with rhodium coating is around 90%; I’m sure the cast, machined, and polished/coated surface of say a BLF GT to be slightly less. So maybe the ratio of light from the reflector versus light directly from 0-30deg. is more like 2:1 rather than 3:1.
But the reason for using these emitters is to effect a longer throw, not to put the light on an integrating sphere to get a lux reading. Your very own OptoFire uses that 30deg. half angle since that’s the aperture size of the RLT you used,. And the lens is approximately the same size as the reflector on the GT - yet it throws farther than a Black Flat installed in a GT with a reflector - despite the GT’s reflector having over four times the surface area of the RLT collar you used. A collar which you noted is about 33% efficient at collecting light from 30deg - 90deg. So using your theory a larger collar (with the same aperture angle) would be more efficient - but I don’t think so, because any errors on the surface would be greatly magnified dur the distance of the reflector from the LES. But for a larger emitter it may be beneficial.
The intensity of a flashlight depends on two things, the emitter’s luminance (cd/mm^2) and the front area of the optic.
Try playing around with these calculators, you might see how things work when you adjust the value sliders:
These are some advanced calculators I have made to help me estimate the final performance of the custom flashlights I build, and I decided to share it with you guys so you can do the same