Has any one ever experimented with primary optics on LEDs? Ususally the primary optics (the dome) is fixed. But Luminus has given us an open book with the SBT/CBT 90 LEDS having a flat glass window, it would be easy to attach a primary optic with some NOA-61, or to mock it up with a dab of mineral oil so it's all a similar refractive index. If you could narrow down the emissions of the LED to 60-90 degrees you could increase the amount of light going though an aspheric lens in front of it with less losses than if you used a pre-collimating lens with 2 extra glass-air junctions/reflections.
Thor labs for example has an aspheric condenser lens, 10mm diameter 8mm EFL, and a 4.2mm back focal length. Luminus datasheet for the CBT-90 says its .67mm from the emitting suface to the face of the glass. Combine that with a 3mm thick 1/2 sapphire window from thor labs(cheapest windows they have ), and that puts the emitting surface 3.67mm away. Granted you are losing the refracting of the back of the lens, only the front, I would think that would have a pretty narrow angle compared to the usual lambertian pattern.
I'd like to check it out, and I have a light in mind for it but I also have a nasty case of polyprojectitis. Just wondering if there is any prior work on here, of if I could get any gears turning for any of the usual suspects that like to project XR-E dies on the side of buildings miles away. :nana:
Thor labs for example has an aspheric condenser lens, 10mm diameter 8mm EFL, and a 4.2mm back focal length. Luminus datasheet for the CBT-90 says its .67mm from the emitting suface to the face of the glass. Combine that with a 3mm thick 1/2 sapphire window from thor labs(cheapest windows they have ), and that puts the emitting surface 3.67mm away. Granted you are losing the refracting of the back of the lens, only the front, I would think that would have a pretty narrow angle compared to the usual lambertian pattern.
I'd like to check it out, and I have a light in mind for it but I also have a nasty case of polyprojectitis. Just wondering if there is any prior work on here, of if I could get any gears turning for any of the usual suspects that like to project XR-E dies on the side of buildings miles away. :nana:
