If you get the chance, please post a pic of the components you are working with. I have been experimenting with a glass rod out of an automotive foglight but am looking for inspiration..
I assume you mean the optical components. I can provide the links to the heatsink, wall beamshots, outdoor beamshots and video.
This post shows the low beam unit on the left which has
these lenses one per LED in the Narrow 10417 model. This is the light unit I am messing with. The LEDs and lenses are arranged in a triangle. On the XP-G, I get more like 18-20 degrees FWHM than the listed 16.5 degrees, which is nice for trail, but too wide and high for the road.
Beamshot of low beam unit with three Carclo 10417 lenses taken at 4 feet from the wall (no light meter at that time to determine 50% max but guestimated it at 18-20 degrees):
The same post (#319) has the link for the source of the donor fresnel lens. It also has a picture of two of them, and the right one has it's center cut out. The cutout piece was sanded to fit, and mounted in the black bezel in front of it that fits the light with the Carlclo 10417s. It subs in for the glass cover lens shown in front of that.
The fresnel lens has an hourglass symbol at its center, when it is on its side as if topppled over, I defined that as horizontal, and the retangular prisms long axes are also horizontal. Vertical is 90 degree WRT that with the hourglass symbol in a normal orientation.
I tested the light with no lenses other than the 10417 not even a cover glass and the two orientations of the fresnel lens in the Set 1 and Set 2 picture montage. I then reset the aim to optimize the light on the road and took the third.
Thinking about all the results, tells me that a lot of the peripheral light has been reduced but that does not show up in a room with light filtering in through a blind. The main area of the beam is more even and slightly lower toward the bike, and the hot spot made less different than the rest of the beam. In effect, the fresnel lens has tightened the beam to about 10 degree FWHM, maybe a bit narrower, leaving much reduced spill. BUT it did not widen and flatten the beam much, if at all. I need a truly dark outdoor situation to see that better. Each prism is similar to the lens you are thinking of but not wider in the center.
The donor lamp's beam is a bright band along the vertical axis of the hourglass logo.
Rotate the bulb 90 degrees and it is a foglight-like horizontal beam.
Both photos with 3 Mpl Phone camera set on no flash and +3 stops exposure with room lit by filtered light through shade. Faint stripes are artifacts of the bulb/lens. I meant the lower one to be off center, but no the top. They'll work for this purpose well enough.
I suspect I don't see that with the triple LED light because I have three off-center light sources.
Thanks: you made me see I can test that easily. I could mask two of the three 10417's and tape the fresnel so it centers on the third to test whether it works with a single center source. I could mask the top one and the bottom two would be in line and repeat a test of two light sources on the center line of the lens.
The results are that without the reflector and being set at the correct focal point, the fresnel lens just evens out the main beam and seems to drop the light off more rapidly at the edge. If the prisms are in a certain position, some elongation of the beam occurred.
Beamshot with glass cover lens:
Beamshot with fresnel lens:
The first picture and the second are the same light, same lenses. The first at the standard beamshot settings, the second with the cell phone camera at +3 stops exposure. So the full extent of the spilll from the beam is lost with the cell camera. The masking tape strips are 36" long. So the original beam in the cell phone pic is almost 30 degrees wide across the bright area, whereas the fresnel lens cuts that to 22 degrees, but leaves a larger spill area in its place. The main difference is the center of the beam isn't as bright and the bright area is more uniform with the fresnel lens in place. The tape is more washed out in the center of the first beam and the light meter confirms the greater uniformity. It makes a more useful beam on the road at this angle. So the Set 1 and 2 pictures suggest it is as much the very bright center part of the beam which if 1' wide at 4' is 38' wide at 125 feet away that is causing the glare and flare in the pictures.
So this lens plus a bill to cut off the above the horizon light, will give a more motorist-friendly beam with the current setup. Riding it shows a big improvement in approaching driver response to the light. The lower angle gave me glare off my clear plastic map pocket on the front bag, so I removed the pocket. Remounting hte bag and light to get the light further forward would help. I am thinking of how to reliably attach a bill to help the horizontal cutoff.
So three in line would need a lens more like
this.
