There is a light that I’ve been dreaming of for a while:
- zoomie
- good throw, OK (or better) flood
- big-edc size (think B158 or a little bigger). 45-50 mm lens, 21700 battery.
- e-switch
I spent quite a lot of time thinking through several obstacles. Today I made the fist sketch. It uncovered other ones.
First, some numbers. A focused zoomie with a lens that has f-number of 1 collects only 20% of light. All the rest hits the flashlight body.
I wanted to improve it and I evaluated several options.
#. Mirror adds rings to the beam around the emitter image.
#. TIR lens should be similar
#. Precollimator lens increases the projected emitter size without significantly affecting throw.
It also greatly narrows the flood beam. Maybe it should be defocused together with the main lens to get rid of that effect…
It’s relatively cheap. It can recycle nearly all of the lost light.
#. Waiven collar. It makes the image of the same size, but brighter. It’s less good at improving efficiency, can recycle only about a third of collected light. The rest is wasted either by not being reflected (as far as I understand it reflects only the most promising frequency) or not re-emitted (and probably ending up as heat). It also reduces beam width, though slightly less than a precollimator.
#. 2-stage collar. A part of the collar is mounted on LED PCB and a part near the lens. It should collect slightly more light than a regular one, but the main advantage is that it has smaller effect on the flood beam. Since the near-led part doesn’t have to collect a lot of light, it can have wider opening and thus:
- block less light from the lens
- be slightly lower, allowing deeper de-focus
2-stage collar acts funny when zooming. It comes out of focus very quickly, making the beam lose a lot of intensity in the initial zooming stage and much less later.
2-stage collar seems like the best option as it allows a fairly wide beam and extreme throw distance in the same light. Though the legal challenges may make it infeasible. Legalities aside, it’s going to be costlier too. For the budget we can have either a good thrower or a good flooder. Or neither. But I see no way to do both (though maybe some precollimator defocusing would help).
When it comes to the emitter / driver I see 3 good options:
1.Dedomed SST-40 with buck-boost driver to keep it exactly at the current that we want. FET won’t work because 21700-30T will blow the LED.
Very high throw, good efficiency, the highest price.
2. XHP35 HI with a boost driver. Less throw, less price, easier to manufacture, better efficiency, better flood. But throw is much worse and there’s the dark cross in the middle of the focus beam.
3. XP-L HI. Oldie, but still a good option. Paired with FET+1 for a good price.
Now, my drawing:
For the purpose of drawing, I used a 50 mm lens. I guess a 45 mm would be better really. And I certainly made some parts too thin. And tolerances too tight. It’s a sketch, you know. Also, the drawing uses a 2-stage collar where the moving part is Fresnel style. Being Fresnel style is not important, I just liked to draw it like that.
Problems:
- I failed to account for the threads for battery insertion. Easy fix.
- There is no switch. And the only sensible way to put an e-switch that I see is to FW3A it.
- Cooling is bad. I mean really, really bad. And I see no way to fix it.
At the end, I’s also point out one potential obstacle. Collar needs to be positioned very precisely. Will various abuses that EDC light will endure make the collar lose focus over time?
Thoughts?