Aspheric lights - recycling sidespill back into the emitter

Reading the posts about the Deft-X, someone mentioned that it may use a Weiven Collar (which is a patented device). This device consists of a hemispherical reflector that is place upside down on top of the emitter. Light emitted to the sides from the bare emitter hits this reflector and is reflected directly back at the emitter. This recycled light increases the surface brightness of the emitter by exciting the yellow phosphor layer on top of the LED as well as being reflected upwards. The Weiven Collar has a hole in the center to allow the beam to penetrate and hit the aspheric lens.

Reading about this got me to thinking… is there any way something similar could be applied to a zoomable light? Here’s some ideas off the top of my head (Note: I do not have a Deft-X and have not seen inside one):

1. Mount LED on a thin pillar with a diameter slightly smaller than the diameter of the hole at the top of the collar. Attach the Weiven collar to the sliding bezel along with the lens. When the bezel is extended, the collar and lens are held at the correct distance for maximum excitation of the emitter and maximum throw through the lens. When the bezel is retracted, the collar would sink below the emitter allow the emitter to come very close to the back of the lens for a wide flood. Problems: Need for pillar means light could probably not be mounted on traditional star except in a large light. Also the hemispherical shape of the reflector might make for an excessively large light.

2. Instead of a hemispherical reflector, make the reflector out of a series of concentric rings on the inside of the bezel. The bottom edge of each ring would be angled to reflect light back to the emitter when light is in zoom mode. These rings would need to be chromed in order to provide maximum reflection. They could be either cut right into the aluminum or molded from chromed plastic. Problems: Cutting the grooves at just the right angle inside the bezel is probably extremely difficult. Molded plastic would work better, but could still be tricky to engineer. Also if the bezel isn’t extended to just the right distance, the reflections might not be focused properly.

3. Apply reflective safety tape to the inside of the sliding bezel and inside of the pill around the emitter. A car or bicycle reflector works by total internal reflection. Light aimed at such a reflector penetrates the top of the plastic, then bounces off the right angles at the bottom of the little pyramids inside the reflector before exiting along the same path it came in. It is possible to purchase reflective flexible automotive or athletic tape that works along this same principle. There’s no reason this tape couldn’t be applied to the inside of an aspheric light to hopefully recycle some of the light hitting the side of the bezel and allow for higher surface brightness. If this method works it could be exceedingly easy and cheap to make. The only modification necessary would be to allow sufficient room on the inside of the sliding bezel for the thickness of the reflective tape. Other than that, the light could be constructed using all the same techniques as for any other budget zoomable light. Reflectors of this type may have another advantage: There’s no need to focus the reflector onto the emitter as the light hitting the tape should be reflected back automatically at the correct angle to hit the emitter.

This third method sounds like something someone should try out. It could be very quick and easy to test especially with a non-zooming aspheric light. Spend $10 to buy some of the right kind of white reflective tape. Unscrew the aspheric lens of your light, then apply the tape to the inside of the bezel. Screw the lens back on and see if lux goes up.

"but could still be tricky to engineer".

I think that's the biggest thing about it. It would all have to be engineered to be perfect. If not, then it would actually be worse than stock. Just like the Wavien ring, it would have to have the exact angles to reflect the most light exactly back to where it will do the most good. I don't think it can be done in a budget manner, that is untill the Chinese come out with $5 copies of it, LOL.

I have thought about trying it myself, with a Maglite double aspheric and a home made ring, but it just gave me headaches trying to figure out how to do it, so I dismissed it as something I can wait for, till someone makes copies of the rings.

This is why I think my third idea of applying reflective safety tape to the inside of the bezel may be the best option. If it works, it would be extremely cheap and require little or no extra engineering. Also because reflective safety tape reflects incoming light back to its source regardless of angle, it does not need to be precisely placed or engineered as would be the case with the Weiven Collar.

Sure, it might not be as efficient as a Weiven Collar, but any recycled light is better than nothing.

idea 1 seems the most practical, for the diy’er

con - pillars don’t make great heatsinks, so the sooner that pillar makes contact with a mass that can spread the heat, the harder you’ll be able to drive the emitter

pro - a lot of lights have hollow pills, which is great if you have the right diameter copper rod to force in that hole.

the lens has a focal length for the stock emitter location - but if you use a shorter focal length lens, then that rod could sit up higher than the pill.

someone here modded the zyc10s zoomie by using a shorter focal length lens, xml, and pillar. I think it was viffer.

a better start, due to the amount of room inside the head, might be the tractor supply 3xd zoomie.

i think the problem w/ less efficient, is some of that light will reach the lens, and traveling in a random direction. it won’t be a clean beam. I like aspheric throwers because they have a clean beam….spill doesn’t reflect off fog/snow etc.

if that doesn’t bother you, i suppose it is worth a shot.

I tried the reflective tape trick once in a different set-up but what was the same was that light that was not getting out of the flashlight was reflected back to the led with Scotch reflective tape (in my set-up about 50% of the light hit the reflective tape). I was surprised to notice that output did not increase and that led tint did not change. Perhaps the reflected angle of the reflected light is not precise enough to make a noticable difference.

I think that’s exactly the point of the Waiven doodad - the hole is there so that the emitted/re-emitted/re-bounced around light has a relatively narrow angle, which is exactly what you want with an aspheric to avoid weird beam artifacts.

Personally I’m a touch dubious about the reflected light re-exciting the phosphor. I’ve read that LED makers are working on developing a way of doing this so as to reduce the heat loss caused by internally reflected light, but at present they go at great pains to get those photons out of the phosphor and not have them come back (the silicon dome, mainly). My take on the Waiven collar is that it simply bounces around the light emitted off the desired angle (30 deg?) until it find its way out of the hole and hits the aspheric, i.e. the efficiency gains come from collecting and using that previously unwanted/ wasted light, not from any other trickery. Then again, what I know about LED technology can be written on a 20mm star.

First I’d try with a fixed focal length aspheric and use some kind of OP reflector (that fits within that focal length) with the base drilled out and inverted over the LED. That in my mind would be the closest we’ll get to a Waiven collar.

well, the tint shift suggests that re-exciting the phosphor has some role.

I guess someone could estimate how much of the output increase is from redirected light, and how much is due to phosphor excitation with an integrating sphere.

measuring the overall output of an emitter when it is bare, w/ floody reflector, w/ throwy reflector, and w/ wavien collar should give some approximation, since the reflectors would give some idea of the IS’s deviation with respect to beam profile.

Nice .

Lol… I tried exactly that but it didn’t make a difference.

It’ll only work for aspheric light

true and I’m about as far an expert on this as possible. Still, at the end of the day, if someone on here can reproduce it I very much doubt they’ll care the whys and wherefores :slight_smile: I just remembered the name of the reflector I have - Boom SS. When I get another linear driver in I’ll bolt an XM-l to a block of alu and give it a whirl. Something like: emitter>space (15mm?)>piece of card/box with 20mm dia hole (?)> wall. See how much light hits the wall with and without a Boom SS upended on the LED. MIght fiddle a bit with the aperture on the Boom too. Should be a fun little project and if there are any easy gains to be had they’ll be apparent pretty quickly.

@ezarc - that made me laugh :slight_smile: The whole contraption might be too long to fit within the focal length of an aspheric though, as they’re pretty short (10-15mm?).

yeah, i’m definitely not expert, and like you I’ll take ANY gain in that kind of light…

since wavien collars are too expensive for most folks, we might not see budget copies unless we do that sort of testing, find an acceptable solution and it becomes fairly common.

iow, this stuff is still too far on the fringe for the chinese to hear about and want to copy. heck, there’s only few ‘regular’ fixed aspheric throwers available…

I’m still thinking that the right size christmas ornament, cut in half, is a good way to begin experimenting. In fact, I think the owner left some in the attic of the place I’m renting. time to go check lol

worth a try, it’s not like you have anything to lose! I bought that Boom years ago for not very much, then found that everyone panned them as being too floody, so it’s been sitting in my parts boxed unused since then. When I get my DrJones driver I’ll hook everything up and have a play.

I remember a thread on mtbr forum where trout and others experimented with making wavien type collars with a ball-end mill in aluminium and Im sure that some gains in output were achieved.

It would be great if a homebrew hack could be found cos I dont want to pay wavien $80 for a reflector!

yeah, they had some success but ahorton didn’t see enough improvement to make it worth pursuing. It also looked fiddly as hell. Perhaps part of the problem was that they focused (doh!) more on the phosphor re-excitation aspect, rather than collecting and channeling the side scatter.

I’m afraid that “collecting and channeling the side scatter” won’t work; the laws of optics forbid it. The wavien collar increases die luminance by reflecting light back to the die, where it adds to the original luminance.
Dedoming does something similar (—> thread)

I thought about this exact thing to do, too.
I used an aspheric zoomie and reflectivetape from an old constructionsitethingwithalamponit (is it called beacon?). To my surprise, I wasn’t able to see any difference in throw.
The main problem with this method is, that the sliding tube for the zooming mechanism is a pretty precise part, so that the zooming wouldn’t work that good anymore.