# Wavien collars are SOLD OUT [limited production]

I see what you were talking about now, this image with the “rotated parabolic reflector”

“The parabolic reflecting collar is made by rotating the parabolic curve around the axis which goes through the focus and is parallel to the directrix. The resulting reflector is round with a parabolic surface. Light emitted from the LED placed at the focus is reflected from one side of the parabolic surface, becomes a parallel beam, incidence onto the opposite parabolic surface, and refocused back to the LED itself. One major difference between this parabolic recycling collar and the spherical recycling collar as shown in FIG. 1 is that the light emitted from a point at and near the focus will be reflected by the parabolic reflector twice and back to the same point where the light is emitted. With this property, with used with packages with multiple LEDs and multiple colors, each LED will be able to perform recycling of its own light independently and each LED with its own color will be able to improve the brightness independent of the other LEDs and colors.
[0009]
The parabolic reflecting collar is positioned such that higher angle light rays are reflected twice, off opposing wall reflecting portions, back to their point of origin. Preferably the light source is an array of multiple LEDs having different colors and sizes.”

So the thing is that it doesn’t actually work. The lines are not reflected back to the point of origin as descibred in the patent. Would be cool if it did, but nope. It would need to be a different shape than a parabola, and then it would still only work from light rays originating from the center, not any point on an LED. ![](https://i.imgur.com/n6a2bSZ.png)

This is what the double-parabolic method is, one forward facing and one rear facing parabola will return the light rays to their origin:

Basically what the wavien collar does but far more complicated to set up and less effective because it has to reflect 3 times.

I meant the height of the entire collar. Sorry for not being clear enough.

11.48mm

Thank you!

Agreed, hence my skepticism about that particular patent, I don’t see how much light recycling can be achieved with this arrangement, nevermind precisely bouncing it back to individual different coloured LEDs in a multiple array.

But perhaps there is also some secret technique not revealed in the patent itself, which wouldn’t be unusual.

It would be nice if you could show us a ray-trace for the spherical collar, it might help those who have ordered this one and demonstrate your point even more clearly. If you could simulate the light source being a small LED in the middle of the reflector (Lambertian), even better.

PS: I tracked down DrJone’s paper that I remembered, at Flashlight Optics - Dome, Dedoming and Throw

It’s from 2013

(Edit: 2012)

so I daresay there have been plenty of developments since, particularly in phosphor design, domes, and the latest back-illuminated LEDs, but still gives plenty of insight today.

I’m still skeptical about light recycling in general, particularly in modern LEDs where I hope a high proportion of the LED light is absorbed in the phosphor with little wasted, but agree that the collar is still a clever way of scooping up more of the off-axis light and re-directing it in the desired direction.

I’ll be watching this thread with interest, having no experience myself.

I have questions about light recycling as well:

-does it work in warm leds just as well or for best results use cool leds? Cool leds have a high remaining blue peak so lots of options for recycling, but warmer leds will convert recycled light more efficient in new fluorescent light. Perhaps there is an optimum colour temperature?

-Is a rough die surface (i.e. a dedomed led) better than a shiny surface? (i.e. HI versions of Cree leds)

-are modern phosfors that are rougher and give better spectrum less suitable for luminance increase by light recycling than the good old ugly Cree phosfors

FWIW, a sliced and sanded high CRI 4000K Samsung LG351D did warm up from 4000K to 3500K with a tint shift from slightly green to yellow-rosy, and a considerable throw increase, a clear sign that light recycling does happen in modern, warm tinted leds.

Now that sounds very interesting!!!

Firstly these are just my theories, feel free to tear them apart.

As I understand it the warm LEDs use a thicker, or more dense phosphor, which whilst absorbing more blue from the LED, attenuates it more in the thicker phosphor hence generally lower output.

So I would expect the cooler ones to benefit more from e.g. recycling from the collar, less attenuation of the blue from the less dense phosphor, then the returned light hits the front surface which is a more efficient place for it to be. I’d expect the overall tint to end up warmer, but if you just want the cooler brighter output I don’t see the blue light as being wasted, without recycling.

I think the shiny surface of the HIs may be a protective encapsulant for the phosphor surface and the bondwires. It wouldn’t be practical to sell a raw LED with exposed bond wire (handling damage). Hence the flat designs now available.

If of suitable refractive index, even though flat, it may also provide a matching function (refractive index) between the phosphor and air interfaces, much as the dome does. Which I think would reduce internal light recycling, but improve it from e.g. an external collar, encouraging the blue to escape or return.

Perhaps the phosphor underneath is already rough, which I think may be better.

Though I think an engineered textured surface could be best, and we are seeing this sort of thing nowadays.

I’ve thought about trying a silicone conformal coating on de-domed emitters to see what difference it makes, such as https://uk.rs-online.com/web/p/conformal-coatings/0494714/

But phosphors are already a suspension of the compounds in a silicone base, so maybe no point except for protection.

I think someone used to sell something similar called LED seal, at higher price.

I like to use conformal coat on circuit boards anyway (trained this way), though I prefer strippable acrylic based versions for that, when the temperature rating and inertness of silicone is not necessary…

That makes sense, and confirms DrJones ideas.

I think it is possible using a different shaped surface, but clearly a parabola does not work.
A different shaped surface may not work well for anything that is not in the center of the LED too, which would make it useless.
I don’t know if I can modify this ray tracing program to have custom shaped surfaces, but that would be one way to test and figure it out.

Here is a spherical surface reflecting all the rays back at the LED:

Obviously in the real world the rays don’t go through the LED, they hit it and scatter, and also add energy to the phosphor.

Man, just maxed out my PP to come and find this…

Enderman, you may want to edit the title of this thread to indicate that these are sold out, unfortunately.

Question for Enderman or anybody: how do you affix this to the flashlight body? I watched Marinebeam’s YouTube video about proper alignment of the collar, but once you figure that out, how does one keep it fixed in place?

Hot glue
You want to fixate it with something slightly flexible.

Thanks for that tip. I found that video at https://www.youtube.com/watch?v=HXAz-TvPDVA and it is very interesting, a clear explanation of how it works.

I note that Marinebeam used the term “light recycling” in the sense of simply bouncing around the stray light back onto the LED, which is the way I was thinking of it.

Quite how much “light recycling” is occurring due to re-use of the blue portion by re-stimulating the phosphor and actually adding to the effect, I wonder. Surely it can only be a second-order effect, not the main reason for the collar ?

The phosphor cannot be re-energised by the light wavelengths that it originally emitted, only by the minority shorter wavelength blue light. That’s how phosphors work, converting shorter wavelengths to longer.

I suggest that the majority of the recycling effect is simply by scattering from the surface of the phosphor, where it’s reflectance and colour (i.e. yellowish) are the important factor.

Nope, it’s the blue light which makes up a substantial part of the spectrum of cool-white LEDs.
When light is converted in such phosphor it’s isotropically scattered. This makes the LED brighter from all angles.

The converted part of the spectrum becomes more pronounced (there is not additional blue light coming from the phosphor when you add the collar).

The Osram Black Flat basically has a polished silicone surface. If the collar were to work just by reflection and scattering it wouldn’t work very well the Black flat. It would be much worse compared to dedomed Cree LEDs which have a rough phosphor surface.

Ok, for cool white there will be a greater re-stimulation than warmer tints. But as Marinebeam showed, the majority of the work of the collar is to direct the light through the hole, at the condenser (aspheric), without any being “wasted” simply heating up the inside of the head of the torch. As in a standard zoomie.

I see the collar as mainly performing a pre-collimation function, whilst scooping up stray light from a Lambertian emitter (120 degree cosine function) and recycling it until it can escape in the desired direction.

I’m not talking about reflection from a transparent silicone surface, that would be silly, but scattering from the (maybe rough or textured) phosphor lying beneath.

Consider, on a standard zoomie you could fix a plain circular aperture in the same place as the hole in the collar and it would have no effect on the output. It is the circular reflecting interior of the collar that “recycles” the off-axis light that makes it so clever.

As a bonus there is the re-stimulation effect, which I’m sure happens, but to what extent I’m not sure.

Also consider, another reason why warmer tints are less bright than cooler is because the conversion in the phosphor has an efficiency loss. An LED with no phosphor at-all would be blue, and highly efficient, but of little use to us.

The more you “recycle” (or as I think of it re-stimulate the phosphor) with the escaping blue light, the less efficient the overall process becomes, in the limit if the blue component was totally recycled by re-stimulation, then all you’d have left would be the warm emission from the phosphor. So you might as well just have used a well designed warm LED in the first place.

And as Marinebeam elegantly explained, in a standard reflector based torch the on-axis light that doesn’t hit the reflector turns into spill, whereas the hotspot is created by the off-axis light that does hit the reflector.

Meaning if you want a thrower that is practical (with some spill) you might be better looking at extreme reflector designs.

Edit: the deeper the parabolic reflector, the better.

If you want to focus an image of the die with zero spill (wasted ? light), then an aspheric with a collar is the way to go.