Sanding the led dome on the cree?

[Ralph_S]

If the flashlight manufacturers got together, maybe they could persuade Cree to lower the metal ring around the emitter, and use a thin, flat cover slip instead of a lens. If the cover were flat, then centering it would not be crucial. A flat cover could allow more light to head toward the sides, into a reflector.

In other words, the current Cree lens looks like an attempt to help manufacturers who don't want to add their own reflectors. However, most of the flashlights mentioned on this forum have their own reflectors, so the flashlight manufacturers have to counteract the lens built into a Cree. I think that a flat cover could reduce costs, improve focus, reduce light and dark rings, and allow slightly shorter reflectors.

This is not my specialty, so I may be missing something. Thanks for any feedback

 

[kenzo]

I dont know if i'm understanding you properly, but it seems they have done that with the XP-E?

 

[TITAN1833]

Why not sand the lenses on your prescription glasses, then all your lights will be smoothed out...

Good one :laughing:

 

[L.E.D.]

Sanding the dome on a Cree XR-E wouldn't do anything about the Cree ring anyway, the ring is generated by the reflection off of the surrounding metal ring, thought it might smooth out the checkered-grid pattern that bare XR-E's seem to put out. The dome on the XR-E is indeed GLASS. The dome on the XP-E, that might be a different story..?

 

[L.E.D.]

I think that a flat cover could reduce costs, improve focus, reduce light and dark rings, and allow slightly shorter reflectors.

This is not my specialty, so I may be missing something. Thanks for any feedback

There are no "dark rings" or rings of darkness as some like to claim. It's just a ring of brightness between the hotspot and the outer spill, and this ring of brightness gives the ILLUSION of a ring of darkness. If you measure the lux on the inside of the ring between the hotspot and compare it tp the lux of the outer spill, it is NOT a ring of darkness.

 

[saabluster]

Sanding the dome on a Cree XR-E wouldn't do anything about the Cree ring anyway, the ring is generated by the reflection off of the surrounding metal ring, thought it might smooth out the checkered-grid pattern that bare XR-E's seem to put out. The dome on the XR-E is indeed GLASS. The dome on the XP-E, that might be a different story..?

I keep hearing this idea people have that the "Cree ring" is caused by the outside of the metal ring. This is not the case as it is from the inside of the ring where Cree has formed it into a crude reflector to boost the output of the package. Therefore frosting the glass dome will help to smooth out the Cree ring. And yes it also helps with the + on the MC-E as well. This has been verified by myself recently. I bought Armour Etch and it works beautifully for the job. The beauty of doing this as opposed to adding a diffusion material is that you are reducing the amount of reflecting surfaces that the light has to travel through.

 

[L.E.D.]

I keep hearing this idea people have that the "Cree ring" is caused by the outside of the metal ring. This is not the case as it is from the inside of the ring where Cree has formed it into a crude reflector to boost the output of the package. Therefore frosting the glass dome will help to smooth out the Cree ring. And yes it also helps with the + on the MC-E as well. This has been verified by myself recently. I bought Armour Etch and it works beautifully for the job. The beauty of doing this as opposed to adding a diffusion material is that you are reducing the amount of reflecting surfaces that the light has to travel through.

So it comes from the INSIDE of the ring. Great information, thanks. Can you post any comparison beamshots of a regular Cree vs. an etched Cree in the same light?

 

[saabluster]

Can you post any comparison beamshots of a regular Cree vs. an etched Cree in the same light?

I don't have anything to post at this time. I have been doing R+D with components outside of a light.

 

[electrothump]

Why not sand the lenses on your prescription glasses, then all your lights will be smoothed out...

Ha!

 

[Ralph_S]

Poster #1 in the following thread (https://www.candlepowerforums.com/threads/208887) shows that the dome over the emitter on his DBS came off, resulting in a more focused beam. (The beamshots don't have the same exposure.) Poster #3 in that thread says the phenomenon is nothing new, but lumens and color will suffer. Poster #5 in that thread also lost a dome, and got a tighter hotspot and a color shift.

If a (flat) cover remained over the emitter, then presumably the color shift could be avoided. If no phosphor were pulled off, then maybe no lumens would be lost, since all of the light would remain visible. Why have the cost and positioning issue for a lens to focus the light (mostly away from the reflector), and then diffuse the light (so it reaches the reflector)?

There are no "dark rings" or rings of darkness as some like to claim. It's just a ring of brightness between the hotspot and the outer spill, and this ring of brightness gives the ILLUSION of a ring of darkness. If you measure the lux on the inside of the ring between the hotspot and compare it tp the lux of the outer spill, it is NOT a ring of darkness.

OK, that makes sense. I had wondered whether there might be an illusion.

I dont know if i'm understanding you properly, but it seems they have done that with the XP-E?

I will look at the XP-E.

Thanks