Led coloration


Flashlight Enthusiast
Dec 13, 2006
*Out There* (Irvine, CA)
What causes an led to emite a yellow ring ( I have a cree based led that has a yellow ring from about 180 to 200 degrees angle from the emitter yes behind itself, my assumbtion is that it is jsut too much phosphor around the edges to lower cost using a cheaper less precise phosphor placement.

So any ideas yes this has a 200 degree emitting pattern to my estimates it throws ligh tbackwards. but its yllow.


Flashlight Enthusiast
Apr 7, 2004
Lost In Space
hmm, all these "white" things are just blue leds with yellowish phosphors, mabey, at that angle (out the side) the emitted light is passing through More phosphors.
like if you assume that the emitting thing is mostly flat, and has little original light bending compared to higher dome things, the phosphors are on top of the blue light output.
at that angle even if its not exciting the extra phosphors, it still is being "filtered" through them and they are yelowish.

so i would assume that side shooting light from it, is passing through more yellow :)

there is also the reflection off the dome itself, and the yellow phosphors are all high, so excited or filtered that location should have much more yellow comming out. also the phospors are being excited on the bottom, more than they are on the top (so to speak).

like the example of glow paint: if you hit a light shade covered in glow paint with light on the inside, the stuff on the inside puts out more light, even if it bleeds through to the other side.

any reflector or optic will send the side light foreward and probably blend it with the rest of the light, any "area" lighting useing it will blend with others needed to be an area light.
so it shouldnt be a problem ?

of course that is just speculation, but it sounds good eh :)

if it didnt hit phosphors , then it wouldnt be "efficient" at all, the more phosphors it hits, the more overall light it will put out, so blue ring, yellow ring, no ring, all would have some caveat of some type.
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Flashlight Enthusiast
Jul 21, 2003
Eastern Pacific, LAX DM03 sw actual
This has been the topic of lengthy threads. Some of it has been covered in NEWBIES thread or two.
There is clearly somthing reflecting a tinted ring. I beleive it is the silver coated copper ring which retains the glass lens. Many disagree.
One thing which is for sure. The seoul semi conductor does not suffer from this problem.