dark sport in L4

who can notice a dark spot in their l4. mine seems to be a little dimmer in the middle and its driving me insane, i cant tell whether im seeing things or whether its actually there. when i hold the light against the table then move it u a little bit and i look at the table i can see a dark spot, then when i move it away a few inches it dissapears. when i shine it at the ceiling it appears the center of the beam is darker then the outside. Does anyone else have this? is this a bad LED, are their some not like this?

It's the infamous donut hole of the L4. Some have it, some don't. Some have an ugly green tint, others are perfectly white. The whole thing is called the Luxeon lottery. I've seen L5s with the donut hole, too, but no L6s so far.

it's fairly normal.. i've got the same effect in my Streamlight 3AA Luxeon.

If the reflector were perfectly smooth and the die placed exactly at the focal point of the reflector, you would have a significant donut hole!

I have this doughnut hole pattern in my KL4 and in one of my two L5s. This is a perfectly normal occurrence with the type of LED and reflector used, and is nothing whatsoever to be concerned about.

cool thanks guys.

Yup, got a donut hole in my L4 as well. Disappointing, but I can't see it when I stare into the beam. /ubbthreads/images/graemlins/grin.gif

if you stare into the beam that much, then you shouldn't be seeing anything else much either. /ubbthreads/images/graemlins/grin.gif
Oh and I guess I was lucky since my L4 has no donut hole...

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BlindedByTheLite said:
it's fairly normal.. i've got the same effect in my Streamlight 3AA Luxeon.

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Yeah but, yeah but, yeah but -- isn't that a 1W Luxeon in them things? With a single die in the middle? Unless it's off-center, a low dome that's not in the exact middle of a reflector can sometimes create a dark spot, but then the beam would be lopsided as well. Whatcha got?

what if the die on the LED is off center, I hear this is commoon with Red Luxeons...and the white ones have that layer over the top, so it would be hard to tell!

i wonder if everyones light has the hole thing and some people just cant see it

The doughnut hole in my KL4 is barely noticeable, not obvious. But it *is* there.

I also notice a doughnut hole, but mine is very, very slight.

I have never heard of or seen (I have three, have seen five) any L4 without at least a very subtle donut hole. It's the price you pay for a big die(s) and small reflector. Still one extraordinary light.

It will be very interesting to see if single die LEDs can evolve into super efficient 100w/lmn uber-emitters. Then you could have very small lights that would throw like a C3/SRTH/N2.

I'll quit dreaming now.

Brightnorm

My KL4 has it, I didn't notice it until someone mentioned his had it. When you check it against a wall you can just barely see it (at least on mine).

GregR

ok good ill stop being OCD now and leave it be, basically everyones has it. its not a flaw lol.