Cree XR-E frosting question.

I have been reading all of the cool things being done with the Cree XR-E.

I have read that the lens is glass.

Would there be any advantage to frosting the lens?

Thanks for any thoughts.

Are you sure the XR-E led dome is made of glass? I would have guess it was made of silicone :huh2:

I don't know for sure, but I thought I read that they are glass.

The dome is made of glass and filled with silicone, I believe.

The lens came off one of my XR-E's and it looked like a solid piece of hard plastic. I put it back in again and the LED still works. I might risk taking it out again to take a photo' of it.

Colin.

Here are pictures of the lens detached from the XR-E...I could not focus close enough in the second picture, but you can see that the lens is solid.
The ring around the edge is from the adhesive - that didn't hold it in place. :thumbsdow






Colin.

Great photos. Sorry to hear the cree came apart.

Does the cree still work with the lens removed?

Perhaps we could remove the lens and turn down the metal ring so that the cree can be used with current 180* reflectors....

Has anyone tried smoothing the top of the dome so that it looks more like the dome of a luxeon batwing emitter?

It is glass, and I think MillerMods said it's half sphere of glass which Ganp's photo seems to confirm.

From looking at the leds, in order from clearest to most frosted:
Cree -Glass - Very Clear
Luxeon -Plastic - Clear
Seoul Zled & Luxeon K2 - Silicone - Hazy

You could frost the dome, but I don't know what benefit it would have. Might smooth out a beam, but you could just use a textured reflector... It would be risky etching the dome, likely it would come off or kill the led.

RCatR, I'd think with just the dome removed it would be closer to 180* but the ring may block a little light. But then the die is exposed and may not last long.

hmmm. interesting! Since your led is screwed anyway, why dont you try it without the dome and see how long it lasts and what beam you get.

Let us know what happens to it

AlexGT

Yeah, the lens will come off if you push it too hard.

I know it will withstand 50G crash shock and not phase it (tested), and 1600 G's according to CREE's testing.

I've mounted the LED in a metal box and had people throw it at a wall, many times. The lens stays intact.

When you push or pull on it, you are *seriously* abusing the poor thing.

It is in fact glass.


I noticed what appears to be bubbles underneath the silicone gel in your LED. If this is in fact the case, the company that mounted the CREE to the MCPCB either didn't de-humidify the LED properly before reflow, or they overheated it. Not good, not good at all.

The adhesion of the lens can be quite compromised by improper use of pick and place machines, which would be used by the company that mounted the CREE LED to the MCPCB.

Newbie,
I read a post that to solder an XRE emmitter, you had to heat it in an oven for 24 hours. This was to dehumidify it. Is this true?
Mike

i would frost that glass dome with that product of which the name i can't remember, where some cpfers use to frost bulbs with.

then hopefully, the frosted dome will become a near 180 degree light emitting dome

talk about christmas and frosting...mmm...log cakes...(the irony is, i have never ate a log cake )

chesterqw said:

i would frost that glass dome with that product of which the name i can't remember. )

Click to expand...

Armour etch???

OK...I took the lens off the XR-E again to take some macro shots. Here it is after cleaning it up a bit.
From the side it does not look as though there is a shell and inner filling, and the center feels just as hard as the dome.
The ring around the edge where the adhesive was looks as though it may be a different material than the center, or it may be that it is all the same material but just smoothed at the edge for better adhesion....I can't tell, and i am putting it back in one piece as the LED still works.
While the lens was out though I took a shot of the die - just for interest.



I would have thought if it is glass and you managed to frost it, the light intensity would drop too much. :candle:

Colin.

Hi Ganp!

Can you put a regular reflector on that domeless CREE? I would like to see what the beam looks like say an IMS27 or similar. Anyone knows what life expectancy we could get with a domeless CREE?

BTW I did etch some bulbs and posted beam comparisons a few months back, if you try armour etch just be very careful and quick at removing it from the glass since it works very fast, it only takes seconds to etch some glass. I removed the cream with water which might not be suitable for the CREE, just food for tought.

https://www.candlepowerforums.com/threads/120285

Let us know how it goes and what kind of beam you get,

HTH
AlexGT

I don't want to frost my dome - I've only just cleaned it!


AlexGT - Hi...I'll have a go at using a reflector and a collimator with the domeless Cree (time permitting) and if it seems stable enough I'll take some beamshots as well.
I checked your link...nice work :goodjob:
Many years ago we used hydrofluoric acid to etch glass - making soft focus photo' filters...VERY NASTY STUFF...

If anyone really wants to frost their dome, just wiggle it around a bit and it will probably drop off like mine did!!!! Then you can frost it without damaging the die :ironic:

Colin.

Very cool - thanks for the nice pics

Will