Reducing the metal ring of a CREE led?

Can the metal ring around the glass of a CREE led be filed down? I was wondering if this can be done to get more lambertian light dispersion even if its only 5-10 degrees more of light it would probably improve throw.

Credit for pic goes to kryosphinx, who posted here
http://candlepowerforums.com/vb/showthread.php?t=128311&page=3

Thanks!
AlexGT

I believe the beam distribution is dictated by the silicone goo and glass lens itself. I believe modifying the package will be detrimental to the health of the LED with no gain or benefit in light distribution. :shrug: I have an early preproduction part that was weak on dome retention and the dome got knocked off. Flux suffered and I don't recall any noticible change in the distribution of light itself.

AlexGT said:

Can the metal ring around the glass of a CREE led be filed down?

Click to expand...

Well this new member from Germany did, to mod a Fenix with a Cree.

Have a look. Very small and fiddly work

Post

It looks to me that it was done purely to get everything to fit not for
optimizing beam etc.

Yeah, I doubt you could remove the metal and still have the led protected. The metal is part of the thing that holds the silicone in.

I do agree though that if the metal encasing wasn't so tall, or the die so low, that more side light might get out...

Doubtful it would change the distribution as desired, the Lambertian pattern is dictated solely by the dome shape, and the part that has most effect is higher than the surrounding ring. In other words, the light coming out near the base is negligible at best.
The dome almost certainly employs internal reflection to direct the light upwards, optimizing the lambertian pattern. Any scuffs/mods to the bottom would be detrimental, and cause light output to DROP, not improve, so any attempt to reduce the ring height at best will have no effect, but is actually nearly certain to reduce your output if any scuffing occurs (maybe not a noticeable amount)
If you have the Cree already, light it up in the "open" and put a sheet of paper beside the emitter an inch or two away, and you'll see that little to no light is coming out "sideways".

If they raised the die height a lot then it wouldn't have the 75 degree beam it has...

I got mine today, looks like the die is mounted on top of the square base along with the gell and metal ring and all?!? Quite interesting. I would not handle it by the dome/ring.

But unlike a luxeon, prying this off if you used thermal epoxy should be easier by prying on the square base since that's solid and not hidden under a plastic case like a luxeon. So that's good news when you want to upgrade to a better bin or different led, as you should be able to re-use the led for something else!

Why would CREE want to go and do a different die height if they would like to compete against Lumileds? All reflectors and optics are designed mostly around lumileds, wouldn't it be easier for gaining market to have lambertian emmision instead of the 70 degree emmision? What were they thinking????

Do you think if we do an email campaign or letter campaign they would introduce a lambertian model? Maybe convince manufacturers to write them too!

AlexGT

Perhaps patent issues?

Perhaps that is also why their phospur isn't just on the die, but still sprayed everywhere (bond wires/etc).

And perhaps Cree want's to use optics, and more light forward, the better for an optic. I don't know any led manufactor that offers reflectors, only optics for their leds..

AlexGT said:

Do you think if we do an email campaign or letter campaign they would introduce a lambertian model?
AlexGT

Click to expand...

No.

Most manufacturers design their own custom reflectors/optics anyhow, the majority of times.

It is just a pain for the hobbyist.

Give it time, it took years before reflectors were out that were suitable for the Luxeon, in the beginning, it was all optics.

It may be, that the dispersion pattern found on the XR-E is part of what makes it's light extraction so efficient, or it is a natural byproduct of the changes they used to extract so much light.


There are a number of reasons why I definitely prefer this distribution, personally.


Oh yeah, I was thinking something about teaching the old dogs on cpf new tricks or something along those lines, or was it something like pulling people out of a rut...

dunno

I asked about the necessity of the narrow viewing angle and was told by a fellow at Cree that the part does what it does and as well as it does it with a result of the distribution pattern it has. This is not just an arbitrary aspect.

I agree with Newbie that there are some advantages to this distribution pattern and the secret is to work with a new part and not try to limit it to that which we have become familiar with. :shrug:

Keep in mind that unlike Lumileds, this XR-E die will be used by other packagers and perhaps we will see a more Lambertian pattern from one of them.

That metal ring just pops off... trust me is very easy... It happened to me.
It's nice that the half sphere is actually glass instead of lumiled's plastic!

Anyone know what the retangle base is made of? Almost looks like pcb material, with silver plating stuff with holes like the SS's cree on board stuff??!?

I believe the base is ceramic. When I ground the board I soldered the LED to into a circle shape to fit it in the E1, I also had to grind away about 0.5mm of the edges of the LED base. This material was much harder to grind than pcb material, so I conclude its ceramic.

Oh, before I forget: I also read elsewhere in this forum that it is ceramic

Cheers,

Julez

Seems like it is ceramic as the only tool I have that will cut/grind it is diamond.

I was thinking it could be ceramic too, but didn't get rough with it to see yet.. thanks for the info.