my own XML2, XHP50.2 HI´s, not chemical dedomed, as good as XPL HI´s

I have done this long time ago with XHP70, and used only 1000 grit sandpaper to leave the surface little bit muddy and claen everything with isopropyl alcohol. Results are amazing in terms of throw and beam looks phenomenal.
Only downside is lumens lost up to 20%…

Great work Lexel !

Ok, i just tried it with XPL2 HD, i can confirm, it is harder then it looks.

You really have to have the good size shim and it would be nice if you have it from alu or another hard material, since the plastic convoy butterfly spacer which i used is too soft.

I (accidently) cut off the rim of the spacer and ended up quite low, but i managed to get a nice and clean cut. (Don’t know if there is any material left to sand it down to get it even flatter)
Do i see a bondwire over there ?

The result is good, but not what i hoped for, throw improved but it still shows the ugly yellow/greenish corona

Have to compare it with fresh charged cells against a XPL-HI to get real world results and see if it outthrows XPL-Hi

You need to remove all phosphor around the die to get rid of the yellow corona.

That would turn it into a blue corona and reduce the lumen output.

I think this is how skylumen do it too… he shave dome on sst40 lately and it doesnt turn out green. Output is great too. Here is his sst40 shave dome led.

You can keep a tiny layer, but practically speaking removing most of it will imrpove the beam quality.

Maybe cutting it away at an edge, say 45 degrees, makes for the best beam? Nice work Yokiami!

So Lexel when are you going to start offering the dedomed LEDs for sale?

I would like to see this done to Samsung LH351D as well…

why selling those?

all you need are 2 slightly different washer thickness one for cut and one for sanding
get 1500 and 5000 grit paper for 7$ from Ebay
and a razor blade

Interesting idea. Did you sand leds under water or dry? Did you measure the throw of the xhp 50.2?

Why sell ’em? Because we’re lazy maybe? A bit unsure of ourselves? Prefer your proven results over trying it with our own precious emitters? Some of us drink coffee, you know. Caffeine is not great for steadiness of hands.

the amount of domed emitters which usually get sliced
which I have in my box I can count on my fingers 5 XPL W2-2B
a few XML2
Nichia I would not really make sense to do it on high CRI which have a wonderful tint

I would do it on orders, but shipping time from China for emitters is slow and Mouser does only have good bins of XHP35HDs

Can you tell us what washer thickness did you use?

1mm and 1.2mm for XML

on Flip chip Emitters you could get closer to the phosphor, as they have no bond wires

I have a question. How about slicing the dome and then applying a thin layer of transparent lacquer? Like some modders do with dedomed emitters for the phosphorus protection. That would make the silicone surface smooth even without polishing. My only concern is whether there is any such a kind of lacquer that would not destroy the silicone. Is that even possible?

I wonder if that’s actually a good thing.
I read that manufacturers rough up surfaces to get a wider range of incidence angles and therefore improve extraction efficiency.
Maybe it would be best to polish only up to fairly-rough grit?

extraction efficiency is for the blue diode, to get the photons out of the semiconductor
Most LEDs have a perfectly shiney surface like XML2, XHP and XPL are textured to reduce the tint shift, but photon extraction has nothing to do with dome texture

On my C8F build with XP-L2s:
I shaved them, then sanded using 1500 grit, then when about 1.5mm away from the phosphorus layer (checked under my microscope), I THEN mounted these three shaved XP-L2s onto my Sofirn C8F build’s provided MCPCB. With the three LED on the MCPCB, I finally used Tarnex (silver polish) on my larger knife sharpening stone (fine diamond dusted metal sharpening stone). It took about six passes to “polish” the leds down to about 1/2mm from the phosphorous.

As I got closer to a fully sanded surface, the sanding slowed down and I had to keep rinsing the stone as the buildup from the leds would get between the led’s and stone. Took about 30 minutes total time: and the longer I went at it, the slower my rotations went. AND… the last pass, the Tarnex was on very liberally and the passes were very slow.

For me, the trick was to not go any faster than the leds (on the star, in the hand) would let me. If they started “jumping” up or “jittering” (or squeaking even)… time for a full stone rinse and NEW Tarnex. I found the MOST downward pressure was needed at the LAST pass. But when done, they led faces were like mirrors- very happy results!!!

I have an SST-40 I am pulling and shaving and will do this same process. Perhaps another agent (besides Tarnex) would work, but I found it to be very good for my LED shaving process. FWIW…