Hereās some attempted beamshots of the standard Trustfire Mini-01 vs the de-domed mini-01. Both are on a fresh AW IMR16340.
Standard Mini-01
De-domed
Standard Mini-01
De-domed
Thanks HAL so I donāt have to repeat myselfā¦.
I think you have one chance to get a smooth surgical precise, parallel to the emitter cut with the sharpest, thinnest razor blade. Maybe oil the blade before the cut too.
The issue of color separation on the XM-L is well covered in this thread on CPF:
long story short, the light emitted straight out the top travels through less phosphor than that emitted at oblique angles.
It appears from the evidence that de-doming increases the amount of scattered light, and reduces the light āfocusedā forward by the dome, thus increasing the amount of light focused by the reflector into the hot spot. Makes sense.
From my de-domed mule light, the color separation problems are improved. Not sure why that is; more diffusion mixing the light from what is left of the dome perhaps.
I want to cut my XM-L dome but donāt have a razor. Will a butter knife work? If not, I think I have a piece of a brick around somewhere that is pretty sharp. Could just throwing the emitter at something sharp like a rosebush work? Yeah, probably. Thatād what I will do. Iāll let you know what happens.
Thank you, HAL and LowLumen. You both have cleared up most of my confusion.
Matt, nice job with the Mini-01!!! Looks great. Now, if only I had more than just one, Iād attempt the de-doming as well. 
Man, I am still so tempted.
As HAL mentioned, a Dremel works well to polish - start with a hard polishing tip, careful not to grind it down too much, then finish off with a felt wheel or tip. At least this worked for me. I donāt have a tiny razor blade, and made my initial slice with a very small pocket knife blade. This cut was parallel and done carefully, but it wasnāt as smooth as it could have been. This, I believe, doesnāt matter so much if you are going to finish and lightly grind/polish with a dremel. I corrected the imperfection of my first cut with the dremel actions.
Also, as an extreme de-doming noob, I find it important to suggest that with the Cree XM-L, the emitter wires could be protruding further up into the dome on some of our LEDs. This would explain why it works for some so well, and not so well for others. I started with a slice of only 50% of the original dome removed, and obviously missed any wires, which gave me a little more room for polishing. It makes me wonder if we can accurately assess the depth our cut should be by very closely examining our LED from a side angle. I donāt have a magnifying glass or anything, and my 41 year old eyes are having trouble spotting emitter wires arching up into the dome of any of the LEDs that Iāve examined in the last ten minutes.
Also I wanted to note, again as an extreme de-doming noob, that I did mine on an under-driven drop-in. The results are impressive, but still not as great as it could be on a well-driven emitter. I just managed to improve on an otherwise crappy drop-in.
Thanks Jaffo
See post 31 here for more beamshot comparisons Olight S10 Baton & S10-Ti
Once i had polished the dome down to about 0.5mm with the dremel, i held the pill and rubbed it against a glasses cleaning cloth to give it a final polishing.
Cheers
Matt
Rosebush was a dud. It didnāt even scratch the dome. Those thorns sure are sharp but I guess not sharp enough. Any other ideas?
I once stepped on a rusty nail. It went right through my shoe! Ouch! I just donāt know how that can be applied to this particular conundrum we are having. I feel I am close. Sharp does seem to equal cutting or stabbing from my empirical observations and my a posteriori experience.
The Cree XM-L spec sheet gives some useful critical dimensions: (Ā± .13mm)
The die is .73mm tall, dome + die is 3.02mm.
Allow for some thickness of the solder bond, and leave some dome to save the bonding wires. (itās not much here as mine is so close and somehow spared the bonding wires.)
Select a spacer washer thickness for the blade as guide. I think you can still get straight razor blades at most drug stores. This job can be done with a simple jig and work to surgical precision.
That is not evident at all from the page you cite, which only repeats whatās already been mentioned here. We know as basic fact that the dome has index>1 and concentrates the light. Itās not clear why a slightly wider beam collimates significantly despite same exit aperture. It was a guess that the shape of reflectors (simple parabolic?) is somehow more optimized (and by optimized I mean not bother to optimize at all) to a point source, and for whatever reason focus a flat emitter better than the beam out of the domed lens. Itās also entirely possible several factors combined, like reduced thickness of an optically imperfect material.
Are you drunk or something?? im seeing completely off topic posts all over from youā¦ā¦.
The reference on CPF was about XM-L color separation only, not the focus issues.
āIt appears from the evidence that de-doming increases the amount of scattered light, and reduces the light āfocusedā forward by the dome, thus increasing the amount of light focused by the reflector into the hot spot. Makes sense.ā
The only āevidenceā from your post is some guy did the sim in optics SW in that thread, so now Iām confused what other evidence youāre talking about.
Itās on topic. I am just attempting to find a suitable alternative method to de-dome a XM-L emitter for the masses. Not everyone has free access to high tech instruments like razors so I thought I would do the grunt work of theorizing a surrogate approach.
By using a butter knifeā¦ a brick or a rosebush hmmm
Agenthex, isnāt this pretty much exactly what youāve been trying to tell me de-doming does? I just got done confirming this in my head with further reading and more posting from you guys.
I am likely to accept further āevidenceā to be what I experience myself after I successfully de-dome an LED. It kinda appears to be whatās going on here.
Yeah, I donāt know why I thought a butter knife would work. That was silly.
That link only re-affirms whatās been said on the subject of color/tint. If you look at the prior wiki link, the question of how a simple change in geometry significantly increase collimation isnāt so simple without some knowledge of how these reflectors are actually designed (or ill-designed).
I am on the fence to do this, might try it with my UF2100 and see what happens, will a 1A tint shift to something warmer like a 1C or 2B?
ILFL, Did you connect a battery directly to the led? Mine had a cracked solder at the negative side of the mpcb, resoldering fixed the problem.
And a rosebush wasn't? To prove you aren't drunk tell me what this says.
I cut the silicone off right around the edges. Maybe I got to close to the led.