I’m looking for an alternative to dedoming. Dedoming seems to damage some LED’s or reduce output. Can domes be cut to leave just a thin layer remaining? I’ve been looking but can’t seem to find anyone who tried. Specifically I’m looking to do a triple XP-L and then use Carclo optics.
I thought this was the popular approach before gas or hot de-doming was discovered/invented. Very hard to get an optically clear cut, IIRC, never tried it myself, though.
I have tried it
Quote
“I would also highly recommend using the thinnest, sharpest razor blade you can find, I broke open a new gillette razor to salvage a blade to do the mod, and cutted the dome in a single straight push cut, the remaining silicon looks very clear and shinny, no need to polish…”
i’ve read a few posts of gasoline dedoming and using led seal spray afterward
Thanks, that was the thread I needed. I want to cut then polish the remaining dome. All to properly fit a Carclo triple. I never really got comfortable completely dedoming. Worried about loss of Phosphorus or degrade over time.
I’m also interested in fitting XP-Ls into a Carlco optic without de-doming (well, without the tint shift anyway). Could you let us know how it goes, and if/how it changes the tint?
Yes I will. I’m a quad and triple junkie and this project has been back burner for too long.
FWIW: There is still some tint shift when cutting the dome as far as I remember.
And you can't polish silicone. It ends up diffused. That is, if you get lucky and don't knock it off and break the bond wires. ;)
Ask me how I know...
I have a 4000 grit Black Arkansas stone. Was hoping that I could polish all three LED’s at once with very light pressure.
It would probably be approximately like trying to polish partially-dehydrated jello.
Or silicone calk…
I’ve cut lots of domes. I cut the dome as close to the die as possible on all my test bench emitters (to make it less blinding). You can make the cut fairly smooth but your not going to be doing any sort of polishing afterwards. It’s not like the consistency of the top of the dome anymore that’s nice and shiny, it’s still really clear (if you cut in a single motion with a SHARP blade) but it’s not glossy like an unaltered dome.
I’ve repaired domes that I scuffed with a drop of clear coat.
I’ve also buffed them - plastic polish works well.
I’m too cheap to buy LED seal.
I’ve built a handful of little triple xp-l lights over the past few months using the carclo optics. I’ve done the hot dedome (both unintentionally when flowing leds, and intentionally with a razor to lift the dome off while it’s hot) a few times. And I just sliced my first dome (an mt-g2) approximately 20 minutes ago.
Personally, I’m a fan of the gas dedoming - especially for triple xp-l’s when you’ve got three of them flowed onto an mcpcb already. You don’t want to mess one of them up during dedoming and have to reflow just one of the three. For me, at least, gas dedoming is significantly more fool-proof.
Check the leds with a power source to confirm they’re all working, then dump them in some gasoline for a few hours. Carefully remove them and rinse everything off with some isopropyl alcohol when they’re all dedomed and let them air-dry. Then rock and roll. I haven’t used led seal enough to say definitively how big of a difference it makes - though it seems pretty clear that it’d make the leds much less delicate. Don’t want to knock one of those bond wires accidentally and have to reflow one.
Yes there is a pretty significant tint shift (though I understand that’s going to be the case regardless of which method you go with). I’ve found the tint of dedomed V5 2A’s to be fairly good. Some end up with a green tint, but overall they seem less green than most of the XM-L2 1A’s that I’ve dedomed. Like any, it’s something of a lottery, but on average the dedomed tint on XP-L V5 2A’s seems to be fairly neutral.
There’s also another thread on here showing some tests with XM-L2’s and XP-L’s comparing light output both before and after dedoming, and the XP-L’s don’t seem to lose much output at all after dedoming (unlike the XM-L2, which loses something like 10-15%).
I wondered about this and thought maybe one could make a jig from 2 stacked centering discs and make the cut under alcohol to lube the blade.
Microtome cuts are often done with glass knives. Just an idea…