We do not force MEM to reveal his secrets of dedoming, but an actual throw comparison with some real numbers would definitely bring some light into the whole discussion. And since he is obviously the only one who has succesfully dedomed an xp-g3, his input would be appreciated
I just dunked one into a gasoline, wish me luck (Stuff that I use takes 24-36 hrs to do the job and even after that time the dome will not fall off by itself but if I budge it a bit it will leave nice and clean LED die, at least with XM-L2/XP-G2)…
I wasn’t meaning to insinuate asking was wrong, it was just a strange way to posit the request, but again, that’s just my opinion.
It’s obvious that both MEM and djozz have a firm grasp of the behavior of LED’s and the physics involved, so with the limited data points we have at this time its probably a little premature to make sweeping assumptions one way or another. A test of two emitters, both prepped the same way, used in the same host with the same parameters would be really beneficial in determining if the new XP-G3 is going to perform as well as the older XP-G2.
djozz - Excellent work, once again! Love it!! Also, lot of things look'n good for the XP-G3. De-doming is still yet to be determined, but doesn't look promising for us laymen modders.
I did not ask him to reveal de doming secret but to reveal results in XP-G3 vs OLD (not new) XP-G2 S4 2B de domed battle. Is this also a secret? Don’t make me laugh
Djozz already did such test(only with sliced XP-G3) with B158 host and he got about 50% lower performance than with de domed old type xp-g2 s4 2b.
Well known variables are that de domed vs sliced emitter should have maximum 20% better performance over sliced so properly de domed G3 will still not be able to reach OLD xp-g2 s4 2b. He could reach and have better performance than new production s4 2b but it will never reach old S4 2B. Learn difference between new and old production process xp-g2-s4 2b emitters(Gaston01, other guys and myself learned that on a hard way).
Real variables would be :
- de domed g3 v de domed OLD production type XP-G2 S4 2B(cause that emitter was king of throw until Cree messed it with new production process XP-G2 S4 2B)
- same host
- same driver
- same battery
same lux meter(and it does not have to be super accurate to tell % difference between them)
Djozz did all that with B158 host only with sliced G3 and not de domed one. Add max 20% gain on de domed one and it will still not reach it.
I would really like that G3 or any other new emitter could have same or better throwing potential than old production XP-G2 S4 2B emitter and I am among the first one that would buy larger quantities of it.
I still need to see (or experience) this to believe it… I believe the ‘old’ XP-G2 S4s are still the Throw King, by far.
PS: I’m also worried about the beam profile of the XP-G3s. To me, it does not look promising. And, the other caveat, as we all know, to have this LED properly dedomed, we’ll have to send them to MEM for some ‘special’ attention. Yep MEM, you’re probably smiling while reading this…
I’m just combining some information I gathered from being here for a while, I do not know the exact physics behind it (I’m a biologist, in led physics just a BLF-amateur, i.e. DrJones knows better than me what happens to photons).
*The Cree leds used to have a very smooth phosfor layer and showed a lot of tint shift and gained a lot of illuminance upon dedoming
*I have had Luxeon Q leds, Oslon Square leds, Nichia leds that all have rougher phosfor layers. I dedomed or sliced them all and the illuminance never became anything impressive. The tint shift was also less (qualitative observation).
*The latest XP-G2 and XP-G3 have a rough phosfor layer and thusfar the throw after dedoming them seems less than impressive.
The source of improved illuminance upon dedoming (following DrJones’ explanation from back in 2012) is that after passing the phosfor layer, remaining blue photons that are leaving the phosfor layer at high angles are reflected back into the die and have another chance of being absorbed by the phosfor and then emitted at increased wavelength (and thus luxvalue) and at a perhaps lower angle that will escape the die, thus adding to the illuminance and causing a tint shift away from blue.
What if the outer edge of rougher phosfor without silicon dome, that has less surface area parallel to the die surface than a smooth layer of phosfor (this is entirely my own assumption), shows much less internal reflection in the first place, so even without dome the light at high angle can escape anyway? Then less photons are ‘recycled’ (is this word also patented by Wavien? ), and illuminance and tint shift are less increased. So less throw.
That’s certainly a possibility I suppose. The thickness of the phosphor on the edges could also play a role as well, but that’s only a guess on my part.
Either way, unfortunately, I guess there’s not much we as end users can do about it one way or another.
Thanks again for taking the time to do the testing.
well, 2 days after, this is the result: (Dome was swollen and separated at the edges of the emitter and, as you can see, some of the phosphor left on the dome, also some of the silicone from the dome left stuck on the entire die, usually, after this time die is left nice and clean with XP-G2 or XM-L2, I just have to clean silicone around the die and it’s nice and slick but with XP-G3 … well you can see, I would call it a fail and I have siriuos doubts that “diluted” this or that actuall works as stated by MEM.)
I did few quick tests, just connected some batteries directly to this leds and observed current draw
Sirius, you do know that the square in the middle is the die, right? That phosphor around the edge doesn’t even matter. You can probably just scrape it back to get straight edges again and it will be fine.
