There has been some talk about this newest Luxeon because it has the 3535 footprint so it is a direct swap for xp-boards. Mouser started selling these about two weeks ago, so I borrowed my girl-friend's credit card (I do not own one, and she is a very kind and understanding person :-) ) and did my first (and only) Mouser order. Ordering from Mouser was even more expensive than I already thought because dutch taxes appeared to want their share as well :-( So no Mouser orders for me from now on.
But on to the led:
The test-led was a 5700K 70 CRI Luxeon Q . The die size is 1x1mm, placing this led in the 'xp-e category' , so I will directly be comparing this led to the XP-E2 R3. However, when the leds are visually compared, the LuxeonQ die appears larger than the XP-E2 (but smaller than XP-G). This is caused by the phosfors being further away from the die (part of the light comes from outside the die-area), this is because there is a transparant layer between the die and the phosfor, so a significant part of the light goes sideways. But perhaps also the optical properties of the dome plays a role. (picture shows xp-g top left, luxeonQ top right, xp-e2 bottom, very low current, actually in series so they see the same current)
the dies from above picture next to each other:
Close-up of the led showing how the light is going sideways as well:
If you can 'parallel' your eyes here's a stereo pair, for 3D vision.
The die from above shows quite a lot of blue, but when the led is illuminating things, the tint and colour reproduction is ok.
Of course what is most interesting for us flashaholics is the performance, so I did an output test, the same way as I did a few other led-tests before (which is: not overly precise but I'm confident that the general picture of the test is correct) . The led was reflowed onto a 16mm Sinkpad (mind that the performance at the higher currents on a traditional aluminium board will be poorer than I measure here) the board was mounted on an abundance of aluminium, a reflector placed on top and it was directly connected to my humble power supply. Current readings came from the power supply, voltage was measured over the (thick) led-wires by a DMM, ceiling-bounce lux-readings were converted to estimated lumens coming out of the reflector, so the numbers can actually almost be achieved in an actual flashlight. (the picture shows the reflector next to the led, during measuring, the reflector was placed over the the led).
For comparison I did the same test with a XP-E2 R3 (from IS) on a Sinkpad. I could have compared the results with the XP-E2 data from match, but I thought it would compare easier (and fairer) if I compared them with the same set-up. The XP-E2 results I got compare quite well to match's results by the way (the lumens that I measure are less because I do not measure bare led lumens in a integrating sphere like match, but out-the-reflector lumens, so there's been already a light loss there)
Here are the results of the LuxeonQ and XP-E2 measurements:
Observations:
-the output of the LuxeonQ up to 1.6A is very similar (a bit lower) to the XP-E2, but is much better at higher currents, peaking at about 4A, the thermal management of the 1x1mm die is excellent! But the performance is significantly less than a XP-G2 (see my XP-G2 data from a few months ago). So everything, 'virtual' die size and output, is a bit in between XP-G2 and XP-E2.
-the led voltage is low, lower than both the xp-g2 and xp-e2 at 3A, and also climbing slower than the xp-g2. So the led is easily regulated at all currents with 7135 current regulators and a single li-ion.
-although already far above the current with maximum output, the LuxeonQ survived 6.1A without noticable damage. The XP-E2 died at 5A, only very little output was suddenly leftover and a gloomy dark spot appeared in the beam on the ceiling. The bond wires were intact, but the die only conducted very little current with hardly any output and showing dark areas:
Conclusion sofar is that the Luxeon Z has a output performance in between the XP-E2 and the XP-G2, but because the virtual die-size is also in between those, it does not outperform them, at least not much.
This would change however, if the LuxeonQ can be dedomed and have its superior performance over the XP-E2 straight from its 1x1mm bare die (the luminance of the die at 4 amps should be unsurpassed). That way it could significantly outperform both the XP-E2 and XP-G2 in throwing capability 
.
So off I went trying to dedome the thing. First I tried the gasoline method, because that is the most common way to dedome (at least here at BLF :-) ). I used petroleumether, but that does the same as gasoline. Pictures at 0 hours, 6 hours and 30 hours (that does not look right 
):
So at this point I pried the dome off with tweezers. Here's the carnage in 3D:
One led down :-(
I usually do hot dedoming, but as you can see, it looks like the phosfor is embedded in the silicone, so I would not expect the result to be different.
So there was only one method leftover: slicing the dome off with a razor blade, I used a paperclip placed around the led as a guidance and spacer for the blade (the paperclip had the right thickness to leave a very small layer of silicone (0.2mm?) over the die and slice the top off the dome. I had one C8-pill leftover so I reflowed the led board in there, with a qlite driver (3.04A worth of 7135 regulators).
I put the pill into my Uniquefire UF-T20 aspheric, that does 108klux at 1meter with a dedomed XP-G2 on a qlite. I measured the throw, and ouch , only 55 klux at 1 meter, and what an ugly hotspot (in contrast, the beam from the LuxeonQ in a reflector light is very nice):
I expected a lot of light reflected to the side without being reflected back into the phosfor, so I decided to slice the dome back further, just into the phosfor area, to do this I sanded the paperclip a bit thinner and sliced another bit off the dome, this time with a scalpel (because the led-board was soldered in already I could not use the razor blade):
And the result: exactly the same ugly hotspot, and 66klux at 1 meter. It hardly improved.
At this point I believe there is no way you can improve the throw of the LuxeonQ much with any of the available dedome tricks.
Conclusion of these tests:
In my opinion the Luxeon Q is interesting for flashlight use because it performs as well as the newest Cree's with a slightly different die size that could be just what you need. I have not checked, but because of the bit fuzzy light I expect a nice smooth beam, even using a smooth reflector. But new breakthroughs in throw it will not give because dedoming does not work.
And now for the unexpected giveaway for anyone who endured to read up to this point (a fun new custom at BLF :-) ) : I have 5 bare LuxeonQ 5700K leds leftover (no boards!), and will send them free (worldwide, no tracking, just in a plain letter) to 5 enthousiasts for this led who respond to this thread. If more than 5 people want one, I will do a random.org thing to pick out the lucky receivers.
Thanks for reading!
I love BLF’s new hidden giveaway custom. Keeps the riff raff at bay?
I could use another interesting led so please count me in!
(thermal conducitivity is sky high compared to alumina).