4 emitters tested: Cree XP-E2, JR 3535, small die Nichia 219B, Luxeon Rebel lime colour

Four emitters were tested on direct-thermal-path MCPCB's, three white 3535 leds of comparable die size, and the new Rebel in the colour lime. Current, voltage and light output was measured using a laboratory power supply, a cooled copper mount and a home made integrating sphere (the set-up was as described in my XP-L tests):

A Cree XP-E2 R3 1D, obtained from illumn.com

A chinese 3535 size (XP footprint) cool white led branded 'JR' obtained from dx.com

A Nichia 219B 5700K led with a smaller xpe-size die, obtained from kaidomain.com

A Luxeon Rebel lime, obtained from domeanima.pt.

Unfortunately 2 out of four are currently unavailable from where I bought them, the JR led has simply disappeared from the dx.site (don't worry about that, the tint was a horrible angry blue white), the small die Nichia 219B is sold out at Kaidomain. But these tests do give an insight into some leds other than the (for flashlights) so common Cree.

First the three small die white leds. I tested an XP-E2 R3 1D before, but with a bit different set-up, so I included a new one in this test series for fair comparison.

*The XP-E2 measured a bit different from the last one I tested, the maximum output is a tiny bit higher, but the maximum output is reached at 2.1A now, with the other XP-E2 I tested that was 2.6A. I really wonder if more is the matter except that it was a different emitter (but from the same batch of four that I bought more than half a year ago). RaceR86 recently showed that there is at least a good variety in led voltages in equally spec'ed XM-L2's.

*The JR led is clearly the worst performer, the output is a bit less than the XP-E2, and also the Vf increases much faster with increasing current. You can direct drive it on a li-ion though no problem, freshly charged it will settle at about 2A.

*The Nichia performs very well compared to the XP-E2, although with a higher Vf. But there are two reasons why it still may not beat the XP-E2 as a high-surface-brightness-extreme-throw emitter: 1) the die is slightly larger than the XP-E2 (it does not look like that on the picture but the dome is shallower so optically the die sizes look equal), 2) Nichia's are a pain to dedome. I might have a go at dedoming and see how it performs. This small die 219B does also come in 90CRI btw, like its bigger die brother, and that would be a great small light emitter. I have not seen this 90CRI version for sale yet though.

The last tested emitter is the Luxeon Rebel in the new lime colour. This led is not a single colour led, like most colour leds, but is a phosfor-converted led ('PC-lime'). It uses a blue photon pump with a phosfor layer on top, like any white led. Looking at the spectrum through a grating it looks like even that the underlying led is a violet 405nm emitter btw, but that might be not true, have to look that up. Anyway, it is supposed to be a super-efficient led with a pretty broad spectrum going from cyan to red, but with a maximum output at ~560nm (not my graph):

Here is what measured:

The lime spectrum is pretty much in the range where the luxmeter in my integrating sphere gives almost correct lux-values, so the lumens will not be too far off. And it performs very well indeed, with 1100 lumen at 3.5A with a great low Vf it beats the XP-G2 (but not the XM-L2). The die size is a bit larger than the XP-G2, but it should make for a descent thrower emitter.

I had a C8 doing nothing so with some usual trouble I put the Rebel into it. Not greatly centered, but the beam was ok. Note that in the pictures the lime colour looks more like green, but in reality the colour is a beautiful lime :-)

I measured (NCR18650B, 2.85A tail current -no switch- on a Qlite RevA, but stock switch) 750 lumen OTF of the flashlight, with 38 klux at 1 meter throw :-) With some fine-tuning it could even be a bit better.

I doubt that dedoming (if at all succesful with Rebel leds) would yield a bigger throw, because in white leds the improved surface brightness of a dedomed led is caused by recycling of blue light that in second instance is converted by the phosfor, and in the lime Rebel all blue light is already converted by the phosfor in the first place.

Some pictures to show that the lime Rebel not only shows up the greens, but also some yellow and red, and even a bit towards the blues (again, on the photographs the lime looks more green than lime), the comparison light is a 3500K 80CRI Cree:

This is a fun flashlight :-) , possibly the only lime thrower flashlight in the world ?

Thanks for reading!

ORSM testing!

Thank you for sharing.

I am not sure I understood anything about that recycled blue light converted in dedomed white leds though. Could you elaborate some on that?

Is there a purpose for the lime (green) color? Other than it looking like a glow stick?

Either way, thanks for all the research…very cool!

Ah, you beat me to it; I have a single PC Lime emitter waiting to go into a SK58, and a triple — one lime and two PC ambers also waiting. The latter is to make an almost-no-blue-light with better color rendering to supplement the PC ambers we use at home at night. (the low/no-blue evening light is our cure for insomnia; YMMV on that issue)

IIRC this is the article you need: DrJones - Flashlight Optics - Dome, Dedoming and Throw

Thanks for posting this info djozz!

Thanks. Amazing effort. Its hard not to like the lime green.

TY wight

sorry I did not answer your question, I understand that DrJones' lecture made it more clear?

> dedoming (if at all succesful with Rebel leds)

I put four of the amber PC Rebel (10mm square boards) into SK68s and #3 zoomies.
One of the four I accidentally dedomed without even noticing it, probably a momentary shake of the soldering iron tip.

It came right off — found the dome later — and left a very clean emitting surface that zooms/floods a bit better than the domed ones.

Thanks Djozz. This thread slipped by me.

I gotta say. That is a lot of lime you got there. :D

Thanks for doing this great test. That Lime emitter looks really interesting!

Don’t you watch TV? These are used for hunting ghosts and bigfoot. :stuck_out_tongue:

Thanks Hank, this is good to know.

I’ve been a little hesitant to attempt dedomes with these somewhat pricey colored LEDs. Sounds worthwhile, although I’d be looking at deep/photo red right now and lime green, so it’s not exactly the same thing… but it sounds like the dome wasn’t really on there that securely from what you say.

Are you joking or do they really use lime green on the TV shows? I’m just curious. EDIT: for clarification I have not seen the TV shows, so I don’t know what it looks like. That’s why I’m asking!

Sometimes what one sees is from a camera using an NVD - Night Vision Device - which renders the captured colour a sort of greenish monochrome. It would not be said to be lime though.

I’ve edited my post to add clarification. I see now that I was really very unclear, sorry! I can recognize the footage you describe for what it is. I just thought that maybe powerful lime-green flashlights were in style for ghost hunters now or something. I have not seen those shows or previews or anything.

Nice review!

Here I added the XPE2 for comparison:

Thanks Djozz!!!

Love the comparisons!
So the NIchia is doing a pretty good job!?

Now looking forward to your new XPH test from intl.Outdoor.!!

It is said that if you had two objects (one red and one green) that appear to have equal brightness in daylight, at night the green one will appear much brighter.

Yes djozz. It did. I tend to forget enough of these things over time that I am unsure what was meant.