Yes, I measured the bare die luminance of the 219C and observed the in-flashlight results were much less. This was before I discovered this stray light effect in my investigation of the XPG3, so I didn’t understand the discrepancy then. But if you look at the dedomed 219C the white area around the die is significantly lit.
In my led surgeries it appeared that the 219C is different from the old Cree leds like XP-G2 in that the phosfor is not a compact rigid layer right on top of the light emitting surface, but a layer of phosfor mixed silicone that is inside a white-coloured shallow square cup surrounding the die. On top of that I assume that it is a flip chip design so the light does not enter the phosfor containing layer directly, but passes the die base first.
Thanks, I used your numbers to determine the luminance of the 219C D240 (R9050) shaved at 2A: 41.8cd/mm^2. With 12 of these and
UCLp lens the Meteor should do 34kcd. Thats not too bad. The 219Bs do 20kcd with dome and are probably similar without. I really like the beam profile and throw, but higher efficiency would be really nice (especially less heat!).
Using your calculations I get peak 154 cd/lm for D320.
Assuming current-handling of 219D is the same (yes, I know how good this assumption is), it should do 210 cd/lm 195 cd/lm in D340 bin. This number may be way off, but I believe 219D is worth testing.
Is that taking into account the clear aperture of the lens?
Lenses usually have 95% CA, or even less for cheaper quality ones.
The outside circumference is not very aspherical and therefore may not contribute to the lux in the spot.
The best way of being sure is putting a circle of paper or metal in front of the lens which has a smaller diameter than the lens, in order to ensure you’re only calculating lux and area for the clear aperture.
Based on looking into the front of the lens from a distance, nearly the full 62mm diameter is active. This area estimation seems to give a consistent measure of the dedomed xpg2 luminance at 510Kcd at 4ish amps.
I assume that “luminous intensity” is the cd measured directly above the LED. That does not necessarily indicate a higher die luminance. The fact that the 219c and 219d have different proportionalities between the intensity and lumen output means they have different emission patterns, which is supported by their different quoted “directivity” angles in the links above. So the 219d simply has a different shaped dome which directs more light forward.
Also your estimated luminance of 154cd/mm^2 for the 219c d320 seems high. My measurement in the UF1504 puts the effective luminance at 100cd/mm^2 at 5.5A. Assuming 90% lens transmission that is 111cd/mm^2 die luminance. And according to Texas ace’s test of this LED the max output is only 5% greater than the output at 5.5A.
I updated the luminance values for all LEDs shown in the test chart in first post, including SYNIOS DMLQ31.SG!
To ensure more realistic values for 'real-life' conditions (flashlight use / secondary optics) I established a new testing method to determine the luminance with a SMO reflector. All upcoming and already existing tests will use this method!
Updating of my other tests will be done in the next hours / days.
The SYNIOS are still very nice LEDs with high luminance (at max current 195.0 cd/mm²), but at much lower current as other known LEDs (Black Flat, XP-G2 S4 dd).
I’m doing some calculations…
All flat LEDs, emitting light only on the top surface should have the same cd/lm.
I compared several of koef3 tests and found:
Dedomed Luminus SST-40 does 0.324 cd / lm
Cree XHP 35 HI E2 does 0.318 cd / lm
Blackie does 0.294 cd / lm
Cree XHP 35 HI C4 does 0.293 cd / lm
About 10% variance, not bad.
But now let’s do the same calculations for Synios P2720 DMLQ31.SG. Result? 0.213 cd / lm.
Can anyone explain that?
ADDED:
If I get wiki right, the correct result is 1/π cd/lm or 0.318 cd/lm. So all LEDs other than Synios are within 8% of it.
ADDED:
So if this LED delivers as many lumens as it was measured to - it should do about 292 cd/lm².
Your test without reflector has shown 295 cd/mm²……what’s up?
I think you might be overestimating the accuracy of optical measurements. koef3 goes to a lot of effort to increase it, but there are practical limits.
That’s 33% too low. When all 4 others are within 8% of the expected result.
No, I don’t think this is a measurement error. Or even several, adding up.
I think the emitter doesn’t do what we expect or there’s some error in the method.