eds, I’m thinking life probably bit him in the arse. Divorced maybe, possible legal action as the wife sometimes likes to file charges to get him out of the house and then put a restraining order on him to leave her alone, in a case like that he’d have zero access to the goods and she might even toss it all in a dumpster out of spite. Perhaps he had an accident at work, fell and got hurt, was in the hospital, she might have done him like this while he was recovering, who knows. Life has a funny way, of sneaking up on ya when everything’s all right…
Edit: I should clarify, I have no information leading to this kind of statement. I’ve lived enough life to have had this kind of thing happen or seen it happen. I married my first wife twice, shame on me. Isn’t it ironic?
You will measure the lumen output? I am interested to see your results.
I did some testing of output and dome slicing on the XPG3 (haven’t posted any results yet) similar to the testing on the XPL V6 I performed. I agree with your thoughts above, that since the lumen output is even higher than the S4 2B and the die areas are similar, the XPG3 intensity or luminance should be very high. From people’s testing, however, the dedomed XPG3 does not perform well. I thought the only explanation was that the LED must lose a lot of output from dedoming, for whatever reason. But from my testing, after slicing as close as I could without hitting the phosphor, the output was ~81% of the initial domed output (@7A). This is not so bad a loss, so the luminance should still be very high. But when I tested it in a C8 I get similar unimpressive lux numbers as everyone else.
Same here, the G3 just doesn’t like to throw at all for whatever reason.
They are great little powerhouses for the price though, cheap enough to toss them in all those cheap ebay lights we all have laying around with a worry.
I don’t care about lumens, and I don’t have an integration sphere :C, I will only be measuring lux.
It’s obvious that an XP-G3 has more lumens from that graph.
The XPL-HI is pretty close to the XP-G3, I was able to get over 800kcd with an XP-L HI at 6A while the XP-G2 for over 900kcd at 6A (both with no collar)
So even though the XP-L HI has much larger die area (nearly 2x as much) it still almost got the same intensity as the XP-G2.
This gives me high hopes for the XP-G3 which has almost the same lumens as the XP-L HI with the die area of the XP-G2.
The question is, will dome shaving negate the higher lumen output of the XP-G3? FIND OUT IN THE NEXT EPISODE! xD
I’m definitely not happy with the status of this but I admit I’m not angry.
Looking at his other threads in other forums, he seems to float from hobby to hobby, sometimes taking months to get back to some forums. Hopefully he drifts back here eventually
From my testing dome shaving reduces output only by 20%, but the lux is still bad. Hence the mystery.
Regarding your aspheric light results, the XPG2 should be significantly more intense than the XPL HI. One explanation is that the focus was not perfect or the lens has defects. These things would have more of an effect with the smaller XPG2 die. For example if an area of the lens is slightly misshapen, it will refract light from a point close to the focus point but not directly at it. With the XPL HI in place the error might not be significant; it would still refract light coming from the die. But with the smaller XPG2 die the misshapen spot might miss the die completely.
You can test this by going to whatever distance you measured the lux from and looking directly into the lens (either at a very low setting or using Sun viewing glasses or something). The lens should look completely filled with light. If there are areas not filled with light this could explain the measurements.
@Enderman and EasyB,
I do not pretend to know exactly what is going on with dedoming and throw, but DrJones does a bit better, and in his lecture on the subject, he states that what is not happening is that the extra throw from dedoming comes from the smaller apparent die size (which comes with an altered emission profile as well, compensating the apparent smaller die), and what is happening is that the extra throw comes from photon recycling because photons at an angle can no longer escape from the die and are reflected back into the phosfor, which is excited and the new photon has a new chance of being emitted at an angle hitting the reflector/lens.
My own little theory is that the XP-G3 with its loose flaky phosfor lets the light escape well at all angles, wether it is dedomed/ sliced or not, so there’s no photon recycling taking place, so no extra surface brightness, no throw gains.
Easy, do you notice much, or any, tint shift in the sliced XP-G3 ?
Well, if that was true, then there would be no difference between domed and dedomed when using a wavien collar, no?
Also, my first hypothesis was that dedoming removes a layer of the new phosphor, but I read somewhere that there might actually be phosphor mixed INSIDE the dome material, which might be the reason it gets more lumens.
I also believe DrJones’ explanation, but do not completely understand it.
I think there really is additional mystery with the XPG3, though. With my measurement setup I can pretty directly measure the luminance of the LED since I’m measuring the luminous intensity (cd) above the LED and I can measure the die area. I have measured this for the dedomed XPL V6, dedomed new XPG2, and XHP35 HI, and the luminance values are pretty consistent with lux measurements done in flashlights (dividing the measured cd by the frontal reflector or lens area) after accounting for the 5-20% losses from the reflector/glass. These two measurements are essentially different ways of measuring the same thing, the die luminance.
For the XPG3, according to my measurements, there is an increase in luminance upon dedoming. Similar to the XPL V6 I measured, the output drops upon slicing some of the dome off, then goes back up when more of the dome is sliced. This indicates the luminance increased. In the end, the sliced output is about 80% of the domed output, which is not too bad a drop, and the calculated luminance is very high, higher than the dedomed new XPG2 (at typical direct drive currents). But when it’s put in a flashlight the effective luminance drops to about 50% of the expected value. So according to my bench test of the dedomed XPG3 it has a very high luminance and should be a great thrower, but something is causing the discrepancy between the bench test and the in-flashlight tests.
Unfortunately I was not paying attention to the tint in my tests.
The in-flashlight-test what you call ‘effective luminance’, is that measuring the throw?
The only route that the light can go in a flashlight that does not contribute effectively to throw is sideways. The deepest parts of a reflector does a very bad job at getting the light to the hotspot, and of course in an aspheric light that light goes nowhere at all.
So I assume then (and it makes sense too) that the sliced/dedomed XP-G3 has a different emission profile from the domed one, sending less light forward. But in the old style leds that were so good for throw the light will not escape to the side because of internal reflection at the edge of the die so despite the absence of a dome enough light is recycled and subsequently forced forward that throw is increased.
Yes, in-flashlight test is measuring the throw (cd).
DrJones light recycling explanation of the luminance increase seems to require the emission profile be significantly altered, as you are talking about. But the emission pattern of dedomed LEDs is just that of a lambertian surface, cos(theta). This is what I don’t understand about that explanation. The analogy to light recycling with a reflecting aperture (wavien) is incomplete; the emission pattern of an LED with a RA is obviously altered, but that of a dedomed LED is not. Looking at the cree datasheet for the XPL HD and HI, the emission patterns are slightly different, but both are very close to lambertian.
I expect the emission pattern of the dedomed XPG3 to also be lambertian.
