I wonder if I may have damaged the LES somehow. I used 70% alcohol to clean off flux. I wonder if that may have gotten on the LES and caused this issue?
I do not have a spare aspheric lens - maybe I should get one for this purpose.
I don’t think the LES will be damaged so easily. I think it’s more of a focal point problem. The height of each emitter is actually different, so the centering ring and emitter of the same package size should not be universal.
You can try changing the distance between the emitter and the reflector.
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Focal point problems can result in a hole in the middle of the beam, but only in extreme cases that noticeably affect beam profile, enough to make the entire hotspot/corona look misshapen, which does not appear to be the case here. Also, I would guess that the SFT25’s LES is large enough relative to the T3’s reflector that it would take a lot of displacement in height to cause focus issues, more than the height difference between any pair of common 3535 LEDs, domed or domeless.
I’ve previously had a sliced 219C in a T3 exhibiting the same issue, due to unevenly distributed phosphor. The solution was to deliberately adjust the reflector height so that it is out of focus (!), which mixes the beam slightly better than a perfectly in-focus setup. But doing so likely compromises throw, which is more or less the point of this LED.
Without an aspheric lens, maybe it would be possible to directly take an underexposed photo of the emitter on moonlight to check for surface variation? Or project the image of the die using a “pinhole camera” instead of aspheric lens. I am not sure whether cleaning residues can cause this issue; if so, I’d imagine that the damage would be readily visible even when the emitter is off.
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I stuck an F8 6500k SFT-25R@8A in a C8 host, I am very impressed with the throw, it does have the “green egg” hotspot, but it really doesn’t bother me.
I have a couple F9 5700k to try, and just ordered a couple F9 5000k, I am intrigued to see how they perform.
I used a round file on a 3030 centering ring to fit, the 3535 rings I have were too big for this emitter and fit way too loose.
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Even after changing to OP reflector, the center of the hotspot remains greener than the rest.
Congratulations! For my M21A mod, I also had to cut up a 3535 gasket and glue it into a 5050 gasket. The F9 5700k measurd 252,000cd. I curious how your F8 6500K performs!
Interesting, I did not had this type of beam in my test. Which SFT-25R did you bought and where? I have the suspicion that different batches from different vendors have different properties of the phosphor layer…
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The one with this issue is a F8 6500K from KD, installed in a T3.
The F9 5700K samples I have installed in a M21B and M21A are much better.
So different batches (I think from pre-production runs) give different results. That is good to know. If someone wants an LED which is more sophisticated it is better to wait for mass-production samples.
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Mine was also F8 6500k from KD
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If these arent in production yet how is it that wurkkos is selling the ts12 with sft25r as an option?
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It’s not that it’s not in production, it’s just that it’s not in mass production or is in the beta testing stage.
These emitters are in fact in production, but Luminus has not listed them on its website, calling them “preliminary products” and their datasheet are only available through dealers.
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I still suspected that your(@Intrepidus @14500 ) problem was caused by the focus, but after I touched the emitter in turbo with stick for some reason and it burned out and I got a blue SFT25, it seems that the phosphor is not so indestructible.
Maybe there was a problem with KD’s batch of samples during production or reflow or something. Also, there is obviously a black dot on the emitter in @Intrepidus ‘s photo. Could this be the problem?
hope you can try other samples to see if the problem can be solved.
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Could be just flux residue or something. But in any case, driving this LED with higher currents can likely cause damage to the phosphor layer due to this dark overheating spot.
The phosphor layer does not seem to be protected with some sort of protective layer. Perhaps the phosphor layer (or the silicone with these phosphor particles embedded in) became gel-like due to the high heat and was therefore extremely easy to smear.
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After seeing this photo I’m starting to suspect it might actually be a focus problem. Under optimal focus, the hotspot and corona should both be sharply defined, with the corona being about as thick as the diameter of the hotspot. This beamshot might not be the complete beam, but the hotspot seems to have a fuzzy boundary, and the corona is barely seen.
I might try sanding the bottom of the gasket by a few 0.1mm’s and see if it makes things better. Also these circular gaskets are terrible for precise centering.
I think the dot in the first photo was on the lens?
I have wondered if the hot spot issue couldn’t be related to focus, but it really doesn’t bother me.
This seems to be the case here. I hope they change this before mass-production.
This is what happened to my first sample that I tried cleaning with isopropyl alcohol after it developed some burn marks.
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I suspect now that I may have slightly damaged the phosphor layer by tapping the emitter while reflowing onto a MCPCB, trying to get rid of excess solder. Might this be plausible?
Curious enough to wake me up!
Will try a few variations…
Thanks for the heads-up!
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