LH351D 90CRI Spectrum Tests

Here’s the Convoy 5700K sliced in Wurkkos FC11 (shallow light OP reflector, plain lens, on high):

Good for a day time use light since your eyes are adjusted to >5000K ambient above BBL light already.

Not bad at all.

If anyone is curious what these look like under a TIR with all the phosphor removed:

450nm and 25000K CCT (if that is even a thing, I guess it is technically.)

Is this the color we saw on the first power LEDs? We all had those Ledlensers and fakes on our keychains. Stable fluorophores had yet to be found I guess. I remember, when I was in microscopy, fluorochroms had really little photon staticstics like 60000 for this green substance whose name I forgot. You could watch them fading. Or is this a completely different story?

No it’s distinctly solid blue. More like a fake UV or “blacklight” I guess but very “visible”

UltraTac A7P w/ no phosphor LHD and Sofirn C01R

A diy monochromatic blue LED. How did you get the phosphor off?

I think the old Ledlenser Photonenpumpe also was just blue.

You know, the usual. Force it into a too small TIR with a mediocre centering ring and keep tightening. It ripped it off nicely in one piece and I scraped with tweezers what tiny little bit was left.

SST-20 JA3 2700K tested with differents type lens

I sliced two Sofirn sourced 2700K and it lowered the CCT quite a bit :

CCT = 2369K (Duv –0.0014) (Ra) = 95.9 [ R9 = 72.9 ]

This is in a Sofirn IF25 at lowish output (2 LEDs at 50~100lm or something).

This is great because this is exactly what I wanted, a very warm 3535 LED with high CRI, which apparently doesn’t exist.

In the same flashlight (it’s a tint ramping light) I got Convoy sourced 5000K, also sliced :

CCT = 3877K (Duv –0.0004) 93.5 [ R9 = 60.2 ]

I’m surprised of how much the CCT was reduced compared to yours, in your FC11 it reduced to 4500K. In this case 4500K kind of was what I was aiming at for the max CCT in this light, I should probably have gone with the 5700K instead.

The TIR in IF25 is quite a bit larger I think than the C01S and C01S is very low output so I suspect those 2 things can cause different results.

As far as the Convoy 5K goes did you measure it before the slice? I assume it’s under 5000K slightly since it’s R2 bin.

This was measured at a pretty low output, here is turbo (should be around 3~4A per LED) : CCT = 2437K (Duv –0.0021) (Ra) = 94.0 [ R9 = 65.5 ], and lowest : CCT = 2357K (Duv –0.0013) (Ra) = 96.0 [ R9 = 73.3 ]

I didn’t measure the 5000Ks before slicing them but I’ll put one in another light so I’ll do it now.

5000K from Convoy (bin F2R2S2) with beaded TIR :

100 mA CCT = 4693K (Duv 0.0019) (Ra) = 93.4 [ R9 = 62.4 ] IES TM-30-15 Rf = 90.42 Rg = 98.89

1A CCT = 4729K (Duv 0.0026) (Ra) = 92.0 [ R9 = 56.2 ] IES TM-30-15 Rf = 90.17 Rg = 98.87

sliced with beaded TIR:

100mA CCT = 3651K (Duv –0.0016) (Ra) = 93.8 [ R9 = 60.9 ] IES TM-30-15 Rf = 90.88 Rg = 100.11

1A CCT = 3777K (Duv –0.0012) (Ra) = 92.6 [ R9 = 55.9 ] IES TM-30-15 Rf = 90.28 Rg = 100.13

The duv increase at higher current is strange, same behavior in the IF25 I modded with the 5000K leds (the 2700Ks have the classic current up -> duv down), so there is a middle tint point where the duv doesn’t move at all with current changes. The 5000K LH351D in my Wurkkos FC 11 behaves normally ( current up -> duv down)

I suspect that “mid point” correlates to the non-linear shape of the BBL?

Edit; and the Convoy LED being closer to 4700K than 5000K makes total sense. It still only changed by ~1000K CCT it just started out much lower than you probably thought.

The tint mixes in a straight line :

(disregards the black dot, I don’t know how to display several measurements in Osram colorcalculator without doing the tint mix calculation :person_facepalming: )

“mid point” wasn’t really the right word, but at around 2800K the duv doesn’t change with current, under that it goes down with current (behavior of the 2700K lh351d from Sofirn), above it goes up with current (behavior of the 5000K lh351d from Convoy)

I was under the impression that 1000 CCT was still quite a lot ? Maybe it’s because I sliced it very low ?

Here is the point I was trying to make and it’s just a hunch I do not know enough to be sure this is even true:

Lets say as we increase current it always makes this same slant (yes I oversimplified it). At some point our slant starts to become parallel with BBL at higher CCT so we will no longer have the change in Duv since Duv is fixed to BBL while at lower temps it is almost perpendicular to BBL.

Ah ok I understand, here are the 2 leds in the IF25, at lowish, midish and turbo :


(forgot to add the output on it, but higher CCT means higher output, and again please ignore the black dots and lines)

So indeed the inclination between the two is similar, and for the higher CCT one it crosses the BBL, since the tint shift is not very angled in the first place for LH351Ds. (I’m not sure those are the right words, English isn’t my first language)

Aside from that, I was curious about the effect on tint depending how low the slicing is, this is with the LED from the wurkkos FC11, with the same beaded TIR as previously :

Original :

0.1A CCT = 4769K (Duv 0.0058) (Ra) = 91.2 [ R9 = 51.0 ]
0.5A CCT = 4826K (Duv 0.0061) (Ra) = 90.5 [ R9 = 48.2 ]
1A CCT = 4875K (Duv 0.0059) (Ra) = 90.2 [ R9 = 46.4 ]
2A CCT = 4917K (Duv 0.0055) (Ra) = 89.7 [ R9 = 43.9 ]

(so actually even with this bin the duv doesn’t decrease a lot, even goes up a bit at 0.5A

Washer thickness of 1.52mm :

0.1A CCT = 4544K (Duv 0.0050) (Ra) = 91.4 [ R9 = 51.6 ]
0.5A CCT = 4605K (Duv 0.0051) (Ra) = 90.8 [ R9 = 49.0 ]
1A CCT = 4680K (Duv 0.0046) (Ra) = 90.5 [ R9 = 47.6 ]
2A CCT = 4706K (Duv 0.0044) (Ra) = 90.0 [ R9 = 44.6 ]

1.20mm :

0.1A CCT = 4343K (Duv 0.0031) (Ra) = 92.0 [ R9 = 54.3 ]
0.5A CCT = 4405K (Duv 0.0034) (Ra) = 91.4 [ R9 = 51.6 ]
1A CCT = 4462K (Duv 0.0032) (Ra) = 91.0 [ R9 = 49.7 ]
2A CCT = 4525K (Duv 0.0027) (Ra) = 90.5 [ R9 = 47.2 ]

1.00mm :

0.1A CCT = 4083K (Duv 0.0019) Index (Ra) = 92.3 [ R9 = 54.9 ]
0.5A CCT = 4147K (Duv 0.0023) (Ra) = 91.7 [ R9 = 52.2 ]
1A CCT = 4202K (Duv 0.0022) (Ra) = 91.2 [ R9 = 50.1 ]
2A CCT = 4293K (Duv 0.0017) (Ra) = 90.7 [ R9 = 47.4 ]

0.85mm :

0.1A CCT = 3798K (Duv 0.0023) (Ra) = 92.2 [ R9 = 52.6 ]
0.5A CCT = 3859K (Duv 0.0026) (Ra) = 91.5 [ R9 = 50.1 ]
1A CCT = 3918K (Duv 0.0025) (Ra) = 91.0 [ R9 = 48.0 ]
2A CCT = 4017K (Duv 0.0020) (Ra) = 90.4 [ R9 = 45.2 ]

0.85mm is the thickness I used previously, on this one it shaved a tiny amount of phosphor on one side so the results might be skewed a bit, although looking at the led at very low output I don’t see any irregularities, it hasn’t happened before, maybe this led was soldered slightly higher.

So the 1000K reduction was because it was a close shave.

I did an relative output test depending on washer thickness yesterday, I’m not sure if it’s still on topic for this thread or if I should post another one ?

With LH351D bin F2R2S2 from Convoy, washer thickness of 1.26mm :

0.1A 89.2%
0.5A 89.5%
1A 89.6%
2A 89.5%
3A 89.3%

1.00mm :

0.1A 84.5%
0.5A 84.6%
1A 84.2%
2A 84.4%
3A 82.5%

0.85mm :

0.1A 80.8%
0.5A 81.1%
1A 80.9%
2A 80.5%
3A 79.6%

I feel that around 1mm is a pretty good spot since there are no duv gain going further down, while the output continue to decrease.

Kaidomain 5700K @ 1A w/ Frosted TIR:

According to the picture in the simon’s store, the last one should be V2Q1S2

Updated. His description does not match the picture