Samsung LH351C 5000 K CRI90 color and output test

I will have a look when I’m at home later, could very well be :slight_smile:

Why did The_Driver deleted his post?

No idea, btw I just checked and I do have some of those leds still.

:+1:

You are being nosy ;)

Maybe because I don't need any anymore. :)

Thanks, I already found some. :)

These LEDs are very efficient for their size, 90CRI and the possiblity of having a good tint together with high luminance (when shaved). In part this is achieved by a slightly lower R9 value when shaved.

Nah I'm not noisy, as a rule not even my farts are when needed (because ;-) ninja).

Aaah! You said nosy! :-D

I still have two, wonder what will do with 'em some day. Powered by an XHP70 boost driver a quadkenstein aspheric build sounds appealing to me, albeit one with just two emitters would also do by carefully adjusting the current output.

How did it go Barkuti?

Wellp, it didn't go. Can't recall what I was planning by the time but I used another emitter. They're still in my emitter cache box.

I see. I think this LED might have some potential for high CRI throwers. More efficient than SST-20. Also green but dedoming is said to fix that.
But maybe they aren’t so good, it’s hard to tell without knowing die size…or testing. :slight_smile:

Any lumen to candela measures done already. Is it more like nichia 219c or sst-20?

I took the picture above and measured die size. Magnified by the dome, about 2.2 mm side. Assuming refraction index of about 1.5 that would be very roughly 3.2 mm².
And it’s flip chip.
So…despite much higher efficiency than SST-20 it’s unlikely to compete….though I would still love to see it dedomed as I have no idea of how good or bad is the calculation method that I used above. :wink:

Well, I’m not sure if those will be a throwy ones…
I hoped those could have similar to xl-l hi beam pattern, but now I assume beam pattern should be more or less like nichia 219c.
219c is probably their main competitor which samsung’s should beat with similar light quality and better output.
SST-20 95CRI are still great leds that thanks to its high R9 do not have real competitors yet.
Look like lh351c have the same phosphor dice size as lh351b, but dome is same size as lh351d.

Just to reference here is a photo of LH351C next to SST-20 and XP-L HI.

Hotspot is quite big next to two others.

I can not see how these can be effectively dedomed, it looks like the phosfor is mixed with silicon, just like many other leds (i.e. all Nichia’s), so there is not a transition to a different material between silicon and phosfor area that has a weak adherence, like in the classic Cree’s.

But these can be sliced very effectively, if you are very good at it you can slice it up to a tiny bit into the phosfor layer, leaving a matt surface, just like a dedomed Cree, and I suspect with the same quality of photon recycling.

Thanks sungar. :slight_smile:

I haven’t sliced any led yet, so no doubt I’m not good at this… I’m also a bit afraid that lumen output will drop to the level that there will not be any significant increase in throw.
Anyway, djozz whats your best way to do it?

Here are some beamshots (4500k locked) under quad LEDiL ANGIE-S optics:

XP-L HI V4 3A:

SST-20 J5 FB4:

LH351C GE4RTMF:

Surprisingly in the camera Cree leds were much greener than Samsung leds. My eyes however saw this other way around. XP-Ls are colder, more blue ones. LH351C looks more like pure 5000k, but wilt slight too much green in it. Everything else then a white ceiling look better under Samsungs. In my opinion Crees have tendency to overexposure green in colorful scenes.

Where did you find the XP-L HI V4 3A? Though your pic shows a greenish tint more similar to 3C.

Hank had this listed as an option for 4XP 33MM MCPCB:

On one hand you might be right this is 3C as I don’t see 3A XP-Ls available as bare led.
On the other it look more like 5200k-5300k than 4900k to the eyes. On camera it look totally different.

Hi Agro, what is that calculation method you used to estimate the actual die size? It seems like the magnification would depend on the refractive indeed and geometry of the dome.

By the way when I measure the apparent die size, just estimating with calipers, I get something closer to 3mm wide. Not sure if some difference in perspective, like using a macro lens or something, could cause some difference in apparent die size in maukka’s image. The large apparent die size is supported by the large beam size in my picture here. Hotspot size is very similar to sliced XHP50.2.

I assumed a hemispherical dome and formula from here.
1.5 refraction index = 1.5x magnification.
I averaged edge lengths because the photo is not straight from above.