I had the opportunity to buy some Osram Oslon leds (at RS-Online, through work, I managed to incude it in an order for some other parts, at work, I did pay for them myself by the way). I am curious about any led that is not a Cree because in flashlight country there is a narrow focus on Cree (apart from that one high CRI Nichia led), and perhaps not always rightly so. One of the leds was a Oslon SSL 80deg. 4000K 96 CRItyp. ( partnr. LCW CQ7P.CC-KRKT-5L7N ). It was the closest I could get to the well-known Nichia 219 4500K 92CRI. A newer led with a bit more output that I'd rather had was the Oslon Square 4500K 96CRI typ. (LCW CQAR.CC-MPMR-5J7K-1) but I could not get that one from RS-Online unfortunately. (I did however get a Oslon Square 3500K 80CRI in this order, I'll report about that one some later time).
But now on to the Oslon SSL 80deg. 4000K 96 CRI typ. Although this one is not the closest match to the Nichia219 that Osram makes, it has some interesting features; a led die that appears to be bit smaller than the xpg or Nichia219, it has a narrow emission angle (80 degrees), a bit narrower even than the good old XR-E (XR-E: 90deg. XP-G2: 115deg. Nichia219: 110 deg. Oslon Square: 150deg.), and a CRI even better than the 219 (I am sure you will see the difference ;-) ).
First I did a reflow onto a 16mm xp-g Sinkpad. The solder pads of the two do not really match, but are close enough for a succesfull reflow (see for a picture of that in my thread on the Oslon Black IR 850nm). The mismatch was such though that the led was not really sucked tight onto the board, as happens usually in reflows, so thermal transfer may be less than optimal in this test (but I will ignore that ). This is the test set-up:
The led-board is mounted on aluminium, the led is directly connected to a power supply, the current is measured by the power supply, the voltage is measurend over the led wires by a DMM, the lux was measured ceiling bounce, with a OP-reflector placed over the led (no lens). the lux-numbers were converted into lumens using comparison flashlights with known outputs. For really precise measurements this set-up leaves a lot to be desired, but this is what I have and I am sure the general picture of the findings is valid. In the graph I compare the results with similar measurements on the Nichia 219 on copper I did a few months ago. Only real difference is that during the Nichia measurements the reflector had a AR-coated lens on top, so for a precise comparison you should add 1 or 2% to the Nichia values (that are already higher).
The first two things that strike from this graph is that at any current the output of the Oslon is a bit less than the 219 (at 1.5A it is 21% less), and that the maximum output is reached at a lower current than with the Nichia. The output of this high CRI Nichia is considered already utter meh by the cool white fans, well, this one is worse, at 1.5A just about half the output of a cool white XP-G2. On a brighter note, the Vf is considerably less than the Vf of the Nichia. Considering that the high Vf is one of the major limitations of using the Nichia219 in single cell flashlights, this lower Vf of the Oslon (it is close to the Vf of the XP-G2) is a real improvement, at 1.5A, using a lineair driver with a li-ion battery it stays into regulation during most of the drainage of the battery.
As a conclusion from these measurements I think this led will not shock the flashlight community, but because of the narrow emission angle it will be a nice led in a small high CRI aspheric light, e.g. a sk68 type of light.
Because I had it still lying about not doing much, I swapped the xpg of a Ultrafire M5 with this led. It will be the last time that I sanded a 16mm Sinkpad down to 10mm (and made it thinner too, to fit it into the M5), I have some of the new 10mm Sinkpads in the mail from VoB
Here is the result, compared to a Nichia 219 mod (bottom=Maratac AAA copper with Nichia219):
No beamshots because I can't get the tint right on picture, but the Oslon looks quite a bit warmer than the Nichia (and not as pink), the difference seems to be even a bit larger than I expected from going from 4500K to 4000K. The beam pattern of this mod is really nice by the way, emitters with narrow beam angles give very distinct hotspots (even with the OP-reflector) with a good bright spill. The light coming from the flashlight is beautiful, the tint is nice and it seems like the 96CRI really shows.
I put a small projection lens in front of the flashlight and made two pictures of the projected led, at two focus points, these pictures give an idea of how the hotspot would look if this led is put into an aspheric light:
It is the most messy phosfor-layer I have seen in a led thusfar, there is even a bit of blue light leaking from the edge of the die! But look, the spot is more or less round, I like that in an aspheric! I have one of these leds leftover, I will try it in a small aspheric and report about the results.
Thanks for reading, I am afraid I will be the only one ever to use this led in a flashlight, but who knows this post will inspire someone :-)