Which LEDs are high in 480 nm? Most cool white LEDs have a dip around 480 nm, and blue Osrams are 450 nm and very low in 480 nm.
If you refer to the cyan-dip, basically all LEDs have it. Some High-CRI emitters have less of a dip (Nichia 519a) but the only emitters that truly don’t have one are based on a violet or near-UV pump, instead of blue like most LEDs, and rely on a blue-cyan phosphor instead of the directly emitted blue light.
There’s 3 options for that:
- Nichia Optisolis (Most power, 1A max)
- Seoul Sunlike (0.5A max)
- Yuji VTC (very high Vf, low power)
None of them are particularly powerful or have very good beams inside an optic/reflector, as they’re designed for LED strips and lamps, but can be made to work on flashlights, especially the optisolis.
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You might like the Nichia E17A Azure that Hank can put in some of their lights. It doesn’t have a peak at 480nm but seems to be pretty high in it.
Hank also has XP-E Cyan which IIRC peak at 490-495, not sure how wide the spectrum from them is though.
Bridgelux Thrive also have very little cyan dip. They appear to be quite similar to Optisolis and SunLike emitters in that regard.
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It would be very interesting to get them to someone with a Sekonic, I wounder if Cheule is interested in testing them out.
They’re clearly phosphor converted, but they have an interesting effect when mixed with other lights, almost a slight fluorescence effect like they’re using a higher-frequency pump.
I’ve read all the information I could from their website, but to be honest most of it is way over my head though.
I’ve converted several of the bulbs in my home to the 1W 2835 emitters and they look nice to me, but I only have an Opple, no Sekonic.
Just to be clear, the “cyan XPE” isn’t actually a colored XP-E made by Cree, it is an aliexpress LED that claims to be made by Epileds, it just looks like an XP-E clone so that’s what the marketing calls it.
There is no datasheet for it or any real information, but it fits a 3535 footprint and runs at up to 2-3A current, maybe a bit more.
IIRC u/duckduckgoneforgood on reddit found and tried it in a D1 and D4 with good results, so Hank (Emisar/Noctigon) added it as a hidden option. The same base LED is available in many colors, the other notable one is nicknamed the “XPE pink”, it has 70cri and the bare emitter looks the same, the beam is basically pure magenta but with decent color rendering for a colored LED, it is also available from Hank.
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LEDs with wavelengths close to ultraviolet wavelengths from 375–395 nm are cheap already on the market as anti-counterfeiting lamps, fake documents. Diodes with shorter wavelengths are still expensive but are already in the field with wavelengths less than 247 nm. It is best to use lamps with two fixed spectral wavelengths with Blue of 460nm and Red of 660nm.
What’s the intended application?
Before LEDs were available with good R9 (red) values, a couple of DIYers would try white LEDs mixed with red LEDs on a multiple MPCB board- if you need white with additional 480nm, this colour-mixing method might be your best option.
If you just need 480nm, you could look into the CREE XEG line, rated at 3A, PC Cyan peaks at 480 nm, and has some additional longer wavelengths.
Cutter electronics sells MPCBs, I don’t know any other sources for these unusual LEDs.
Thanks everyone. I’m looking for something I can easily buy in a light or add to one. I don’t want monochromatic but ideally more 480 nm than a white can have. E17A azure and “XP-E” cyan seem close to what I want, but the relative intensity for E17A azure is only 0.6 at 480 nm and I don’t know about the “XP-E”. Any other options?
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If you want it for flashlight use and don’t need a concentrated beam, Hank might be able to put together a D4K mule (no optic or reflector) with a lot of E17A, iirc 16 of them. You can make up for the lower relative intensity through sheer amount of light. The “XPE” is much brighter but it is a 490nm emitter.
If you’re ok with using unusual footprints, the Cree XE-G PC-Cyan is perfect, the peak is perfectly at 480nm, and they’re specified to work fine at up to 3A, possibly a bit more.
There’s no spec sheet from them, but they’re more powerful than the E17A, but still not particularly powerful overall. Mine are in a D4K which came with the noFET firmware. Did a quick eyeball test with a few of my lights to find what matches and Deep Red SST20s might be the best comparison - I have red SST20s in one channel of a dual channel D4S and it might be similar when taking the different optics into account. Slightly less perceived brightness to my eyes than the SST20s, but not a huge difference.
My other data point I found close enough to be worth mentioning would be slightly more throw and less flood in a D4 than a domed 519A in a D2 with frosted optic, comparable perceived brightness to my eyes.
I also have XP-E pink in a D4, which are very similar but a tiny bit throwier (less scatter, I guess)
Looks good, anywhere I can buy the XE-G in a light or as an LED?
As far as I’m aware, MPCBs only currently available in 20mm (or as triples) from Cutter Electronics in Australia, they also do the boards with the LEDs pre soldered…
I’ve been asking this forum if they know any other sources for a while now, no luck 
The cyan “XP-E” seems like a good option, 490 nm works for me too. How many amps should it be driven at? It says 700mA but probably can be higher because D4Ks are usually more than 700mA?
1-1.3A should be just fine, it is approximately the current per-led of the 5A-noFET driver in a D4. It just might not be the best for running them nonstop.