Check-in / Update: RE "460nm" diodes.

We've all been a little skeptical of the "460nm" diodes that have appeared in a few places online and here on LPF. An owner of one of the "460nm" labbies has one en-route to me now to have it's wavelength tested, and I'll let everyone know my findings when it arrives.

But as an interim update, I'll say that I'm not nearly as skeptical of this claim as I was a month ago.

I've been testing and binning a lot of diodes in an attempt to find something approaching 460. I'm not there yet, but after 60 diodes, I've found one that has come fairly close:



It's 458nm, and it takes a full current of 1.8A to get there. So it's not quite 460, and certainly would be another nanometer or two further away if I was only running it at the ~1A that we've heard of these other "460s" operating at. That said, it's pretty close.

This particular diode came out of an M240, and it was by far the highest wavelength I've seen out of 24 pcs from an M240, 12 pcs from DTR (M140), 15 pcs from an A145, and 3 others that I didn't have projector origins recorded for (certainly A series though).

So, in theory, if the Chinese are binning diodes, these 460s are more than realistic. It took me almost 60 diodes to find a 458. Some of the Chinese outfits making cheap Lazerer/LasersMan/YourLasers pointers are surely deeling with hundreds and hundreds of diodes a day. If just one enterprising employee thought to ask their boss for a spectrometer, chances are good that they'd find a 460 fairly regularly.

So, with that said, it would be awesome if Styropyro would finally tell us where he's getting these 460s from (if they end up being 460 when I test the one that's en route). But absent that, I think we can all still expect to see these high wavelengths appearing on LPF from time to time. I'm sure that if someone like DTR grabbed a spectrometer, he'd be able to find a few.

Final Notes:

• My approach wasn't to run every diode at 1.8A off the bat. Instead, I ran each diode at lasing current of around 250mA and recorded the wavelengths. Then I separated off the top readings (in that case, it was the diodes that measured 448 and 449 at 250mA). Those were the diodes I pushed to 1.8A. I lost one (the 448) in the process, but the other (the 449) ended up netting me a 458 @ 1.8A of current.
• A lot of people have asked about color, and whether it looks different from normal 445s. This is kind of a funny question, because what's a "normal 445?". Here's my take. If I put this 458 up against another diode in the 450+ range, I can't usually the difference. If it's up against something in the 445 to 450 range, I can. And if it's up against another diode that is 445 or lower, then even a "disinterested 3rd party" (ie, a layman) would spot that the 445 (or lower) was "purply" and the 458 was "cyany".
• Another interesting comparison. If I consciously select a low wavelength like 442, and then put this 458 between the 442 and a 473, the 458 looks closer in colour to the 473 than it does to the 442.
• And finally, according to the relative brightness comparison, a 458 running at 2W of output, should have a beam brightness equivalent to 3,280mW of 445. I can't subjectively confirm this because I haven't actually collimated this 458 yet, but I'm certainly excited to do so. Beam: (458nm 2000mw) vs. (445nm 3280.96mw)

Interesting stuff. Do you have a rough estimate of the A vs M series wavelengths?

Very interesting results, can't wait for more op:

DTR said:

Interesting stuff. Do you have a rough estimate of the A vs M series wavelengths?

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Yep, more or less - assuming you run at least 1A of current, and let it run for about a minute, I'm seeing:

- The A series seems to average mid 440s.
- The M series seems to average high 440s, or very low 450s.

For the A series stats, the thread over on PL from a while back is much more conclusive than my testing, and there was definitely a different between the A130 and A140 models (the A130 were actually higher, surprisingly). However, I've done a bunch of M series testing now, and there's one really clear reality:

- We shouldn't be calling M series diodes "445s". I've only run into maybe ~15% of the M series diodes that will even drop below 445 at threshold current, and ALL of those will still end up above 445 with any reasonable amount of current. In other words, I think every M series diode is going to be higher than 445 with even 1A of current. If I were to estimate an average when there's 1A of current, I'd put it at 448 to 450 based on my testing so far.

M series are definitely trending higher in wavelength. I've got an H series en route to test also.

Anything special about 460 nm?

lazeristasUVISIR said:

Anything special about 460 nm?

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It's a lighter, and therefore much more visible blue.

hmmm... H series? :thinking:
I'm gonna have to research that one cause its new to me.

I suppose the manufacturer is shifting the wavelength more up to make it brighter.
It is more efficient than running the "normal" 445nm on higher currents.

Very nice info.Thanks for taking the time to do this and it makes sense when you think about it. Getting the wl up by another 10 nm would be a good next step for projector quality since it's closer to a true blue and not indigo.

Nice findings! got photos to compare your lowest, middle and highest wavelength for these 445 diodes?

I'll grab some photos once I used this diode in a build.

What doesn't make sense is that fact that the A140s supposedly dropped in wavelength from the A130s (according to the thread on PL, not my own testing).

But yes - I think we're going to see a movement towards a sweet spot. If you look at Chroma a bit, it seems like the "sweet spot" would be somewhere around 468nm. At this point, you can get the pure blue, but also still get colour similar to the lower blow wavelengths by introducing some red.

Very interesting op:

Jim

Nice work man, this is very cool.