A140 Different shades of blue?

Well, consider that also the manufacturers gives a certain range, for laser diodes wavelenghts, especially for high power blue ones ..... as far as i remember, Nichia was giving a range of 15nm (from 440 to 455) for their "445nm" diodes.

And also if a human eye cannot measure single wavelenghts, they have enough discrimination for see the difference from two colors side by side, also for 10nm of difference.

Some of the studies I read the other night said the ability for the brain to differentiate between colors depends a lot on the colors presented. People are better able to tell the difference between colors when the pallet is limited. So if you have two or three slightly different blues, you can tell the difference between them, but if you add other colors, reds and greens and yellows, etc.. the ability to differentiate between the blues diminishes greatly.

And I know the eye/brain can differentiate between 5nm (589 definitely looks different from 594, for example).. and probably less as well. a 2nm difference side by side might even be noticeable. I'll play with it more when I do another a140 build and measure it. I have one more sleeve I made for the trustfire hosts left, so if I can find time to run to the office, it might even happen this afternoon.

It also depends on where in the spectrum it is. 5nm is a relatively large difference in the 590-range, but in the 660-range or 530-range, it's almost nothing.

Ok. Did an a140 build and another m140 build today. Just checked them.

The a140 came out as 441.5nm.



and interestingly enough, the second m140 came out as 442nm...



So I retested the first m140 build. And sure enough, it was 448.6nm, about the same as the initial test.



So.. Unless DTR accidentally got his diodes mixed up when he sent me these and mixed up the a140 and m140 diodes.. I'll have to say the m140 diodes are no different than the a140 diodes.. and the wavelength you get is still the luck of the draw.

And as far as side by side comparisons.. I honestly can't tell the difference between 441 and 448. When it gets dark i'll set up the camera and see if it shows any difference.

I thought that would be the case. I have also notice about the same mix of efficiency in the m140 and a140 diodes which leads me to believe that they are the same as well. Thanks for the wavelength measurements.:beer:

qumefox said:

Some of the studies I read the other night said the ability for the brain to differentiate between colors depends a lot on the colors presented. People are better able to tell the difference between colors when the pallet is limited. So if you have two or three slightly different blues, you can tell the difference between them, but if you add other colors, reds and greens and yellows, etc.. the ability to differentiate between the blues diminishes greatly.

And I know the eye/brain can differentiate between 5nm (589 definitely looks different from 594, for example).. and probably less as well. a 2nm difference side by side might even be noticeable. I'll play with it more when I do another a140 build and measure it. I have one more sleeve I made for the trustfire hosts left, so if I can find time to run to the office, it might even happen this afternoon.

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A simple diagram to show some of what you're talking about: ellipses on the standard 1931 CIE diagram.



From experiments, a human can't distinguish one color from another if the 2 colors are both inside the same ellipse. These ellipses (called MacAdam ellipses) are plotted as examples of how big the regions of indistinguishable color are in different regions of the diagram.

You notice that in the blue region of the diagram, the ellipses are tiny, so humans are actually pretty good at distinguishing between shades of blue. Not so good when it comes to shades of green, though. There's a LOT of really complicated science out there on human color vision, it's an intense field that's really hard to wrap your head all the way around.

Another problem is that monitors are largely incapable of displaying the exact colors of monochromatic wavelengths. Below is another CIE diagram, showing the typical color gamut of an LCD display. An LCD can't display any color outside this triangle, so now imagine the MacAdam ellipses on this chart: On the right side in the green to red region is the only area that an LCD can come close to showing true monochromatic light colors. At least from my first glance, it seems that monochromatic red and LCD red may fall in the same ellipse, but blue doesn't appear that it would.

qumefox said:

And as far as side by side comparisons.. I honestly can't tell the difference between 441 and 448. When it gets dark i'll set up the camera and see if it shows any difference.

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Ok I have a correction on this after playing with it more in the dark. I can't tell any difference between the colors of the 'dots' However the 'beam' color is a different matter. The beam on the 441 is noticeably more purplish than the beam on the 448.

And pullbangdead.. Interesting, however, if you plot the color response of commonly used camera sensors in the vast majority of 'affordable' cameras.. meaning not multi-thousand dollar DSLR's etc.. You'll see that gamut in the blue range is noticably *less* than that of the LCD... Which was my point. Display's aren't the limiting factor currently. Camera's still are.

I'd agree on the camera limitation - a good screen can reproduce more detail in color differences that most camera's can capture.

There is a good reason for this though: Camera's are built to take 'nice' pictures of the world around us, and do a lot of postprocessing of whatever comes out of their sensors. Things with a very saturated color are rare in nature, and when cyan-blue-violet colors are concerned, the most obvious thing would be the sky on a clear day. I think camera's actually prevent rendering the sky violet, even if you choose the wrong color balance etc.

When talking about laser colors this always presents a problem, since what the camera makes of these monochromatic beams is often quite different from what our eyes see.

qumefox said:

And pullbangdead.. Interesting, however, if you plot the color response of commonly used camera sensors in the vast majority of 'affordable' cameras.. meaning not multi-thousand dollar DSLR's etc.. You'll see that gamut in the blue range is noticably *less* than that of the LCD... Which was my point. Display's aren't the limiting factor currently. Camera's still are.

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:beer: We're on the same page. It's just an interesting visual aid to see how we see things (pun intended).

Wow, I didn’t expect so much good information so fast on this post. Thank you everybody commenting on this!

aryntha said:

Interesting though, if it's that noticeable and describable as 'sky' blue... Could be off spec but in a fortunate way.
I wish cameras rendered blue differences readily -- they don't... but I don't suppose you could take a shot at well, taking some shots.
Any comparisons you could describe as far as the difference? I don't suppose you've ever seen a 473nm DPSS blue?

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No I haven’t seen (in person) a 473nm, but from videos and images I’ve seen, the dot looks to be the color of this new diode from DTR, but the beam is definitely closer to 450nm. I’m waiting for 2 custom hosts to be finished so I can mount these in proper heatsinks. I’ll take a picture of them side by side to see if even the camera and see the difference. It may not be true color, but I wonder if it WILL see a difference.

qumefox said:

Ok. Did an a140 build and another m140 build today. Just checked them.
The a140 came out as 441.5nm.
and interestingly enough, the second m140 came out as 442nm...
So I retested the first m140 build. And sure enough, it was 448.6nm, about the same as the initial test.
So.. Unless DTR accidentally got his diodes mixed up when he sent me these and mixed up the a140 and m140 diodes.. I'll have to say the m140 diodes are no different than the a140 diodes.. and the wavelength you get is still the luck of the draw.
And as far as side by side comparisons.. I honestly can't tell the difference between 441 and 448. When it gets dark i'll set up the camera and see if it shows any difference.

Click to expand...

I got my first diode from Greg at StoneTek, and I’m pretty sure he didn’t have any M140s to ship out, but I got my second diode from DTR. If he does have M140s being shipped out and he did mix an m140 with the a140, is it possible that the A140s run on the shorter wavelength than M140s? Not that within 10nm even matters anyways but…

DTR said:

I thought that would be the case. I have also notice about the same mix of efficiency in the m140 and a140 diodes which leads me to believe that they are the same as well. Thanks for the wavelength measurements.:beer:

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So as far as getting an A140 or an M140, power-wise doesn’t really matter?
And thank you DTR for the diode :thanks: I may still be a noob at this, but it sure is fun!

I doubt he got them mixed up. Right now there is no evidence to support the m140's are any different than the a140's, and the wavelengths you get are just the luck of the draw.

The only thing I hate is that the 448nm ones is a low power build. heh.

Its hard to determine any significant difference in wavelengths between series of diodes, no matter if its A130, A140 or M140. The spread between individual diodes is so large that you would need a shitload of each type to come to any conclusion... and even then you have have gotten them all from a same batch so it doesnt mean that all diodes of that type number follow your findings.

If there is a difference in diodes, that would have meant they were binned.. and if they'd been binned for higher wavelengths, you wouldn't have seen a 442nm diode in a projector meant to have higher wavelength 'brighter' diodes.

The fact that a 442nm diode came out of a m140 is proof enough for me they aren't binned and the diodes are the same, meaning the wavelengths are random, and that your just as likely to get a 'high' wavelength diode out of a a140 as you are a m140.

DTR already stated he's seen the same mix of efficiencies out of the m140 as he has the a140. Now i've shown that the m140 also contain 'low' wavelength 445's as well.. About the only other thing i'd need to be 'conclusive' as far as i'm concerned is finding a 'high' wavelength diode in a a140. And I just happen to have one more a140 diode I haven't tested yet.. so we'll see how the crapshoot goes when I put it in a housing and test it.