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638nm vs 660nm - color compare

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Mar 13, 2017
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I'm not sure how other people might feel. I don't think the difference between these two colors is that great.

Unfortunately, I'm usually use my smartphone camera. but my Blackshark isn't a very good camera.



IMG_20210622_015322.jpg
can recognize different two colors anybody?

Left : LPC 826 (420mW)
-> i think 826 have a wavelength shift a little.

Right : Sharp 185mW (100mW)


Still, I don't feel a dramatic difference.
 



farbe2

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i do own a measured 665nm 100mW and a 638nm 180mW pointer. I see these colors quite differently. Next to each other, 665nm looks a little purple. The 638nm looks more like a deep orange to my eyes.
I think the 665nm one looks way more "red" and nice than 638nm.
 

LiveRay

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i do own a measured 665nm 100mW and a 638nm 180mW pointer. I see these colors quite differently. Next to each other, 665nm looks a little purple. The 638nm looks more like a deep orange to my eyes.
I think the 665nm one looks way more "red" and nice than 638nm.
Interesting, I thought only cameras see it as purple.. I have seen 660nm leds and to my eyes its just pure crimson red. 638nm looks orange and the center even yellow when it gets bright, unlike 650nm
 

icecruncher

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My 635 and 633 lasers look way more orange to me than the 650-660 diode lasers I have. Still red but with a slight orange tint.

Some people are much more sensitive to color variance than others. Also the 635 is more sensitive to the human eye, so it is perceived as brighter also.

"Most" projectors are now using 635nm diodes instead of 650 because of how much "brighter" they are. I have however seen a couple custom projectors that use both to catch more of the visible color spectrum
 

RedCowboy

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650-660nm is a much prettier red than 637-638nm IMHO but it's also less visible to our eyes, knife edge a bunch of 650nm beams or live with the 638nm which isn't bad until you see a 650-660nm next to it. lol

---Edit---

Actually I just compared both side by side indoors with bright ambient back-lighting and the difference is not very much, however try looking at the beams at night when there's high humidity or indoors in fog and the 650-660nm is a deeper blood red, however the 637-638nm sure isn't bad. :) Note: I was comparing single mode laser diodes, the multi mode reds can have awful divergence which detracts from everything aesthetically IMNSHO.
 
Last edited:

Teslanium1856

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I'm not sure how other people might feel. I don't think the difference between these two colors is that great.

Unfortunately, I'm usually use my smartphone camera. but my Blackshark isn't a very good camera.



View attachment 73003
can recognize different two colors anybody?

Left : LPC 826 (420mW)
-> i think 826 have a wavelength shift a little.

Right : Sharp 185mW (100mW)


Still, I don't feel a dramatic difference.
If you defocus the lasers to large spots so that they don’t overexpose the camera you can probably easily see a difference in color.
 

bostjan

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The left one is the 660 nm, you can tell by the way the camera picks it up (NIR excites the blue pixels just a tiny bit, whilst visible red does not, so the closer to NIR, the more pinkish the camera records it). That said, cameras do not represent subtle differences in wavelength the way the human eyes do. To my eyes, 660 nm appears as a deep red and 638 nm appears as a slightly orangish red. Anything beyond 650 nm, though, to me, looks red. I have some 808 nm diodes that simply appear as dim red lasers. The big difference is how they interact with NIR-sensitive devices. There simply isn't a way to record how this appears to the human eye with a camera.
 

Teslanium1856

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The left one is the 660 nm, you can tell by the way the camera picks it up (NIR excites the blue pixels just a tiny bit, whilst visible red does not, so the closer to NIR, the more pinkish the camera records it). That said, cameras do not represent subtle differences in wavelength the way the human eyes do. To my eyes, 660 nm appears as a deep red and 638 nm appears as a slightly orangish red. Anything beyond 650 nm, though, to me, looks red. I have some 808 nm diodes that simply appear as dim red lasers. The big difference is how they interact with NIR-sensitive devices. There simply isn't a way to record how this appears to the human eye with a camera.
That’s why I mentioned spreading the light out, that way it won’t overexpose the camera.
 

kecked

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I use to buy 642nm diodes as a compromise. I was trying for krypton red 647.
 

bostjan

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That’s why I mentioned spreading the light out, that way it won’t overexpose the camera.
Yes. It's much more than that, though. The RGB sensors in the camera work differently from the colour cones of the human eye on a fundamental level, especially when it comes to NIR light.
 




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