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FrozenGate by Avery

What is the wavelength of pure violet?

What is the wavelength of pure violet?

  • 390 nm

    Votes: 1 4.5%

  • 395 nm

    Votes: 0 0.0%

  • 400 nm

    Votes: 4 18.2%

  • 405 nm

    Votes: 11 50.0%

  • 410 nm

    Votes: 2 9.1%

  • 415 nm

    Votes: 3 13.6%

  • 420 nm

    Votes: 1 4.5%

  • 425 nm

    Votes: 0 0.0%

  • 430 nm

    Votes: 0 0.0%

  • 435 nm

    Votes: 0 0.0%
  • Total voters
    22
Tha Greenlander said:
Thank you very much for showing me this tool. However I think some of it may be slightly off?

Let's take for example 532nm, 473nm and 650nm:
HEX Tool:
532nm
Your Tool:
532nm

HEX Tool:
473nm
Your Tool:
473nm

HEX Tool:
650nm
Your Tool:
650nm

My eyes see the color as being much more similar to the HEX tool then the tool you mentioned. Not saying this tool is bad, not at all, just having some doubts(myself).
Click to expand...

What HEX tool are you using?

It took me long enough, but I finally realize that the German website is useless, both the numbers in the "physical" column and one marked "CIECAM02."

By the way, 650 red is beyond the range of sRGB and most other RGB systems.) Same for 405.
 





Never mind, I found the HEX tool. It's the one here on LPF. I saw that a while back, but was looking for something better. So far everything I've found is actually worse.

By the way, my 980 arrived yesterday. $15 from Laserlands. It has a very strong second harmonic at 490 (cyan). Now I have another reference wavelength (490).
 
Voted for 400nm. I think those 395nm LED's look slightly more violet than the 405nm lasers, so it should probably be inbetween...

Also nice work on your color chart. It's certainly better than the other ones I've seen. I'd keep 450nm slightly bluer but the "pure blue" on 460nm sounds right to me. Other than that the 520nm green could be slightly bluer.

How can you see that harmonic? Might buy one of those, do you have a link?
 
Atomicrox said:
Voted for 400nm. I think those 395nm LED's look slightly more violet than the 405nm lasers, so it should probably be inbetween...

Also nice work on your color chart. It's certainly better than the other ones I've seen. I'd keep 450nm slightly bluer but the "pure blue" on 460nm sounds right to me. Other than that the 520nm green could be slightly bluer.

How can you see that harmonic? Might buy one of those, do you have a link?
Click to expand...

I think the purest violet is the lowest wavelength people can see before running into the gray problem, which starts out at 395 ±5 then increases with yellowing of the lenses and corneas due to lifetime exposure to uv (mostly solar). I think I voted for 400 nm too.

Thanks for the compliment on the color chart. I'm still doing a huge amount of research on this, and maybe not updating it often enough. I'll take your advice on 450 and 520.

As for how I see the harmonic, I'm afraid to discuss it here because it involves "a slightly crazy 980 nm laser experiment." But it's Laserland on eBay for $15. I just looked at it again (no dark room needed, I'm in a brightly lit public library). The cyan is just this incredibly vivid color that I've never seen before. Neither 4-color printing nor RGB systems can capture anything like it. It leans a bit towards robin's egg blue (Tiffany & Co. blue).
 
hwang21 said:
Wait 490nm? :drool:
Click to expand...

We can't tell you. It's a secret. At $14.48 for 5mW, if everyone knew about this, well, we'd be in trouble. Also, you're not actually getting 5mW of cyan, it's just a second harmonic. The primary (980nm) looks just as bright, so you're getting two colors of equal apparent brightness. But like I said, we can't talk about it.
 
I can tell you now that the disconnect between communication and perception is a huge part of this. There is also the fact that different people perceive the same wavelength differently.

To my eyes 383nm looks the "most" violet to me; the least "gray" tinge that UV has and the least "blueing" of higher wavelengths. The ~417nm that most "405nm" sources put out still looks rather blue to me.
 
zyxwv99 said:
Yes, that's it.
Click to expand...

Do you figure a similar one from another seller will work or is that a "bug" in that particular pen? Just found out that laserlands won't sell to my country.

Found this one, looks the same: 980nm 5mW IR Infra Red Laser Pointer Pen | eBay

Sigurthr said:
I can tell you now that the disconnect between communication and perception is a huge part of this. There is also the fact that different people perceive the same wavelength differently.

To my eyes 383nm looks the "most" violet to me; the least "gray" tinge that UV has and the least "blueing" of higher wavelengths. The ~417nm that most "405nm" sources put out still looks rather blue to me.
Click to expand...

To me 405nm looks very violet at low power density (beam or unfocused dot) and unsaturated "greyish cyan" when focused to a small dot.

Comparing my new 500mW 405nm to a ~200mW (low wavelength) 445nm it's clear that the beams of both are more slanted to violet then to (regular) blue - I was quite surprised to see the color of the 445nm so close to violet on a side by side comparison. OTOH the dots are completely different. Also the beam of my 3W (high wavelength) 450nm Dominator is almost blue, with only a very slight tint of violet. It's dot looks almost the same color as the 445nm, though. When I point each of those three lasers at the ceiling while looking at a white wall I can see they're really very different colors (as a bonus the 405nm fluoresces everything in the room!)

Color perception is really weird.
 
Last edited:
20mW of 405nm looks like light purple to me, almost like a light purple with white sparkles or something it's weird and I can't really focus on the dot

445nm looks like a deep sea blue ish to me, can't tell the purple tinge too well by itself but it's clear when other lasers are brought next to it
 
Sigurthr said:
I can tell you now that the disconnect between communication and perception is a huge part of this. There is also the fact that different people perceive the same wavelength differently.

To my eyes 383nm looks the "most" violet to me; the least "gray" tinge that UV has and the least "blueing" of higher wavelengths. The ~417nm that most "405nm" sources put out still looks rather blue to me.
Click to expand...

Thanks for the info about what 383nm looks like to you. The published literature just say 395 ±5, but that means only about half of people tested fall within that range.

If you look at the hue discrimination curve on this graph (Physiology of the Eye - Hugh Davson - Google Books) you'll see that it tends to be pretty weak in the violet.

Your claim of what wavelength 405s are does not quite coincide with the results obtained by others here at LPF who have tested them with digital spectrometers. Of course they are not all spot on. In fact, it's nice when someone can tell me the tested wavelength of their laser instead of just what the ad said.

The idea that people see wavelengths differently is an urban legend based on a little bit of science. Of course it's not an all-or-nothing proposition, but it's not nearly as true as people think. As for the alleged disconnect between color names and perceived hues, that's true if you try to assigned a wavelength to every named spectral color and vice versa.

For example, cyan is all over the map, not just in English, but in nearly all the world's cultures and languages. However, just because you can't a counter-example doesn't mean it can't work for other hues. In fact, there's a whole science devoted to how accurately a color name can be connected to a hue. The answer depends, more than anything else. on what color you're talking about. Not on differences in perception. Not on cultural or linguistic differences. All those other things play a secondary role: the main thing is "which color is it?"

What complicates these discussions is when the naive version of a science was contradicted long ago, and where the refutation has been widely publicized, but where the latest science shows that the naive version was not as wrong as was previously supposed.
 
Interesting question.

Scientists have recently discovered that there are more genetic alleles for colour cones than previously thought. Men not only describe fewer colours than women, but they typically see fewer colours, because females often have a mosiac of different colour cones from having two sets of genes. Thus, men are, at best, trichromats, and women can be tetrachromats or even pentachromats.

The perception of red is pretty much universal, we believe. Green is perceived by one of three different types of colour cones (or perhaps more than one type in polychromats). Thus, green is perceived in slightly different ways, depending on which protein your mid-range colour cones are using. Some are more sensitive to longer wavelengths than others.

There is no colour cone sensitive primarily to violet. Violet is perceived well by rod cells and perceived poorly by low-wavelength cones. As the wavelength decreases below 400 nm, the colour cones no longer respond at all, and the connective tissues in the eye begin to absorb the light more and more, so that less of it reaches the rod cells.

So, I guess your question is about where, personally, I see the most violet/gray ratio. Sadly, I cannot give you a good answer, since I am colour blind to blue and violet, seeing a sort of greenish gray and gray instead (with pure wavelengths, usually appearing more brownish if they reflect off certain things), but I would like to know the general answer.
 
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