Wavelength to Color Demonstration

Hey,

I was looking into a small on-line demo tool to show for which wavelength what the color looks like, so I can imagine how such lasers would look like.

Spectrum drawings are plentiful, but I wanted a tool that I can select a specific wavelength and get its color in a big painted area.

After some searching I found this nice tool that works for each wavelength between 350nm to 780nm, you also get the RGB values for each, and can see which seems brighter to you:

Determining RGB Color from a wavelength in C#

From the 4 different wavelengths I have (405, 473, 532 and 650) it seems to be accurate.

The page includes explanations, source code and also an executable file inside a zip (tested for viruses and trojans).

I thought it could be interesting to post,

Ohad

Well it's never gonna be accurate because your monitor combines 3 colors to obtain the rest, but they're still just 3 separate wavelengths.And brightness wise, it wouldn't work either.For instance, your monitor can't create 405nm so you can't really tell how bright it would be to you.The 405nm that the monitor produces is actually still red and blue which have different properties.

On my monitor.. the 632nm color (on the 1st page of that link) looks very
ORANGE to me... while my 5mW 632.8nm HeNe Laser looks very RED to me.

But still a nice try looking for something standard to show Laser wavelengths...:yh:

Jerry

Spectrum drawings or anything that has to do with a monitor are going to be approximations. Put some sunlight through a prism and let it shine on a white surface and you'll have your wavelengths lol

Switch said:

Well it's never gonna be accurate because your monitor combines 3 colors to obtain the rest, but they're still just 3 separate wavelengths.And brightness wise, it wouldn't work either.For instance, your monitor can't create 405nm so you can't really tell how bright it would be to you.The 405nm that the monitor produces is actually still red and blue which have different properties.

Click to expand...

Obviously the monitor can't produce coherent light for each wavelength, but correct me if I'm wrong - our eyes only tell between 3 different colors (RGB receptors) and all other colors are due to two or more of our receptor types reacting to the light.

405nm triggers some response in the red receptor and some in the blue, and in effect if you produce light with these two colors separately in the right proportion and mix it, to our eyes it looks exactly the same as 405nm, no?

Also the monitor may not be calibrated well so it can distort the colors, but if I see that 4 wavelengths on the monitor look pretty much like my 4 laser types, I can assume it's a good approximation for other wavelengths, right?

Ohada is right. Monitors use R,G,B phosphors exactly because the eye only has sensors for these wavelengths. The color sensation that you get from light of a specific wavelength is just the brains interpretation of the 3 stimulus levels for the 3 receptor types; light in itself does not have a color.

There are ways to calibrate cameras, monitors, and printers so that the color rendition they deliver comes as close as possible to what you actually see, however that is a science in itself (professional publishers have to do that).

Honestly, 405nm looks blue while its violet, and 532 looks like a strange green far from the real green, and also as jerry said, 635 nm isn't real too.

yours,
Albert

ohada said:

Obviously the monitor can't produce coherent light for each wavelength, but correct me if I'm wrong - our eyes only tell between 3 different colors (RGB receptors) and all other colors are due to two or more of our receptor types reacting to the light.

405nm triggers some response in the red receptor and some in the blue, and in effect if you produce light with these two colors separately in the right proportion and mix it, to our eyes it looks exactly the same as 405nm, no?

Also the monitor may not be calibrated well so it can distort the colors, but if I see that 4 wavelengths on the monitor look pretty much like my 4 laser types, I can assume it's a good approximation for other wavelengths, right?

Click to expand...

Yes but will the brightness curve also be the same? :undecided: I can't really tell....I would suppose that monitors have to anticipate that too so the color rendition is as close to reality as possible.
And of course other properties , like the difficulty we have to focus on 405nm or fluorescence , won't become obvious on the monitor because it doesn't depend on our receptors alone, but I guess you don't really care about that right now.

And light does have a color , it's given by the wavelength, but of course we can only talk about color from the point of view of our eyesight.

Erm... monitors don't even emit 405nm in the first place. It only does down to 450-something.

Colour mixing and actual wavelengths cannot be compared. If you have a 593.5nm laser and a fully analogue rgb laser, no matter how much you tweek the intensities you'll never be able match the true 593.5mn.

405nm isn't reproduced on screen or in print

I agree it has it's weakness, but it can help to visualize very approximate colors. For my monitor, (these do vary) this looks much like it does to my eye... Ohada's application, and my camera seem to see 635 and 632.8, which I left out of the pic), as more orange, to my eye it's more red...