goofy color experiment that had a result I didn't anticipate.

[norbie]

I've been doing this dumb experiment with my other laser pointers for a while where I would fire two laser beam colors at the white glass cover for the light in my ceiling fan in my room and observe what the overall color of the combined light looked like. I got the usual results of mixing 650 nm Red with 445 nm blue and came up with a magenta looking color. I mixed a 100 mw 405 nm with a 5mw 650 nm and got a good purplish color. I never had much luck mixing 532 nm with 405 nm as the green always overpowered the violet. Mixing 445 nm and 532 gave me a cyan looking color.


Well I got the 589 nm Spartan laser from Dragon Lasers in the mail yesterday and had been wanting to see what color would show up when I fired the 589 nm and 445 nm beam together at my white glass cover. I knew I wouldn't get green, but I was expecting a color that was almost white. I had gotten almost white when I had fired my 445 nm, 650 nm and 532 nm all together at my ceiling cover before and assumed almost yellow 589 and 445 nm blue would just give me something close to white as well. So what color did I get? I got a lavender looking color. Maybe a bit darker than lavender but lighter than violet or purple.

Any reason 589 nm light + 445 nm light would look a bit purple?

 

[ElektroFreak]

589 is yellow-orange, which can also be made by combining red and green so it still adds the effect of red+green when combined with blue. Since 589nm is orangeish, it would be heavy on red and light on green if you were to create the same hue by combining red and green colors. Since red and blue make violet/magenta colors it means that 589 + 445nm in just the right proportion = lavender. That's my theory anyway..

 

[Blord]

With three colors green, blue and red you can create any colors you want. That is how the RGB projectors works. Vary the ratio between the color and you could get pink/lavendel.

 

[daawood123]

Sorry for thread jacking, but to make yellow, you use what ratio of red/green? 30mw green with 250mw red?

And wouldnt the different beam diameters sort of make the "yellow" look crap?

 

[ElektroFreak]

^Yes and no. The ratio depends on what kind of yellow hue you want. Less green and more red would be red-orange, while more green and less red would be yellow-green. Varying the ratio changes the hue.

Regarding beam diameters, when you combine to get yellow there is very often a red tinge around the beam where the red beam is fatter than the green, but whether it looks "crap" is a matter of opinion. A pure yellow beam from a yellow laser source is cleaner-looking, but you can't change the shade, whereas by combining lasers and changing their power ratio you can achieve any shade.

 

[daawood123]

ah, but wouldn't it be possible to alter the reds beam diameter by passing the beam through a hole the same size as the green beam, so only a specific amount of light got through, meaning it would equal the diameter of the green beam, giving a better yellow with no red around it?

 

[Smeerworst]

Just throwing a picture into this

Large crystal mineral, make nice effects.

589nm + 450nm

 

[ARG]

593.5nm and 473nm gives a nice white It's a much nicer white than RGB.

 

[Smeerworst]

593.5nm and 473nm gives a nice white It's a much nicer white than RGB.

I tryed it with 589 and 473

 

[ARG]

You don't have 593.5nm Smeer? I thought you had it all 589nm and 473nm would look just as good I imagine.

 

[ElektroFreak]

^looks pretty lavender to me, but more so with 473nm.

@daawood123: The aperture idea isn't quite so simple unfortunately. In order to change the beam diameter it's necessary to use optics such as lenses rather than a hole.

 

[Bionic-Badger]

An RGB setup should be able to produce any white a 473nm/593.5nm mix can. Of course it all depends on whether you have actual control over each channel's output power, and how well the dots line up.

 

[Cyparagon]

The CIE color space will give you an approximation of what colors are possible when mixing single wavelengths.

Draw a line between the two wavelengths you are using, and everything on that line is attainable by varying the power of the two components.

It also works for more than two. For RGB for example, you can draw a triangle with the three wavelengths as the triangle's points, and every point inside the triangle is attainable by varying the power of the components. You'll notice if you use a slightly more cyan-blue, you can get white with only two colors. I made these a couple years ago with argon (488nm) and SFG (589nm):

(grating to show there are indeed only two wavelengths)