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making fabulous laser beam?

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But seriously though.

Can you combine red, green and blue laser beams with dichros into a single white laser beam, then pass it through something like a prisms and get a "rainbow" laser beam with controllable divergence?


Just knife edging red, green and blue won't produce such gradient and even if it did it wouldn't look smooth.

When I searched laser rainbow I only found this


Would be cool to blend each beam like these smoothly in cost of brightness.
 
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10fenny

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Interesting....
I would like to know as well.
I'm sure it would depend on how/what angle you combined beams. I'm super newb still.. But a prism would split white light if its an even combination of spectrums?
Hmm as I type this idk if im getting ahead or behind myself on this one.
I'm asuming its a lot more complicated than that so sorry to blab!
It might be easier to just mimic a laser rainbow for a better effect. That way you could control divergance/intensity for each color.
 
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Yes you can combine them into a single white beam, that is no big deal, but passing it through a prism I suspect you can't get a rainbow of colors but only the three you started with, that's all that should be there in the white light.

Alan
 

crazyspaz

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yea you only get the 3 beams you started with. I've done it a while ago when my little RGB chinese module was still alive (RIP)
 
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Hmm what if you substituted combining 3 different colors for a "natural" whitelight laser like a Krypton Ion laser?
 
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I think you would get better results using a scanner, or a projector. It would look like a full rainbow but would be far easier.
 
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Good idea. I thought of that too at first.

Scanning will destroy the divergence of the "beam", right?

And a scanner won't do I think, you'll need a full blown projector with analog modulated red, green and blue as well.
Even then though it doesn't look that great color-vise (maybe the analog modulation on my modules is poor) and also the scanning of the beam kind of dims it. I don't know enough about how our eyes work to understand why the speed of the scanners affect the perceived brightness, but they do. And on the other, brighter/slower end our eyes see the "flickering effect" which also sucks.
 
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In theory you could use a linear track and scan that way. You could compensate the brightness by increasing the laser power. Also the color blending might be better if you take speed up to 40 kHz
 
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Increasing laser power would work if the exponential increase in cost wasn't an issue for me and/or there wasn't a cheaper alternative.
And with scanners you're adding too much to the divergence even with the shortest scanned line I guess.
My modules are 30kHz. I don't know if the extra 10kHz will make it good enough when it comes to color modulation for doing a realistic rainbow gradient.

So yeah, laser projectors will work for certain people doing certain types of rainbows
 
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crazyspaz

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Hmm what if you substituted combining 3 different colors for a "natural" whitelight laser like a Krypton Ion laser?
Nope, that "white" light it still made up of several specific wavelengths. It would only split into said wavelengths, not a gradient accross the whole spectrum.

You could always get a supercontinuum laser :) (if you have a sizable wallet!)
 

rhd

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I think you could just use a projector projecting a thin horizontal rainbow line into a cylindrical lens to turn the expanding "beam" into a non diverging one.
 




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