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Dichro Confusion?

NRGLite

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Hi guys!
I was thinking about making a monster red laser, and 'monster' means combining lots and lots of diodes (in my imagination anyways ;) ), so I was thinking whether I could dichro two different hues of red into one beam of medium red. Suddenly I realized there was such a thing as infrared lasers. Couldn't you dichro infrared plus a shade of orange to equal red?? But that's where I'm confused, cause green lasers leak IR but somehow it doesn't combine to form a different color? I sense I have something confused here, please help me clear this up.
 

Cyparagon

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I was thinking whether I could dichro two different hues of red into one beam of medium red.
No. The transmission curve of a dichro is not a step function, it is somewhat gradual. It can be done with 660 and 635, but you'll have no results with 638 and 642 for example.

Couldn't you dichro infrared plus a shade of orange to equal red??
No. One thing you might not know about infrared: it is invisible. It therefore has no effect on the other color you see.
 

NRGLite

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Yes, Cyp, I know that infrared is invisible. I am just wondering why you can dichro visible colors, but suddenly when you go into longer wavelengths you suddenly can't do it! Where's the line?!
 

Cyparagon

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Where's the line?!
You're asking where the line is between visible and invisible wavelengths is? That isn't a step function either, and it's rather subjective, but is commonly reported as 700nm.
 

diachi

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Yes, Cyp, I know that infrared is invisible. I am just wondering why you can dichro visible colors, but suddenly when you go into longer wavelengths you suddenly can't do it! Where's the line?!
When you combine lasers using dichros you still have two separate wavelengths in the end. So if you combined 650nm with 808nm, you'd still have 650nm and 808nm, just combined into one beam. It would be no brighter than the 650nm alone because you cannot see 808nm. If you combine 532nm and 650nm your eyes would interpret it as yellow or orange, but it would still be 650nm and 532nm.

You can then use another dichro to split the 650nm and 808nm back into two beams.

To combine multiple reds you *can* use a dichro, but a a PBS cube (Polarazing beam splitter) or knife edging method is generally a better way to go.

I'll grab a picture of my 1W knife edged/telescoped red when I get home to give you an example.
 
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