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Thread: Impossible optic?

  1. #1
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    Default Impossible optic?

    I just want a Dichro that passes red in one direction and reflects in the other. Sounds simple right? It would make beam combining a breeze.

    Does such an optic exist at a reasonable price?

    Optics made of unobtainium, handwavium coated with wishalloy or corodeium need not apply.
    This space for rent.

  2. #2
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    Use two colors of red and get the right Dichro. 640nm and 660nm for example

  3. #3
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    Sounds like a polarizing beam splitter to me.

  4. #4
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    Quote Originally Posted by dnar View Post
    I just want a Dichro that passes red in one direction and reflects in the other. Sounds simple right? It would make beam combining a breeze.
    Does such an optic exist at a reasonable price?
    For the same frequency and polarization? No. It doesn't exist at any price.

    However, there are dichros that will pass 660 nm red and reflect 642 nm red. (Search for "semrock" here on PL and you'll find links to the original group buy where I ordered a bunch of them, as well as various threads where people have installed them in their projectors.)

    There is also a PBS cube, which will pass a horizontally polarized beam while reflecting a vertically polarized beam of the same frequency. (This is how you combine a pair of 660 nm reds to get more power, for example.)

    But if you have two lasers of the same frequency and the same polarization, the only way you can combine them is to position the beams very close together using the knife-edge mirror trick. And you'll end up with a beam that is wider than what you started with.

    Sorry, but that's Physics for you... (Always dashing our hopes with rigid laws!)

    Adam

  5. #5
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    Such a device would probably violate Kirchhoff's law and the second law of thermodynamics.

  6. #6
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    Quote Originally Posted by Eidetic View Post
    Sounds like a polarizing beam splitter to me.
    what he said!!!
    "its called character briggs..."

  7. #7
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    I think what he meant was a semi-transparent mirror maybe? Like they use on laser output windows?

  8. #8
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