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Thread: 445nm split and recombine beam?

  1. #41
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    Quote Originally Posted by loopee View Post
    Couldn't you also do it this way and remove the need for the waveplate

    Basically split and stack using four HR mirrors

    Attachment 19666Attachment 19665Attachment 19664


    Attachment 19667Attachment 19669Attachment 19668


    Standing ovation! I'm speechless! What a very cool concept!

    If a mount(s) could be designed to fine tune the mirror angles and insertion into the beam then this would be an awesome way to tame these crazy diodes.

    In theory you could do this a couple of times on the same beam. What is so elegant about this solution is the flatter the beam, the more you could use its width to thicken up the height of the output beam.

    Very impressed

  2. #42
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    Quote Originally Posted by loopee View Post
    Couldn't you also do it this way and remove the need for the waveplate
    Now that is a GREAT idea!

    If these were available why couldn't we use them for 650nm and other diodes that need beam improvement?

    All we need now is someone to do R&D and build some.

    Gene

  3. #43
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    Quote Originally Posted by Phredy1 View Post
    Now that is a GREAT idea!

    If these were available why couldn't we use them for 650nm and other diodes that need beam improvement?

    All we need now is someone to do R&D and build some.

    Gene
    650 beams are pretty much square, splitting and recombining them would leave you with... another square...

  4. #44
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    Gentlemen (and ladies)

    #1: cant use a dichro. Gonna have to be a PBS. dichro cant pass 445 and also reflect it. Gonna have to be one or the other.

    #2- This all reminds me of that guy "Rube, or ruge, or crap...i always forget his name) the guy who makes enormously complex machines to accomplish simple tasks. Frank nailed it above. If you really want a round, small nnice tight beam, shoot it through a pinhole. simple, quick, easy, cheap. 2 watts of blue costs what, $400, $500 in a home brew? Shoot it through the hole and lose some power and get a perfect beam.

    what the heck is that guys name...its driving me nuts now!!!

    -Marc
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  5. #45
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    rube goldberg

    one of the only proper names in the dictionary too

    also I dont think he meant dichro... could be a H/V combine optic... I got one one from junktronix with my 2 CNI reds... looks like a dichro but passes one polarization and reflects another just like a PBS.... it was just easier to deal with a PBS in my setup

  6. #46
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    loopee,
    I'm not sure I understand how this helps. The problem with the 445 diode beam after the collimnator is that the small dimension is the divergent axis. Cutting and stacking in the near field won't solve this.

  7. #47
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    Quote Originally Posted by loopee View Post
    Couldn't you also do it this way and remove the need for the waveplate

    Basically split and stack using four HR mirrors

    Attachment 19666Attachment 19665Attachment 19664

    Attachment 19667Attachment 19669Attachment 19668

    In this configuration you are splitting the Slow Axis in half and stacking it. This does absolutely nothing for correcting the fast axis. In fact it would make it worse because at a distance your fast axis will still diverge to the same size, but your slow axis is now half the width. You just went from a rectangle at a distance, to a skinnier more obvious rectangle...
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  8. #48
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    Quote Originally Posted by laserkits View Post
    In this configuration you are splitting the Slow Axis in half and stacking it. This does absolutely nothing for correcting the fast axis. In fact it would make it worse because at a distance your fast axis will still diverge to the same size, but your slow axis is now half the width. You just went from a rectangle at a distance, to a skinnier more obvious rectangle...
    Not to make a stupid remark here, but why can't we split at the fast axis by just turning the whole lot 90 degrees on its side?

    It may be more rubbish in the near field but the beam would be a lot more symmetrical in the far field.

    Also, keep in mind that a retro bouncer turns the entire BEAM on its side, not just shift polarization like a 1/2 wave plate would. So you'd have a set of fast axes going in either direction: The rectangle would not be more thin and obvious, but it would become a cross.

  9. #49
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    Quote Originally Posted by Stoney3K View Post
    The rectangle would not be more thin and obvious, but it would become a cross.
    Not so in this example, which is the one I was speaking about.
    http://www.photonlexicon.com/forums/...chmentid=19664
    http://www.photonlexicon.com/forums/...chmentid=19668
    In this configuration the retro bouncer has taken one half of the slow axis, turned it 180 degrees about its axis (not 90) and then stacked it with the remaining half of the slow axis. In this configuration you will have a skinnier rectangle at a distance than you would if you did nothing at all... The aspect ratio of the diverged beam has increased, not decreased, so this has made the beam worse and not fixed anything...
    You have to remember that you are working in the near field of the laser here. The divergent or "fast" axis is the skinny one.

    The Beam exits the diode like this:

    IIIIIIIIIIIIIIIIIII

    At a short distance it diverges to this:

    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII

    And at a long distance it diverges to this:

    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII
    IIIIIIIIIIIIIIIIIII

    Of course there is also some divergence in the slow axis so the above diagram is not exact, but shows how the beam changes over distance.
    Last edited by laserkits; 09-29-2011 at 05:40.
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  10. #50
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    Default Additional from Lasever

    Quote Originally Posted by Saarlaser View Post
    Greetings from Germany

    This will work. It is like to have 2 500mw diodes, with half size emitter of that of 1w. Then you couple them by a PBS.
    But the polarization is lost. We need the polarization for coupled into higher power.

    A thought from Lasever.

    (Our 445nm 1w is 2x4mm with 2-3x0.5mRad.)


    David
    Last edited by Lasever; 09-29-2011 at 07:08.
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