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Thread: Narrowing 635nm

  1. #1
    Join Date
    Apr 2010
    Grand Rapids, Mi

    Default Narrowing 635nm

    Wondering what happens to LASER light if shaped with a simple drilled hole in a piece of black anodized aluminum. I can't believe what a brick 635 throws out at 100', I really like the color of the center point where they all converge. I could easily give up the power and be happy with the color balance if the fat beam could just be masked more narrow. Could someone help me understand what happens as i'm sure it isn't this simple.


    leading in trailing technology

  2. #2
    Join Date
    Dec 2008


    The fat beam isn,t the only problem with the fat beam but also the divergence. Shrinking the beam with a telescope would increase the already huge divergence so that,s not an option. If you do only beamshows a set of scanners with bigger mirrors would be the best option. That in combination with a 445 and an aixize lens gives more or less the same beamdiameter.

  3. #3
    Join Date
    Sep 2006


    Simple optics: If the image you project at infinity is too large, you can reduce (mask off ) your original with loss off power.

    Just like knife edging: you can use it to lay beams on top of each other, but you can also use it to clip off unwanted parts of your beam.

  4. #4
    Join Date
    Jan 2006
    Charleston, SC


    Best bet is to build a 1:1 keplerian collimator (that is, both lenses are the same size and focal length) and place the pinhole plate at the focal point in the center. Then move the pinhole towards the laser (towards the first lens) and you'll begin masking the beam. Stop when you have the ideal balance between beam diameter and power for your application.

    Be prepared to lose 10-20% power across the lenses, and that doesn't even begin to account for the loses when you start moving the pinhole.


  5. #5
    Join Date
    Aug 2010
    London or Spain depending on the weather


    Seems to me that you are going to have to bite the bullet.
    If you mask as Buffo suggested you can focus at whatever distance you like but as Edison points out you will need big scanner mirrors (which will slow you down) AND get huge losses.

    Alternatively you can always go back to huge gas lasers or pay a small fortune for high end diodes from the big companies.

    Basically when collimating as with interferometry "what starts big ends up small and vice versa!

    Good luck
    Last edited by catalanjo; 08-09-2010 at 22:58. Reason: Buffo instead of Bart + addenda

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