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Engraving laser machine with a lens

  1. Jul 17, 2013 #1
    I have a laser beam(engraving laser machine) and then use a lens for focus the beam but my lens has a crack on the center of lens and when i use my laser in high power the beam diameter will bigger and burning area zone is bigger so:
    1- Does the crack doesn't let the maximum focus?in law or high power?
    2-1- I if i use two lenses with a exact distance, does the final beam diameter will be smaller than one lens?
    2-2- Does the focus distance will be double?
    2-3- Does the power will be double?
    2-4- does a real distance(focus distance) between two lenses is necessary? if i put the second lens in focus distance of first lens, it will broken or not?

    I am wait for your help.

    Thank you
  2. jcsd
  3. Jul 17, 2013 #2


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    The crack will probably be full of air which has a different refractive index to the glass the lens is made of. So it's possible to get reflections and scattering off the surface of the crack.
  4. Jul 17, 2013 #3


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    The crack is always a deviation from the ideal shape. Sure.

    Not necessarily, but it is possible.
    Depends on the lenses (in general: no).
    Energy conservation? ...

    If the laser intensity is sufficient, you can even heat lenses (which are designed to let most light through it), sure.
  5. Jul 18, 2013 #4

    Andy Resnick

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    You should replace the lens.
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