• US 20050046856A1
  • Filed: 09/30/2003
  • Published: 03/03/2005
  • Est. Priority Date: 11/17/2000
  • Status: Active Grant
First Claim
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1. A wavemeter for a high repetition rate gas discharge laser having a laser output beam comprising a pulsed output of greater or equal to 15 mJ per pulse, sub-nanometer bandwidth tuning range pulses having a femptometer bandwidth precision and tens of femptometers bandwidth accuracy range, for measuring bandwidth on a pulse to pulse basis at pulse repetition rates of 4000 Hz and above, comprising:

  • a focusing lens having a focal length;

    an optical interferometer creating an interference fringe pattern;

    an optical detector positioned at the focal length from the focusing lens;

    a bandwidth calculator calculating bandwidth from the position of interference fringes in the interference fringe pattern incident on the optical detector, defining a DID and a DOD, the respective distances between a pair of first fringe borders and between a pair of second fringe borders in the interference fringe pattern on an axis of the interference pattern, and according to the formula Δ





    D02], where λ

    0 is an assumed constant wavelength and D0=(DOD

    DID)/2, and f is the focal length.

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