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Compensation for geometric effects of beam misalignments in plane mirror interferometers

  • US 7,330,274 B2
  • Filed: 05/13/2003
  • Issued: 02/12/2008
  • Est. Priority Date: 05/13/2002
  • Status: Expired due to Fees
First Claim
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1. A method comprising:

  • using an interferometer in an interferometry system to produce an output beam comprising a phase related to an optical path difference between paths of two beams, at least one of which contacts a measurement object in the interferometry system, wherein the two beams are derived from an input beam and the interferometer comprises interferometer optics spaced from the measurement object;

    providing precalibrated information that accounts for contributions to the optical path difference caused by a deviation of at least one of the beam paths from a nominal beam path due to an imperfection in at least one of the interferometer optics or an imperfection in a light source used to produce the input beam;

    determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and the precalibrated information; and

    moving the measurement object with respect to the interferometer based on the determined position.

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