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Interferometer calibration methods and apparatus

  • US 7,110,122 B2
  • Filed: 07/21/2004
  • Issued: 09/19/2006
  • Est. Priority Date: 07/21/2004
  • Status: Expired due to Fees
First Claim
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1. A method for calibrating an interferometer having first and second reflecting surfaces and an optical gap between the first and second reflecting surfaces, the method comprising the steps of:

  • a) providing an actuator adapted to control the optical gap in response to application of an electrical signal;

    b) illuminating the interferometer with a beam of substantially monochromatic light having a predetermined wavelength, the beam being oriented at a first predetermined angle of incidence to at least one of the first and second reflecting surfaces;

    c) detecting light reflected from the interferometer at a second predetermined angle to the at least one of the first and second reflecting surfaces while varying an electrical signal applied to the actuator, thereby establishing a calibrated relationship between the applied electrical signal and an optical path length of the interferometer; and

    d) correcting the calibrated relationship for application to subsequently incident light having at least one second angle of incidence differing from the first predetermined angle of incidence.

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