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Film measurement system with improved calibration

  • US 5,771,094 A
  • Filed: 01/29/1997
  • Issued: 06/23/1998
  • Est. Priority Date: 01/29/1997
  • Status: Expired due to Term
First Claim
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1. A method for measuring one or more films of a sample, comprising the steps of:

  • directing a beam of broadband radiation towards the sample such that radiation from the beam modified by the sample includes at least one persistent wavelength marker;

    detecting intensity of radiation of spectral components from the beam that is modified by the sample to measure the one or more films at a plurality of wavelengths in the broadband simultaneously by means of a first detector array of multiple pixels, said array having been calibrated with respect to a calibration function and having a prior pixel position of the marker associated with the calibration function;

    determining a current pixel position of the at least one persistent wavelength marker from the beam that is modified by the sample; and

    correcting said calibration by reference to said prior and current pixel positions of the at least one persistent wavelength marker.

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