Patents by Inventor Reed A. Christenson

Reed A. Christenson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • System and method for compensating polarization-dependent sensitivity of dispersive optics in a rotating analyzer ellipsometer system
    Patent number: 5521706
    Abstract: An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.
    Type: Grant
    Filed: June 24, 1994
    Date of Patent: May 28, 1996
    Assignee: J. A. Woollam Co. Inc.
    Inventors: Steven E. Green, Shakil A. Pittal, Blaine D. Johs, John A. Woollam, David W. Doerr, Reed A. Christenson
  • System and method for compensating polarization-dependent sensitivity of dispersive optics in a rotating analyzer ellipsometer system
    Patent number: 5504582
    Abstract: An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a stationary compensator, positioned between an analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The use of a light fiber to carry light from a source thereof, to a polarization state generator, is also disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.
    Type: Grant
    Filed: November 14, 1994
    Date of Patent: April 2, 1996
    Assignee: J. A. Woollam Co. Inc.
    Inventors: Blaine D. Johs, Shakil A. Pittal, Steven E. Green, John A. Woollam, David W. Doerr, Reed A. Christenson
  • Ellipsometer
    Patent number: 5373359
    Abstract: To sense characteristics of a sample, an ellipsometer includes a pivotal diffraction grating positioned to receive white light from the analyzer without further focusing of the light after the light leaves the sample. The diffraction grating is focused on the sensor at a predetermined angle with a precision of at least plus or minus one-half degree using an alignment-sensing means positioned between the analyzer and diffraction grating. The sensor includes an aperture through which the incident beam of light is transmitted, light-sensitive areas on opposite sides of said sensor and a comparator for comparing the signal from said light-sensitive areas. Equality of the light from the light-sensitive areas indicates that the incident beam of light is perpendicular to the diffraction grating.
    Type: Grant
    Filed: September 18, 1992
    Date of Patent: December 13, 1994
    Assignee: J. A. Woollam Co.
    Inventors: John A. Woollam, Blaine D. Johs, David W. Doerr, Reed A. Christenson