Patents by Inventor Shakil A. Pittal

Shakil A. Pittal 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).

  • Patent number: 5805285
    Abstract: Disclosed is a dispersive optics system, in the context of sample substrate system investigating spectroscopic reflectometer and the like systems, which, in use, produce a plurality of "Orders" of essentially single wavelength beams of light from a polychromatic beam of light. In use the availability of more than one "Order" of essentially single wavelength beams of light allows simultaneous measurement of more essentially single wavelength beams of light, over a larger range, than would be possible were only one "Order" of essentially single wavelength beams of light present. Filters are present to reduce the effects of stray light on detector elements and to allow separating the wavelengths in overlapping regions of adjacent Orders. Also disclosed is a quadrant detector means of dispersive optics alignment, and a compensator means for reducing the effect of detector element polarization state dependence.
    Type: Grant
    Filed: March 17, 1997
    Date of Patent: September 8, 1998
    Assignee: J.A. Woollam Co. Inc.
    Inventors: Blaine D. Johs, Ping He, Steven E. Green, Shakil A. Pittal, John A. Woollam
  • Patent number: 5666201
    Abstract: Disclosed is a dispersive optics system, in the context of ellipsometer or polarimeter and the like systems, which, in use, produces a plurality of "Orders" of essentially single wavelength beams of light from a polychromatic beam of light. In use the availability of more than one "Order" of essentially single wavelength beams of light allows simultaneous measurement of more essentially single wavelength beams of light than would be possible were only one "Order" of essentially single wavelength beams of light present. Filters are present to reduce the effects of stray light on detector elements and to allow separating the wavelengths in overlapping regions of adjacent Orders.
    Type: Grant
    Filed: September 20, 1995
    Date of Patent: September 9, 1997
    Assignee: J.A. Woollam Co. Inc.
    Inventors: Blaine D. Johs, Ping He, Steven E. Green, Shakil A. Pittal, John A. Woollam
  • 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
  • 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