Patents Assigned to Ann Koo
  • Film stress measurement system having first and second stage means
    Patent number: 5118955
    Abstract: A system for measuring the curvature of a surface includes a laser for emitting a beam of light to be incident upon the surface; a photodetector for detecting light reflected by the surface; a first stage for selectively moving the surface in a direction normal to the direction of the incident beam; a second stage for selectively moving the photodetector in a direction normal to the reflected beam; a sensor connected to the photodetector for detecting the displacement of the reflected beam relative to the photodetector.
    Type: Grant
    Filed: May 26, 1989
    Date of Patent: June 2, 1992
    Assignee: Ann Koo
    Inventor: David Cheng