The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 28, 1995
Filed:
Sep. 21, 1992
Chris L Koliopoulos, Tucson, AZ (US);
Shouhong Tang, Tucson, AZ (US);
Phase Shift Technology, Inc., Tucson, AZ (US);
Abstract
A sheet flatness measuring system consists of a frame carrying a structured illumination system for producing illumination beneath the frame in a periodic pattern of opaque and illuminated lines. A flat base or table, having a surface parallel to the structured illumination system, is placed beneath the structured illumination system to be illuminated by it. A sheet of reflective or semi-reflective material, the flatness of which is to be measured, is placed on the table. The reflection of the structured illumination is viewed from the sheet a by video camera, typically mounted in a central location above the center of the table on which the sheet is placed. The structured illumination pattern is moved to different positions, and multiple video images are digitized and compared in a computer to calculate the local slope at each point or pixel in the image of the sheet viewed by the camera. From this slope information, the computer derives an output representative of variations in the surface flatness of the sheet undergoing measurement.