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:
Jul. 18, 1989
Filed:
Oct. 24, 1983
Cheng-Chung Huang, Sunnyvale, CA (US);
Lockheed Missiles & Space Company, Inc., Sunnyvale, CA (US);
Abstract
Two optical beams of different frequencies are focussed as concentric spots, one spot being larger than the other, on a reflective surface whose roughness is to be measured. The smaller spot has a maximum dimension that is smaller than any significant deviation of the profile of the surface from spatial uniformity, and the larger spot has a minimum dimension that is larger than any significant deviation of the surface profile from spatial uniformity. The two beams are reflected from the surface along a common path with a phase difference that is measured by a heterodyne interferometric technique. The phase difference measurement is indicative of the roughness of the surface, and is substantially insensitive to vibration of the surface.