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:
Oct. 31, 2006
Filed:
Jun. 19, 2003
Joseph C. Marron, Ann Arbor, MI (US);
Joseph C. Marron, Ann Arbor, MI (US);
Light Gage, Inc, Bloomfield, NY (US);
Abstract
Frequency-scanning interferometry is applied to common-path interferometers for measuring topographical features of test objects. A reference element located adjacent to a test object functions as both a beamsplitter and a reference surface. A first portion of a measuring beam reflects from the reference surface of the reference element as a reference beam, and a second portion of the measuring beam transmits through the reference element to and from a surface of the test object as an object beam. Both beams are conveyed along a common path to a detector that records a plurality of intensity variations produced by constructive and destructive interference between localized portions of the object and reference beams associated with different transverse coordinates on the test object surface. An illumination frequency of the measuring beam is incrementally modified through a range of different frequencies sufficient to alternate the intensity variations between conditions of constructive and destructive interference, which occur at modulation frequencies sensitive to path length differences between corresponding points on the surfaces of the test object and reference element.