Patent Number: 7,102,761

Title: Scanning interferometry

Abstract: An interferometry method includes: imaging test light reflected from at least a first portion of a test surface to interfere with reference light on a camera and form an interference pattern, wherein the imaging defines a depth of focus for the light reflected from the test surface, and wherein the test light and reference light are derived from a common source; varying an optical path length difference between the test light and reference light over a range larger than the depth of focus, wherein the optical path length difference corresponds to a difference between a first optical path between the common source and the camera for the test light and a second optical path between the common source and the camera for the reference light; and maintaining the first portion of the test surface within the depth of focus as the optical path length difference is varied.

Inventors: De Lega; Xavier Colonna (Middletown, CT), Grigg; David A. (Glastonberry, CT), De Groot; Peter J. (Middletown, CT)

Assignee: Zygo Corporation

International Classification: G01B 9/02 (20060101)

Expiration Date: 9/05/02018