Patent Number: 8,797,537

Title: Interferometer with a virtual reference surface

Abstract: An imaging interferometer includes optics defining an interferometric cavity, in which the optics include a first beam-splitting optic positioned to separate an input beam into a test beam and a reference beam, a second beam-splitting optic positioned to transmit the test beam to the test surface, receive the test beam back from the test surface, and thereafter recombine the test beam with the reference beam, and a third optic positioned to direct the reference beam from the first optic to the second optic. The interferometric cavity defines a virtual reference surface positioned along a path for the reference beam between the second and third optics. The interferometer also includes an imaging channel positioned to receive the recombined test and reference beams, where the imaging channel includes an imaging detector, and at least one imaging element configured to image the test surface and the virtual reference surface onto the detector.

Inventors: Freischlad; Klaus (Tucson, AZ)

Assignee: Zygo Corporation

International Classification: G01B 9/02 (20060101)

Expiration Date: 8/05/12018