Patent ID: 7417743
Filing Date: 2008-08-26
Classification: G01B

Abstract:
1. Apparatus comprising: an interferometer comprising a main cavity and an auxiliary reference surface, the main cavity comprising a partially reflective surface defining a primary reference surface and a test surface, the interferometer being configured to direct a primary portion of input electromagnetic radiation to the main cavity and an auxiliary portion of the input electromagnetic radiation to reflect from the auxiliary reference surface, wherein a first portion of the primary portion in the main cavity reflects from the primary reference surface and a second portion of the primary portion in the main cavity passes through the primary reference surface and reflects from the test surface, the interferometer being further configured to direct the electromagnetic radiation reflected from the test surface, the primary reference surface, and the auxiliary reference surface to a multi-element detector to interfere with one another to form an interference pattern, wherein the auxiliary reference surface is tilted so that the paths of the electromagnetic radiation reflected from the primary reference surface and auxiliary reference are non-parallel at the multi-element detector.