Patent ID: 6882432
Filing Date: 2005-04-19
Classification: G01B

Abstract:
1. An interferometry method for characterizing a test object, the method comprising: forming an optical interference image by combining different portions of an optical wave front reflected from multiple surfaces of the test object and at least one reference surface, the multiple surfaces of the test object and the at least one reference surface defining a set of cavity surfaces; recording an interference signal at different locations of the optical interference image in response to tuning the frequency of the optical wave front over a range of frequencies, wherein the interference signal includes a contribution from each pair of different surfaces in the set of cavity surfaces; for each location, calculating a frequency transform of the interference signal at a frequency corresponding to each of selected pairs of the different surfaces in the set of cavity surfaces and extracting the phase of the frequency transform at each of the frequencies corresponding to the selected pairs of surfaces; and determining at least one of i) a surface profile of at least one of the test object surfaces and ii) a relative optical thickness profile between two of the test object surfaces, based on at least some of the extracted phases.