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Abstract

The invention features an interferometry system for a measuring a surface profile or thickness of a measurement object. In one aspect, the interferometry system includes: a broadband infrared source which during operation generates broadband infrared radiation including central wavelengths greater than about 1 micron; a scanning interferometer which during operation directs a first infrared wavefront along a reference path and a second infrared wavefront along a measurement path contacting the measurement object, and, after the second wavefront contacts the measurement object, combines the wavefronts to produce an optical interference pattern, the first and second infrared wavefronts being derived from the broadband infrared radiation; a detector producing data in response to the optical interference pattern; and a controller which during operation causes the scanning interferometer to vary the optical path difference between the reference and measurement paths over a range larger than the coherence length of the broadband source and analyzes the data as a function of the varying optical path difference to determine the surface profile.

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First Claim