Patent Number: 7,826,063

Title: Compensation of effects of atmospheric perturbations in optical metrology

Abstract: In general, in a first aspect, the invention features a method that includes using an interferometry assembly to provide three different output beams, each output beam including an interferometric phase related to an optical path difference between a corresponding first beam and a corresponding second beam, each first beam contacting a measurement object at least once, monitoring the interferometric phases for each of the three different output beams, and deriving information about variations in the optical properties of a gas in the first beam paths from the three monitored phases.

Inventors: Hill; Henry A. (Tucson, AZ)

Assignee: Zygo Corporation

International Classification: G01B 11/02 (20060101)

Expiration Date: 2019-11-02 0:00:00