title: Two-color interferometer for surface characterization using two frequency doublers and a four-phase-step method.
abstract: A high-accuracy, two-color interferometer for characterizing a processed surface is described. It is composed of two frequency doublers. It is not affected by air turbulence and mechanical vibration because it is a complete common-path interferometer, and the effects from different reflectivities of various materials are canceled by a four-phase-step technique that shifts the phase of the interference fringe in steps of π/2. The processed surface is measured with subnanometer resolution.
authors.forename: H
authors.initials: H
authors.lastname: Matsumoto
authors.forename: L
authors.initials: L
authors.lastname: Zeng