ワンステップ位相シフト法を用いたアブラムソン干渉計による表面形状計測

概要

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An Abramson interferometer has been known as one type of oblique incidence interferometers. It can record an interferogram for rough or uneven nonoptical surfaces. However for a fringe analysis, a conventional multi-step phase shifting method has difficulties in applying to this interferometer because of quasi-common path arrangement in optics. For the solution of this problem, the Abramson interferometry using a one-step phase shifting method is proposed. For practical applications, two problems are overcome in this interferometer, elimination of the influence of multi-reflection and decreasing of error due to deviation from the reference carrier frequency are proposed in this one-step phase shifting method. A spatial filter is set up in optics and a revised algorithm in one-step phase shifting method is proposed. An experiment is made for demonstrating availability of this method using a Si wafer.
1998-09-05