Microscopic Coordinate Measurement by Four-beam Laser Interferometry

Abstract

A new method for measuring the three-dimensional coordinate of a microscopic scanning stage is proposed. Four laser interferometers linked with optical fibers are used to determine the position of the corner point of a corner mirror attached to the stage. The three-dimensional coordinate of the corner point is calculated by using only the length information given by the four laser interferometers. The method is traceable from the practical definition of length, and facilitates the optical alignment necessary to the interferometers. A commercial three-dimensional stage is calibrated by the proposed method with the coordinate accuracy of 20-30 nm.