Determination of two-dimensional phase shifts in three-beam laser interference patterns

This paper describes a method of determining two-dimensional phase shifts. In this method, the two-dimensional phase shift is divided into horizontal and vertical components, and each component of the phase shift is determined by pattern correlation, Pythagorean theorem and linear interpolation with subpixel accuracy. The computer simulation and experiment have shown that the method is useful for the determination of phase difference between two three-beam interference patterns. The method can also be used to determine the phase shift in other multi-beam interference patterns.