Simplified carré's method for phase extraction

Abstract

A phase-shifting algorithm for speckle patterns with a constant but unknown phase shift is proposed. The algorithm is based on the well known Carré's method. Prior to applying the phase-shifting algorithm a speckle pattern background is removed. In this process, manual intervention is minimal and high computational speed is achieved. In addition, high-frequency phase signal would not be filtered out in the noise reduction process as is the case in band-pass filtering technique. Its validity is tested on the deformation measurement using digital speckle shearing interferometry (DSSI).