Phase step calibration and phase measurement in image plane holography using BaTiO3 crystal as a recording medium

Abstract

A real-time visual approach for the calibration of phase step in image plane holography using BaTiO₃ crystal as a recording medium is reported. In this method, the diffuse object is illuminated symmetrically with two collimated beams and a pump beam is added at the crystal plane. Each illuminating beam generates an individual interferogram at the observation plane when the object is subjected to load. A π phase shift to one of the illuminating beams results in the complete disappearance of the fringes due to phase reversal between the individual interferograms, and at 2π phase change, the fringe pattern is restored. After calibration, a single-beam illumination configuration is used for phase measurement. We present the theory of the method and experimental results for a centrally loaded diaphragm rigidly clamped along the periphery. © 1998 Society of Photo-Optical Instrumentation Engineers.