Deformation measurement by digital speckle pattern interferometry using holographically recorded object in LiNbO3 as a reference

Abstract

A new method, to the best of our knowledge, in digital speckle pattern interferometry is introduced. It depends on extending the applicability of using LiNbO3 crystal as a holographic recording medium for the evaluation of the difference in displacement between two similar objects (master and test), and displaying the comparison result in the form of an interference pattern. The method is a two-stage process. In the first stage, two states (un-displaced and displaced states) of the master object are recorded in a LiNbO3 crystal using the usual holographic arrangement. In the second stage, various phase stepping algorithms are applied, using the reconstructed wavefronts of the master object as a holographic optical element to produce a reference wave field in the comparison process. Recording and analysis of the difference correlation fringes are performed using the phase wrapping algorithm and real experiment.