Use of Reflection Holograms in Holographic Interferometry and Speckle Correlation for Measurement of Surface-displacement

Abstract

When a special case of a Denisyuk set-up [1] is used for double-exposure holographic interferometry, namely, with the photographic plate fixed to one point of the object under study and plane illumination through the plate, some interesting advantages can be obtained. The stability requirements are drastically reduced (a general translation and a rotation around an axis parallel to the illumination direction can be allowed); the optical set-up is very simple; white-light reconstruction can be used. For the determination of in-plane displacement patterns, one can either use fringe-order subtraction between two symmetrical off-axis views (eventually Moire subtraction), or use speckle correlation techniques. The most important advantage is that Cartesian components of displacements can be determined with complete object motion compensation by combining holographic and speckling techniques. Some practical applications of the method and its drawbacks are presented.