Quantitative Determination of Displacements and Strains from Holograms

In this chapter, procedures for quantitative determination of displacements and strains directly from holograms are presented. This presentation begins with the definition of projection matrices and discussion of their application in holographic analysis. Then, system geometries used for recording and reconstruction of holograms are defined in terms of the illumination, observation, and sensitivity vectors. This is followed by a discussion of determination of displacements for the cases when the fringe order is known, when the fringe order is unknown, and when multiple holograms are used. Next, the fringe-vector method, relating the holographically determined strains and rotations to the object surface via the projection matrices based on the object’s local surface normals, is outlined. Finally, recent advances in electronic acquisition, storage, processing, and display of optical interference information is discussed and their implementation in quantitative measurements of displacements, due to static and dynamic loading conditions, is illustrated with representative examples.