DUAL-PLATE SPECKLE PHOTOGRAPHY DATA-PROCESSING ALGORITHM

In dual-plate speckle photography, the images corresponding to both de formation states are recorded on separate photographic plates. In this way, two major limitations of speckle photography, large rigid body d isplacements of the specimen and the 180-deg displacement direction am biguity, can be overcome, When both photographic plates are placed wit h the glass base of one of them between the emulsions and they are ill uminated by a narrow laser beam, a pattern of circular fringes is gene rated. Displacements can be measured by evaluating the distance betwee n the center of the fringe pattern and the undiffracted laser beam. A new algorithm for the fully automatic analysis of such fringe patterns is presented. Its performance is tested using computer-simulated frin ges and compared with performance obtained using a previously develope d algorithm.