Comparative Method Of Fringe Evaluation For Electronic Speckle Pattern Interferbmetry

A new method is proposed for the fringe evaluation in electronic or digital speckle pattern interferometry (ESPI or DSPI). A series of interferometric speckle patterns, at least three, are recorded and stored during the deformation of the object. The subtraction of each two of the speckle patterns gives the correlation fringes corresponding to the deformation between the two exposures. These correlation patterns are interrelated. The phase differences between each two exposures can be determined by comparing the phase relationship between these correlation fringe patterns. The method is suitable for dynamic or large deformation measurement. The principle of this method is discussed and the computer simulation and experimental results are given.