A new algorithm to reveal the order and sign of fringes formed by dual-beam electronic speckle-pattern interferometry is described. When combined with a previously reported phase-extraction method, it makes possible the evaluation of displacement absolutely and continuously over the entire surface of the object from a total of five frames. This technique is particularly useful when displacement is spatially discontinuous and temporally fast and the amount of data is large. A model experiment showing the validity of this method is presented. (C) 1997 Optical Society of America
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