Sign determination to measure non-monotonous displacements in temporal speckle pattern interferometry without a temporal carrier

Abstract

In this paper, we present a generalized function to automatically detect the correct sign of non-monotonous displacements in temporal speckle pattern interferometry without the introduction of a temporal carrier in the optical setup. This approach can be used with any phase retrieval technique. Here, when the phase change is evaluated, the sign ambiguity is resolved due to a function that determines the correct sign of the displacement between two consecutive speckle interferograms. The errors introduced by the proposed function are determined using computer-simulated speckle interferograms, and its performance is analyzed using three phase recovery techniques and different phase distributions and average speckle sizes. A relation between the sliding window used to compute the correct sign and the speckle sizes is also presented. Finally, the presentation is illustrated with an experimental application of the proposed method to detect the correct sign of the out-of-plane displacement field of a metal plate.