Sign determination in temporal speckle pattern interferometry without using a temporal carrier

Abstract

In this paper, we present a novel method to detect the correct sign of non-monotonous displacements in temporal speckle pattern interferometry without the introduction of a temporal carrier in the optical setup. The present work is based on a previous one, where the sign ambiguity is eliminated due to a function that determines the correct sign of the displacement between two consecutive speckle interferograms. Although that approach does not need the introduction of a phase-shifting facility orspatial carrier fringes in the optical setup, the intensities of the object and the reference beams must be recorded separately, which complicates the application of this method for the analysis of non-repeatable dynamic phenomena. Here, the proposed function can be applied when the displacement fields between the successive frames are in the nanometer range, and there is no need to acquire the intensities of the object and the reference beams. The performance of the proposed function and its limitations are determined using computer-simulated speckle interferograms. Finally, an experimental application of the proposed method is also illustrated.