Measurement of non-monotonous phase changes in temporal speckle pattern interferometry using a correlation method without a temporal carrier

• Measurement of non-monotonous displacements using a correlation method without a temporal carrier in TSPI systems.
• The sign ambiguity is resolved due to the introduction of a function that gives the correct sign of the displacement.
• The performance of the method is determined through a numerical analysis.
• Results are also compared with those obtained using the Fourier Transform technique.
• Results obtained from the processing of experimental data are finally presented.

Recently, a phase evaluation method was proposed to measure nanometric displacements by means of digital speckle pattern interferometry when the phase change introduced by the deformation is in the range [0,π) rad. This method is based on the evaluation of a correlation coefficient between two speckle interferograms generated by both deformation states of the object. In this paper, we present a novel technique to measure non-monotonous displacements in temporal speckle pattern interferometry using a correlation method without a temporal carrier. In this approach, the sign ambiguity is resolved automatically due to the introduction of a function that determines the correct sign of the displacement between two consecutive speckle interferograms. The rms phase errors introduced by the proposed method are determined using computer-simulated speckle interferograms. An application of the phase retrieval method to process experimental data is also presented.