Phase extraction in digital speckle pattern interferometry using variational mode decomposition and high-order ambiguity function

Digital speckle pattern interferometry (DSPI) is an optical measurement technique for deformation detection of composite materials. In this techniques, the traditional phase extraction method requires unwrapping, which leads to the reduction of measurement sensitivity. Therefore, a new phase extraction method based on variational mode decomposition (VMD) and high-order ambiguity function (HAF) is proposed in this paper. Firstly, the CCD camera is used to collect the speckle image before and after the deformation of the object, and a series of inherent mode components are obtained by VMD. Secondly, a de-noising method based on normal distribution is proposed to extract the components containing fringe information and reconstruct it to obtain the reconstructed speckle image. Finally, the phase of the reconstructed speckle pattern is calculated by HAF method and the deformation information of the composite materials is obtained by using the phase map. The measurement results show that the proposed method can extract phase map directly without the requirement of unwrapping.