Research on image filtering algorithm used for laser speckle pattern interferometry deformation measurement

Laser speckle pattern interferometry is a kind of high-precision deformation measurement method by analyzing images of speckle patterns. Deformation of measured object can cause phase change of laser light reflected by the object and speckle fringe can be formed. The background noise is large and the phase jump is not clear in the image of speckle fringe. According to the character of the image, a kind of two-step filtering algorithm is used to enhance image quality. First, adaptive filtering algorithm is used to process original speckle fringe image. And then after three-dimensional phase image is formed by phase unwrapping of the speckle fringe phase image, mean smoothing filtering is used to reduce burr in three-dimensional phase image. The experimental results show that this two-step filtering algorithm can keep detail information in the speckle fringe image and get good deformation measurement results.