A DSSPI phase unwrapping method for improving the detection efficiency of CFRP-reinforced concrete defect

Digital shear speckle pattern interferometry is a non-destructive detection method for non-contact measurement of object deformation and defects in an entire field. In recent years, this technology has been widely applied in the field of non-destructive detection of concrete. However, the defect detection of this technology usually requires steps such as stripe processing, phase extraction, phase filtering, and phase unwrapping, which are cumbersome and reduce detection efficiency. Therefore, this paper proposes a method to unwrap the noisewrapped phase directly. Combining the Zernike polynomial and the wrapped Kalman filter, the phase unwrapping is transformed into the problem of solving the fitting coefficient in the noise-wrapped phase, thereby reducing the detection steps and improving the detection efficiency. In this paper, the unwrapping applicability and robustness of the algorithm are verified through simulation and experiment, and the algorithm's performance for unwrapping the noise wrapping phase is verified by comparative experiments in the actual environment for the first time. The results show that the algorithm has the best phase unwrapping effect (RMSE = 0.0168 rad, Time = 5.18 s), reflecting its advantages compared to traditional phase unwrapping methods. At the same time, the algorithm was applied to the internal defect detection of CFRP-reinforced concrete, and the detection results show that the algorithm can effectively detect the location of internal defects, providing a new detection approach for non-destructive detection of concrete.