Single-frame temporal phase-shifting shearography for real-time nondestructive testing

Abstract

Shearography, which is an effective nondestructive testing (NDT) tool, can detect internal defects of composites materials. Temporal phase-shifting (TPS) shearography has a simple setup and high accuracy. It is suitable for quasi-static detection because it requires the acquisition of a sequence of speckle patterns before and after specimen deformation. To achieve dynamic shearographic NDT, this study adopted high-frequency synchronous driving mode of camera and piezoelectric transducer (PZT) phase shifter to generate and acquire phase-shifted patterns. Subsequently, a single frame TPS shearography requiring one phase-shifted pattern in the deformed state was proposed. Finally, using parallel computing technology and efficient approximations of arctangent function, a real-time four-step TPS shearographic NDT technique with high-quality phase imaging was developed. The experimental results demonstrate the effectiveness and robustness of the proposed method. The results show that the proposed method could reach a rate of approximately 24 fps (frames per second) at the spatial resolution of megapixels for defect detecting.