Internal defect detection method based on dual-channel speckle interferometry

A novel dual-channel speckle interferometry based on a monochromatic camera is proposed to quantitatively characterize internal defects in materials. The sensor of the monochromatic camera is divided into two independent and simultaneous imaging channels by integrating dual-biprism and dichroic filters. The combination of electronic speckle pattern interferometry and digital shearography allows for the simultaneous measurement of out-of-plane displacement and slope. The [4+1] phase-shifting algorithm is employed to dynamically detect of the sequential phase. The effectiveness and accuracy of the proposed method are verified by testing a centre-loaded circular plate. Furthermore, the developed system performs non-destructive testing on a thin metallic plate with internal defects. The experimental results show that the proposed method can successfully localize and detect internal defects.