Measurement of out-of-plane first-order displacement derivatives in orthogonal shear directions using dichroic mirrors

This work proposed a temporal phase-shift digital shearography system for simultaneous measurement of first-order displacement derivative in orthogonal shear directions. Dual lasers with wavelengths of 532 and 637 nm, three splitter prism structure, two dichroic mirrors with different response wavelengths, and the color complementary metal-oxide-semiconductor are used in the system. Two dichroic mirrors can be used as shear mirrors to realize shearing in orthogonal directions at the same time. The system realizes the measurement of the first-order displacement derivative information in the orthogonal direction of the round metal aluminum plate of diameter 250 mm. The experimental results show that the overall displacement integral peak to valley error in the x and y directions is 2.7% to 14.8%, which verified the reliability of the system.