Robust dynamic phase-shifting common-path shearography using LCPG and pixelated micropolarizer array

Authors：Yan, Peizhen; Liu, Xiangwei; Dong, Jingtao; Wang, Yonghong^*; Wang, Biao; Li, Jianquan; Sun, Fangyuan

Source：Optics and Lasers in Engineering, 2022, 153: 106997.

DOI：10.1016/j.optlaseng.2022.106997

• Liquid crystal polarization grating
• Common-path shearography
• Pixelated carrier phase
• Nondestructive testing

A concise and dependable dynamic phase-shifting shearography system based on common-path interferometer is proposed. Two lateral sheared images with common optical path are generated using a liquid crystal polarization grating (LCPG). The sheared images of the object under test interfere with each other, and a pixelated micropolarizer array is used to introduce pixelated carrier, enabling the measurement of dynamic deformation using dynamic phase-shifting. Compared with the ordinary imaging system, the shearography system only needs to insert LCPG between an imaging lens and a camera with pixelated micropolarizer array. The system is resilient to environmental disturbances benefitting from the compact common-path and dynamic phase-shifting method. Theoretical analysis and experiments have been completed, showing that the system can fully exploit the advantages of shearography and improve the reliability of shearography applications.