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Overview of Digital Shearography for NDT

Digital shearography, an interferometric nondestructive testing (NDT) technique, has proven to be an invaluable tool for material inspections and evaluations by providing a full field and noncontact measurement of surface displacement derivatives, or straininformation. Compared with holography and electronic speckle pattern interferometry (ESPI), environmental disturbances, such as a random rigid body movement, have less of an effect on digital shearography since rigid body movements do not generate strain information. This has enabled use of digital shearography for various applications outside of the laboratory. In the last decade, due to the rapid development of digital cameras and computer science, the measurement sensitivity and efficiency of shearographic technology has increased tenfold, thus increasing its utility. Here, we will present a brief review of shearography, including its basic principles, hardware configurations, and algorithms. Recent developments and applications are described and demonstrated. The overall review will be based on learning and understanding and will not provide a deep exploration into the principles and related derivative applications.



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