The main applications of temporal phase shift shearography are in NDT and strain measurement. The most important application of temporal phase shift shearography, called digital shearography for simplicity, is for NDT, which enables flaws in objects/ materials to be found without damaging them. Compared to conventional NDT methods, such as ultrasonic, radiographic, magnetic article, dye penetrant, eddy current, and acoustic emission methods, digital shearography has the advantages of full-field measurement, high sensitivity, easy visualization, quick measurement speed, and real-time display of test results. Due to these distinct advantages, digital shearography has been widely accepted by the automotive and aerospace industries as a recommended NDT method for rubber and composite materials. The details of digital shearography for NDT have been described and discussed in Refs. 3 and 4. In this section, potentials and limitations of temporal phase shift shearography for NDT are reviewed, practical applications using different loading methods are demonstrated, and a few recent developments, such as NDT for testing relatively large objects and for measuring mirror-like surfaces, are presented and discussed.
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