Shearography: An optical measurement technique and applications

This article reviews shearography and its applications. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). It was developed to overcome several limitations of holography by eliminating the reference beam. It does not require special vibration isolation; hence, it is a practical tool that can be used in a field/factory environment. Shearography has already received considerable industrial acceptance, in particular, for non-destructive testing. In non-destructive testing, shearography reveals defects in an object by identifying defect-induced deformation anomalies. Other applications of shearography include strain measurement, material characterization, residual stress evaluation, leak detection, vibration studies and 3-D shape measurement.