Review of Shearography for Dual-Directional Measurement

Shearography is a coherent optical technique that allows the identification of first derivative deformation in shearing direction. Due to direct measuring strain information, shearography suited for non-destructive testing and evaluation (NDT/NDE). However, if there small defect parallel direction, direction has no noticeable change, not visible. Therefore, development system with dual-directional simultaneous measurement derivatives both x- y-directions highly demanded field NDT/NDE. It inspect complicated defects, such as long narrow slots, microcracks, etc. This paper presents review different systems developed last two decades. After brief overview shearography, will display shearographic techniques—temporal phase-shift (TPS) spatial (SPS) methods. TPS dual-shearing are static measurements, while SPS useful dynamic measurements. The basic theories, layouts, comparisons presented. advantages disadvantages practical applications discussed.