NDT by speckle rotational shear interferometry

Speckle rotational shear interferometry has been used for NDT of diffuse objects. Shear is obtained by placing a pair of Dove prisms before a double aperture arrangement. For centrosymmetric objects, defects appear in a fringe-free field when shear is introduced about the centre, unlike other shear techniques where defects appear in a parent fringe structure. Furthermore, by eccentric loading and rotational shear applied about the centre, sensitivity for defect detection can be enhanced. A qualitative theory and experimental results are presented. © 1985.