Shear measurement in digital speckle shearing interferometry using digital correlation

Accurate computations of surface slope deformation based on digital speckle shearing interferometry fringe patterns require a precise measure of the amount of shear introduced. A previous method of employing image processing, while providing accurate and fast measurements, is limited by the need to place a tape target on the object surface. In this paper, a novel method employing digital correlation is demonstrated to obviate this requirement while maintaining accurate mensurations of shear. It also allows automated measurement procedures to be readily incorporated.