A holographic speckle shearing technique for the measurement of out-of-plane displacement, slope and curvature

Abstract

A holographic speckle shearing technique combining image plane holography is presented which enables the measurement of out-of-plane displacement, slope and curvature for flexural members. Slope is obtained both as moiré of displacement fringes as well as by speckle shear interferometry. The curvature fringes occur as moiré of two speckle slope patterns. The image plane holography enables the use of white light or quasi-monochromatic light for filtering, thereby resulting in reduction of speckles in the fringe pattern. The results are presented for a centrally loaded circular diaphragm with its edge rigidly clamped.