Multiple-aperture one-shot shearography for simultaneous measurements in three shearing directions

Abstract

A new shearography configuration was developed to simultaneously acquire images of a specimen in three different shearing directions, the proposed configuration is capable of performing measurements of shearography with multiple shearing directions using just one single interferogram. The device uses a three aperture mask and a single imaging lens to produce interference speckles with carrier fringes in three different directions. A set of three wedge prisms are used in combination with the three apertures to produce simultaneous shearing interferograms for three different orientations. A single high-resolution image of the specimen is captured for each loading level and the phase maps are computed by FTM (Fourier Transform Method). Additionally, as the device has no movable parts and just a single shot image is acquired, it is very compact, robust and can be successfully used outside the optical bench. The paper presents the optical setup and a practical application for the new technique.