Strain analysis of transparent samples using digital shearography and holography

Abstract

Digital shearography is an optical technique that allows direct measurement of strain in deforming samples. In this work, we show the method's suitability in the evaluation of microscopic deformations in acrylic glass that may not be evident as birefringence. To generate the speckles, nominal roughness was induced at the front surface of the sample. Strain induced in the sample in the order of 40 microstrains was resolved using the shearographic set-up. For a more complete investigation of the deformation, the displacements in the material were also mapped using Fourier digital holography to complement the shearographic results.