Out-of-plane displacement measurement by electronic speckle pattern interferometry in presence of large in-plane displacement

Abstract

We measured out-of-plane displacement in presence of large in-plane displacements and deformations by electronic speckle pattern interferometry (ESPI). By means of digital speckle photography (DSP) the large in-plane displacement is measured and then compensated by software from interferometric images, before calculating the phase distribution related to the out-of-plane deformation. This means that decorrelation effects are not present and that the use of intermediate images is not necessary. The optical phase was extracted by spatial phase shifting, which enables the study of rapid transient events. The proposed method was applied to different combinations of out-of-plane deformation and large in-plane displacement. The compensation of large in-plane displacement allows us to maintain the contrast of ESPI fringes.