Application of Digital Image Correlation Techniques in Spatial Phase Shifting Interferometry

Spatial phase shifting interferometric techniques allow a quantitative determination of optical path length changes and displacements in axial direction with low demands on the stability of the experimental setup. Lateral wave front changes and in-plane displacement components can be detected by application of digital image correlation techniques on the pure object wave intensity distribution. In this contribution different methods for the reconstruction of the object wave intensity in the image plane are characterized and compared in order to combine image correlation techniques and interferometry for simultaneous data acquisition. The obtained data are applied to decrease decorrelation effects in Electronic-Speckle-Pattern Interferometry (ESPI) that are caused by lateral displacements of the speckle field. Therefore, a maximal speckle overlap of the initial interferogram with the intensity pattern of the deformed state is achieved by shifting interferogram subareas with subpixel-accuracy corresponding to the lateral speckle displacement field. The utilizability of the methods is presented by application on technical and biological specimen.