Estimation of the phase error in interferometric measurements by evaluation of the speckle field intensity.

Intensities recorded with CCD or CMOS sensors represent spatially averaged values of the intensity across the area of a pixel. In this work we investigate the influence of spatial averaging in interferograms on the evaluated phase from an object wave with well resolved, fully developed speckles. Based on an analytical description of the averaging process, a procedure is developed to create a quality map for the evaluated phase, in order to give an estimation of the expected error at each point. The proposed method uses only the local intensity distribution of the object wave for the qualification of the phase values. The theoretical results are tested and verified by means of numerically generated objective and subjective speckle fields.