Micro/nano displacement measurement using sub-pixel DSCM

A selection method of subset size in sub-pixel displacement registration is proposed. The algorithm principle of interpolation, fitting of distribution of the correlation coefficients and gradient-based methods are introduced. Using computer-simulated speckle images, their precision and efficiency depending on the subset size are studied. The optimal method and subset size are presented in various measurement ranges, which offer measuring bases for sub-pixel in DSCM.