On the numerical processing of speckle photograph fringes

Abstract A one-dimensional analysis of a double exposed speckle photograph is used to calculate the errors in displacements that arise if the diffraction halo is not divided from the fringe pattern prior to calculation of the fringe spacing. Relative errors in displacements calculated from fringe maxima are higher than those calculated from fringe minima. They are also a function of fringe visibility, increasing as visibility becomes lower.