Fourier transform holography using pseudo-random phase shifting of

Abstract

A phase mask comprised of a square array of phase shifting areas arranged in pseudo-random pattern is illuminated with a beam of electromagnetic radiation, as a result of which an array of pseudo-randomly phase shifted beams emerges from the phase mask and impinges upon an object transparency to be intensity-modulated thereby and come to a focus on a Fourier transform plane. The power spectrum of the beams distributes in orthogonal directions on the Fourier transform plane from its center maxima in a distinct pattern of series of fringes. The technique of apodization is employed to suppress the fringes to thereby reduce the coherent noise of a hologram to a minimum.