Abstract

Optical implementation of iterative phase retrieval algorithms (such as the Gerchberg-Saxton algorithm) for reconstruction of phase information from amplitude or intensity measurements is of interest for application to such fields as atmospheric and astronomical imaging, crystallography, and electron microscopy.¹,² In a proposed system employing successive signal iterations through a coherent optical processor in a cavity, unwanted amplitude information builds up on the phase-information bearing beam. Saturating an amplified signal can compensate for this. When two beams are coupled in a photorefractive crystal such as BaTiO₃, amplifications of the signal beam can occur at the expense of pump beam depletion. At saturation of the amplitude gain, signal amplitude variations are clipped, preserving phase information. Current work includes characterizing amplitude stripper performance, examining the gain curve calculated from the input and output signals, and looking for maximum saturation sufficient for amplitude stripping relative to the coupling coefficient. Future work includes inserting the amplitude stripper into an optical phase retrieval system and evaluating its effectiveness.

© 1989 Optical Society of America