Volume holograms for image restoration

Abstract

The angular selectivity of volume diffraction gratings is exploited to form a spatial-frequency filter. The filter is recorded in a thick recording medium as a superposition of several simple gratings or as a single grating with a modulation that varies in depth. Such a device can have controlled angular selectivity so as to alter the relative amplitude and phase of selected spatial-frequency components. A coupled-wave formalism is used to analyze the angular selectivity of this device and experimental results demonstrate its usefulness in improving motion-blurred images.