Photographic printer utilizing a photoactivated liquid-crystal light valve in order to enhance image processing

摘要

A photographic printer has a lamp which projects light through a cut- off filter, a filter unit, and a diffusion plate. The light travels further through a film negative, an objective lens, and to a polarizing beam splitter. The beam splitter provides the light to a spatial light modulator and to an exposing/enlarging lens. The spatial light modulator includes a light modulating layer of a homeotropically oriented nematic liquid crystal having a negative dielectric anisotropy. Layers of transparent electrodes in the spatial light modulator are provided with a predetermined voltage of a predetermined frequency. A write CRT, controlled by a controller and control unit, provides light to the spatial light modulator so that the light from the beam splitter can be modulated with an appropriate correction. The modulated light and the light from the beam splitter are made incident on a photographic color paper. The photographic printer has improved compensation for blur caused by dust on the optical path. Each pixel or minute region is controlled for reflectance.