An ac‐operated liquid‐crystal light valve has been constructed and operated. The multilayer structure, consisting of a photoconductor, light‐absorbing layer, dielectric mirror, and liquid crystal, is capable of efficiently modulating a high‐intensity light beam with a comparatively weak light source. The dielectric mirror and absorbing layer provide high reflectance and optical isolation without the use of a metal mosaic reflector. The use of ac and insulated electrodes promises long lifetime. The light valve is applicable to television projection display and optical data processing.