A simple AO liquid crystal light valve is described in this paper, which consists of two parallel glass plates with electrode film on each side, enclosing a CdS photoconduc-tive film prepared byevaporation, a nematic liquid crystal layer and a dielectric mirror. By placing the cell between apair of crossed polarizers, projecting a white light image on the write-in side of the valve and using He-Ne laser as read-out beam, a incoherent to coherent image converter system is established and a coherent image with several gray scale can be obtained.