There is hopefully expected a projection display using spatial light modulators (SLMs) converting a faint input-image into a brilliant output-image. A conventional liquid crystal SLM loses more than 50% of a reading light in polarizer. To solve this problem, we developed a new SLM consisting of polymer-dispersed liquid crystal (PDLC) and Bi12SiO20 photoconductive layers. This SLM needs no polarizer, because it lets a reading light pass or scatter depending on whether a writing light is incident upon the photoconductive layer. We calculated the dependence of the resolution of the device on the several parameters including thickness, dielectric constants and conductivities of the dielectric mirror and PDLC layer by using a new electrical image method. A high-definition SLM with limiting resolution (36 - 50 lp/mm) was fabricated by stacking the optimized mirror and PDLC layer. In cooperating the device into a Schlieren optical system consisting of an LC panel as an input image source and a 1 kW Xenon lamp as a projection light source, we performed high-contrast green image projection with a total luminous flux of 1500 lumen.