We report an optically addressed, liquid-crystal-based spatial light modulator demonstrating a resolution of 25 line pairs/mm at 50% modulation transfer function and more than 40-line-pair/mm limiting resolution by using a 25-μm-thick silicon Schottky diode-array photosubstrate. This resolution is obtained concurrent with a high photosensitivity of approximately 20 μW/cm(2) and a contrast ratio of over 200:1. The high resolution and photosensitivity obtained with the thin photosubstrate are explained by a fringing field and an equivalent-circuit model, respectively.