Integrating mode for an optically addressed spatial light modulator

We describe the integrating-mode operation of an optically addressed spatial light modulator that incorporates a ferroelectric liquid-crystal light-modulating layer and an amorphous-silicon photodiode. This mode of operation uses a higher drive frequency and produces a readout response that extends over several driving periods, thereby permitting cw operation. The response characteristics of the device can be adjusted by varying the amplitude and offset of the applied voltage. Spatial resolution of 40 line pairs/mm, response times of 1 ms, and contrast ratios of 30:1 were achieved in this mode. We compare the integrating mode of operation with our standard reset mode of operation, whereby the electrical driving frequency is sufficiently low that the liquid crystal can respond fully to the voltage level during each part of the drive, and the device is reset fully to its off state during the forward-bias part of each electrical bias period.