Characteristics of a liquid crystal IR chopper for pyroelectric IR sensors

We have developed an IR chopper utilizing the electro-optical effect of liquid crystals for pyroelectric sensors. This IR chopper primarily consists of liquid crystals and Si substrates with wire-grid polarizers. We have investigated theoretically the relationship between the characteristics of this IR chopper and its structure. It is confirmed that the theoretical calculations of the IR modulation degree are in approximate agreement with the experimental results. Under the condition that the IR radiation is emitted from a blackbody whose surface temperature is 150 °C, a degree of modulation of 7.4% is obtained.