采用新型偏振分光元件液晶偏振光栅设计了长波红外偏振成像方案，实现了长波红外液晶偏振光栅的制备，并对该方案进行了实验验证。分析了基于液晶偏振光栅的偏振成像光路中有效成像视场角与所用光栅周期的关系，计算得出在实验光路参数下最大视场角对应的最佳光栅周期。使用Mueller矩阵推导了光路中偏振态的转化，根据偏振态转换矩阵设计了分时偏振成像方案，并针对误差传递控制对成像方案参数进行优化。基于液晶光控取向技术制备液晶波片，使用所制备波片测量了液晶在8.6~12 μm波段的双折射率和7.5~12 μm波段的透过率。基于测得的液晶材料特性和计算所得最佳光栅周期，选取光栅参数并制备液晶偏振光栅，测量了所制备长波红外液晶偏振光栅在8.6~12 μm波段的衍射效率，在10 μm附近达到90%以上的衍射效率。使用制备的长波液晶偏振光栅搭建偏振成像光路，按设计方案进行分时偏振成像，对所得图像进行预处理，解算偏振信息并与预设数值比较，实现了小于1°的偏振角测量误差。

A long-wave infrared polarization imaging method proposed using liquid crystal polarization grating as a novel beam splitting element. The fabrication of liquid crystal polarization grating was achieved， and the method proposed was experimentally verified. The relationship between the effective imaging angle of view and the grating period used in the polarization imaging optical path based on liquid crystal polarization grating was analyzed， and the optimal grating period corresponding to the maximum angle of view with the experimental optical path parameters was calculated. The transformation of polarization states in the optical path was derived using the Mueller matrix， and a time-division polarization imaging method whose parameters were optimized by minimizing error transfer was designed based on the polarization state transformation matrix. A liquid crystal wave-plate was fabricated， with which the birefringence in 8.6–12 μm band and the transmittance in 7.5–12 μm band of liquid crystal materials were measured. A liquid crystal polarization grating was manufactured according to the optimal grating period and grating parameters based on the measured liquid crystal material characteristics. Diffraction efficiency of the long-wave infrared liquid crystal polarization grating in 8.6–12 μm band was measured， reaching a diffraction efficiency of more than 90% at around 10 μm wavelength. An experimental polarization imaging system was constructed with the prepared long-wave liquid crystal polarization grating and wave-plate to accomplish polarization imaging and imaging processing that calculate the polarization states. Comparisons between preset values and measured values show that a measurement error of less than 1° was achieved.