Abstract: A long-wave infrared polarization imaging method was designed and experimentally verified using liquid crystal polari-zation grating as a novel beam splitting element while the fabrication of liquid crystal polarization grating was achieved. The effective imaging angle of view and grating period was analyzed to optimize the grating period and maximize an-gle of view corresponding to the optical path parameters on the basis of the designed polarization imaging method based on liquid crystal polarization grating. The transformation of polarization states were derived using Mueller matrix and parameters of the time division polarization imaging method were designed and optimized. Liquid crystal polariza-tion gratings available for long-wave infrared have been manufactured using liquid crystal material on double-side AR coated ZnSe substrates with photo-alignment technology, whose diffraction efficiency achieves 90% at 10μm wave-length. Birefringence index and transmittance of the liquid crystal material were respectively measured under 10-12μm band and 7.5-12μm band with wave-plates manufactured using same materials. 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. A measurement error of less than 1 degree was achieved by comparisons between the preset values and measured values.

Key words: Liquid crystal polarization grating, Polarization beam splitting, Polarization imaging, Long-wave infrared Imaging, Infrared polarization imaging