Tunable retarder made of pentaprisms and liquid crystal

Abstract

A polarization beam splitter and tunable retarders were combined into a single element by using Si pentaprisms and liquid crystal (LC). An LC layer that was sandwiched between the two pentaprisms acted as a polarization beam splitter that reflected s-polarized light and transmitted p-polarized light. The other two LC layers that were attached to the outer surfaces of the pentaprisms acted as tunable retarders; i.e., they changed the polarization states of the reflected and transmitted light beams. When these beams were reflected back to the former LC layer (the beam splitter), wavelength selection took place owing to the wavelength dependence of the polarization state. This performance was confirmed by optical experiments in the infrared region.