Integration of liquid crystal elements for creating an infrared Lyot filter

An infrared Lyot filter was fabricated by integrating a polarization beam splitter and two retarders into a single device. A liquid crystal layer was constructed between two silicon pentaprisms that were designed suitably so that light was incident on this layer at 28°. At this angle, the liquid crystal transmitted p-polarized light (Brewster's angle) and reflected s-polarized light (total internal reflection). The p- or s-polarized light was directed to another liquid crystal layer (retarder) between the prism and a mirror, which induced a wavelength-dependent retardation in the reflection process. Consequently, the light that returned to the beam splitter was transmitted or reflected depending on wavelength.