ABSTRACT
Linear polarizers may be classified into three categories: birefringent, dichroic, and reflective. Birefringent linear polarizers are made of uniaxial crystals, which belong to hexagonal, tetragonal, and trigonal crystal systems. The chapter explains the following calcite birefringent linear polarizers: Nicol prism, Glan-Thompson, Glan-Taylor, Wollaston prism, Rochon prism, and Senarmont prism. Polaroid is the trade name for the most commonly used dichroic material, which is a plastic sheet of iodine-impregnated polyvinyl alcohol. Reflective linear polarizers such as Brewster windows and wire-grid polarizers transmit the desired polarization and reflect the orthogonal polarization. Polarcor, developed by Corning, consists of elongated silver crystals in borosilicate glass. The degree of polarization of the transmitted beam can be increased using a number of Brewster plates in tandem. Light can be circularly polarized using a phase difference of 90° between the orthogonal polarization components of light, such as in a Fresnel rhomb or a quarter-wave plate.
