A system consisting of a thin, transparent film on an absorbing metallic substrate can function as a reflection polarizer. For given optical constants, analysis yields the angles of incidence at which reflection of either component of polarization is extinguished. For each such polarizing angle, any one of a set of discrete film thicknesses can be employed to obtain polarized light. The polarizing characteristics of several illustrative film-substrate systems have been calculated. Criteria for evaluating the performance of a reflection polarizer included the magnitude of the reflectance of the unextinguished component, and the sensitivity of the extinguished component to departures from the polarizing angle and from the optimum film thicknesses. These criteria responded in a systematic manner to variation of the reflectance of the substrate and the refractive index of the film. High reflectance of the unextinguished component and low sensitivity of the extinguished component can be attained.
M. RUIZ-URBIETA and E. M. SPARROW, "Reflection Polarization by a Transparent-Film-Absorbing-Substrate System," J. Opt. Soc. Am. 62, 1188-1194 (1972)