Reflection polarization by a system consisting of two transparent films on an absorbing substrate

The conditions under which a system consisting of two transparent films on an absorbing substrate functions as a polarizer are analyzed. The analysis yields that for given optical constants of the films and substrate there exists a range of polarizing angles at which either component of polarization can be suppressed. At any angle in this range any one of an infinite number of discrete film thicknesses can be employed to obtain polarized light. The performance of this polarizer is measured by numerically calculating the sensitivity of the suppressed component to small departures of the theoretical polarizing angle, thicknesses and wavelength, and by calculating the magnitude of the unsuppressed component. A variety of films substrate combinations have been studied. The substrates-aluminum, rhodium and gold are selected as they span the range of excellent to intermediate reflectors. The refractive indices of the films do not correspond to any specific material but are varied over a realistic range of practical interest. The advantages of this system with respect to the single film - substrate are enumerated.