The general approach to the design of thin film polarizers is outlined by reference to the principle of equivalent layers, and an analytical expression is derived for the number of quarter-wave layers required in a mirror structure to provide a specified polarization transmittance ratio (ifP = T{double up tack} T⊥). It is shown that the high polarization ratio and the small sensitivity of this parameter to the angle of incidence are conflicting specifications which require a compromise solution in practice. Also, to achieve simple and precise monitoring of the optical properties of the layers during deposition, double half-wave filter systems are shown to be preferable to multilayer quarter-wave mirrors as polarizers. The results of measurements on double half-wave polarizers for use with large aperture Pockel's cell shutters and Faraday isolators in high power neodymium glass lasers are presented with particular reference to transmittance, polarization ratio, superficial unifromity and laser damage threshold. © 1979.
