Use of Plastics in the Fresnel Rhomb

Abstract

IN this note the suitability of the new optical plastics for use in the Fresnel rhomb is discussed. Because the polarizing angle for a dielectric-to-air surface varies very little with change of frequency, and its polarizing properties are affected less by surface deterioration and the presence of films than is the case with metallic surfaces, polarization by internal reflexion remains the most satisfactory means of producing circularly polarized white light. The problem exists as to what is the most suitable non-metallic medium for this purpose. It is hoped that the following considerations will show that choice is not restricted to the classical glasses adopted since Fresnel's time.