Birefringence of Sapphire, Magnesium Fluoride, and Quartz in the Vacuum Ultraviolet, and Retardation Plates

Abstract

Measurements of the birefringence of sapphire, magnesium fluoride, and synthetic quartz from 3000 A to 1500 A are reported and are followed by a discussion of the methods of achromatizing quarter-wave plates and of linearizing the path retardation of a multiwave plate against wavelength (equichromatic wave plates).