title: 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).
authors.forename: V
authors.initials: V
authors.lastname: Chandrasekharan
authors.forename: H
authors.initials: H
authors.lastname: Damany