Formulas for the coma and astigmatism of wedge prisms used in converging light

Abstract

Wedge prisms are generally eschewed as an optical component for use in convergent light in a well-corrected optical system because they introduce aberrations in most configurations. Nevertheless, wedge prisms have several properties (aside from dispersion) which make them useful in many applications. First, they can be used to deviate a line of sight by a small angle. Second, they deviate a line of sight without reflection and therefore preserve the image orientation. Third, they can be used to correct the aberration of a tilted beam splitter in convergent light. Fourth, they can be used to tilt, or correct the tilt of, an image plane. In this paper simple formulas are presented for third-order coma and astigmatism of a wedge prism used in converging light. Also, configurations are described in which wedge prisms can be used in converging light without introducing coma or astigmatism. Finally, these formulas are applied to the design of a well-corrected optical system.