Abstract

Optical components with cylindrical surfaces are hard to test in most interferometers because a cylindrical reference wave-front needs to be produced. A grating which produces a high-quality cylindrical wave-front in the first diffracted order has been used to test cylindrical surfaces in a phase-measuring Fizeau interferometer. The test arm of the interferometer contains the grating and the test surface. A plane reference wave-front is produced by a transmission flat. The test surface is placed so that its center of curvature is at the center of curvature of the reference cylindrical wavefront. The test beam is reflected back by the test surface to the grating which then diffracts the test beam back into the interferometer. This paper describes this technique, and shows results of testing cylindrical surfaces using this technique.

© 1990 Optical Society of America