Radial shearing interferometer for in-process measurement of diamond turning

Abstract

A stable interferometer with two zone plates to measure a concave mirror figure is developed. The principle of the measurement is based on the radial shearing interference in which the measuring wavefront from the entire mirror surface under test is referred to that from the central part. On-machine experiments show that the interferometer is stable and compact enough to be applicable to in-process measurement for diamond turning at about 0.06 ?m p-v accuracy.