PS/PDI with two optical fibers for absolute surface figure measurement for large aperture optics

Interferometric error caused by face plate of CCD image sensor for recording interference pattern

Abstract

A phase-shifting point diffraction interferometer (PS/PDI) with two optical fibers is appropriate for absolute surface figure measurement for large aperture optics. Interference pattern formed on CCD image sensor contains several wavefront error or interferometric error caused by imaging optics. Suppression of the interferometric error is attempt by using CCD image sensor, which has no face plate. Interference pattern is formed on the surface of CCD image sensor without any optics.