Surface figure metrology based on geometric phase components

Abstract

A geometric phase component is very attractive in optical metrology because its meta-surface characteristic enables traditional optical systems to be more compact and multi-functional. In this presentation, we introduce two types of geometric phase components, i.e. a geometric phase lens and a polarization grating in surface figure metrology. Their features of polarized beam splitting and phase retardation play a role of wavefront shearing device, and simple shearing interferometers can be designed. We focus on the instrumentation of a radial shearing interferometer using a geometric phase lens and a lateral shearing interferometer based on a polarization grating. With the aid of a polarization pixelated CMOS camera, each interferometer can provide the phase map corresponding to the sheared wavefront as a snapshot measurement. In the experiment, various wavefronts generated by a deformable mirror and shapes of several mirrors were measured and compared with other commercial devices.