Two-step spatial phase-shifting radial shearing interferometery with circular gratings

Abstract

This Letter presents a simple radial shearing interferometery with circular gratings to measure the radial first-order derivative of arbitrary wavefront phase. Two spatial phase-shifted radial shearing interferograms can be simultaneously obtained by the system, and a two-step phase-shifting algorithm with arbitrary phase-shift value is proposed for phase retrieval. The measurement for spherical wave has shown the feasibility and validity, and the optical system is used to measure the radial first-order derivative of projection wavefront phase of a propane flame with plane incident wave.