Spherical-carrier lateral-shearing interferometry for large-aperture wavefront sensing

For high-precision and convenient wavefront detection of large-aperture optical elements, here we propose a method of spherical-carrier quadriwave lateral-shearing interferometry (QWLSI) using a Fresnel zone plate (FZP) reducer. Compared to plane wave incidence, the spectral-shift formula for the interferogram caused by spherical wave illumination needs to be investigated. In this paper, the spectral-shift formula is derived for the first time in theory, and its correctness is verified through 4- and 8-inch window glass experiments. The 4-inch wavefront measurements showed relative PV errors around 1% and RMS errors below 2%, while the 8-inch system achieved relative PV and RMS errors both below 3% compared to Zygo interferometer. The proposed method features high-precision and high-stability common-path interferometry for large-aperture wavefront sensing.