title: An Efficient Correction Algorithm for Eliminating Image Misalignment Effects on Co-Phasing Measurement Accuracy for Segmented Active Optics Systems.
abstract: The misalignment between recorded in-focus and out-of-focus images using the Phase Diversity (PD) algorithm leads to a dramatic decline in wavefront detection accuracy and image recovery quality for segmented active optics systems. This paper demonstrates the theoretical relationship between the image misalignment and tip-tilt terms in Zernike polynomials of the wavefront phase for the first time, and an efficient two-step alignment correction algorithm is proposed to eliminate these misalignment effects. This algorithm processes a spatial 2-D cross-correlation of the misaligned images, revising the offset to 1 or 2 pixels and narrowing the search range for alignment. Then, it eliminates the need for subpixel fine alignment to achieve adaptive correction by adding additional tip-tilt terms to the Optical Transfer Function (OTF) of the out-of-focus channel. The experimental results demonstrate the feasibility and validity of the proposed correction algorithm to improve the measurement accuracy during the co-phasing of segmented mirrors. With this alignment correction, the reconstructed wavefront is more accurate, and the recovered image is of higher quality.
authors.affiliation: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Yue
authors.affiliation: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China.
authors.forename: Shuyan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Nie
authors.affiliation: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China.
authors.forename: Zongyang
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004867:Equipment Design; D055096:Optical Devices; D055095:Optics and Photonics