title: Angles-centroids fitting calibration and the centroid algorithm applied to reverse Hartmann test.
abstract: In this paper, we develop an angles-centroids fitting (ACF) system and the centroid algorithm to calibrate the reverse Hartmann test (RHT) with sufficient precision. The essence of ACF calibration is to establish the relationship between ray angles and detector coordinates. Centroids computation is used to find correspondences between the rays of datum marks and detector pixels. Here, the point spread function of RHT is classified as circle of confusion (CoC), and the fitting of a CoC spot with 2D Gaussian profile to identify the centroid forms the basis of the centroid algorithm. Theoretical and experimental results of centroids computation demonstrate that the Gaussian fitting method has a less centroid shift or the shift grows at a slower pace when the quality of the image is reduced. In ACF tests, the optical instrumental alignments reach an overall accuracy of 0.1 pixel with the application of laser spot centroids tracking program. Locating the crystal at different positions, the feasibility and accuracy of ACF calibration are further validated to 10-6-10-4rad root-mean-square error of the calibrations differences.
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Hui
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Zhengzheng
authors.initials: Z
authors.lastname: Xia
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Liquan
authors.initials: L
authors.lastname: Dong
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Lingqin
authors.initials: L
authors.lastname: Kong
authors.affiliation: Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Zhao