We present optical characterization, calibration, and performance tests of the Mesospheric Airglow/Aerosol Tomography Spectroscopy (MATS) satellite, which for the first time for a satellite applies a linear-astigmatism-free confocal off-axis reflective optical design. Mechanical tolerances of the telescope were investigated using Monte-Carlo methods and single-element perturbations. The sensitivity analysis results indicate that tilt errors of the tertiary mirror and a surface RMS error of the secondary mirror mainly degrade optical performance. From the Monte-Carlo simulation, the tolerance limits were calculated to $\pm$0.5 mm, $\pm$1 mm, and $\pm$0.15$^\circ$ for decenter, despace, and tilt, respectively. We performed characterization measurements and optical tests with the flight model of the satellite. Multi-channel relative pointing, total optical system throughput, and distortion of each channel were characterized for end-users. Optical performance was evaluated by measuring modulation transfer function (MTF) and point spread function (PSF). The final MTF performance is 0.25 MTF at 20 lp/mm for the ultraviolet channel (304.5 nm), and 0.25 - 0.54 MTF at 10 lp/mm for infrared channels. The salient fact of the PSF measurement of this system is that there is no noticeable linear astigmatism detected over wide field of view (5.67$^\circ$ $\times$ 0.91$^\circ$). All things considered, the design method showed great advantages in wide field of view observations with satellite-level optical performance.
The Microchannel X-ray Telescope on board the SVOM mission: in-flight scientific performance
AIM-CEA/DRF/Irfu/Departement d’Astrophysique, CNRS, Universite Paris-Saclay, Universite Paris Cite（天体物理学与核物理研究所，法国国家科学研究中心，巴黎萨克雷大学，巴黎 Cité 大学）；Centre National d’Etudes Spatiales, Centre spatial de Toulouse（法国国家空间研究中心，图卢兹航天中心）；Space Park Leicester, University of Leicester（莱斯特大学，莱斯特太空公园）；College of Science and Engineering, School of Mathematics and Physics, Kanazawa University（金泽大学，理学院，数学与物理系）
