Research on in-orbit refocusing strategy of space camera based on the design of front mirror tube made of resin matrix composite

The in-orbit defocus of the long focal length high-resolution space optical camara has a complicated defocus variation and lasts for a long time based on cyanate resin matrix composites material optical-mechanical structure design, the camera’s refocusing decision in-orbit cannot rely on a single mode in its operational stage on orbit. Based on the theory of composite characteristics and focusing mechanism of space camera, this paper analyzes and builds the camera's in-orbit parametric defocusing model. Comprehensively considers the actual resource usage of the satellite in each stage of operation and user application requirements, a phased on-orbit refocusing strategy is studied and designed. Taking a long focal length and large aperture high-resolution camera designed of cyanate resin matrix composites material with the secondary mirror adjustment mode as an example, using focusing data in the initial in-orbit commissioning period, the defocusing model parameters were determined through fitting and optimizing, and the trend analysis and prediction of camera focus position changes were carried out according to the defocusing mathematical model. And the camera refocusing position tracking and presetting were completed based on the trend prediction during the satellite service phase, and obvious results on image quality were achieved.