Research on the line-of-sight thermal stability of off-axis catadioptric star camera based on thermo-opto-mechanical analysis

To address the issue of line-of-sight (LOS) thermal drift in a high-pointing-accuracy catadioptric star camera, rarely studied, optical, structural, and finite element models (FEM) were developed. The correlation between rigid-body displacement and LOS error was analyzed, and a linear optical model was constructed to identify the primary mirror as the critical optical component. Topological and parametric optimizations integrating LOS stability were performed on it. Through simulations under different temperature conditions, it was found that the uniform temperature rise had the most significant impact on LOS error. Under this condition, the simulated LOS errors for the catadioptric and reflective systems were 0.002438 ″/°C and 0.002735 ″/°C. The thermal test validated the reliability of simulation results, with experimental LOS errors of 0.002587 ″/°C and 0.002883 ″/°C, showing approximately 5% relative errors. The findings of this study provide engineering references for the structural optimization and thermal control design of space optical cameras.