Optimized design of Φ480mm light-weighted SiC primary mirror and load-bearing tower supporting structure for primary and secondary mirrors

As the core component of the optical system, the design of the main mirror not only directly determines the image quality of the camera but also influences the mechanical balance, thermal stability, and the economic efficiency and difficulty of the overall design and manufacture of the space camera. Given the core position of the main mirror in the performance of the camera, achieving its dual optimization design of high precision and lightweight has become the key technical bottleneck and breakthrough point for promoting the innovation of space camera technology and ensuring the efficient and stable operation of the camera in the extreme space environment. <br/><br/> In this paper, the SiC material with high specific stiffness and excellent thermal conductivity is selected as the mirror body material, and the flat back open structure and triangular lightweight holes are adopted. The weight is successfully reduced to 6.7 kg, and the lightweight ratio exceeds 70%, which realizes the structural strengthening and thermal stability improvement of the Φ480mm aperture primary mirror. Additionally, to address the challenge of imaging stability for large-aperture and long-focal-length cameras, this paper designs the support structure of the carbon fiber load-bearing tower for the primary and secondary mirrors and adjusts the support structure based on the topological optimization results to ensure stable connection and support between the primary and secondary mirrors and effectively resist the influence of space environment changes on imaging quality. To verify the scientificity and practicability of the design scheme, finite element simulation analysis is conducted to verify the analysis and optimization. The static analysis results indicate that the total rigid body displacement of the mirror assembly meets the requirements. The modal analysis verifies that the first-order natural frequency of the entire structure of the camera's primary and secondary mirrors is 142.76 Hz, which satisfies the stiffness requirements. The sinusoidal and random vibration analysis shows that the maximum stress generated by each component is small. The above analysis verifies that the mirror and its supporting structure meet the stiffness and strength requirements and possess good dynamic performance. The design scheme can fulfill the strict optical design requirements of space astronomical cameras and lays a solid foundation for enhancing the overall performance of space cameras.