Optimal Design of Large Aperture Primary Mirror of Spaceborne Solar EUV Imager Based on Optomechanical Coupling Analysis.

This paper proposes a parametric modeling and multi-objective optimization method based on optomechanical coupling analysis to address the design optimization of large-aperture primary mirrors in space-based solar extreme ultraviolet (EUV) imaging instruments. By establishing a parametric model of the primary mirror and combining topology optimization with dimensional optimization, the influence of key parameters-including mirror thickness, rib width, and lightweight hole dimensions-on the mirror surface shape accuracy (RMS) and structural fundamental frequency is systematically analyzed. The study employs finite element simulation and optomechanical coupling data processing algorithms to extract the rigid-body displacement and surface shape error of the primary mirror under gravitational loading and identifies high-impact parameters through sensitivity analysis. After optimization, the RMS values of the mirror's surface shape in all three directions under a 1 g gravitational load are all better than 4.5 nm, meeting the requirements for spaceborne payloads. Experimental validation shows that the surface shape RMS of the assembled primary mirror is only 0.022λ (with λ = 632.8 nm), and the system wavefront error is less than 0.08λ, significantly surpassing the design specification requirement of 0.1λ.