Lightweight 3D-printed fused silica mirrors for x-ray astronomy: design, analysis, and manufacture

Le résumé fourni par la source

The current challenge in manufacturing X-ray optics for astronomy is to combine high spatial resolution imaging with low-mass mirrors to enable a large collecting area. Traditional high-resolution mirrors rely on thick (15 mm to 20 mm) glass ceramic shells, where mass and thickness constrain the achievable collecting area. Recent advances in Additive Manufacturing (AM; 3D printing) of fused silica addresses this limitation by integrating advanced lightweighting features into the mirror designs – such as regular Triply Periodic Minimal Surfaces (TPMS) and stochastic Voronoi lattices – while figuring and polishing techniques deliver the required surface roughness and form accuracy on the thin lightweight shells. Additionally, by directly printing the final geometry and avoiding extensive material removal, AM of fused silica could reduce mass, waste, time, and cost during production. Previous studies have demonstrated that AM fused silica can be polished to sub-nanometre roughness; this work extends those results towards X-ray applications by performing AM design optimization on grazing incidence optics for the first time. We designed a simplified grazing incidence mirror prototype, 100 mm×100 mm segment of a cylinder with an inner radius of curvature of 244.5 mm, and generated three variants: a 5 mm thick solid prototype, an 8.5 mm thick TPMS-latticed prototype, and an 8.5 mm thick biomimetic Voronoi-latticed prototype. Parameter optimisation and validation was performed on both latticed versions using finite element analysis to determine the most suitable lattice parameters. Using this approach, we reduced the mass of the TPMS and the Voronoi latticed prototypes by 41% and 29%, respectively, relative to an identical solid geometry. The printed prototypes were characterised at INAF-OAB in preparation for lapping and polishing; these results are presented in a companion paper. This study presents two viable lightweighting strategies for X-ray mirrors in fused silica, which could, in the future, be adopted for the design of the successor to the Chandra X-ray Observatory.

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