Evaluation of diffraction-limited performance of a large optical antenna for cislunar optical communication system

Future Earth–Moon optical communication requires a telescope that can maintain diffraction-limited performance despite severe thermal fluctuations, radiation, and launch loads. Fine Cordierite®, developed by Kyocera, offers ultra-low CTE, high stiffness, radiation resistance, and machinability for complex structures, enabling monolithic and highly athermal optical systems. However, large monolithic telescopes made entirely of this brittle ceramic had not been realized due to the difficulty of assembling precision optical and structural components. Leveraging two decades of accumulated manufacturing and assembly expertise, Kyocera has successfully developed the first all–Fine Cordierite® telescope. This paper summarizes its design, fabrication, and optical performance.