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Fine pointing and tracking concepts for optical intersatellite links

Free-space optical communication (FSOC) has been promoted for decades as an enabling technology for high-throughput satellite connectivity. However, in order for FSOC to be economically competitive with other technologies (e.g., conventional RF links), the overall manufacturability, including production cost and schedule, needs to be improved. One of the major cost and complexity drivers in FSOC systems tends to be the small-space optical assembly associated with fine pointing and tracking. These assemblies typically employ precision optical elements with sensitive alignment requirements, and they sometimes also rely on time-consuming calibration steps which further increase cost and production schedule. In this paper we present two fine pointing architectures that support high-accuracy pointing, while also featuring simplification of the small-space optical assembly hardware, reduction in the number and complexity of constituent components, full self-calibration capability, and relaxation of otherwise-strict, cost-driving subassembly requirements. One architecture is proposed for short-range applications requiring only limited point-ahead angles, whereas the other architecture supports larger point-ahead angles.