OPTICAL COMMUNICATIONS TERMINALS WITH PRECISE POINTING

Increasing data bandwidth requirements from spacecraft systems is beginning to pressure existing microwave communications systems. Free-Space optical commu-nications allows for larger bandwidths for lower rela-tive power consumption, smaller size and weight when compared to the microwave equivelant. However opti-cal communication does has a formidable challenge that needs to be overcome before the advantages of the tech-nology can be fully utilized. In order for the communi-cation to be successful the transmitter and receiver termi-nals need to be pointed with a high accuracy (generally in the order of ≤10µ radians) for the duration of communi-cation. In this paper we present a new concept for precise pointing of optical communications terminals (termed the Precise Pointing Mechanism). In this new concept we combine the separate pointing mechanisms of a conven-tional optical terminal into a single mechanism with a targeted goal of less than 3µ radians pointing accuracy within a field of view of 10 ◦ by electromagnetically ac-tuating the whole telescope assembly over 6 degrees-of-freedom. This paper discusses the principles of operation of this new terminal, the design and modeling of an en-gineering model using a combination of permanent mag-nets and reluctance force electromagnets to provide the actuation with the required pointing precision