Active pointing for terrestrial free space optics

Fixed-pointed free space optics (FSO) systems must use beamwidths that are broadened sufficiently to account for building motion, wind loading, and other pointing instabilities. System design tradeoffs for an active pointing system for terrestrial free space optics include: gimbaled transceiver vs. gimbaled mirror vs. fast steering mirror (FSM); separate tracking beacon vs. track on communication beam; and quadrant vs. array tracker. Some general tradeoffs are discussed, and the specific approach selected for fSONA´s newly developed commercial actively pointed FSO product is described. The system uses a single FSM to steer both transmit and receive beams, and which has the potential for 20 dB or more additional link margin relative to fixed pointed solutions. The system uses totally frictionless mechanical technology, has nearly 100 Hz bandwidth, ±0.25° field-of-regard, and uses fSONA standard transceiver technology (52 Mbps to 1.25 Gbps).