Conformal Free-Space Optical Communications Terminal Designs for Highly Confined Vehicles

We propose novel designs for free-space optical communications transmitter and receiver terminals. The designs emphasize reduction or elimination of large, gimbal-based protrusions, include a minimal number of components at the surface, use fiber optics to keep supporting components remote from the surface, and minimize moving parts. The transmit terminal is composed of a fiber switch, fiber bundle, and surface lens. Switching the communications signal among individual fibers in a bundle coarsely steers the beam with a moderate divergence over a large field of regard via lens refraction. The receive terminal uses a microlens to couple the incident optical signal into an individual fiber in another bundle routed to remote optical detectors. Each fiber in the bundle collects power from a distinct solid angle of space; the use of multiple fibers enlarges the total field of view of the receiver. The microlens-to-fiber-bundle design is scalable and modular and can be replicated in an array to increase aperture size. The microlens (array) is moved laterally with a piezoelectric transducer to optimize coupling into a given fiber core in the bundle as the source appears to move because of relative motion between the transmitter and receiver.