The simplified architecture is a minimal system for a deep-space optical communications transceiver. For a deep-space optical communications link the simplest form of the transceiver requires (1) an efficient modulated optical source, (2) a point-ahead mechanism (PAM) to compensate for two-way light travel, (3) an aperture to reduce the divergence of the transmit laser communication signal and also to collect the uplink communication signal, and (4) a receive detector to sense the uplink communication signal. Additional components are introduced to mitigate for spacecraft microvibrations and to improve the pointing accuracy.

The Canonical Transceiver Architecture simplifies the design of the deep-space optical transceiver. Innovative technologies enabling its implementation include a single photon-counting detector array, two-photon absorption downlink tracking, a low-power point-ahead mechanism, and a sub-Hertz vibration isolation platform.

The Canonical Transceiver implements this simplified architecture (see figure). A single photon-counting “smart focal plane” sensor combines acquisition, tracking, and forward link data detection functionality. This improves optical efficiency by eliminating channel splits. A transmit laser blind sensor (e.g. silicon with 1,550-nm beam) provides transmit beam-pointing feedback via the two-photon absorption (TPA) process. This vastly improves the transmit/receive isolation because only the focused transmit beam is detected. A piezoelectric tip-tilt actuator implements the required point-ahead angle. This point-ahead mechanism has been demonstrated to have near zero quiescent power and is flight qualified. This architecture also uses an innovative 100-mHz resonant frequency passive isolation platform to filter spacecraft vibrations with voice coil actuators for active tip-tilt correction below the resonant frequency.

The canonical deep-space optical communications transceiver makes synergistic use of innovative technologies to reduce size, weight, power, and cost. This optical transceiver can be used to retire risks associated with deep-space optical communications on a planetary pathfinder mission and is complementary to ongoing lunar and access link developments.

This work was done by Gerard G. Ortiz, William H. Farr, and Jeffrey R. Charles of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at under the Physical Sciences category. NPO-46073

This Brief includes a Technical Support Package (TSP).
Simplified Architecture for Precise Aiming of a Deep-Space Communication Laser Transceiver

(reference NPO-46073) is currently available for download from the TSP library.

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