Performance of the Adaptive Optics System for Laser Communication Relay Demonstration’s Ground Station One

The Laser Communication Relay Demonstration is NASA's multi-year demonstration of laser communication to a geosynchronous satellite. The mission currently has two optical ground stations (OGS), with one in California (OGS1) and one in Hawaii (OGS2). The optical system consists of an high order adaptive optics system, the transmit system and a camera for target acquisition. The adaptive optics (AO) system is responsible for compensating the downlink beam for atmospheric turbulence and coupling it into the modem's single mode fiber. The mission required a coupling efficiency of 50% which necessitates a high-order AO system. To achieve this performance, the adaptive optics system uses two deformable mirrors with one mirror correcting for low spatial frequencies aberrations with large amplitude and a second deformable mirror correcting for high spatial frequencies aberrations with small amplitude. The system uses a Shack-Hartmann wavefront sensor. Another aspect of the system design necessary to achieve the system performance under the stressing turbulence conditions is a system bandwidth. The system can operate at framer rates of 20 kHz. We present an overview of the design of the system and measured AO system performance.