ESA Optical Ground Station Upgrade with Adaptive Optics for High Data Rate Satellite-to-Ground Links-Test Results

In this paper, we present the design, fabrication and factory acceptance testing results of the receive (RX) adaptive optics add-on to the ESA optical ground station (1 m telescope). The system is suited to be operated with laser communication systems at 1064 nm wavelength or alternatively with one in the 1550 nm region. The wave-front sensor is a Shack-Hartmann-sensor (21 sub-apertures across the pupil), matched to a 24×24 actuator deformable mirror (DM). The system is able to remove a large part of the turbulence induced and static wave-front errors by using more than 300 degrees of freedom ("modes"). Due to a special high-speed infrared camera, the control loop can run at an update rate of 4 kHz in excess. Furthermore, we present an outlook on the future use of an adaptive optics system in the Coudé path of the ESA optical ground station, supporting pre-distortion of the uplink beam.