Conception and development of an adaptive optics testbed for free-space optical communication

Abstract

Optical free space communications are an efficient approach to transmit high data-rates with small antennas and low power consumption over large distances. Possible scenarios are links between satellites, up- and down-links from and to ground stations as well as all kinds of links between aeronautical vehicles. The links that involve propagation of the electro-magnetic wave through the atmosphere are critical. Here, signal quality may be degraded severely due to wave-front distortions. With the exploitation of adaptive optics these wave-front distortions can be compensated and system performance enhanced. In the framework of this thesis, a laboratory testbed is built up which offers the scientist a comfortable support for the development and test of techniques related to adaptive optics and free-space optical communication. The core components are a hot-air optical turbulence generator, a deformable mirror, and a Shack-Hartmann wave-front sensor. The emphasis of this thesis lies on the development and test of the turbulence generator, the overall concept of the testbed, and its optical design. The testbed makes is possible to reproduce test scenarios with realistic ratios of aperture size over Fried parameter.