Channel measurements are an important prerequisite for the investigation of free-space optical communication through the atmosphere and the design as well as optimisation of systems. In addition, newly developed concepts, such as methods for single-mode fibre coupling or diversity methods for suppressing signal interference, must be implemented and demonstrated.
The Oberpfaffenhofen Optical Ground Station is regularly used for this purpose. It is located on the roof of the institute building and has a telescope to which various electro-optical systems can be directly attached. So far, measurements of the turbulent optical transmission channel, tests of various measuring instruments (e.g. wavefront sensors for adaptive optics) as well as the investigation and demonstration of quantum key distribution have been carried out with it.
Currently, the ground station is being converted and upgraded as part of a major investment project. For this purpose, a new telescope system with an aperture diameter of 80cm (previously 40cm) is being set up, which will have satellite and aircraft tracking functionality. Processing of the received signal will be made possible by means of a so-called Coudé feed-through in the station's control room (Coudé room). This opens up completely new experimental possibilities - especially with regard to the use of adaptive optics.
Image: Florian Moll for DLR