In collaboration with companies TESAT and SPACEOPTIX, researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF (Fraunhofer IOF) have developed a transmitting and receiving telescope for satellite-based laser communication, which could form the basis for such a network as a series product. The telescope was developed over the course of three years for TESAT’s SCOT135 system, a scalable optical communication terminal specifically designed for use in medium earth orbit and geostationary orbit. Crucially, and unlike science-oriented telescopes, the telescope can be manufactured not only in small quantities, but also in series. The transmitting and receiving telescope developed at Fraunhofer IOF mounted in the rotary fork. The telescope is designed for integration into the SCOT135 laser terminal produced by TESAT. Courtesy of Fraunhofer IOF. Fraunhofer IOF spin-off SPACEOPTIX will produce the telescope, having already manufactured five systems for TESAT. The company expects to produce 50 units per year. The first flight models were delivered to TESAT in June. The SCOT135 system is expected to achieve a bandwidth of up to 100 Gbit/s and bridge distances of up to 80,000 km with the help of the telescope developed in Jena. “This is new in combination with terminals, which are built in large numbers and will eventually be linked to form an inter-satellite network,” said Henrik von Lukowicz, project manager and head of the Optical and Mechanical System Design department at Fraunhofer IOF. “We have developed a universally applicable telescope that is both a transmitter and receiver unit.” When used in space, the telescope must withstand both the environmental stress encountered there and the stress caused by the operation of the system itself. “Relatively high laser powers are used in laser communication systems. Up to 50 [watts] are used here. For a space telescope, this is a relatively high amount of power that propagates through the system,” said von Lukowicz. “This leads to heat build-up, which can cause changes to the optics. But of course, the performance of the system must not be impaired as a result. Thermal management was therefore a particularly important aspect of our design.” In addition to thermal regulation, a wide range of expertise from Fraunhofer IOF was incorporated into the design development, based on years of experience with space projects at the institute. “This involves a wide range of issues, such as how to manufacture particularly lightweight components for space flights, methods for the robust adjustment of components and the finest structuring of the optics for precise performance,” said von Lukowicz.
