Optical Surfaces Ltd. has received an order from Tesat-Spacecom GmbH of Backnang, Germany, for a high-performance, thermally stabilized beam expander. It will be used as part of Tesat’s optical system test bed for verification of laser communication terminal (LCT) performance. Tesat-Spacecom designs and manufactures payload equipment for communication satellites. Its LCTs are the result of more than 20 years of optical communications development. The US Missile Defense Agency’s NFIRE satellite, built by General Dynamics, and Germany’s TerraSAR-X satellite, both launched in mid-2007, each carry a Tesat LCT. This equipment enables high-volume point-to-point data transfers. With a range of 45,000 km and a transfer rate of more than 5 Gb/s, this technology is revolutionary, and communication via laser allows a 10 times higher data rate compared to a microwave link. “Optical Surfaces Ltd. was selected to produce the critical 10× beam expander for our optical system test bed because of their impressive track record in preparing high-performance optical systems for telescope and space projects,” said Dr. Andreas Weichert, who is responsible for the Tesat optical system test bed. Using proprietary techniques, Optical Surfaces’ craftsmen will produce two concave off-axis parabolic mirrors with a combined wavefront accuracy of lambda/35 rms. The mirrors form the principal optical elements of the common-focus 10× beam expander. The surface accuracy will enable the beam expander to provide sustained high optical performance over the complete field of view (±0.1° at large aperture). The invar beam expander, designed for vacuum conditions at 10-6 mbar, offers high stability for thermal gradients that may be as much as 10 °C along the length of the instrument. For more information, visit: www.tesat.de