Athermal laser launch telescopes

ESO has developed a concept for a compact laser guide star unit for use in future Adaptive Optics (AO) systems. A small powerful laser is combined with a telescope that launches the beam, creating a single modular unit that can be mounted directly on a large telescope. This approach solves several of the stability problems experienced with a number of first generation laser guide star systems around the world. Four of these compact laser guide stars will be used for the new VLT 4LGSF Adaptive Optics Facility (AOF), to be installed on UT4 in Paranal. The design is passively athermalized over a large temperature range as well as under the influence of thermal gradients. TNO has developed the laser launch telescopes and successfully demonstrated its performance under operational conditions. The technology will also serve as a testbed ahead of the construction of the future European Extremely Large Telescope, which will also have multiple laser guide star units.