The ALFA Laser and Analysis Tools

Abstract

The optimal performance of adaptive optics systems can only be maintained if the wavefront reference is bright and compact. Experience has shown that both of these important criteria are remarkably difficult to achieve with laser guide stars, and this contribution gives an account of the methods by which ALFA attempts to reach them. First, the production of a high quality, high power laser beam is described. However, this quality is unavoidably compromised along the path to the launch telescope. In order to rectify this, a new set of diagnostic tools which monitor the quality of the out-going beam has been installed, and these are also described. Lastly, we outline a number of possible modifications on which we are working. If successful, these may allow a substantial improvement in the beam quality.