[Keiko, Eleonora]

I report the characterization of the beam we did yesterday at the AS bench in preparation for ASC work (pic1).  We measured the beam with the beam profiler along its path after the last lens before the WFSs.  Zero point of the measurement is show in pic 2.

The beam is very astigmatic: the focusing points for the two beam cross sections are ~15 cm apart. In this configuration the Gouy phase at each WFS will be very different for the two axis. We will try to study a better configuration, which should also allow for a longer lever arm of the last steering mirrors before WFSs. In fact, we will soon replace them with PZT mounts to be used as actuators for the WFS DC centering loops.