What is AO ? How does it work ?

There are lots of sites around the world that give a good introduction to AO. Among others:

• A tutorial by Andrei Tokovinin at CTIO
• This is a nice article on active and adaptive optics written by L.Noethe and N.Hubin from ESO
• This site maintained by the AO group at the Canada-France-Hawaii Telescope. has an extensive list of AO links

There are also a couple of good monographs on Adaptive Optics. For instance:

• F.Roddier's edited "Adaptive Optics for Astronomy", Cambridge University Press, 1999
• J. Hardy, "Adaptive Optics for Astronomical Telescopes", Oxford University Press, 1998