Multi-Conjugate Adaptive Optics: the MAD challenge

E. Marchetti, Ph. D.
European Southern Observatory

In Astronomy, the idea of enlarging the Field of View that is
corrected by an Adaptive Optics system was first proposed 35 years ago
by Dicke.

The concept of Multi-Conjugation was better developed in the late
80's, but it reached the level of maturity necessary for its practical
implementation only one decade later.

The new millennium has seen the Multi-Conjugate Adaptive Optics (MCAO)
become a reality with the first observations of the Solar Vacuum Tower
Telescope and, immediately after, with the ESO's MCAO Demonstrator
(MAD).

MAD was initially conceived as a pathfinder for the European Extremely
Large Telescope and for the 2nd generation instrumentation at the
VLT. Originally thought only to demonstrate MCAO feasibility, MAD
turned out to be a powerful tool for performing scientific
astronomical observations never before attempted from ground-based
telescopes.

A science demonstration campaign, which was successfully carried out
in 2007-2008, revealed the outstanding potentiality of the MCAO
technique and produced to date 10 refereed papers.

This talk is a journey through the MAD experiment, starting from the
pioneering days when the MCAO concept was formulated and then
consolidated, going through the steps of the MAD implementation and
finally concluding with the scientific achievements on sky.

I will introduce the basic MCAO theory, highlight the main technical
aspects and present the technical and scientific results. Finally, I
will briefly outline the future perspectives for MCAO.