Future Extremely Large Telescopes [ELT], with diameters going from 30 to 50 m, will be, in the next twenty years the corner stone of the ground-based astronomy at visible and infrared wavelengths.
Some of the most important questions of modern astrophysic should be addressed with these new giants. Indeed, the combination of their high resolution capability (a few milli-arcseconds) and their large collecting area will allow the study of the formation and evolution of the very first galaxies in the universe, but also the detection and the characterisation of telluric-like extra-solar planets.
Nevertheless, the atmospheric turbulence which is already the main limitation of 10-m telescope performance will be critical for this new generation of telescopes. Atmospheric turbulence but also telescope defects (such as wind shake for instance) will significantly degrade the image quality by a factor larger than one hundred.
Adaptive Optics [AO] is and will be one of the major challenges of the ELT developments. The idea is to develop an adaptive telescope integrating deformable mirrors at the very heart of the telescope. In addition to this first stage of correction, the scientific instruments themselves will be equipped by dedicated AO systems, optimized with respect to the observational constraints (very good image quality, correction over a large field of view …). Whatever are their own characteristics, AO systems for ELTs have all some specific constraints related to the new type of telescopes (mirror segmentation, computational issues for control laws …). Another essential point for most of the systems will be to have access to a large part of the sky and thus to make use of artificial laser guide stars. Here again, the large telescope size brings new specific issues in that particular area (cone effects, large spot elongation ...). And nevertheless, it is essential for an ELT to have at its disposal an AO correction for most of its observations in order to reach the highly ambitious astrophysic goals.
Currently 3 ELT projects are under studies both in Europe and in the US. In the European project, called E-ELT (European ELT), a 42-m telescope is considered as a baseline. On the US side, a Thirty Meters Telescope (TMT) and a twenty one meters telescope (the Giant Magellan Telescope) are considered. For each telescope several instruments (corresponding to several ambitious scientific programs) are also in a very preliminary design phase (Phase A studies).
The main conference goal is to gather international AO specialists in order to share and to exchange around subjects and specificities related to the application of AO on giant telescopes. Hence the conference will address the nine following topics with dedicated session for each of them:
Astrophysical needs and high level requirements for AO on ELTs
AO modes and instrumental concepts
Laser Guide stars
Wave Front Sensing