Pyramids, layers and no laser guide stars!
Roberto Ragazzoni, Marco Dima, Jacopo Farinato, Demetrio Magrin, Valentina Viotto
INAF - Astronomical Observatory of Padova
A decade after the first achievement into the improved capabilities in sensing by the pyramid wavefront sensor and from the outlining of novel classes of Multi Conjugated Adaptive Optics experimental verification of such approaches has been vastly proved by results from MAD onboard VLT and from FLAO onboard LBT. Refinement and extensions of these techniques promises to achieve similar goals within references scattered in a Field of View much larger than the one being compensated, an approach only marginally exploited in the so-called Multiple Field of View approach while the adoption of virtual DMs would allow a much deeper exploitation of such possibilities. As in the meantime the diameter of the largest project shortened somehow it is time to gather all these concept, to assemble -possibly- in an efficient way in order to continue to pursue the goal of achieving diffraction limited imagery at a level concorrential with what is being promised by artificial references, by the usage of solely natural guide stars. The resulting approach is a robust one (as it is not incompatible with Laser generated beacons) and can be implemented into existing optical design of the current extremely large telescopes under development