New tomographic Adaptive Optics (AO) concepts require a good knowledge of the system geometry and characteristics.
These parameters are used to feed the tomographic reconstructors. In this paper we present a method
to precisely identify the parameters required to construct an accurate synthetic set of models such as inuence
functions, mis-registrations, directions of analysis or altitude of the DMs. The method is based on a multiparameter
t of the interaction matrix. This identication method nds also its application in high contrast AO
systems, such as SPHERE : in that case it is used as a diagnostic tool in order to precisely realign the system.
The method has been tested and successfully implemented on HOMER, SPHERE and GeMS. Experimental
results for these three systems are presented.
Wide Field Adaptive Optics (WFAO) concepts, such as Ground Layer AO (GLAO), Laser Tomography AO
(LTAO) or Multi-Conjugate AO (MCAO) are currently under study in the perspective of future ELT instruments.
In that context, the experimental validation of the various smart control solutions proposed by several teams
in the past years is now essential. In this paper we present experimental validation and comparison of different
control laws for LTAO concept from the simplest least-square to the optimal Linear Quadratic Gaussian solutions
including Virtual DeformableMirror and Pseudo-closed loop approaches. This study is performed using the Onera
WFAO facility (HOMER bench). The four control laws are tested and compared in terms of performance and
robustness. In particular, low and high noise conditions are explored, for several different fields of views. We
also highlight their experimental optimization by the tuning of parameters in control laws.
Adaptive Optics (AO) has a limited corrected field of view because of the anisoplanatism effect. Wide Field
AO (WFAO) concepts, such as Multi-Conjugate AO (MCAO), have been developed to overcome this limitation.
These complex WFAO systems raise critical challenges such as tomographic control and calibrations. We present
new results obtained in closed-loop configuration with the laboratory bench HOMER which is devoted to implementation
and validation of these WFAO concepts in the perspective of future VLT/ELT AO systems. Turbulence
is generated with rotating phase screens and multi-directional analysis is performed. Tomographic control relies
on Linear Quadratic Gaussian control (LQG). The correction can be applied thanks to two Deformable Mirrors
(DM). We also focus on calibration issues and models identification. We investigate in particular identification
of relative geometry of the wave front sensors, DM altitude and asterism and its impact on performance.