Optimal phase reconstruction in large field of view: application to multiconjugate adaptive optics systems

摘要

We propose an optimal approach for the phase reconstruction in a large Field Of View (FOV) for Multiconugate Adaptive OPtics (MCAO). This optimal approach is based on a Minimal Mean Square Error (MMSE) estimator that minimizes the mean residual phase variance in the FOV of interest. It accounts for the C_n~2 profile in order to optimally estiamte the correction wavefront to be applied to each DM. This optimal approach also accounts for the fact that the number of DM will always be smaller than the number of turbulent layers since the C_n~2 profile is a continuous function of the altitude h. Links between this optimal approach and a tomographic reconstruction of the turbulence volume are established. In particular, it is shown that the optimal approach consist in a full tomographic reconstruction of the turbulence volume followed by a projection on the deformable mirrors accounting for the considered FOV of terest. The case where the turbulent layers are assumed to match the mirror positions (model-approximation approach), which might be a crude approximation, is also considered for comparison. This model-approximation approach will rely on the notion of equivalent turbulent layers.