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Wide Field AO simulation for ELT: fourier and global E2E approaches

Abstract 191

Submitted by Cyril PETIT


C Petit, T. Fusco, B. Neichel, J-F Sauvage, J-M Conan




The next generation of Extremely Large Telescopes [ELTs] will provide a dramatic advance in our understanding of the universe. In this context, several Wide Field of view Adaptive Optics [WFAO] concepts like Multi-Conjugate AO [MCAO], Multi-Object AO [MOAO] or Ground-Layer AO [GLAO] are under study. Simulating such kind of systems is, however, one of the main issues to be addressed (especially in term of computation time). In this paper, we present two simulation approaches allowing to deal with the ELT complexity with a reasonable computational cost. First a Phase Spectrum Density [PSD] simulation tool which can provide fast but realistic PSFs for performance evaluation. This will lead to a rapid exploration of the WFAO parameter space. This simulation tool is based on Fourier domain "Maximum A Posteriori" tomography reconstruction. Then an end to end approach based on a iterative criterion minimisation instead of a crude matrix inversion followed by matrux vector multiplications. After a brief presentation of the theoretical basis of the methods, we compare the results with a full existing and fully validated end-to-end simulation code available at ONERA. An analysis of the two approaches advantages and limitations (w.r.t LGS tomographic reconstruction) is presented and several solutions are proposed to overcome them. The combination of Fourier and End2end approach is now use for the phase A design of all the WFOA systems for the E-ELT.

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