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Centro de Astrofísica da Universidade do Porto

Wave-front reconstruction for the non-linear curvature wave-front sensor

C. M. Correia, J.-P. Véran, O. Guyon, C. Clergeon

Abstract
Non-linear curvature wave-front sensing (nlCWFS) delivers outstanding sensitivity and high dynamic range by lifting the linearity constraint of standard curvature wave-front sensing. This is achieved by taking full advantage of diffraction, which encodes wave-front aberrations into patterns of diffraction-limited interference speckles. Originally nlCWFS has been proposed for extreme AO, but it could also be used when the number of modes to measure is lower.The trade is set by a non-linear wave-front reconstruction which involves computationally intensive non-linear algorithms. One such example is the Gerchberg-Saxton iterative algorithm proposed originally. In this paper we propose an approximation that allows us to use the framework developed for phase-diversity to compute the maximum a-posteriori wave-front estimate. We characterize this reconstructor in terms of accuracy and sensitivity to noise and compare its performance to that of the Gerchberg-Saxton algorithm. Finally, we assess the computational requirements of our reconstructor, and discuss its possible real-time implementation.

Proceedings of the Third AO4ELT Conference
(Eds.) S. Esposito, L. Fini

INAF - Osservatorio Astrofisico di Arcetri

2013

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Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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