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30 January 2003 Multiple resolution (and field of view) adaptive optics: for ELTs only
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For reasonable Field of View (of the order of several arcmin), the pupil overlap in the high altitude layers is marginal or non existing for 8m class telescopes and dominant for 100m class apertures. Starting from this matter of fact, we formulated a multiple resolution, multiple Field of View version of the layer oriented adaptive optics approach which looks at the same layer with field apertures and spatial resolution that are mutually compensating each other: a larger field, allowing for the collection of more photons from natural stars, is used to sample the layer with a finer spatial detail, and viceversa. In this way the small field of view, with coarse spatial sampling, gives information on the behavior of the atmosphere for a large thickness around the focused layer, at the expense of the detailed information in a thin slab centered on the layer itself. Such lacking information is obtained from the wider field channel. This requires the coaddition of the two pieces of information at the level of the Fourier pair of the reimaged layer, which can be accomplished, in a practical way, directly in the spatial domain rather than in the Fourier one. The consequences on the sky coverage estimations and on the hardware implementations are discussed. Finally some comments are given about other degrees of freedom that can be used to improve the performance of layer oriented adaptive optics.
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Adriano Ghedina, Roberto Ragazzoni, Enrico Marchetti, Emiliano Diolaiti, Massimo Cecconi, and Jacopo Farinato "Multiple resolution (and field of view) adaptive optics: for ELTs only", Proc. SPIE 4840, Future Giant Telescopes, (30 January 2003);

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