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Proceedings Paper

Wavefront sensing through spatial filters: the case for coronographic, high-contrast AO systems
Author(s): Markus Feldt; Joana B. Costa; Micaela Stumpf; Hans-Martin Schmid; Alessandro Berton; Stefan Hippler; Remko Stuik; Jorge Lima
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Paper Abstract

For applications like direct imaging detections of Exo-Planets from the ground e.g. in the CHEOPS project, extreme adaptive optics (XAO) systems using DMs with > 1000 actuators and correction frequencies of ~2kHz are proposed to be used in combination with coronographic devices. If the XAO and science channel work at the same wavelength it is a natural idea to combine the coronograph with the XAO's beam splitter (BS) to make use of the light that would otherwise just be lost. However, the location of the BS in the focal plane and the severe field limitation of the AO by a small (~0.3'') aperture in the focal plane imposes a spatial filtering on the wavefront sensor signal. In this paper, we examine the effect of the spatial filter on the "AO control radius" and the Strehl ratio provided by the system in a semi-analytical way, numerical simulations for various wavefront sensor types and a laboratory verification experiment.

Paper Details

Date Published: 25 October 2004
PDF: 9 pages
Proc. SPIE 5490, Advancements in Adaptive Optics, (25 October 2004); doi: 10.1117/12.550883
Show Author Affiliations
Markus Feldt, Max-Planck-Institut fur Astronomie (Germany)
Joana B. Costa, Max-Planck-Institut fur Astronomie (Germany)
Micaela Stumpf, Max-Planck-Institut fur Astronomie (Germany)
Hans-Martin Schmid, ETH Zurich (Switzerland)
Alessandro Berton, Max-Planck-Institut fur Astronomie (Germany)
INAF, Osservatorio Astronomico di Padova (Italy)
Stefan Hippler, Max-Planck-Institut fur Astronomie (Germany)
Remko Stuik, Leiden Observatory/Univ. Leiden (Netherlands)
Jorge Lima, Univ. de Lisboa (Portugal)

Published in SPIE Proceedings Vol. 5490:
Advancements in Adaptive Optics
Domenico Bonaccini Calia; Brent L. Ellerbroek; Roberto Ragazzoni, Editor(s)

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