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Proceedings Paper

Image plane phase-shifting wavefront sensor for giant telescope active and adaptive optics
Author(s): François Hénault
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Paper Abstract

Since the realization of the twin Keck telescopes of 10-meter diameter built atop the Mauna Kea in Hawaii, the technology of segmented mirrors has become a cornerstone for on-going projects of Extremely Large Telescopes (ELT). Here the individual mirror segments should actually be phased together (i.e. reconstruct the surface of an ideal continuous, giant mirror) within accuracies typically better than one tenth of the operating wavelength. This could be achieved using existing Wavefront Sensors (WFS), but may also involve the development of alternative methods: in this communication is described a new generation WFS operating in the image plane and able to sense differential piston errors of the segments with residual uncertainties inferior to 25 nm by means of a phase-shifting technique. We describe the principle of the method in both monochromatic and polychromatic light and present its achievable performance in terms of limiting magnitude of the guide star in presence of various noise sources. It is emphasized that the technique is also applicable for co-phasing sparse aperture interferometers, or more generally to any Adaptive Optics (AO) system making use of image plane WFS evaluating telescope wavefront errors (WFE) in real time.

Paper Details

Date Published: 16 September 2011
PDF: 12 pages
Proc. SPIE 8149, Astronomical Adaptive Optics Systems and Applications IV, 81490A (16 September 2011); doi: 10.1117/12.892752
Show Author Affiliations
François Hénault, CNRS H. Fizeau, Univ. de Nice Sophia Antipolis, Observatorie de la Côte d'Azur (France)

Published in SPIE Proceedings Vol. 8149:
Astronomical Adaptive Optics Systems and Applications IV
Robert K. Tyson; Michael Hart, Editor(s)

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