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Proceedings Paper

The GRAVITY Coudé Infrared Adaptive Optics (CIAO) system for the VLT Interferometer
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Paper Abstract

GRAVITY is a second generation instrument for the VLT Interferometer, designed to enhance the near-infrared astrometric and spectro-imaging capabilities of VLTI. Combining beams from four telescopes, GRAVITY will provide an astrometric precision of order 10 micro-arcseconds, imaging resolution of 4 milli-arcseconds, and low and medium resolution spectro-interferometry, pushing its performance far beyond current infrared interferometric capabilities. To maximise the performance of GRAVITY, adaptive optics correction will be implemented at each of the VLT Unit Telescopes to correct for the e_ects of atmospheric turbulence. To achieve this, the GRAVITY project includes a development programme for four new wavefront sensors (WFS) and NIR-optimized real time control system. These devices will enable closed-loop adaptive correction at the four Unit Telescopes in the range 1.4-2.4 μm. This is crucially important for an e_cient adaptive optics implementation in regions where optically bright references sources are scarce, such as the Galactic Centre. We present here the design of the GRAVITY wavefront sensors and give an overview of the expected adaptive optics performance under typical observing conditions. Bene_ting from newly developed SELEX/ESO SAPHIRA electron avalanche photodiode (eAPD) detectors providing fast readout with low noise in the near-infrared, the AO systems are expected to achieve residual wavefront errors of 400 nm at an operating frequency of 500 Hz.≤

Paper Details

Date Published: 24 September 2012
PDF: 9 pages
Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 84467W (24 September 2012); doi: 10.1117/12.926558
Show Author Affiliations
S. Kendrew, Max-Planck-Institut für Astronomie (Germany)
S. Hippler, Max-Planck-Institut für Astronomie (Germany)
W. Brandner, Max-Planck-Institut für Astronomie (Germany)
Y. Clénet, LESIA, Observatoire de Paris, CNRS, Univ. Paris Diderot (France)
C. Deen, Max-Planck-Institut für Astronomie (Germany)
E. Gendron, LESIA, Observatoire de Paris, CNRS, Univ. Paris Diderot (France)
A. Huber, Max-Planck-Institut für Astronomie (Germany)
R. Klein, Max-Planck-Institut für Astronomie (Germany)
W. Laun, Max-Planck-Institut für Astronomie (Germany)
R. Lenzen, Max-Planck-Institut für Astronomie (Germany)
V. Naranjo, Max-Planck-Institut für Astronomie (Germany)
Udo Neumann, Max-Planck-Institut für Astronomie (Germany)
J. Ramos, Max-Planck-Institut für Astronomie (Germany)
R.-R. Rohloff, Max-Planck-Institut für Astronomie (Germany)
P. Yang, Max-Planck-Institut für Astronomie (Germany)
F. Eisenhauer, Max-Planck-Institut für extraterrestrische Physik (Germany)
A. Amorim, Lab. de Sistemas, Instrumentao e Modelao em Cincias e Tecnologias do Ambiente e do Espao (Portugal)
K. Perraut, Institut de Planétologie et d'Astrophysique de Grenoble (France)
G. Perrin, LESIA, Observatoire de Paris, CNRS, Univ. Paris-Diderot (France)
C. Straubmeier, Univ. of Cologne (Germany)
Enrico Fedrigo, European Southern Observatory (Germany)
Marcos Suarez Valles, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 8446:
Ground-based and Airborne Instrumentation for Astronomy IV
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)

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