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Proceedings Paper

Simultaneous water vapor and dry air optical path length measurements and compensation with the large binocular telescope interferometer
Author(s): D. Defrère; P. Hinz; E. Downey; M. Böhm; W. C. Danchi; O. Durney; S. Ertel; J. M. Hill; W. F. Hoffmann; B. Mennesson; R. Millan-Gabet; M. Montoya; J.-U. Pott; A. Skemer; E. Spalding; J. Stone; A. Vaz
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Paper Abstract

The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feedforward approach to stabilize the path length fluctuations seen by the LBTI nuller.

Paper Details

Date Published: 4 August 2016
PDF: 7 pages
Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 99071G (4 August 2016); doi: 10.1117/12.2233884
Show Author Affiliations
D. Defrère, Univ. of Arizona (United States)
Univ. de Liège (Belgium)
P. Hinz, Univ. of Arizona (United States)
E. Downey, Univ. of Arizona (United States)
M. Böhm, Univ. of Stuttgart (Germany)
W. C. Danchi, NASA Goddard Space Flight Ctr. (United States)
O. Durney, Univ. of Arizona (United States)
S. Ertel, Univ. of Arizona (United States)
J. M. Hill, Univ. of Arizona (United States)
W. F. Hoffmann, Univ. of Arizona (United States)
B. Mennesson, California Institute of Technology (United States)
R. Millan-Gabet, California Institute of Technology (United States)
M. Montoya, Univ. of Arizona (United States)
J.-U. Pott, Max-Planck-Institute for Astronomy (Germany)
A. Skemer, Univ. of California, Santa Cruz (United States)
E. Spalding, Univ. of Arizona (United States)
J. Stone, Univ. of Arizona (United States)
A. Vaz, Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 9907:
Optical and Infrared Interferometry and Imaging V
Fabien Malbet; Michelle J. Creech-Eakman; Peter G. Tuthill, Editor(s)

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