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Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope Interferometer

Defrère, D. and Hinz, P. and Downey, E. and Böhm, M. and Danchi, W. C. and Durney, O. and Ertel, S. and Hill, J. M. and Hoffmann, W. F. and Mennesson, B. and Millan-Gabet, R. and Montoya, M. and Pott, J.-U. and Skemer, A. and Spalding, E. and Stone, J. and Vaz, A. (2016) Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope Interferometer. In: Optical and Infrared Interferometry and Imaging V. Proceedings of SPIE. No.9907. Society of Photo-Optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 99071G. ISBN 978-1-5106-0193-2.

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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.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Defrère, D.0000-0003-3499-2506
Hinz, P.0000-0002-1954-4564
Ertel, S.0000-0002-2314-7289
Mennesson, B.0000-0003-4205-4800
Millan-Gabet, R.0000-0003-0447-5866
Pott, J.-U.0000-0003-4291-2078
Skemer, A.0000-0001-6098-3924
Spalding, E.0000-0003-3819-0076
Additional Information:© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE). The authors are grateful to M. Colavita, O. Absil, A. Matter, and J. Meisner for helpful discussions on fringe sensing and water vapor OPD measurements. LBTI is funded by a NASA grant in support of the Exoplanet Exploration Program. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofísica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:Infrared interferometry, Nulling interferometry, Fringe tracking, Water vapor, LBT, ELT
Series Name:Proceedings of SPIE
Issue or Number:9907
Record Number:CaltechAUTHORS:20170112-111237433
Persistent URL:
Official Citation: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; Simultaneous water vapor and dry air optical path length measurements and compensation with the large binocular telescope interferometer. Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 99071G (August 4, 2016); doi:10.1117/12.2233884.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73469
Deposited By: Ruth Sustaita
Deposited On:21 Jan 2017 02:03
Last Modified:07 Apr 2020 18:57

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