Reference : Tests with a Carlina-type diluted telescope. Primary coherencing
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/113004
Tests with a Carlina-type diluted telescope. Primary coherencing
English
Le Coroller, H. [Observatoire de Haute-Provence, 04870, Saint-Michel l'Observatoire, France]
Dejonghe, J. [ > > ]
Regal, X. [Observatoire de Haute-Provence, 04870, Saint-Michel l'Observatoire, France]
Sottile, R. [Observatoire de Haute-Provence, 04870, Saint-Michel l'Observatoire, France]
Mourard, D. [Université Nice-Sophia Antipolis, Observatoire de la Côte d'Azur, CNRS UMR 6525, BP 4229, 06304, Nice Cedex, France]
Ricci, Davide mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)]
Lardiere, O. [AO Laboratory, Mechanical Engineering Department, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada]
Le Vansuu, A. [Observatoire de Haute-Provence, 04870, Saint-Michel l'Observatoire, France]
Boer, M. [Observatoire de Haute-Provence, 04870, Saint-Michel l'Observatoire, France]
De Becker, Michaël mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)]
Clausse, J.-M. [Université Nice-Sophia Antipolis, Observatoire de la Côte d'Azur, CNRS UMR 6525, BP 4229, 06304, Nice Cedex, France]
Guillaume, C. [ > > ]
Meunier, J.-P. [ > > ]
1-Mar-2012
Astronomy and Astrophysics
EDP Sciences
539
59
Yes (verified by ORBi)
International
0004-6361
1432-0746
Les Ulis
France
[en] instrumentation: interferometers ; atmospheric effects ; instrumentation: adaptive optics ; telescopes ; balloons ; instrumentation: high angular resolution
[en] Aims: Studies are under way to propose a new generation of post-VLTI interferometers. The Carlina concept studied at the Haute-Provence Observatory is one of the proposed solutions. It consists in an optical interferometer configured like a diluted version of the Arecibo radio telescope: above the diluted primary mirror made of fixed cospherical segments, a helium balloon (or cables suspended between two mountains), carries a gondola containing the focal optics. Since 2003, we have been building a technical demonstrator of this diluted telescope. First fringes were obtained in May 2004 with two closely-spaced primary segments and a CCD on the focal gondola. We have been testing the whole optical train with three primary mirrors. The main aim of this article is to describe the metrology that we have conceived, and tested under the helium balloon to align the primary mirrors separate by 5-10 m on the ground with an accuracy of a few microns. Methods: Getting stellar fringes using delay lines is the main difficulty for astronomical interferometers. Carlina does not use delay lines, but the primary segments have to be positioned on a sphere i.e. coherencing the primary mirrors. As described in this paper, we used a supercontinuum laser source to coherence the primary segments. We characterize the Carlina's performances by testing its whole optical train: servo loop, metrology, and the focal gondola. Results: The servo loop stabilizes the mirror of metrology under the helium balloon with an accuracy better than 5 mm while it moves horizontally by 30 cm in open loop by 10-20 km/h of wind. We have obtained the white fringes of metrology; i.e., the three mirrors are aligned (cospherized) with an accuracy of ≈1 μm. We show data proving the stability of fringes over 15 min, therefore providing evidence that the mechanical parts are stabilized within a few microns. This is an important step that demonstrates the feasibility of building a diluted telescope using cables strained between cliffs or under a balloon. Carlina, like the MMT or LBT, could be one of the first members of a new class of telescopes named diluted telescopes.
Researchers ; Professionals
http://hdl.handle.net/2268/113004
10.1051/0004-6361/201117561
http://adsabs.harvard.edu/abs/2012A%26A...539A..59L
http://de.arxiv.org/abs/1201.2596

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