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Proceedings Paper

Design of a nano-satellite demonstrator of an infrared imaging space interferometer: the HyperCube
Author(s): Kjetil Dohlen; Sébastien Vives; Eddy Rakotonimbahy; Tanmoy Sarkar; Tanzila Tasnim Ava; Nicola Baccichet; Giorgio Savini; Bruce Swinyard
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Paper Abstract

The construction of a kilometer-baseline far infrared imaging interferometer is one of the big instrumental challenges for astronomical instrumentation in the coming decades. Recent proposals such as FIRI, SPIRIT, and PFI illustrate both science cases, from exo-planetary science to study of interstellar media and cosmology, and ideas for construction of such instruments, both in space and on the ground. An interesting option for an imaging multi-aperture interferometer with km baseline is the space-based hyper telescope (HT) where a giant, sparsely populated primary mirror is constituted of several free-flying satellites each carrying a mirror segment. All the segments point the same object and direct their part of the pupil towards a common focus where another satellite, containing recombiner optics and a detector unit, is located. In Labeyrie’s [1] original HT concept, perfect phasing of all the segments was assumed, allowing snap-shot imaging within a reduced field of view and coronagraphic extinction of the star. However, for a general purpose observatory, image reconstruction using closure phase a posteriori image reconstruction is possible as long as the pupil is fully non-redundant. Such reconstruction allows for much reduced alignment tolerances, since optical path length control is only required to within several tens of wavelengths, rather than within a fraction of a wavelength. In this paper we present preliminary studies for such an instrument and plans for building a miniature version to be flown on a nano satellite. A design for recombiner optics is proposed, including a scheme for exit pupil re-organization, is proposed, indicating the focal plane satellite in the case of a km-baseline interferometer could be contained within a 1m3 unit. Different options for realization of a miniature version are presented, including instruments for solar observations in the visible and the thermal infrared and giant planet observations in the visible, and an algorithm for design of optimal aperture layout based on least-squares minimization is described. A first experimental setup realized by master students is presented, where a 20mm baseline interferometer with 1mm apertures associated with a thermal infrared camera pointed the sun. The absence of fringes in this setup is discussed in terms of spatial spectrum analysis. Finally, we discuss requirements in terms of satellite pointing requirements for such a miniature interferometer.

Paper Details

Date Published: 24 July 2014
PDF: 10 pages
Proc. SPIE 9146, Optical and Infrared Interferometry IV, 914603 (24 July 2014); doi: 10.1117/12.2057226
Show Author Affiliations
Kjetil Dohlen, Lab. d'Astrophysique de Marseille, CNRS, Aix Marseille Univ. (France)
Sébastien Vives, Lab. d'Astrophysique de Marseille, CNRS, Aix Marseille Univ. (France)
Eddy Rakotonimbahy, Lab. d'Astrophysique de Marseille, CNRS, Aix Marseille Univ. (France)
Tanmoy Sarkar, Lab. d'Astrophysique de Marseille, CNRS, Aix Marseille Univ. (France)
Tanzila Tasnim Ava, Lab. d'Astrophysique de Marseille, CNRS, Aix Marseille Univ. (France)
Nicola Baccichet, Univ. College London (United Kingdom)
Giorgio Savini, Univ. College London (United Kingdom)
Bruce Swinyard, Univ. College London (United Kingdom)


Published in SPIE Proceedings Vol. 9146:
Optical and Infrared Interferometry IV
Jayadev K. Rajagopal; Michelle J. Creech-Eakman; Fabien Malbet, Editor(s)

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