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Proceedings Paper

Fresnel diffractive imager: instrument for space mission in the visible and UV
Author(s): T. Raksasataya; P. Deba; J. P. Rivet; R. Gili; D. Serre; L. Koechlin
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Paper Abstract

We propose a new concept of diffractive optics: Fresnel arrays, for a 4 m aperture space telescope in the UV domain. Fresnel arrays focus light by diffraction through a very thin binary mask. They form images optically and deliver very high quality wavefronts, specially in the UV. Up to 8% of the incident light is focussed, providing high angular resolution and high contrast images of compact objects. Due to their focal lengths of a few kilometers in the UV, large Fresnel arrays will require two spacecraft in formation flying, but with relatively tolerant positioning. Diffraction focusing is also very chromatic; this chromatism is corrected, allowing relatively broad (30 to 100 nm) spectral channels in the 120-350 nm range. A 4 m aperture Fresnel imager providing 7 to 10 milli arc seconds resolution is very competitive for imaging compact and high contrast objects such as protoplanetary disks and young planetary systems, AGNs, and deep sky objects. We have developed prototypes to validate the optical concept and related technologies : first a laboratory setup, then a 20 cm aperture ground-based prototype, which provides high contrast and diffraction limited images of sky objects in the visible and close IR. A new laboratory prototype is also being prepared for validation in the 250 - 350 nm wavelength range.

Paper Details

Date Published: 29 July 2010
PDF: 9 pages
Proc. SPIE 7732, Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, 77322D (29 July 2010); doi: 10.1117/12.857213
Show Author Affiliations
T. Raksasataya, Lab. d'Astrophysique de Toulouse et Tarbes, CNRS, Univ. Paul Sabatier (France)
P. Deba, Lab. d'Astrophysique de Toulouse et Tarbes, CNRS, Univ. Paul Sabatier (France)
J. P. Rivet, Observatoire de la Côte d'Azur (France)
R. Gili, Observatoire de la Côte d'Azur (France)
D. Serre, Lab. d'Astrophysique de Toulouse et Tarbes, CNRS, Univ. Paul Sabatier (France)
L. Koechlin, Lab. d'Astrophysique de Toulouse et Tarbes, CNRS, Univ. Paul Sabatier (France)


Published in SPIE Proceedings Vol. 7732:
Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray
Monique Arnaud; Stephen S. Murray; Tadayuki Takahashi, Editor(s)

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