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dc.contributor.authorKoechlin, Laurent
dc.contributor.authorSerre, Denis
dc.contributor.authorDeba, Paul
dc.contributor.authorPello, Roser
dc.contributor.authorPeillon, Christelle
dc.contributor.authorDuchon, Paul
dc.contributor.authorGomez de Castro, Ana Ines
dc.contributor.authorKarovska, Margarita
dc.contributor.authorDesert, J.-M.
dc.contributor.authorEhrenreich, D.
dc.contributor.authorHebrard, G.
dc.contributor.authorLecavelier des Etangs, A.
dc.contributor.authorFerlet, R.
dc.contributor.authorSing, David K.
dc.contributor.authorVidal-Madjar, A.
dc.date.accessioned2014-12-17T13:38:10Z
dc.date.issued2009
dc.description.abstractThe Fresnel Interferometric Imager has been proposed to the European Space Agency (ESA) Cosmic Vision plan as a class L mission. This mission addresses several themes of the CV Plan: Exoplanet study, Matter in extreme conditions, and The Universe taking shape. This paper is an abridged version of the original ESA proposal. We have removed most of the technical and financial issues, to concentrate on the instrumental design and astrophysical missions. The instrument proposed is an ultra-lightweight telescope, featuring a novel optical concept based on diffraction focussing. It yields high dynamic range images, while releasing constraints on positioning and manufacturing of the main optical elements. This concept should open the way to very large apertures in space. In this two spacecraft formation-flying instrument, one spacecraft holds the focussing element: the Fresnel interferometric array; the other spacecraft holds the field optics, focal instrumentation, and detectors. The Fresnel array proposed here is a 3.6 ×3.6 m square opaque foil punched with 105 to 106 void “subapertures”. Focusing is achieved with no other optical element: the shape and positioning of the subapertures (holes in the foil) is responsible for beam combining by diffraction, and 5% to 10% of the total incident light ends up into a sharp focus. The consequence of this high number of subapertures is high dynamic range images. In addition, as it uses only a combination of vacuum and opaque material, this focussing method is potentially efficient over a very broad wavelength domain. The focal length of such diffractive focussing devices is wavelength dependent. However, this can be corrected. We have tested optically the efficiency of the chromatism correction on artificial sources (500 < λ < 750 nm): the images are diffraction limited, and the dynamic range measured on an artificial double source reaches 6.2 10 − 6. We have also validated numerical simulation algorithms for larger Fresnel interferometric arrays. These simulations yield a dynamic range (rejection factor) close to 10 − 8 for arrays such as the 3.6 m one we propose. A dynamic range of 10 − 8 allows detection of objects at contrasts as high as than 10 − 9 in most of the field. The astrophysical applications cover many objects in the IR, visible an UV domains. Examples are presented, taking advantage of the high angular resolution and dynamic range capabilities of this concept.en_GB
dc.identifier.citationVol. 23 (1), pp. 379-402en_GB
dc.identifier.doi10.1007/s10686-008-9112-y
dc.identifier.urihttp://hdl.handle.net/10871/16076
dc.language.isoenen_GB
dc.publisherSpringer Verlagen_GB
dc.relation.urlhttp://dx.doi.org/10.1007/s10686-008-9112-yen_GB
dc.subjectDiffractive focussingen_GB
dc.subjectFormation-flyingen_GB
dc.subjectExoplanet detectionen_GB
dc.titleThe fresnel interferometric imageren_GB
dc.typeArticleen_GB
dc.date.available2014-12-17T13:38:10Z
dc.identifier.issn0922-6435
dc.descriptionCopyright © 2008 Springeren_GB
dc.descriptionThe final publication is available at Springer via http://dx.doi.org/10.1007/s10686-008-9112-yen_GB
dc.identifier.eissn1572-9508
dc.identifier.journalExperimental Astronomyen_GB


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