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Proceedings Paper

CIAXE: co-axial achromatic interferential coronagraph: first laboratory results
Author(s): Fatmé Allouche; Jean Gay; Yves Rabbia; Pierre Assus
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Paper Abstract

In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.

Paper Details

Date Published: 9 August 2010
PDF: 13 pages
Proc. SPIE 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave, 77314Q (9 August 2010); doi: 10.1117/12.857320
Show Author Affiliations
Fatmé Allouche, ESO (Germany)
Univ. de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur (France)
Collège de France, Chaire Astrophysique Observationnelle (France)
Jean Gay, Univ. de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur (France)
Yves Rabbia, Univ. de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur (France)
Pierre Assus, Univ. de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur (France)


Published in SPIE Proceedings Vol. 7731:
Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave
Jacobus M. Oschmann; Mark C. Clampin; Howard A. MacEwen, Editor(s)

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