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Proceedings Paper

Extinction controlled adaptive mask coronagraph Lyot and phase mask dual concept for wide extinction area
Author(s): P. Bourget; N. Schuhler; D. Mawet; P. Haguenauer; J. Girard; Frederic Gonte
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Paper Abstract

A dual coronagraph based on the Adaptive Mask concept is presented in this paper. ALyot coronagraph with a variable diameter occulting disk anda nulling stellar coronagraph based on the Adaptive Phase Mask concept using polarization interferometry are presented in this work. Observations on sky and numerical simulations show the usefulness of the proposed method to optimize the nulling efficiency of the coronagraphs. In the case of the phase mask, the active control system will correct for the detrimental effects of image instabilities on the destructive interference (low-order aberrations such as tip-tilt and focus). The phase mask adaptability both in size, phase and amplitude also compensate for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve the achromatic π phase shift in the core of the PSF by rotating the polarization by 180°.A compressed mercury (Hg) drop is used as an occulting disk for the Lyot mask, its size control offers an adaptation to the seeing conditions and provides an optimization of the Tip-tilt correction.

Paper Details

Date Published: 13 September 2012
PDF: 10 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 84505I (13 September 2012); doi: 10.1117/12.927284
Show Author Affiliations
P. Bourget, European Southern Observatory (Chile)
N. Schuhler, European Southern Observatory (Chile)
D. Mawet, European Southern Observatory (Chile)
P. Haguenauer, European Southern Observatory (Chile)
J. Girard, European Southern Observatory (Chile)
Frederic Gonte, European Southern Observatory (Chile)


Published in SPIE Proceedings Vol. 8450:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
Ramón Navarro; Colin R. Cunningham; Eric Prieto, Editor(s)

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