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Proceedings Paper

Electro-optical polarimeters for ground-based and space-based observations of the solar K-corona
Author(s): G. Capobianco; S. Fineschi; G. Massone; E. Balboni; A. M. Malvezzi; G. Crescenzio; L. Zangrilli; P. Calcidese; E. Antonucci; M. Patrini
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Paper Abstract

Polarimeters based on electro-optically tunable liquid crystals (LC) represent a new technology in the field of observational astrophysics. LC-based polarimeters are good candidates for replacing mechanically rotating polarimeters in most ground-based and space-based applications. During the 2006 total solar eclipse, we measured the visible-light polarized brightness (pB) of the solar K-corona with a LC-based polarimeter and imager (E-KPol). In this presentation, we describe the results obtained with the E-KPol, and we evaluate its performances in view of using a similar device for the pB imaging of the K-corona from space-based coronagraphs. Specifically, a broad-band LC polarimeter is planned for the METIS (Multi Element Telescope for Imaging and Spectroscopy) coronagraph for the Solar Orbiter mission to be launched in 2017. The METIS science driver of deriving the coronal electron density from pB images requires an accuracy of better than 1% in the measurement of linear polarization. We present the implications of this requirement on the METIS design to minimize the instrumental polarization of the broad-band visible-light (590-650 nm) polarimeter and of the other optics in the METIS visible-light path. Finally, we report preliminary ellipsometric measurements of the optical components of the METIS visible-light path.

Paper Details

Date Published: 13 September 2012
PDF: 10 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 845040 (13 September 2012); doi: 10.1117/12.926896
Show Author Affiliations
G. Capobianco, INAF - Osservatorio Astrofisico di Torino (Italy)
S. Fineschi, INAF - Osservatorio Astrofisico di Torino (Italy)
G. Massone, INAF - Osservatorio Astrofisico di Torino (Italy)
E. Balboni, Associazione Apriticielo (Italy)
A. M. Malvezzi, Univ. degli Studi di Pavia (Italy)
G. Crescenzio, INAF - Osservatorio Astrofisico di Torino (Italy)
L. Zangrilli, INAF - Osservatorio Astrofisico di Torino (Italy)
P. Calcidese, Osservatorio Astronomico della regione Autonoma (Italy)
E. Antonucci, INAF - Osservatorio Astrofisico di Torino (Italy)
M. Patrini, Univ. degli Studi di Pavia (Italy)


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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