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Proceedings Paper

KPol: liquid crystal polarimeter for K-corona observations from the SCORE coronagraph
Author(s): Silvano Fineschi; Luca Zangrilli; Guglielmo Rossi; Luca Gori; Marco Romoli; Gianni Corti; Gerardo Capobianco; Ester Antonucci; Emanuele Pace
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Paper Abstract

We describe the design and first calibration tests of an imaging polarimeter based on Liquid Crystal Variable Retarders (LCVRs), for the study of the solar K-corona. This K-polarimeter (KPol) is part of the visible light path of the UltraViolet and Visible-light Coronal Imager (UVCI) of the Sounding-rocket Coronagraphic Experiment (SCORE). SCORE/UVCI is an externally occulted, off-axis Gregorian telescope, optimized for the narrow-band (i.e., λ/▵λ ~10) imaging of the HeII, λ 30.4 nm and HI λ 121.6 nm coronal emission. We present some preliminary results of the application of LCVR plates to measurements of linear polarized radiation. LCVR plates replace mechanically rotating retarders with electro-optical devices, without no moving parts. LCVR are variable waveplates, in which the change of the retardance is induced by a variable applied voltage. The retardance of a LCVR is a function of the wavelength. KPol observations of the visible coronal continuum of the Sun (K-corona) will be made over the 450-600 nm wavelength band. We have studied the LCVR's properties in this bandpass. We tested a LCVR plate assembled in a linear polarization rotator configuration to measure the polarization plane rotation of input radiation as a function of wavelength. We estimated the LCVR's chromatic response in the KPol wavelength bandpass. The preliminary results show reasonable achromatic behaviour at high regimes of the driving voltage, Vd (i.e., Vd>3 volt).

Paper Details

Date Published: 18 August 2005
PDF: 11 pages
Proc. SPIE 5901, Solar Physics and Space Weather Instrumentation, 59011I (18 August 2005); doi: 10.1117/12.626033
Show Author Affiliations
Silvano Fineschi, INAF-Osservatorio Astronomico di Torino (Italy)
Luca Zangrilli, INAF-Osservatorio Astronomico di Torino (Italy)
Guglielmo Rossi, Univ. degli Studi di Firenze (Italy)
Luca Gori, Univ. degli Studi di Firenze (Italy)
Marco Romoli, Univ. degli Studi di Firenze (Italy)
Gianni Corti, Univ. degli Studi di Firenze (Italy)
Gerardo Capobianco, INAF-Osservatorio Astronomico di Torino (Italy)
Ester Antonucci, INAF-Osservatorio Astronomico di Torino (Italy)
Emanuele Pace, Univ. degli Studi di Firenze (Italy)

Published in SPIE Proceedings Vol. 5901:
Solar Physics and Space Weather Instrumentation
Silvano Fineschi; Rodney A. Viereck, Editor(s)

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