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Proceedings Paper

Wide field of view liquid crystals-based modulator for the polarimeter of the Metis/Solar Orbiter
Author(s): Gerardo Capobianco; Marta Casti; Silvano Fineschi; Giuseppe Massone; Mewael G. Sertsu; Federico Landini; Marco Romoli; Ester Antonucci; Vincenzo Andretta; Giampiero Naletto; Gianalfredo Nicolini; Daniele Spadaro; Alberto Alvarez Herrero; Pilar Garcia Parejo; Matteo Marmonti
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Paper Abstract

Metis is an inverted occulted coronagraph on-board the ESA/Solar Orbiter mission. The visible light path of the instrument will observe the "white" light (580-640 nm) linearly-polarized emission from the solar corona. The coronal polarized brightness allows retrieval of physical parameters such as the electron density and temperature of the K-corona. The Metis polarimeter comprises a quarter-wave retarder, the liquid crystal polarization modulation package (PMP) and a linear polarizer working as polarization analyser. The PMP consists of two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with the fast axes parallels one to each other and a pre-tilted angle of the molecules in opposite direction, in order to maximize the homogeneity of the retardance across instrumental wide field of view: ±7 deg. This presentation reports the characterization of the PMP breadboard (BB), fully representative of the optical/polarimetric performances of the flight model. This characterization consisted in determining the performances of the device in terms of retardance as function of the applied voltage at different temperatures, angle of incidence and the variation of the retardance as a function of the wavelength. The calibrations were performed by measuring the complete Mueller matrix of the PMP-BB. The experimental results have been compared with the parameters of the theoretical model (e.g., depolarization, effective retardance, cells misalignment).

Paper Details

Date Published: 6 August 2018
PDF: 11 pages
Proc. SPIE 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 1069830 (6 August 2018); doi: 10.1117/12.2323371
Show Author Affiliations
Gerardo Capobianco, INAF - Astrophysical Observatory of Torino (Italy)
Marta Casti, INAF - Astrophysical Observatory of Torino (Italy)
Silvano Fineschi, INAF - Astrophysical Observatory of Torino (Italy)
Giuseppe Massone, INAF - Astrophysical Observatory of Torino (Italy)
Mewael G. Sertsu, Padua Univ. (Italy)
Federico Landini, INAF - Astrophysical Observatory of Arcetri (Italy)
Marco Romoli, Univ. degli Studi di Firenze (Italy)
Ester Antonucci, INAF - Osservatorio Astronomico di Torino (Italy)
Vincenzo Andretta, INAF - Osservatorio Astronomico di Capodimonte (Italy)
Giampiero Naletto, Univ. degli Studi di Padova (Italy)
Gianalfredo Nicolini, INAF - Osservatorio Astrofisico di Torino (Italy)
Daniele Spadaro, INAF - Osservatorio Astrofisico di Catania (Italy)
Alberto Alvarez Herrero, INTA Instituto Nacional de Técnica Aeroespacial (Spain)
Pilar Garcia Parejo, INTA Instituto Nacional de Técnica Aeroespacial (Spain)
Matteo Marmonti, Optec S.p.A. (Italy)

Published in SPIE Proceedings Vol. 10698:
Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave
Makenzie Lystrup; Howard A. MacEwen; Giovanni G. Fazio; Natalie Batalha; Nicholas Siegler; Edward C. Tong, Editor(s)

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