Visible-light channel of the Metis/Solar Orbiter coronagraph: On-ground polarimetric calibration

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00639435" target="_blank" >RIV/67985815:_____/25:00639435 - isvavai.cz</a>

Výsledek na webu

<a href="https://hdl.handle.net/11104/0369959" target="_blank" >https://hdl.handle.net/11104/0369959</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202452951" target="_blank" >10.1051/0004-6361/202452951</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Visible-light channel of the Metis/Solar Orbiter coronagraph: On-ground polarimetric calibration

Popis výsledku v původním jazyce

Context. Metis is the solar coronagraph on board the ESA/NASA mission Solar Orbiter (SolO), launched in 2020. It is designed to acquire simultaneous images of the solar corona in visible polarized light (580-640 nm), and in the narrowband H I Lyman-alpha line (i.e., 121.6 nm). The instrument visible-light channel includes a polarimeter composed of two liquid crystal variable retarder (LCVR) cells, a quarter-wave plate, and a linear polarizer, with the LCVR cells acting as the modulating element. By applying a specific voltage to the cells, it is possible to modify the incoming polarized light by changing the direction of the associated vector by a known angle, i.e., the angle of retardance. Aims. The polarimetric characterization of Metis is needed to correctly derive the properties of the plasma in the observed solar corona. This work describes the steps we took to fully characterize the visible channel of the Metis coronagraph, i.e., by deriving the modulation and demodulation matrices for each pixel, the latter being the key element for deriving the Stokes vector of the observed K corona. We completed the characterization by deriving the error associated with the derived values. Methods. The first step is to fully characterize the Metis polarimeter. This is needed to derive the relation between the voltage applied to the liquid crystal cells and the angle of retardance imposed on the incoming polarized light. This step represents the starting point for the calibration of the full instrument. Results. We derived (i) the voltage versus retardance curve associated with the polarimeter and (ii) the demodulation tensor of the Metis coronagraph, which is now used to retrieve the Stokes vector that describes the coronal light polarization state. Conclusions. This calibration is fundamental to disentangle the coronal light from the instrumental effects, such as disuniformity and instrumental polarization.

Název v anglickém jazyce

Visible-light channel of the Metis/Solar Orbiter coronagraph: On-ground polarimetric calibration

Popis výsledku anglicky

Context. Metis is the solar coronagraph on board the ESA/NASA mission Solar Orbiter (SolO), launched in 2020. It is designed to acquire simultaneous images of the solar corona in visible polarized light (580-640 nm), and in the narrowband H I Lyman-alpha line (i.e., 121.6 nm). The instrument visible-light channel includes a polarimeter composed of two liquid crystal variable retarder (LCVR) cells, a quarter-wave plate, and a linear polarizer, with the LCVR cells acting as the modulating element. By applying a specific voltage to the cells, it is possible to modify the incoming polarized light by changing the direction of the associated vector by a known angle, i.e., the angle of retardance. Aims. The polarimetric characterization of Metis is needed to correctly derive the properties of the plasma in the observed solar corona. This work describes the steps we took to fully characterize the visible channel of the Metis coronagraph, i.e., by deriving the modulation and demodulation matrices for each pixel, the latter being the key element for deriving the Stokes vector of the observed K corona. We completed the characterization by deriving the error associated with the derived values. Methods. The first step is to fully characterize the Metis polarimeter. This is needed to derive the relation between the voltage applied to the liquid crystal cells and the angle of retardance imposed on the incoming polarized light. This step represents the starting point for the calibration of the full instrument. Results. We derived (i) the voltage versus retardance curve associated with the polarimeter and (ii) the demodulation tensor of the Metis coronagraph, which is now used to retrieve the Stokes vector that describes the coronal light polarization state. Conclusions. This calibration is fundamental to disentangle the coronal light from the instrumental effects, such as disuniformity and instrumental polarization.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

701

Číslo periodika v rámci svazku

Sept.

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

11

Strana od-do

A197

Kód UT WoS článku

001574075800008

EID výsledku v databázi Scopus

2-s2.0-105016453230