Imaging polarimeters based on liquid crystal variable retarders: an emergent technology for space instrumentation

Alvarez-Herrero, A.; Uribe-Patarroyo, Néstor; Parejo, Pilar García; Vargas, Javier; Heredero, R. L.; Restrepo, René; Pillet, V. Martínez; Iniesta, J. C. del Toro; López, A.J.; Fineschi, Silvano; Capobianco, Gerardo; Georges, Marc; López, M. A. Hernández; Boer, Gerben; Manolis, Ilias

doi:10.1117/12.892732

Cited by 28 publications

(21 citation statements)

References 28 publications

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“…Each PMP consists of two nematic liquid crystal retarders, followed by a linear polarizer as an analyzer. The liquid crystal variable retarders have been successfully qualified for the use in Solar Orbiter (see Alvarez-Herrero et al 2011).…”

Section: The So/phi Instrumentmentioning

confidence: 99%

The Polarimetric and Helioseismic Imager for Solar Orbiter: SO/PHI

Solanki¹,

Iniesta²,

Woch³

et al. 2014

Proc. IAU

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Abstract. The Solar Orbiter is the next solar physics mission of the European Space Agency, ESA, in collaboration with NASA, with a launch planned in 2018. The spacecraft is designed to approach the Sun to within 0.28 AU at perihelion of a highly eccentric orbit. The proximity with the Sun will also allow its observation at uniformly high resolution at EUV and visible wavelengths. Such observations are central for learning more about the magnetic coupling of the solar atmosphere. At a later phase in the mission the spacecraft will leave the ecliptic and study the enigmatic poles of the Sun from a heliographic latitude of up to 33• . A central instrument of Solar Orbiter is the Polarimetric and Helioseismic Imager, SO/PHI. It will do full Stokes imaging in the Landé g = 2.5 Fe I 617.3 nm line. It is composed of two telescopes, a full-disk telescope and a high-resolution telescope, that will allow observations at a resolution as high as 200 km on the solar surface. SO/PHI will also be the first solar polarimeter to leave the Sun-Earth line, opening up new possibilities, such as stereoscopic polarimetry (besides stereoscopic imaging of the photosphere and stereoscopic helioseismology). Finally, SO/PHI will have a unique view of the solar poles, allowing not just more precise and exact measurements of the polar field than possible so far, but also enabling us to follow the dynamics of individual magnetic features at high latitudes and to determine solar surface and sub-surface flows right up to the poles.In this paper an introduction to the science goals and the capabilities of SO/PHI will be given, as well as a brief overview of the instrument and of the current status of its development.

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Section: The So/phi Instrumentmentioning

confidence: 99%

The Polarimetric and Helioseismic Imager for Solar Orbiter: SO/PHI

Solanki¹,

Iniesta²,

Woch³

et al. 2014

Proc. IAU

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“…However, in space missions, rotating or more generally moving parts should be avoided if possible in the instrument, as they are automatically considered as single point failure (i.e., risk items for the mission). Using liquid crystal switching systems could be a solution to modulate temporally the polarization state without rotating optical parts [6]. Unfortunately, liquid crystals are not efficient in wide spectral ranges and cannot be used in the far-ultraviolet (FUV) region, below 250 nm.…”

Section: B2 Modulation Of the Polarization Statementioning

confidence: 99%

Static spectropolarimeter concept adapted to space conditions and wide spectrum constraints

et al. 2015

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The issues related to moving elements in space and instruments working in broader wavelength ranges lead to a need for robust polarimeters, efficient on a wide spectral domain, and adapted to space conditions. As part of the UVMag consortium, created to develop spectropolarimetric UV facilities in space, such as the Arago mission project, we present an innovative concept of static spectropolarimetry. We studied a static and polychromatic method for spectropolarimetry, applicable to stellar physics. Instead of modulating the polarization information temporally, as usually done in spectropolarimeters, the modulation is performed in a spatial direction, orthogonal to the spectral one. Thanks to the proportionality between phase retardance imposed by a birefringent material and its thickness, birefringent wedges can be used to create this spatial modulation. The light is then spectrally cross-dispersed, and a full-Stokes determination of the polarization over the whole spectrum can be obtained with a single-shot measurement. The use of Magnesium Fluoride wedges, for example, could lead to a compact, static polarimeter working at wavelengths from 0.115 µm up to 7 µm. We present the theory and simulations of this concept, as well as laboratory validation and a practical application to Arago.

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“…For the evaluation of the contribution of the IF filter an ellipsometer could be used 7,12 , for the others components of the polarimeter assembly and for the whole polarimeter, a prototype of a Mueller SpectroPolarimeter (MSP) is available and already used in the labs of the INAF-Turin Astrophysical Observatory 14,15,16,17 for this kind of calibrations. Some identified critical points related to the polarimeter that will be investigated are: the homogeneity of the retardance versus angle of incidence and versus temperature 18,19 .…”

Section: Instrumental Polarizationmentioning

confidence: 99%

Polarimetric calibrations and astronomical polarimetry in the V-band with Solar Orbiter/METIS instrument

Capobianco

Fineschi

Focardi³

et al. 2014

SPIE Proceedings

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METIS is one of the remote sensing instruments on board the ESA- Solar Orbiter mission, that will be launched in July 2017. The Visible Light Channel (VLC) of the instrument is composed by an achromatic LC-based polarimeter for the study of the linearly polarized solar K-corona in the 580-640 nm bandpass. The laboratory calibrations with spectropolarimetric techniques and the in-flight calibrations of this channel, using some well knows linearly polarized stars in the FoV of the instrument with a degree of linear polarization DOLP > 10% are here discussed. The selection of the stars and the use of other astronomical targets (i.e. planets, comets,…) and the opportunity of measurements of the degree of linear polarization in the visible bandpass of some astronomical objects (i.e. Earth, comets,…) are also objects of this paper

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Imaging polarimeters based on liquid crystal variable retarders: an emergent technology for space instrumentation

Cited by 28 publications

References 28 publications

The Polarimetric and Helioseismic Imager for Solar Orbiter: SO/PHI

The Polarimetric and Helioseismic Imager for Solar Orbiter: SO/PHI

Static spectropolarimeter concept adapted to space conditions and wide spectrum constraints

Polarimetric calibrations and astronomical polarimetry in the V-band with Solar Orbiter/METIS instrument

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