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12 October 2011 Liquid crystals Lyot filter for solar coronagraphy
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The "Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire", ASPIICS, is a solar coronagraph to be flown on the PROBA 3 Technology mission of the European Space Agency. ASPIICS heralds the next generation of coronagraphs for solar research, exploiting formation flying to gain access to the inner corona under eclipse-like conditions in space. The science goal is high spatial resolution imaging and two-dimensional spectrophotometry of the Fe XIV, 530.3 nm, emission line. This work describes a liquid crystal Lyot tunable-filter and polarimeter (LCTP) that can implement this goal. The LCTP is a bandpass filter with a full width at half maximum of 0.15 nm at a wavelength of 530.3 nm. The center wavelength of the bandpass is tunable in 0.01 nm steps from 528.64 nm to 533.38 nm. It is a four stage Lyot filter with all four stages wide-fielded. The free spectral range between neighboring transmission bands of the filter is 2.7 nm. The wavelength tuning is non-mechanical using nematic liquid crystal variable retarders (LCVR's). A separate LCVR of the Senarmont design, in tandem with the filter, is used for the polarimetric measurements. A prototype of the LCTP has been built and its measured performances are presented here.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Fineschi, G. Capobianco, G. Massone, T. Baur, A. Bemporad, L. Abbo, L. Zangrilli, and V. Dadeppo "Liquid crystals Lyot filter for solar coronagraphy", Proc. SPIE 8148, Solar Physics and Space Weather Instrumentation IV, 814808 (12 October 2011);


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