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arXiv · 1509.05716

Development of a Precise Polarization Modulator for UV Spectropolarimetry

Shin-nosuke Ishikawa·Toshifumi Shimizu·Ryouhei Kano·Takamasa Bando·Ryohko Ishikawa·Gabriel Giono·Saku Tsuneta·Satoshi Nakayama·Takao Tajima
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Abstract

We developed a polarization modulation unit (PMU) to rotate a waveplate continuously in order to observe solar magnetic fields by spectropolarimetry. The non-uniformity of the PMU rotation may cause errors in the measurement of the degree of linear polarization (scale error) and its angle (crosstalk between Stokes-Q and -U), although it does not cause an artificial linear polarization signal (spurious polarization). We rotated a waveplate with the PMU to obtain a polarization modulation curve and estimated the scale error and crosstalk caused by the rotation non-uniformity. The estimated scale error and crosstalk were <0.01 % for both. This PMU will be used as a waveplate motor for the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) rocket experiment. We confirmed that the PMU has the sufficient performance and function for CLASP.

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Shin-nosuke Ishikawa, Toshifumi Shimizu, Ryouhei Kano, Takamasa Bando, Ryohko Ishikawa, Gabriel Giono, Saku Tsuneta, Satoshi Nakayama, Takao Tajima. 2015-09-18. Development of a Precise Polarization Modulator for UV Spectropolarimetry. https://doi.org/10.1007/s11207-015-0774-0

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