Development of a Precise Polarization Modulator for UV Spectropolarimetry

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.

9 pages, 4 figures, accepted for publication in Solar Physics

References in corpus (3)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• The polarization of the solar MgII h and k lines
• On the inversion of the scattering polarization and the Hanle effect signals in the hydrogen Lyman-$\alpha$ line

Cited by in corpus (6)

• Mapping Solar Magnetic Fields from the Photosphere to the Base of the Corona
• Discovery of Scattering Polarization in the Hydrogen Lyman-$\alpha$ Line of the Solar Disk Radiation
• The Polstar High Resolution Spectropolarimetry MIDEX Mission
• The Sunrise Chromospheric Infrared Spectro-Polarimeter SCIP: an instrument for SUNRISE III
• Evidence for the Operation of the Hanle and Magneto-Optical Effects in the Scattering Polarization Signals Observed by CLASP2 Across the Mg II h and k Lines
• Determining the Magnetic Field in the Atmosphere of a Solar Active Region Observed by the CLASP2.1 Sounding Rocket Experiment