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Proceedings Paper

In-flight performance of the polarization modulator in the CLASP rocket experiment
Author(s): Shin-nosuke Ishikawa; Toshifumi Shimizu; Ryohei Kano; Takamasa Bando; Ryoko Ishikawa; Gabriel Giono; Dyana L. Beabout; Brent L. Beabout; Satoshi Nakayama; Takao Tajima
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Paper Abstract

We developed a polarization modulation unit (PMU), a motor system to rotate a waveplate continuously. In polarization measurements, the continuous rotating waveplate is an important element as well as a polarization analyzer to record the incident polarization in a time series of camera exposures. The control logic of PMU was originally developed for the next Japanese solar observation satellite SOLAR-C by the SOLAR-C working group. We applied this PMU for the Chromospheric Lyman‐alpha SpectroPolarimeter (CLASP). CLASP is a sounding rocket experiment to observe the linear polarization of the Lyman‐alpha emission (121.6 nm vacuum ultraviolet) from the upper chromosphere and transition region of the Sun with a high polarization sensitivity of 0.1 % for the first time and investigate their vector magnetic field by the Hanle effect. The driver circuit was developed to optimize the rotation for the CLASP waveplate (12.5 rotations per minute). Rotation non‐ uniformity of the waveplate causes error in the polarization degree (i.e. scale error) and crosstalk between Stokes components. We confirmed that PMU has superior rotation uniformity in the ground test and the scale error and crosstalk of Stokes Q and U are less than 0.01 %. After PMU was attached to the CLASP instrument, we performed vibration tests and confirmed all PMU functions performance including rotation uniformity did not change. CLASP was successfully launched on September 3, 2015, and PMU functioned well as designed. PMU achieved a good rotation uniformity, and the high precision polarization measurement of CLASP was successfully achieved.

Paper Details

Date Published: 11 July 2016
PDF: 6 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99052U (11 July 2016); doi: 10.1117/12.2232278
Show Author Affiliations
Shin-nosuke Ishikawa, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Toshifumi Shimizu, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Ryohei Kano, National Astronomical Observatory of Japan (Japan)
Takamasa Bando, National Astronomical Observatory of Japan (Japan)
Ryoko Ishikawa, National Astronomical Observatory of Japan (Japan)
Gabriel Giono, National Astronomical Observatory of Japan (Japan)
Dyana L. Beabout, NASA Marshall Space Flight Ctr. (United States)
Brent L. Beabout, NASA Marshall Space Flight Ctr. (United States)
Satoshi Nakayama, Mitsubishi Precision Co., Ltd. (Japan)
Takao Tajima, Mitsubishi Precision Co., Ltd. (Japan)


Published in SPIE Proceedings Vol. 9905:
Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Jan-Willem A. den Herder; Tadayuki Takahashi; Marshall Bautz, Editor(s)

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