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Proceedings Paper

Optical alignment of the Chromospheric Lyman-Alpha Spectro-Polarimeter using sophisticated methods to minimize activities under vacuum
Author(s): G. Giono; Y. Katsukawa; R. Ishikawa; N. Narukage; R. Kano; M. Kubo; S. Ishikawa; T. Bando; H. Hara; Y. Suematsu; A. Winebarger; K. Kobayashi; F. Auchère; J. Trujillo Bueno
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Paper Abstract

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The instrument main scientific goal is to achieve polarization measurement of the Lyman-α line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. The optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly-α profiles. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-α is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

Paper Details

Date Published: 11 July 2016
PDF: 10 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99053D (11 July 2016); doi: 10.1117/12.2232312
Show Author Affiliations
G. Giono, National Astronomical Observatory of Japan (Japan)
Y. Katsukawa, National Astronomical Observatory of Japan (Japan)
R. Ishikawa, National Astronomical Observatory of Japan (Japan)
N. Narukage, National Astronomical Observatory of Japan (Japan)
R. Kano, National Astronomical Observatory of Japan (Japan)
M. Kubo, National Astronomical Observatory of Japan (Japan)
S. Ishikawa, Japan Aerospace Exploration Agency (Japan)
Institute of Space and Astronautical Science (Japan)
T. Bando, National Astronomical Observatory of Japan (Japan)
H. Hara, National Astronomical Observatory of Japan (Japan)
Y. Suematsu, National Astronomical Observatory of Japan (Japan)
A. Winebarger, NASA Marshall Space Flight Ctr. (United States)
K. Kobayashi, NASA Marshall Space Flight Ctr. (United States)
F. Auchère, Institut d'Astrophysique Spatiale (France)
J. Trujillo Bueno, Instituto de Astrofísica de Canarias (Spain)


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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