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Proceedings Paper

End-to-end simulations of the visible tunable filter for the Daniel K. Inouye Solar Telescope
Author(s): Wolfgang Schmidt; Matthias Schubert; Monika Ellwarth; Jörg Baumgartner; Alexander Bell; Andreas Fischer; Clemens Halbgewachs; Frank Heidecke; Thomas Kentischer; Oskar von der Lühe; Thomas Scheiffelen; Michael Sigwarth
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Paper Abstract

The Visible Tunable Filter (VTF) is a narrowband tunable filter system for imaging spectroscopy and spectropolarimetry based. The instrument will be one of the first-light instruments of the Daniel K. Inouye Solar Telescope that is currently under construction on Maui (Hawaii). The VTF is being developed by the Kiepenheuer Institut fuer Sonnenphysik in Freiburg as a German contribution to the DKIST. We perform end-to-end simulations of spectropolarimetric observations with the VTF to verify the science requirements of the instrument. The instrument is simulated with two Etalons, and with a single Etalon. The clear aperture of the Etalons is 250 mm, corresponding to a field of view with a diameter of 60 arcsec in the sky (42,000 km on the Sun). To model the large-scale figure errors we employ low-order Zernike polynomials (power and spherical aberration) with amplitudes of 2.5 nm RMS. We use an ideal polarization modulator with equal modulation coefficients of 3-1/2 for the polarization modulation We synthesize Stokes profiles of two iron lines (630.15 nm and 630.25 nm) and for the 854.2 nm line of calcium, for a range of magnetic field values and for several inclination angles. We estimated the photon noise on the basis of the DKIST and VTF transmission values, the atmospheric transmission and the spectral flux from the Sun. For the Fe 630.25 nm line, we obtain a sensitivity of 20 G for the longitudinal component and for 150 G for the transverse component, in agreement with the science requirements for the VTF.

Paper Details

Date Published: 9 August 2016
PDF: 11 pages
Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99084N (9 August 2016); doi: 10.1117/12.2232518
Show Author Affiliations
Wolfgang Schmidt, Kiepenheuer-Institut für Sonnenphysik (Germany)
Matthias Schubert, Kiepenheuer-Institut für Sonnenphysik (Germany)
Monika Ellwarth, Kiepenheuer-Institut für Sonnenphysik (Germany)
Jörg Baumgartner, Kiepenheuer-Institut für Sonnenphysik (Germany)
Alexander Bell, Kiepenheuer-Institut für Sonnenphysik (Germany)
Andreas Fischer, Kiepenheuer-Institut für Sonnenphysik (Germany)
Clemens Halbgewachs, Kiepenheuer-Institut für Sonnenphysik (Germany)
Frank Heidecke, Kiepenheuer-Institut für Sonnenphysik (Germany)
Thomas Kentischer, Kiepenheuer-Institut für Sonnenphysik (Germany)
Oskar von der Lühe, Kiepenheuer-Institut für Sonnenphysik (Germany)
Thomas Scheiffelen, Kiepenheuer-Institut für Sonnenphysik (Germany)
Michael Sigwarth, Kiepenheuer-Institut für Sonnenphysik (Germany)

Published in SPIE Proceedings Vol. 9908:
Ground-based and Airborne Instrumentation for Astronomy VI
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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