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Proceedings Paper

Auto alignment and image tracking system for the SUNRISE telescope
Author(s): W. Schmidt; T. Berkefeld; B. Feger; R. Friedlein; K. Gerber; F. Heidecke; T. Kentischer; O. v. d. Lühe; M. Sigwarth; D. Soltau; E. Wälde
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Paper Abstract

The 1m balloon-borne solar telescope Sunrise will be equipped with a wave-front sensing system for automatic in-flight focusing and alignment of the telescope and for high-precision image tracking. A six-element wavefront sensor measures low order aberrations of the telescope, including defocus and coma. The correction is achieved by moving the focusing mirror and the telescope secondary, respectively, in a closed-loop circuit. The same system measures image motion. The instrument requirements for the tracking are a dynamical range of about 30 Hz and a precision of about 0.005 arcs in the sky. The image motion signal feeds a closed-loop control system that drives both the tip-tilt mirror assembly and the mirrors that are needed for focusing and alignment. The tip-tilt unit is a dual-stage system, built at the Kiepenheuer-Insitut, consisting of a slow component with a large range of about 60 arcs and a fast component with a short range and high bandwidth. A breadboard-version of the Correlating Wavefront Sensor has been successfully tested at the German Vacuum Tower Telescope on Tenerife in summer of 2005. A closed-loop bandwidth of 80 Hz was measured for the tracking system. The wave-front sensor detected image aberrations pre-set by the telescope's adaptive optics system with the required accuracy. Sunrise will be flown in long duration stratospheric balloon flights, with a first scientific flight in 2009.

Paper Details

Date Published: 27 June 2006
PDF: 9 pages
Proc. SPIE 6274, Advanced Software and Control for Astronomy, 62740H (27 June 2006); doi: 10.1117/12.669955
Show Author Affiliations
W. Schmidt, Kiepenheuer-Institut für Sonnenphysik (Germany)
T. Berkefeld, Kiepenheuer-Institut für Sonnenphysik (Germany)
B. Feger, Kiepenheuer-Institut für Sonnenphysik (Germany)
R. Friedlein, Kiepenheuer-Institut für Sonnenphysik (Germany)
K. Gerber, Kiepenheuer-Institut für Sonnenphysik (Germany)
F. Heidecke, Kiepenheuer-Institut für Sonnenphysik (Germany)
T. Kentischer, Kiepenheuer-Institut für Sonnenphysik (Germany)
O. v. d. Lühe, Kiepenheuer-Institut für Sonnenphysik (Germany)
M. Sigwarth, Kiepenheuer-Institut für Sonnenphysik (Germany)
D. Soltau, Kiepenheuer-Institut für Sonnenphysik (Germany)
E. Wälde, Kiepenheuer-Institut für Sonnenphysik (Germany)

Published in SPIE Proceedings Vol. 6274:
Advanced Software and Control for Astronomy
Hilton Lewis; Alan Bridger, Editor(s)

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