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Proceedings Paper

Sub-arcsecond pointing for balloon-borne telescopes
Author(s): Alan Kraut; Kevin Swartzlander; Elton Wong; Graham Orr; Tony Wimer; Yusuke Nakaya; Mark Bullock; Eliot Young; Patrick Little
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Paper Abstract

Astronomical balloon-borne telescopes have the potential to improve seeing over ground-based telescopes, but are compromised by their instability. A one-meter telescope in the Earth's stratosphere could achieve diffraction-limited seeing superior to the performance of any ground-based telescope in optical or UV wavelengths. If the stability issues could be addressed, such a telescope could be used for a variety of scientific purposes, including high- resolution optical imaging, or infrared imaging of targets that are usually precluded from ground-based systems, such as Jupiter, Saturn or Venus. An image stabilization system was developed with the goal of maintaining the position of the image to within 0.1 arcseconds on the focal plane during image acquisition. This effort requires both deriving an error signal and applying that error signal to a corrective element. Using a control loop with an optical reference provides a greater bandwidth than an inertial reference and improves control of high frequency vibrations. The control feedback signal was generated by monitoring the position of an image using a lateral effect cell. A fine steering mirror was used as a diagonal flat to control the position of the image and correct for small disturbances in pointing. To evaluate the system, vibration was induced in a synthetic image and the resultant motion of the image measured. The system was implemented and tested on a 14-inch f/10 Schmidt-Cassegrain telescope. Large disturbances were attenuated by a factor of 10-100, with a noise level of less than 2 arcseconds on the test telescope.

Paper Details

Date Published: 10 July 2008
PDF: 12 pages
Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70123Q (10 July 2008); doi: 10.1117/12.789138
Show Author Affiliations
Alan Kraut, Harvey Mudd College (United States)
Kevin Swartzlander, Harvey Mudd College (United States)
Elton Wong, Harvey Mudd College (United States)
Graham Orr, Harvey Mudd College (United States)
Tony Wimer, Harvey Mudd College (United States)
Yusuke Nakaya, Kogakuin Univ. (Japan)
Mark Bullock, Southwest Research Institute (United States)
Eliot Young, Southwest Research Institute (United States)
Patrick Little, Harvey Mudd College (United States)

Published in SPIE Proceedings Vol. 7012:
Ground-based and Airborne Telescopes II
Larry M. Stepp; Roberto Gilmozzi, Editor(s)

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