10 July 2008 Sub-arcsecond pointing for balloon-borne telescopes
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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.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Alan Kraut, Alan Kraut, Kevin Swartzlander, Kevin Swartzlander, Elton Wong, Elton Wong, Graham Orr, Graham Orr, Tony Wimer, Tony Wimer, Yusuke Nakaya, Yusuke Nakaya, Mark Bullock, Mark Bullock, Eliot Young, Eliot Young, Patrick Little, Patrick Little, "Sub-arcsecond pointing for balloon-borne telescopes", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70123Q (10 July 2008); doi: 10.1117/12.789138; https://doi.org/10.1117/12.789138


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