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Proceedings Paper

High-resolution imaging in the visible from the ground without adaptive optics: new techniques and results
Author(s): Craig D. Mackay; John Baldwin; Nicholas Law; Peter Warner
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Paper Abstract

Many astronomical imaging studies, such as those of weak gravitational lensing, call for better angular resolution than is normally possible from the ground over wide fields of view . For many of these studies astronomers need images which show a consistent point spread function across the field even if this comes at the expense of the ultimate in angular resolution at the centre of the field. Adaptive Optics does not show any prospect of being able to achieve fields of view as large as are needed at visible wavelengths and therefore a new technique of delivering high resolution images from the ground must be developed. Electron multiplying CCDs are available that allow images to be taken at high speed without the usual penalty of read noise. We have developed a new technique called Lucky Imaging which achieves high resolution by selecting the better images from a sequence of images, then shifting and adding each to give a much higher resolution output image. Resolutions in the range 0.1-0.2 arc seconds can be obtained routinely under relatively good conditions on a 2.5 metre telescope working in I band (850 nanometres) and using as much as 30% of the images taken. Even under poorer conditions we find that image selection allows the final resolution to be better than the traditional seeing value by a factor of as much as three. This paper describes the technique and some of the results obtained using this method.

Paper Details

Date Published: 30 September 2004
PDF: 8 pages
Proc. SPIE 5492, Ground-based Instrumentation for Astronomy, (30 September 2004); doi: 10.1117/12.550443
Show Author Affiliations
Craig D. Mackay, Univ. of Cambridge (United Kingdom)
John Baldwin, Univ. of Cambridge (United Kingdom)
Nicholas Law, Univ. of Cambridge (United Kingdom)
Peter Warner, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 5492:
Ground-based Instrumentation for Astronomy
Alan F. M. Moorwood; Masanori Iye, Editor(s)

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