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Proceedings Paper

15x optical zoom and extreme optical image stabilisation: diffraction limited integral field spectroscopy with the SWIFT spectrograph
Author(s): Matthias Tecza; Niranjan Thatte; Fraser Clarke; James Lynn; David Freeman; Jennifer Roberts; Richard Dekany
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Paper Abstract

When commissioned in November 2008 at the Palomar 200 inch Hale Telescope, the Oxford SWIFT I and z band integral field spectrograph, fed by the adaptive optics system PALAO, provided a wide (3×) range of spatial resolutions: three plate scales of 235 mas, 160 mas, and 80 mas per spaxel over a contiguous field-of-view of 89×44 pixels. Depending on observing conditions and guide star brightness we can choose a seeing limited scale of 235 mas per spaxel, or 160 mas and 80 mas per spaxel for very bright guide star AO with substantial increase of enclosed energy. Over the last two years PALAO was upgraded to PALM-3000: an extreme, high-order adaptive optics system with two deformable mirrors with more than 3000 actuators, promising diffraction limited performance in SWIFT's wavelength range. In order to take advantage of this increased spatial resolution we upgraded SWIFT with new pre-optics allowing us to spatially Nyquist sample the diffraction limited PALM-3000 point spread function with 16 mas resolution, reducing the spaxel scale by another factor of 5×. We designed, manufactured, integrated and tested the new pre-optics in the first half of 2011 and commissioned it in December 2011. Here we present the opto-mechanical design and assembly of the new scale changing optics, as well as laboratory and on-sky commissioning results. In optimal observing conditions we achieve substantial Strehl ratios, delivering the near diffraction limited spatial resolution in the I and z bands.

Paper Details

Date Published: 24 September 2012
PDF: 8 pages
Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 844622 (24 September 2012); doi: 10.1117/12.925328
Show Author Affiliations
Matthias Tecza, Univ. of Oxford (United Kingdom)
Niranjan Thatte, Univ. of Oxford (United Kingdom)
Fraser Clarke, Univ. of Oxford (United Kingdom)
James Lynn, Univ. of Oxford (United Kingdom)
David Freeman, Kidger Optics Associates (United Kingdom)
Jennifer Roberts, Jet Propulsion Lab. (United States)
Richard Dekany, Caltech Optical Observatories (United States)

Published in SPIE Proceedings Vol. 8446:
Ground-based and Airborne Instrumentation for Astronomy IV
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)

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