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Proceedings Paper

An EAGLE with arms: a solution to the design of the adaptive multi-IFU spectrograph EAGLE for the E-ELT
Author(s): Robert Content; Peter Hastings
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Paper Abstract

EAGLE is an adaptive multi-IFU spectrograph for the 42-m E-ELT. We present our design of the EAGLE Target Acquisition System (TAS) and IFU system while the spectrograph design is part of a different paper. A modified design of the arms of KMOS, a future multi-IFU spectrograph for the VLT, is used. Their shorter length permits to place more arms in EAGLE than in KMOS. An unusual difficulty in designing the optics was the need for a very high image quality in the pupil images on the deformable mirrors. The solution includes a lens in the arm more complex than in KMOS and a series of mirrors after the arm. The IFU is an Advanced Image Slicer (AIS) with an unusually large anamorphic magnification factor of 3.2. The design makes all IFU fields parallel in the telescope field wherever their positions. Both the anamorphic factor of the AIS and the position of its exit pupil were adjusted to help reduce the size and simplify the design of the spectrograph. The preceding design being our basic design, a different approach that takes advantage of the small field of the main science cases will also be discussed. In this new concept, field selectors permit to have a choice of a large number of small fields or a small number of large fields or a combination of both. Combined with the proper adaptive optics system, the throughput of EAGLE would increase by a factor of more than 2 while maintaining the same cost.

Paper Details

Date Published: 9 July 2008
PDF: 12 pages
Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 701461 (9 July 2008); doi: 10.1117/12.790403
Show Author Affiliations
Robert Content, Univ. of Durham (United Kingdom)
Peter Hastings, UK Astronomy Technology Ctr., Royal Observatory (United Kingdom)

Published in SPIE Proceedings Vol. 7014:
Ground-based and Airborne Instrumentation for Astronomy II
Ian S. McLean; Mark M. Casali, Editor(s)

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