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AESOP: the 4MOST fiber positioner
Author(s): Jurek Brzeski; Gabriella Baker; Sufyan Baker; Rebecca Brown; Scott Case; Tony Farrell; Peter Gillingham; Urs Klauser; Jon Lawrence; Slavko Mali; Rolf Muller; Vijay Nichani; Naveen Pai; Scott Smedley; Sudharshan Venkatesan; Lew Waller
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Paper Abstract

The Australian Astronomical Observatory’s (AAO’s) AESOP project is part of the 4 metre Multi-Object Spectrograph Telescope (4MOST) system for the VISTA telescope. It includes the 2436-fiber positioner, space frame and electronics enclosures. The AESOP concept and the role of the AAO in the 4MOST project have been described in previous SPIE proceedings. Prototype tests, which were completed early in 2017 demonstrated that the instrument requirements are satisfied by the design. The project final design stage has recently been completed. In this paper, key features of the AESOP positioning system design, along with the techniques developed to overcome key mechanical, electronic, and software engineering challenges are described. The major performance requirement for AESOP is that all 2436 science fiber cores and 12 guide fiber bundles are to be re-positioned to an accuracy of 10 µm within 1 minute. With a fast prime-focus focal-ratio, a close tolerance on the axial position of the fiber tips must be held so efficiency does not suffer from de-focus losses. Positioning accuracy is controlled with the metrology cameras installed on the telescope, which measures the positions of the fiber tips to an accuracy of a few µm and allows iterative positioning until all fiber tips are within tolerance. Maintaining co-planarity of the fiber tips requires accurate control in the assembly of several components that contribute to such errors. Assembly jigs have been developed and proven adequate for this purpose. Attaining high reliability in an assembly with many small components of disparate materials bonded together, including piezo ceramics, carbon fiber reinforced plastic, hardened steel, and electrical circuit boards, has entailed careful selection and application of cements and tightly controlled soldering for electrical connections.

Paper Details

Date Published: 8 July 2018
PDF: 17 pages
Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 1070279 (8 July 2018); doi: 10.1117/12.2310062
Show Author Affiliations
Jurek Brzeski, Australian Astronomical Observatory (Australia)
Gabriella Baker, Australian Astronomical Observatory (Australia)
Sufyan Baker, Australian Astronomical Observatory (Australia)
Rebecca Brown, Australian Astronomical Observatory (Australia)
Scott Case, Australian Astronomical Observatory (Australia)
Tony Farrell, Australian Astronomical Observatory (Australia)
Peter Gillingham, Australian Astronomical Observatory (Australia)
Urs Klauser, Australian Astronomical Observatory (Australia)
Jon Lawrence, Australian Astronomical Observatory (Australia)
Slavko Mali, Australian Astronomical Observatory (Australia)
Rolf Muller, Australian Astronomical Observatory (Australia)
Vijay Nichani, Australian Astronomical Observatory (Australia)
Naveen Pai, Australian Astronomical Observatory (Australia)
Scott Smedley, Australian Astronomical Observatory (Australia)
Sudharshan Venkatesan, Australian Astronomical Observatory (Australia)
Lew Waller, Australian Astronomical Observatory (Australia)

Published in SPIE Proceedings Vol. 10702:
Ground-based and Airborne Instrumentation for Astronomy VII
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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