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Proceedings Paper

Hermes: the engineering challenges
Author(s): Jurek Brzeski; Luke Gers; Greg Smith; Nicholas Staszak
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Paper Abstract

The Australian Astronomical Observatory is building a 4-channel VPH-grating High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the 3.9 meter Anglo-Australian Telescope (AAT). HERMES will provide a nominal spectral resolving power of 28,000 for Galactic Archaeology with an optional high-resolution mode of 45,000 with the use of a slit mask. HERMES is fed by a fibre positioning robot called 2dF at the telescope prime focus. There are a total of 784 science fibres, which interface with the spectrograph via two separate slit body assemblies, each comprising of 392 science fibers. The slit defines the spectral lines of 392 fibres on the detector. The width of the detector determines the spectral bandwidth and the detector height determines the fibre to fibre spacing or cross talk. Tolerances that follow from this are all in the 10 micrometer range. The slit relay optics must contribute negligibly to the overall image quality budget and uniformly illuminate the spectrograph exit pupil. The latter requirement effectively requires that the relay optics provide a telecentric input at the collimator entrance slit. As a result it is critical to align the optical components to extreme precision required by the optical design. This paper discusses the engineering challenges of designing, optimising, tolerancing and manufacturing of very precise mechanical components for housing optics and the design of low cost of jigs and fixtures for alignment and assembly of the optics.

Paper Details

Date Published: 24 September 2012
PDF: 15 pages
Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 84464N (24 September 2012); doi: 10.1117/12.924635
Show Author Affiliations
Jurek Brzeski, Australian Astronomical Observatory (Australia)
Luke Gers, Australian Astronomical Observatory (Australia)
Greg Smith, Australian Astronomical Observatory (Australia)
Nicholas Staszak, Australian Astronomical Observatory (Australia)

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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