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Proceedings Paper

The alignment and assembly of the DESI prime focus corrector
Author(s): David Brooks; Peter Doel; Robert Besuner; Brenna Flaugher; Giuseppe Gallo; Gaston Gutierrez; Stephen Kent; Michael Lampton; Michael Levi; Ming Liang; Timothy N. Miller; David Sprayberry; Andrew Stefanik
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Paper Abstract

The Dark Energy Spectroscopic Instrument (DESI), which is currently under construction, is designed to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fibre optic positioners. The fibres in turn feed ten broad-band spectrographs. The prime focus corrector for DESI consists of six lenses that range in diameter from 0.80 - 1.14 meters and from 83 - 237 kg in weight. The alignment of the large lenses of the optical corrector poses a significant challenge as in order to meet the fibre throughput requirements they have to be aligned to within a tolerance of ~50 micrometres. This paper details the design for the cells that will hold the lenses and the alignment and assembly procedure for the mounting of the lenses into the cells and into the complete barrel assembly. This is based on the experience obtained from the alignment of the Dark Energy Camera (DECam) instrument which was successfully assembled and aligned by the same team and we include in the paper the lessons learnt and design modifications that will be implemented on the DESI system.

Paper Details

Date Published: 9 August 2016
PDF: 8 pages
Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99088C (9 August 2016); doi: 10.1117/12.2232489
Show Author Affiliations
David Brooks, Univ. College London (United Kingdom)
Peter Doel, Univ. College London (United Kingdom)
Robert Besuner, Lawrence Berkeley National Lab. (United States)
Brenna Flaugher, Fermi National Accelerator Lab. (United States)
Giuseppe Gallo, Fermi National Accelerator Lab. (United States)
Gaston Gutierrez, Fermi National Accelerator Lab. (United States)
Stephen Kent, Fermi National Accelerator Lab. (United States)
Michael Lampton, Lawrence Berkeley National Lab. (United States)
Michael Levi, Lawrence Berkeley National Lab. (United States)
Ming Liang, National Optical Astronomy Observatory (United States)
Timothy N. Miller, Lawrence Berkeley National Lab. (United States)
David Sprayberry, National Optical Astronomy Observatory (United States)
Andrew Stefanik, Fermi National Accelerator Lab. (United States)


Published in SPIE Proceedings Vol. 9908:
Ground-based and Airborne Instrumentation for Astronomy VI
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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