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Proceedings Paper

Fabrication of the DESI corrector lenses
Author(s): Timothy N. Miller; Robert W. Besuner; Michael E. Levi; Michael Lampton; Patrick Jelinsky; Henry Heetderks; David J. Schlegel; Jerry Edelstein; Peter Doel; David Brooks; Stephen Kent; Gary Poczulp; Michael J. Sholl
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Paper Abstract

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs.

We describe the DESI corrector optics, a series of six fused silica and borosilicate lenses. The lens diameters range from 0.8 to 1.1 meters, and their weights 84 to 237 kg. Most lens surfaces are spherical, and two are challenging 10th-order polynomial aspheres. The lenses have been successfully polished and treated with an antireflection coating at multiple subcontractors, and are now being integrated into the DESI corrector barrel assembly at University College London.

We describe the final performance of the lenses in terms of their various parameters, including surface figure, homogeneity, and others, and compare their final performance against the demanding DESI corrector requirements. Also we describe the reoptimization of the lens spacing in their corrector barrel after their final measurements are known. Finally we assess the performance of the corrector as a whole, compared to early budgeted estimates.

Paper Details

Date Published: 10 July 2018
PDF: 9 pages
Proc. SPIE 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 107060X (10 July 2018); doi: 10.1117/12.2312949
Show Author Affiliations
Timothy N. Miller, Lawrence Berkeley National Lab. (United States)
Robert W. Besuner, Lawrence Berkeley National Lab. (United States)
Michael E. Levi, Lawrence Berkeley National Lab. (United States)
Michael Lampton, Lawrence Berkeley National Lab. (United States)
Patrick Jelinsky, Lawrence Berkeley National Lab. (United States)
Henry Heetderks, Lawrence Berkeley National Lab. (United States)
David J. Schlegel, Lawrence Berkeley National Lab. (United States)
Jerry Edelstein, Lawrence Berkeley National Lab. (United States)
Peter Doel, Univ. College London (United Kingdom)
David Brooks, Univ. College London (United Kingdom)
Stephen Kent, Fermi National Accelerator Lab. (United States)
Gary Poczulp, National Optical Astronomy Observatory (United States)
Michael J. Sholl, Lawrence Berkeley National Lab. (United States)


Published in SPIE Proceedings Vol. 10706:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III
Ramón Navarro; Roland Geyl, Editor(s)

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