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Title: Fabrication of the DESI corrector lenses

Journal Article · · Proceedings of SPIE - The International Society for Optical Engineering
DOI:https://doi.org/10.1117/12.2312949· OSTI ID:1469006
 [1];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [1];  [3];  [4];  [2]
  1. Univ. College London (United Kingdom)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  4. National Optical Astronomy Observatory (NOAO), Tuscon, AZ (United States) and La Serena (Chile)
+ Show Author Affiliations

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.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
AC02-07CH11359
OSTI ID:
1469006
Report Number(s):
arXiv:1807.09371; FERMILAB-CONF-18-339-CD; 1682402
Journal Information:
Proceedings of SPIE - The International Society for Optical Engineering, Vol. 10706; Conference: SPIE Astronomical Telescopes + Instrumentation 2018, Austin, TX, USA, 06/10-06/15/2018; ISSN 0277-786X
Publisher:
SPIECopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

Cited By (2)

The DESI Fiber View Camera System journal May 2019
Performance of Kitt Peak’s Mayall 4-meter telescope during DESI commissioning conference December 2020

Figures / Tables (10)

Figure 1(p. 2)figure Figure 1
Figure 2(p. 3)figure Figure 2
Figure 3(p. 3)figure Figure 3
Table 1(p. 4)table Table 1
Table 2(p. 5)table Table 2
Figure 4(p. 6)figure Figure 4
Table 3(p. 6)table Table 3
Figure 5(p. 7)figure Figure 5
Figure 6(p. 7)figure Figure 6
Table 4(p. 8)table Table 4

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY