Testing process for the WEAVE prime focus corrector lenses for the William Herschel Telescope

Date Issued
2018
Author(s)
Bogunovic, Dijana
•
Jonas, Graeme
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Cochrane, Dave
•
•
Connor, Peter
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Romeril, Abe
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Romeril, Jimi
•
Gers, Luke
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Howick, Eleanor
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Young, Chris
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Reed, Tony
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Tosh, Ian
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Lhomé, Émilie
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Dee, Kevin M.
•
Dalton, Gavin
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Trager, Scott
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Aguerri, Jose Alfonso Lopez
•
•
•
Carrasco, Esperanza
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Abrams, Don Carlos
•
Middleton, Kevin
DOI
Abstract
A new prime focus corrector for the WEAVE project for the William Herschel Telescope is being produced. The corrector consists of six lens elements, the largest being 1.1 m in diameter. It also incorporates an Atmospheric Dispersion Corrector. Testing procedures for the WEAVE prime focus corrector lens elements are described here. Critical issues encountered in practice, including the influence of the lens size, wedge and weight on the testing procedure are discussed. Due to large lens dimensions, a dedicated test tower and lens support system has been developed to measure the optical surface form errors of the concave surfaces and the transmitted wavefront of each lens. For some of the lens elements, sub-aperture measurements have been performed using an off-axis Hindle sphere and the resultant OPD maps have been stitched together. The challenge of testing a wedged lens with a combination of a long radius convex surface and a short radius concave surface has been resolved by using another lens from the system as an auxiliary lens. The practice of testing convex surfaces via internal reflection/transmission through the lens element has been avoided entirely in this case and some discussion justifying the choices of metrology approach taken is given. The fabrication and acceptance testing of the lens elements has been completed within the expected time and budget, and all elements have been shown to meet requirements.
Coverage
Ground-based and Airborne Telescopes VII
All editors
Marshall, Heather K.; Spyromilio, Jason
Series
Volume
10700
Start page
107003A
Conferenece
Ground-based and Airborne Telescopes VII
Conferenece place
Austin, Texas, United States
Conferenece date
10-15 June, 2018
Uri
Url
Issn Identifier
0277-786X
Ads BibCode
2018SPIE10700E..3AB
Rights
open.access
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