Thermal and mechanical design and test of the CCD mount for the WEAVE spectrograph cryostats

Date Issued
2018
Author(s)
Bates, Stuart D.
•
Steele, Iain A.
•
Mottram, Chris J.
•
Jermak, Helen E.
•
Tromp, Niels
•
Kragt, Jan
•
Elswijk, Eddy
•
Pragt, Johan
•
Stuik, Remko
•
Barnsley, Robert
•
Monroe, Charles
•
Dalton, Gavin
•
Trager, Scott
•
Lopez Aguerri, Jose Alfonso
•
•
•
Carrasco, Esperanza
•
Abrams, Don Carlos
•
Middleton, Kevin
DOI
Abstract
WEAVE is the new multi-object spectrograph for the William Herschel Telescope on La Palma. The culmination of prime focus, the large number of fibers and the wide resolution range has required a stringent optical design, which in turn demands a spectrograph with tight positional tolerances and large final focal plane. To capture this focal plane each of the two cryostats has two e2v 6k × 6k CCDs mounted as a mosaic. As well as being cooled to 150K via liquid nitrogen, the positional tolerances for the sensitive areas are flatness 60μm p-v over the entire image area, rotation around X and Y axis +/-50 arcmin, translation in X, Y and Z +/- 50 micron. We have used a Stil confocal measuring head mounted on two Thorlab translation stages to create a X,Y mount, controlled by a Raspberry Pi that is capable of recording measurements in Z to better than 1μm accuracy. This is used to measure the flatness and deformation of the image area under vacuum, and when cooled to 150K and the overall tip and tilt of the image plane to ensure they meet specification and are repeatable. In addition to this measuring system, we use a Thorlabs CMOS camera with a Navitar 50mm lens to ensure each CCDs image area is within specification with regards X and Y translation. In order to satisfy the above requirements, we designed the CCD mount to be adjustable (on initial setup), correctly constrained, isolated from liquid nitrogen boil-off vibration, and thermally insulating.
Coverage
High Energy, Optical, and Infrared Detectors for Astronomy VIII
All editors
Holland, Andrew D.; Beletic, James
Series
Volume
10709
Start page
107091Z
Conferenece
High Energy, Optical, and Infrared Detectors for Astronomy VIII
Conferenece place
Austin, Texas, United States
Conferenece date
10-15 June, 2018
Uri
Url
Issn Identifier
0277-786X
Ads BibCode
2018SPIE10709E..1ZB
Rights
open.access
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