A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument

Sean Bryan*, Peter Ade, Mandana Amiri, Steven Benton, Richard Bihary, James Bock, J. Richard Bond, H. Cynthia Chiang, Carlo Contaldi, Brendan Crill, Olivier Dore, Benjamin Elder, Jeffrey Filippini, Aurelien Fraisse, Anne Gambrel, Natalie Gandilo, Jon Gudmundsson, Matthew Hasselfield, Mark Halpern, Gene HiltonWarren Holmes, Viktor Hristov, Kent Irwin, William Jones, Zigmund Kermish, Craig Lawrie, Carrie MacTavish, Peter Mason, Krikor Megerian, Lorenzo Moncelsi, Thomas Montroy, Tracy Morford, Johanna Nagy, C. Barth Netterfield, Ivan Padilla, Alexandra S. Rahlin, Carl Reintsema, Daniel C. Riley, John Ruhl, Marcus Runyan, Benjamin Saliwanchik, Jamil Shariff, Juan Soler, Amy Trangsrud, Carole Tucker, Rebecca Tucker, Anthony Turner, Shyang Wen, Donald Wiebe, Edward Young

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.10. The system performed well in Spider during its successful 16 day flight.

Original languageEnglish
Article number014501
JournalReview of Scientific Instruments
Issue number1
Publication statusPublished - 1 Jan 2016

Bibliographical note

Funding Information:
SPIDER is supported in the U.S. by National Aeronautics and Space Administration under Grant Nos. NNX07AL64G and NNX12AE95G issued through the Science Mission Directorate, with support for A.S.R. from NESSF NNX10AM55H, and by the National Science Foundation through No. PLR- 1043515. Logistical support for the Antarctic deployment and operations was provided by the NSF through the U.S. Antarctic Program. The collaboration is grateful for the generous support of the David and Lucile Packard Foundation, which has been crucial to the success of the project. Support in Canada is provided by the National Sciences and Engineering Council and the Canadian Space Agency.

Publisher Copyright:
© 2016 AIP Publishing LLC.


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