The TolTEC camera: polarimetric commissioning and performance of the continuously rotating half-wave plate

Dennis Lee; Giles Novak; Marc Berthoud; John Bussan; Robert Golenia; Eric Van Clepper; Grant Wilson; N. S. DeNigris; Zhiyuan Ma; Michael McCrackan; Kamal Souccar; Laura Fissel; Akanksha Bij; Felix Thiel; Itziar Aretxaga; Daniel Ferrusca Sr.; Philip Mauskopf; Emily Lunde; Peter Ade; Carole Tucker; Giampaolo Pisano; Erin Guilfoil Cox; Laurence Sabin; Carlos Carrasco-Gonzalez; Alice Pasetto; Arturo Gómez-Ruiz Sr.; Chat Hull; Jason Austermann; James Beall; Jiansong Gao; Michael Vissers

doi:10.1117/12.2627725

31 August 2022 The TolTEC camera: polarimetric commissioning and performance of the continuously rotating half-wave plate

Dennis Lee, Giles Novak, Marc Berthoud, John Bussan, Robert Golenia, Eric Van Clepper, Grant Wilson, N. S. DeNigris, Zhiyuan Ma, Michael McCrackan, Kamal Souccar, Laura Fissel, Akanksha Bij, Felix Thiel, Itziar Aretxaga, Daniel Ferrusca Sr., Philip Mauskopf, Emily Lunde, Peter Ade, Carole Tucker, Giampaolo Pisano, Erin Guilfoil Cox, Laurence Sabin, Carlos Carrasco-Gonzalez, Alice Pasetto, Arturo Gómez-Ruiz Sr., Chat Hull, Jason Austermann, James Beall, Jiansong Gao, Michael Vissers

Author Affiliations +

Proceedings Volume 12190, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI; 121901O (2022) https://doi.org/10.1117/12.2627725
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

An ambient-temperature Continuously Rotating Half-Wave Plate (CRHWP) modulates the input polarization signal thereby enabling removal of low-frequency (1/f) noise from polarized flux measurements. This 1/f noise arises from atmospheric turbulence as well as from effects intrinsic to certain detectors. Here, we describe the design and performance of the half wave plate rotator and achromatic half-wave plate for the the new imaging polarimeter, TolTEC. These components are mounted in front of the cryostat window and operate at ambient temperature. The Half-Wave Plate Rotator (HWPR) spins the half-wave plate at 2 revolutions per second. The rotation mechanism consists of nine air bearings to provide low-friction motion and a frameless torque motor to directly drive rotation. The orientation of the rotor and half-wave plate are recorded using a high-precision optical encoder. We review the experimental requirements and technical design of the rotator as well as the associated electronics, pneumatics, and software.

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Dennis Lee, Giles Novak, Marc Berthoud, John Bussan, Robert Golenia, Eric Van Clepper, Grant Wilson, N. S. DeNigris, Zhiyuan Ma, Michael McCrackan, Kamal Souccar, Laura Fissel, Akanksha Bij, Felix Thiel, Itziar Aretxaga, Daniel Ferrusca Sr., Philip Mauskopf, Emily Lunde, Peter Ade, Carole Tucker, Giampaolo Pisano, Erin Guilfoil Cox, Laurence Sabin, Carlos Carrasco-Gonzalez, Alice Pasetto, Arturo Gómez-Ruiz Sr., Chat Hull, Jason Austermann, James Beall, Jiansong Gao, and Michael Vissers "The TolTEC camera: polarimetric commissioning and performance of the continuously rotating half-wave plate", Proc. SPIE 12190, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, 121901O (31 August 2022); https://doi.org/10.1117/12.2627725

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