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.
The TolTEC camera: Polarimetric commissioning and performance of the continuously rotating half-wave plate / Lee, D., Novak, G., Berthoud, M., Bussan, J., Golenia, R., Van Clepper, E., Wilson, G., Denigris, N.S., Ma, Z., Mccrackan, M., Souccar, K., Fissel, L., Bij, A., Thiel, F., Aretxaga, I., Ferrusca, D., Mauskopf, P., Lunde, E., Ade, P., Tucker, C., et al.. - 12190:(2022). (Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 2022 can ) [10.1117/12.2627725].
The TolTEC camera: Polarimetric commissioning and performance of the continuously rotating half-wave plate
Pisano G.;
2022
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
