From Event: SPIE Astronomical Telescopes + Instrumentation, 2018
We present our design and development of a polarization modulator unit (PMU) for LiteBIRD space mission. LiteBIRD is a next generation cosmic microwave background (CMB) polarization satellite to measure the primordial B-mode. The science goal of LiteBIRD is to measure the tensor-to-scalar ratio with the sensitivity of δr < 10-3. The baseline design of LiteBIRD is to employ the PMU based on a continuous rotating half-wave plate (HWP) at a telescope aperture with a diameter of 400 mm. It is an essential for LiteBIRD to achieve the science goal because it significantly reduces detector noise and systematic uncertainties. The LiteBIRD PMU consists of a multi-layered sapphire as a broadband achromatic HWP and a mechanism to continuously rotate it at 88 rpm. The whole system is maintained at below 10K to minimize the thermal emission from the HWP. In this paper, we discuss the current development status of the broadband achromatic HWP and the cryogenic rotation mechanism.
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Yuki Sakurai, Tomotake Matsumura, Nobuhiko Katayama, Hiroaki Imada, Kunimoto Komatsu, Hiroaki Kanai, Ryota Takaku, Shinya Sugiyama, Tommaso Ghigna, Teruhito Iida, Hajime Sugai, Hiroyuki Ohsaki, Yutaka Terao, Toshiki Shimomura, Kuniaki Konishi, Haruyuki Sakurai, Junji Yumoyo, Muneyoshi Maki, Junichi Suzuki, Hirokazu Ishino, Shogo Nakamura, Akito Kusaka, Charles Hill, Masashi Hazumi, Hirokazu Kataza, Shin Utsunomiya, Ryo Yamamoto, Makoto Tashiro, and Yukikatsu Terada, "Design and development of a polarization modulator unit based on a continuous rotating half-wave plate for LiteBIRD," Proc. SPIE 10708, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, 107080E (Presented at SPIE Astronomical Telescopes + Instrumentation: June 12, 2018; Published: 9 July 2018); https://doi.org/10.1117/12.2312391.