Dr. Satoru Takakura Profile

Dr. Satoru Takakura

JSPS Overseas Research Fellow at Univ of Colorado Boulder

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Satoru Takakura is a postdoctoral scholar at University of Colorado Boulder working on data analysis of SPT-3G and Simons Array. He has expertise in the polarization modulation technique using a continuously rotating half-wave plate in the POLARBEAR experiment.

SPIE Journal Paper | 27 January 2024 Open Access

Design and performance of a gain calibration system for the POLARBEAR-2a receiver system at the Simons Array cosmic microwave background experiment

Daisuke Kaneko, Sayuri Takatori, Masaya Hasegawa, Masashi Hazumi, Yuki Inoue, Oliver Jeong, Nobuhiko Katayama, Adrian Lee, Frederick Matsuda, Haruki Nishino, Praween Siritanasak, Aritoki Suzuki, Satoru Takakura, Takayuki Tomaru

JATIS, Vol. 10, Issue 01, 018003, (January 2024) https://doi.org/10.1117/12.10.1117/1.JATIS.10.1.018003

KEYWORDS: Calibration, Scanning tunneling microscopy, Sensors, Polarization, Design, Bolometers, Modulation frequency, Telescopes, Planets, Sensor calibration

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SPIE Journal Paper | 6 September 2022

High-precision temperature monitoring system for room-temperature equipment in astrophysical observations

Daiki Tanabe, Masaya Hasegawa, Masashi Hazumi, Nobuhiko Katayama, Shuhei Kikuchi, Adrian Lee, Haruki Nishino, Satoru Takakura

JATIS, Vol. 8, Issue 03, 036003, (September 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.3.036003

KEYWORDS: Mirrors, Sensors, Temperature metrology, Signal detection, Electronics, Polarization, Bolometers, Telescopes, Detector arrays, Resistance

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Proceedings Article | 13 December 2020 Poster

Development of cloud monitoring system at Simons Array

Satoru Takakura, Haruki Nishino

Proceedings Volume 11453, 114532B (2020) https://doi.org/10.1117/12.2561215

KEYWORDS: Clouds, Algorithm development, Infrared cameras, Cameras, Sensors, Detection and tracking algorithms, Polarization, Anisotropy, Microwave radiation, Rayleigh scattering

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Proceedings Article | 9 July 2018 Paper

Cross-polarization systematics due to Mizuguchi-Dragone condition breaking by a continuously rotating half-wave plate at prime focus in the Huan Tran telescope

Frederick Matsuda, Satoru Takakura, Kam Arnold, David Boettger, Yuji Chinone, Masashi Hazumi, Brian Keating, Akito Kusaka, Adrian Lee

Proceedings Volume 10708, 1070849 (2018) https://doi.org/10.1117/12.2313177

KEYWORDS: Polarization, Reflectors, Optical simulations, Telescopes, Beam shaping, Wave plates, Angle modulation, Mueller matrices, Passive millimeter wave sensors, Polarization control

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Polarization modulation using a continuously rotating half-wave plate (HWP) is a promising technique to reduce both low-frequency noise and instrumental systematics for Cosmic Microwave Background (CMB) polarization measurements targeting in ationary B-modes. Although a HWP is best placed sky-side of the telescope optics in order to minimize systematics, >0.5 meter aperture class telescopes must put the HWP elsewhere in the optics chain due to current fabrication limitations in the available HWP size. Polarbear is a ground-based CMB experiment installed on the 2.5m aperture off-axis Gregorian-Dragone type Huan Tran Telescope (HTT) designed to satisfy the Mizuguchi-Dragone condition. Polarbear-2 is a receiver that will be installed on a second HTT in 2018. Polarbear-2 is designed to have a larger field-of-view (FOV) and vastly increased sensitivity to the polarized CMB compared to Polarbear. From the third season of observations, Polarbear has installed a continuously rotating HWP at the spatially localized focus plane between the HTT primary and secondary re ectors which is an optimal location for minimizing the HWP diameter. The HWP's polarization angle re ection with respect to its birefringent axis will theoretically break the Mizuguchi-Dragone condition when placed between the two reflectors and increase cross-polarization systematics. In this study, we analyze how the Mizuguchi-Dragone condition is violated due to a HWP at this location. We then estimate the crosspolarization systematics of the HTT using physical optics simulations. We model an ideal HWP at various angles to estimate the effects of demodulation. We evaluate the increased cross-polarization as the Stokes Q-U mixing term using the Mueller Matrix formalism. It is calculated that this term creates a varying dipole beam pattern whose amplitude ranges from 1% at the center to 10% at the edge FOV pixels for Polarbear and potentially up to 20% for Polarbear-2. We also estimate the leakage of the E-mode into the B-mode angular power spectrum measurements due to this cross-polarization. We show that the cross-polarization systematic error leakage is sufficiently lower than the Polarbear-2 statistical uncertainty thanks to mitigations such as focal plane averaging and sky rotation. Currently for Polarbear-2 we are planning to place the HWP at Gregorian focus, but keeping the HWP at prime focus as a back-up solution in case that there are unforeseen telescope spatial and HWP material size constraints. Through this study we find that even though a HWP between the two reflectors will violate the Mizuguchi-Dragone condition, this HWP at prime focus will still have sufficiently low cross-polarization for Polarbear-2. The prime focus HWP is a potential configuration that can be applied to similar off-axis Gregorian-Dragone telescopes in order to minimize the required HWP diameter.

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