LiteBIRD has been selected as JAXA's strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of-56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT: 34-161 GHz), one of LiteBIRD's onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90a-▪ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.

Sekimoto, Y., Ade, P., Adler, A., Allys, E., Arnold, K., Auguste, D., et al. (2020). Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD. In Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020. SPIE - The International Society of Optics and Photonics [10.1117/12.2561841].

Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD

Gervasi, Massimo;Poletti, Davide;Zannoni, Mario;
2020

Abstract

LiteBIRD has been selected as JAXA's strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of-56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT: 34-161 GHz), one of LiteBIRD's onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90a-▪ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.
slide + paper
Cosmic microwave background; cryogenic telescope; millimeter-wave polarization; space program;
English
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020 - 14 December 2020 through 22 December 2020
2020
Zmuidzinas, Jonas
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020
9781510636934
2020
11453
1145310
none
Sekimoto, Y., Ade, P., Adler, A., Allys, E., Arnold, K., Auguste, D., et al. (2020). Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD. In Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020. SPIE - The International Society of Optics and Photonics [10.1117/12.2561841].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/297764
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