Development of a cold chopper for TAO/MIMIZUKU: cryogenic test

Tsubasa Michifuji; Takafumi Kamizuka; Takashi Miyata; Ichiro Jikuya; Daichi Uchida; Tomoya Kondo; Katsuhiko Yamada; Mitsuhiko Honda; Shigeyuki Sako; Ryou Ohsawa; Kentaro Asano; Kengo Tachibana; Hirokazu Iida; Akira C. Naruse; Itsuki Sakon

doi:10.1117/12.2628837

29 August 2022 Development of a cold chopper for TAO/MIMIZUKU: cryogenic test

Tsubasa Michifuji, Takafumi Kamizuka, Takashi Miyata, Ichiro Jikuya, Daichi Uchida, Tomoya Kondo, Katsuhiko Yamada, Mitsuhiko Honda, Shigeyuki Sako, Ryou Ohsawa, Kentaro Asano, Kengo Tachibana, Hirokazu Iida, Akira C. Naruse, Itsuki Sakon

Author Affiliations +

Proceedings Volume 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V; 121883G (2022) https://doi.org/10.1117/12.2628837
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

Cold choppers are fast beam-switching tip-tilt mirrors installed in the cold optics of mid-infrared instruments. They enable chopping observations, required for ground-based mid-infrared observations to subtract the bright background radiation, without moving telescope mirrors. In the era of next-generation extremely large telescopes, the telescope mirrors cannot be moved due to the size. Therefore, cold choppers are a key technology for groundbased mid-infrared instruments for such large telescopes. In this study, we develop a prototype cold chopper for TAO/MIMIZUKU, the mid-infrared instrument for the TAO 6.5-m telescope, and evaluate the performance in a cryogenic environment at 20 K. It is confirmed that the prototype shows almost the same response as at room temperature and achieves 2-axis square-wave motion with an amplitude of 0.84 deg, a settling time of ∼40 ms, and a frequency of ≥2 Hz. The evaluated power dissipation is ∼5mW. Stability is found to be slightly worse than required (6 × 10⁻⁴ deg) due to mechanical vibration caused by the cryocooler used in the experiment. We plan to mount this chopper on MIMIZUKU to check the effects of such vibrations in the on-board environment.

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Tsubasa Michifuji, Takafumi Kamizuka, Takashi Miyata, Ichiro Jikuya, Daichi Uchida, Tomoya Kondo, Katsuhiko Yamada, Mitsuhiko Honda, Shigeyuki Sako, Ryou Ohsawa, Kentaro Asano, Kengo Tachibana, Hirokazu Iida, Akira C. Naruse, and Itsuki Sakon "Development of a cold chopper for TAO/MIMIZUKU: cryogenic test", Proc. SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 121883G (29 August 2022); https://doi.org/10.1117/12.2628837

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