Preliminary design of GMTNIRS cryostat and optical bench

Sanghyuk Kim; Chan Park; Woojin Park; Sungho Lee; Hanshin Lee; John Good; Gregory Mace; Heeyoung Oh; Ueejeong Jeong; Moo-Young Chun; Cynthia Brooks; Alycia J. Weinberger; Daniel T. Jaffe

doi:10.1117/12.2628411

29 August 2022 Preliminary design of GMTNIRS cryostat and optical bench

Sanghyuk Kim, Chan Park, Woojin Park, Sungho Lee, Hanshin Lee, John Good, Gregory Mace, Heeyoung Oh, Ueejeong Jeong, Moo-Young Chun, Cynthia Brooks, Alycia J. Weinberger, Daniel T. Jaffe

Author Affiliations +

Proceedings Volume 12184, Ground-based and Airborne Instrumentation for Astronomy IX; 121842R (2022) https://doi.org/10.1117/12.2628411
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

GMTNIRS, the Giant Magellan Telescope Near-Infrared Spectrograph, is a high resolution (R = 65,000 - 80,000) near infrared spectrograph selected as a first-generation instrument for the Giant Magellan Telescope (GMT). It simultaneously observes the J, H, K, L, and M bands using five immersion gratings. GMTNIRS will be located on the GMT instrument rotator upper disk and operating in adaptive optics mode. The cryostat and optical bench design is based on the heritage of the highly successful immersion grating spectrograph, IGRINS. The cryostat is octagonal with a width of 1.7 m and a height of 1 m. It consists of top piece, bottom plate, passive radiation shields, and warm window assembly. Cryocoolers, electronics, and vacuum components are installed on the bottom plate. The optical bench system is comprised of two optical benches, bench interface structure, and active radiation shield. It is thermally isolated from the cryostat by eight sets of G10 supports. The sub-bench accommodates the fore-optics, a pupil mask, and an on instrument wave front sensor, while the spectrographs, slit-mask imager, and slit viewing camera are located on the main bench. Structure and thermal analysis have been performed to verify bench flexure by gravity vector change, integrity of the cryostat by vacuum pressure, and temperature distribution at the operating temperature of 70 K. We also present some design strategies to prevent light leakage.

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Sanghyuk Kim, Chan Park, Woojin Park, Sungho Lee, Hanshin Lee, John Good, Gregory Mace, Heeyoung Oh, Ueejeong Jeong, Moo-Young Chun, Cynthia Brooks, Alycia J. Weinberger, and Daniel T. Jaffe "Preliminary design of GMTNIRS cryostat and optical bench", Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 121842R (29 August 2022); https://doi.org/10.1117/12.2628411

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