Development of a mid-infrared refractive index measurement system at cryogenic temperature for the development of an immersion grating to be onboard next-generation infrared space telescope GREX-PLUS

Umi Enokidani; Hideo Matsuhara; Takao Nakagawa; Yasuhiro Hirahara; Ryoichi Koga; Yuan Li; Biao Zhao; Daiki Takama; Hiroshi Sasago; Takehiko Wada

doi:10.1117/12.3019753

23 August 2024 Development of a mid-infrared refractive index measurement system at cryogenic temperature for the development of an immersion grating to be onboard next-generation infrared space telescope GREX-PLUS

Umi Enokidani, Hideo Matsuhara, Takao Nakagawa, Yasuhiro Hirahara, Ryoichi Koga, Yuan Li, Biao Zhao, Daiki Takama, Hiroshi Sasago, Takehiko Wada

Author Affiliations +

Proceedings Volume 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave; 130923F (2024) https://doi.org/10.1117/12.3019753
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

We’re developing an immersion grating made of CdZnTe designed for a high-dispersion mid-infrared spectrograph (10-18 μm, R = λ/Δλ ∼ 30, 000) to be onboard the next-generation infrared space telescope GREX-PLUS. The adoption of an immersion grating will reduce the spectrometer size to 1/n (1/n³ in volume, n: refractive index) compared to conventional diffraction gratings. To determine this absorption coefficient accurately, we need to take the effect of multiple reflection into account that depend on the refractive index. However, the accurate refractive index of CdZnTe (Δn < 10⁻⁴) at 10-18 μm below 20 K has not been measured yet. Therefore, we’re developing a measurement system of the refractive index at cryogenic temperatures in the mid-infrared range. We adopt the minimum deviation method in this system to measure the refractive index, measuring the apex and deviation angle of the prismatic sample of material to be measured. Here we give an overview of the measurement system, as well as preliminary results of the refractive index measurement.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Umi Enokidani, Hideo Matsuhara, Takao Nakagawa, Yasuhiro Hirahara, Ryoichi Koga, Yuan Li, Biao Zhao, Daiki Takama, Hiroshi Sasago, and Takehiko Wada "Development of a mid-infrared refractive index measurement system at cryogenic temperature for the development of an immersion grating to be onboard next-generation infrared space telescope GREX-PLUS", Proc. SPIE 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 130923F (23 August 2024); https://doi.org/10.1117/12.3019753

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