Development of diffraction-limited, high-throughput Germanium echelle grating

Takayuki Kotani; Nemanja Jovanovic; Takashi Sukegawa; Jason Fucik; Evan Kress; Ashley Baker; Rose Gibson; Michael Fitzgerald; Dimitri Mawet; Aoi Takahashi; Motohide Tamura

doi:10.1117/12.3018601

26 August 2024 Development of diffraction-limited, high-throughput Germanium echelle grating

Takayuki Kotani, Nemanja Jovanovic, Takashi Sukegawa, Jason Fucik, Evan Kress, Ashley Baker, Rose Gibson, Michael Fitzgerald, Dimitri Mawet, Aoi Takahashi, Motohide Tamura

Author Affiliations +

Proceedings Volume 13100, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI; 131005T (2024) https://doi.org/10.1117/12.3018601
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

We developed a new germanium reflective echelle grating fabricated by Canon Inc. for HISPEC (The High- Resolution Infrared Spectrograph for Exoplanet Characterization) for the Keck telescope. We employed germanium as a substrate, an ideal material to achieve small wavefront error (WFE) and high diffraction efficiencies close to the theoretical limit, with robust wavefront stability against temperature change. Furthermore, we developed a grating with an apex angle of less than 90 degrees to enhance the diffraction efficiency of both polarization states. We report that the full-size gratings with 80-degree apex angles show very high diffraction efficiencies, 95% of the theoretical limit, and very small WFE (∼ 13 nm). In addition, we present WFE measurements of a small prototype germanium echelle grating under cryogenic conditions, and we confirmed that the WFE of the diffracted beam is almost identical at room temperature and at 84 K.

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

Citation Download Citation

Takayuki Kotani, Nemanja Jovanovic, Takashi Sukegawa, Jason Fucik, Evan Kress, Ashley Baker, Rose Gibson, Michael Fitzgerald, Dimitri Mawet, Aoi Takahashi, and Motohide Tamura "Development of diffraction-limited, high-throughput Germanium echelle grating", Proc. SPIE 13100, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI, 131005T (26 August 2024); https://doi.org/10.1117/12.3018601

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE