Optical design, analysis, and performances of the infrared and visible channels of the warm calibration unit in METIS/ELT

T. Sharma; M. Rutowska; M. Wiest; S. Graf; L. Labadie; C. Straubmeier; A. Eckart; S. Todd; T. Agócs; R. Stuik; B. Brandl; F. Bettonvil

doi:10.1117/12.2630800

29 August 2022 Optical design, analysis, and performances of the infrared and visible channels of the warm calibration unit in METIS/ELT

T. Sharma, M. Rutowska, M. Wiest, S. Graf, L. Labadie, C. Straubmeier, A. Eckart, S. Todd, T. Agócs, R. Stuik, B. Brandl, F. Bettonvil

Author Affiliations +

Proceedings Volume 12184, Ground-based and Airborne Instrumentation for Astronomy IX; 121843L (2022) https://doi.org/10.1117/12.2630800
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

METIS, the mid-infrared imager and spectrograph for the wavelength range 2.9 -13.5 µm (astronomical L-, MN- band), will be one of the three science instruments at the Extremely Large Telescope (ELT). It will provide diffraction-limited imaging, coronagraphy, high-resolution integral field spectroscopy, and low and medium resolution slit spectroscopy. Within the international METIS consortium, the University of Cologne is responsible for the design, manufacturing, integration, and qualification of the Warm Calibration Unit (WCU) of the instrument. In this contribution, we present the current status of the optical design and principle of optical operation of the WCU. The main train of the WCU optics is based on a modified F/17.75 Offner relay, with the optical output parameters matching the plate scale, F-number, as well as the exit-pupil position and size of that of the ELT. We discuss the optical design, and tolerance analysis of the WCU relay optics as part of the Optics FDR review by ESO. In addition, we present the concept and design of the Invar mechanical mounts for the WCU Zerodur mirrors, which are expected to undergo thermal and mechanical stresses. Finally, we present the optical design and analysis of the visible channel of the WCU that is aimed at alignment verification, as well as visualization of the METIS focal and pupil planes.

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T. Sharma, M. Rutowska, M. Wiest, S. Graf, L. Labadie, C. Straubmeier, A. Eckart, S. Todd, T. Agócs, R. Stuik, B. Brandl, and F. Bettonvil "Optical design, analysis, and performances of the infrared and visible channels of the warm calibration unit in METIS/ELT", Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 121843L (29 August 2022); https://doi.org/10.1117/12.2630800

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