The MICADO first light imager for the ELT: a comprehensive tolerance analysis for the relay optics

André Boné; Santiago Barboza; Robert J. Harris; Gabriele Rodeghiero; Jörg-Uwe Pott; Ralf-Rainer Rohloff; Friedrich Müller; Ralph Hofferbert; Peter Bizenberger; José Ramos; Norbert Muench

doi:10.1117/12.2629204

29 August 2022 The MICADO first light imager for the ELT: a comprehensive tolerance analysis for the relay optics

André Boné, Santiago Barboza, Robert J. Harris, Gabriele Rodeghiero, Jörg-Uwe Pott, Ralf-Rainer Rohloff, Friedrich Müller, Ralph Hofferbert, Peter Bizenberger, José Ramos, Norbert Muench

Author Affiliations +

Proceedings Volume 12184, Ground-based and Airborne Instrumentation for Astronomy IX; 1218435 (2022) https://doi.org/10.1117/12.2629204
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51′′) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. In this mode, the ELT focal plane is reimaged to the MICADO focal plane via the relay optics (RO). This subsystem consists of an optical bench made of carbon fiber reinforced plastic, the MICADO calibration assembly, a cover to protect all opto-mechanical components on top of the bench, and an optical assembly. The optical assembly consists of six mirrors, with diameters that go up to around 500 mm. Three of the mirrors are powered, and make a TMA. The remaining mirrors are flat motorized piston, tip-tilt mirrors for interface alignment. The nominal design provides a WFE below 25.3 nmRMS for the full FoV, and a high quality exit pupil. In this work, we present the optical design of the RO, and a comprehensive tolerance analysis. This includes alignment and manufacturing tolerances, mount-induced aberrations, warping of the RO bench, and the thermal behaviour of the complete subsystem, and looking at its effects on the WFE, and exit pupil quality. We have a compliant subsystem, which has been approved at FDR level.

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André Boné, Santiago Barboza, Robert J. Harris, Gabriele Rodeghiero, Jörg-Uwe Pott, Ralf-Rainer Rohloff, Friedrich Müller, Ralph Hofferbert, Peter Bizenberger, José Ramos, and Norbert Muench "The MICADO first light imager for the ELT: a comprehensive tolerance analysis for the relay optics", Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 1218435 (29 August 2022); https://doi.org/10.1117/12.2629204

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