MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO). MICADO can operate in the so-called standalone mode in the absence of MORFEO with the SCAO correction alone. The Relay Optics (RO), is the optical system relaying the ELT focal plane to an appropriate position inside the MICADO cryostat for that SCAO-only stand-alone observing mode. After successfully passing the Final Design Review (FDR), the manufacturing of the RO is in full swing. We present here the current status of the ongoing assembly, integration and verification campaign (AIV), together with its upcoming challenges. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat, motorized tip-tilt-piston mirrors (M1, M5 and M6) and three powered mirrors (M2, M3 and M4) of up to ~500 mm in diameter, the MICADO calibration assembly (MCA) including its deployable unit with a flat mirror (MDU) and a cover to protect all opto-mechanical components on top of the bench. The fabrication of the mirrors has started, while the machining of the mirror mounts is well ahead. The optical bench, as well as all other CFRP parts have been ordered and the manufacturing is completed. In order to get optimum performance and minimal wavefront error (WFE), the mirrors are tested in their mounts before carrying out the final polishing operations. Therefore, all mirror mounts are scheduled to be delivered to the mirror vendor QED Optics by the end of 2024.
A study was performed to investigate edge performance as a function of the mechanical edge profile. There are many edge profiles to consider. A baseline set of curved, straight and corner edge profiles was chosen for MRF finishing and analysis. Each sample edge profile was subjected to a series of uniform removal MRF finishing runs, only considered the leading edge. The results of this study provide a starting point for further investigation and mitigation of edge effects for different profiles during MRF finishing.
This conference presentation was prepared for the Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V conference at SPIE Astronomical Telescopes + Instrumentation, 2022.
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