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Abstract:
MICADO is the ELT near-infrared first light imager. It will provide diffraction limited images thanks to multi- conjugate adaptive optics (MCAO) and single-conjugate adaptive optics (SCAO) modes provided inside the MAORY module. The SCAO capability is jointly developed by MICADO and MAORY consortia and is motivated by scientific programs for which SCAO will deliver the best AO performance (e.g. exoplanets, solar system science, AGNs, etc) even for very faint objects. Numerical simulations were therefore required to assess the overall performance and explore WFS design parameters and associated calibration procedures. This study concluded to choose a Pyramid WFS (PWFS) working in the visible as the baseline for SCAO mode. We discuss the specific developments (PWFS diffractive model, ELT pupil shape, M4 geometry and influence functions, telescope perturbations...) implemented in the COMPASS simulation tool to achieve a fast and accurate ELT scale simulation. Thanks to its speed of computation we were able to span quickly a very large parameters space at the ELT scale. We explore the optimizations performed to deal with PWFS specific calibrations expected at the telescope (modal Basis, optical gains, NCPA management, island effect). We present a detailed error budget for each of the 5 turbulence conditions (seeing from 0.47" to 1.13") and guide star magnitudes between 10 to 17 (unresolved single star). We also studied the case of extended objects such as double stars or disk like source objects such as Titan. We finally conclude on the impact on performance using such extended objects for SCAO and PWFS.
