The European Extremely Large Telescope (ELT) is a ground-based telescope, part of the suit of three giant telescopes under construction. With a 39m diameter, beyond state-of-the-art technologies and instrumentations, ELT will be, in mid-2020, the most complex and most powerful observatory ever built. At the heart of the ELT's Adaptive Optics, ONERA imagines and designs the systems and components that will make it possible to overcome the harmful effects of atmospheric turbulence and deliver an image quality hitherto unsurpassed (10 milli- arc seconds, or 50 nano-radians) and this for almost all the observable sky
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