MORFEO control strategy

Abstract

The ESO Extremely Large Telescope (ELT) will offer unprecedented sensitivity and resolution in the near-infrared, marking a new era for ground-based astronomy. Among its key imaging instruments is MORFEO coupled with MICADO. MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations), formerly known as MAORY, is the largest astronomical adaptive optics system ever designed. It features 12 wavefront sensors and three deformable mirrors, for a total of over 20,000 subapertures and over 6,000 actuators. MORFEO represents one of the greatest upcoming challenges in the field of astronomical adaptive optics. While the design builds upon the heritage of previous AO systems, several architectural choices are entirely new, driven by the unique scale and requirements of this instrument. One of the main challenges is delivering high and uniform wavefront correction across the MICADO field of view. To meet this goal, the MORFEO control strategy adopts a specific approach: sodium laser guide stars are used to sense modes above focus only, since differences in beacon altitude can introduce significant aberrations. Natural guide stars are instead employed to measure and correct for tip, tilt, plate scale variations, and field-averaged focus. In this work, we present the MORFEO control strategy and provide performance estimates across different observing scenarios.