The MCAO module for the E-ELT
The Multi-Conjugate Adaptive Optics (MCAO) module for the European Extremely Large Telescope (E-ELT) is an adaptive optics system including post-focal deformable mirror(s) conjugated to high-altitude layer(s), that complement the ground-layer correction provided by the telescope adaptive M4 and the field stabilization correction provided by the telescope M5. From the wavefront sensing point of view, the MCAO module includes a multiple LGS wavefront sensor for the high-order sensing and a NGS wavefront sensor, to measure the low-order modes. The NGS wavefront sensor will determine the sky coverage of the module.
The MCAO module provides a corrected field of medium to large size, over the baseline wavelength range 750-2400 nm. The candidate instruments fed by the medium and large fields are, respectively, a high angular resolution imaging camera and a multi-object spectrograph. Given the size of the corrected field and the quality of the correction, considering the flexibility in providing different level of correction as a function of the field itself, the MCAO module looks like an AO facility of "intermediate" properties between ground-layer AO (GLAO, wide field with moderate correction, at the level of a seeing improvement) and laser-tomography AO (LTAO pointed mode with high correction level).
The MCAO module is a key facility of the E-ELT due to the science applications that it might enable. The goal is to implement it within two years of the telescope first light.
The conceptual design study started in November 2007. The first phase of the study (requirements analysis and preliminary trade-offs) has ended in October 2008 with the successful completion of the 'Phase 1 Review'.
Within this project OAPd is involved in the study of innovative wavefront-sensing schemes (in alternative to the baseline scheme) and the definition of the high-level requirements for the module control software.
People: A. Baruffolo, J. Farinato, R. Ragazzoni
Collaboration: INAF OA Bologna, INAF OA Arcetri, Office National d'Etudes et de Recherches Aeronautiques (ONERA, FR), European Southern Observatory (ESO)
Publications: Lombini et al. (2008), SPIE 7015,160