28 July 2010 Last progress concerning the design of the piezo stack M4 adaptive unit of the E-ELT
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Abstract
CILAS proposes a M4 adaptive mirror (M4AM) that corrects the atmospheric turbulence at high frequencies and residual tip-tilt and defocus due to telescope vibrations by using piezostack actuators. The design presents a matrix of 7217 actuators (triangular geometry, spacing equal to 29 mm) leading to a fitting error reaching the goal. The mirror is held by a positioning system which ensures all movements of the mirror at low frequency and selects the focus (Nasmyth A or B) using a hexapod concept. This subsystem is fixed rigidly to the mounting system and permits mirror displacements. The M4 control system (M4CS) ensures the connection between the telescope control/monitoring system and the M4 unit - positioning system (M4PS) and piezostack actuators of the M4AM in particular. This subsystem is composed of electronic boards, mechanical support fixed to the mounting structure and the thermal hardware. With piezostack actuators, most of the thermal load is minimized and dissipated in the electronic boards and not in the adaptive mirror. The mounting structure (M4MS) is the mechanical interface with the telescope (and the ARU in particular) and ensures the integrity and stability of M4 unit subsystems. M4 positioning system and mounting structure are subcontracted to AMOS company.
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B. Crepy, S. Chaillot, J. M. Conan, R. Cousty, C. Delrez, M. Dimmler, J. L. Dournaux, S. De Zotti, E. Gabriel, R. Gasmi, R. Grasser, N. Hubin, P. Jagourel, L. Jochum, F. Locre, P.-Y. Madec, P. Morin, M. Mueller, G. Petit, D. Petitgas, M. Pierard, J. J. Roland, J. C. Sinquin, E, Vernet, "Last progress concerning the design of the piezo stack M4 adaptive unit of the E-ELT", Proc. SPIE 7736, Adaptive Optics Systems II, 77362F (28 July 2010); doi: 10.1117/12.856359; https://doi.org/10.1117/12.856359
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