Preliminary design status of the M4AU based on piezo-stack technology


B Crepy (b), S Chaillot (g), JM Conan (d), R Cousty (b), C Delrez (c), M Dimmler (a), JL Dournaux (f), S De Zotti (e), E Gabriel (c), R Gasmi (f), R Grasser (b), N Hubin (a), P Jagourel (f), L Jochum (a), F Locre (b), P-Y Madec (a), P Morin (b), M Mueller (a), G Petit (d), D Petitgas (b), JJ Roland (b), JC Sinquin (b), E Vernet (a)


ESO (a) Karl-Schwarzschild-Strasse 2 - D-85748 Garching bei München CILAS (b) , 8 Avenue Buffon – BP 6319 - 45063 Orléans Cedex, France AMOS © Liege science park - Rue des Chasseurs Ardennais - 4031 Angleur, Belgium ONERA (d) BP72 - 29 avenue de la Division Leclerc - FR-92322 - Chatillon, France Astrium (e), 31, avenue des Cosmonautes - 31402 Toulouse, France Observatory of Paris Meudon (f), 5, place Jules Janssen, 92195 Meudon, France Boostec (g), Zone Industrielle - 65460 Bazet, France


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 piezo-stack actuators. The design presents a matrix of 7217 actuators (hexagonal 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 piezo-stack actuators in particular. This subsystem is composed of electronic boards, mechanical support fixed to the mounting structure and the thermal hardware. With piezo-stack 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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