S. Ilias, F. Picard, K. Le Foulgoc, J. Osouf, C. Larouche, J-S. Caron, P. Topart, S. Garcia Blanco, D. Vincent, J. F. Lepage, B. Gilbert "Large diameter dual-axis MEMS-based mirror for laser beam steering " Proc. of SPIE, 7930, art. no 79300Q, 2011
Résumé: The main goals of this work is the development of a large dual-axis MEMS mirror, ~3mm in diameter, capable of steering a laser beam within an angular cone of 60°. The targeted application involves the control of a laser beam with a particular interest for the resulting far field beam direction and profile. Finite element simulations using ANSYS modeling program were conducted to optimize the mirror design and determine the main characteristics of the mirror. The voltage required to tilt the mirror by 15° around each of the two axes was evaluated to be in the range of 700 V. The construction of this device is based on high precision structural dies assembly which relies on innovative developments in the fields of selective electroplating, deep reactive ion etching (DRIE) and thermocompression flip-chip bonding. The fabrication process involved the microassembly of 4 mirror parts, i.e. address electrodes, thick pedestal, gimbals structure and mirror plate. Single crystal silicon was used as material for the fabrication of the thick pedestal and mirror plate which provided the required large mirror-electrode gap and a high quality mirror with high flatness and low roughness. Soldering based on SnAu was considered for the microassembly of the thick pedestal to the address electrodes die, while Au-Au thermocompression bonding was considered to achieve the assembly of gimbals and mirror. The gimbals were supported by a polyimide sacrificial film to avoid damaging the hinges during mirror plate assembly.
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