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Proceedings Paper

Centimeter-scale MEMS scanning mirrors for high power laser application
Author(s): F. Senger; U. Hofmann; Thomas von Wantoch; C. Mallas; J. Janes; W. Benecke; Patrick Herwig; P. Gawlitza; Moises A. Ortega Delgado; C. Grune; J. Hannweber; A. Wetzig
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Paper Abstract

A higher achievable scan speed and the capability to integrate two scan axes in a very compact device are fundamental advantages of MEMS scanning mirrors over conventional galvanometric scanners. There is a growing demand for biaxial high speed scanning systems complementing the rapid progress of high power lasers for enabling the development of new high throughput manufacturing processes. This paper presents concept, design, fabrication and test of biaxial large aperture MEMS scanning mirrors (LAMM) with aperture sizes up to 20 mm for use in high-power laser applications. To keep static and dynamic deformation of the mirror acceptably low all MEMS mirrors exhibit full substrate thickness of 725 μm. The LAMM-scanners are being vacuum packaged on wafer-level based on a stack of 4 wafers. Scanners with aperture sizes up to 12 mm are designed as a 4-DOF-oscillator with amplitude magnification applying electrostatic actuation for driving a motor-frame. As an example a 7-mm-scanner is presented that achieves an optical scan angle of 32 degrees at 3.2 kHz. LAMM-scanners with apertures sizes of 20 mm are designed as passive high-Q-resonators to be externally excited by low-cost electromagnetic or piezoelectric drives. Multi-layer dielectric coatings with a reflectivity higher than 99.9 % have enabled to apply cw-laser power loads of more than 600 W without damaging the MEMS mirror. Finally, a new excitation concept for resonant scanners is presented providing advantageous shaping of intensity profiles of projected laser patterns without modulating the laser. This is of interest in lighting applications such as automotive laser headlights.

Paper Details

Date Published: 27 February 2015
PDF: 16 pages
Proc. SPIE 9375, MOEMS and Miniaturized Systems XIV, 937509 (27 February 2015); doi: 10.1117/12.2079600
Show Author Affiliations
F. Senger, Fraunhofer-Institut für Siliziumtechnologie (Germany)
U. Hofmann, Fraunhofer-Institut für Siliziumtechnologie (Germany)
Thomas von Wantoch, Fraunhofer-Institut für Siliziumtechnologie (Germany)
C. Mallas, Fraunhofer-Institut für Siliziumtechnologie (Germany)
J. Janes, Fraunhofer-Institut für Siliziumtechnologie (Germany)
W. Benecke, Fraunhofer-Institut für Siliziumtechnologie (Germany)
Patrick Herwig, Fraunhofer-Institut für Werkstoffphysik und Schichtechnologie (Germany)
P. Gawlitza, Fraunhofer-Institut für Werkstoffphysik und Schichtechnologie (Germany)
Moises A. Ortega Delgado, Fraunhofer IWS Dresden (Germany)
C. Grune, Fraunhofer-Institut für Werkstoffphysik und Schichtechnologie (Germany)
J. Hannweber, Fraunhofer-Institut für Werkstoffphysik und Schichtechnologie (Germany)
A. Wetzig, Fraunhofer-Institut für Werkstoffphysik und Schichtechnologie (Germany)

Published in SPIE Proceedings Vol. 9375:
MOEMS and Miniaturized Systems XIV
Wibool Piyawattanametha; Yong-Hwa Park, Editor(s)

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