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Proceedings Paper

Position encoding and closed loop control of MOEMS translatory actuators
Author(s): M. Lenzhofer; A. Tortschanoff; A. Frank; T. Sandner; H. Schenk; M. Kraft; A. Kenda
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Paper Abstract

We present a new method for detecting the accurate position of micro-electro-opto-mechanical system (MOEMS) devices, thus enabling the implementation of closed-loop controls. The ensuing control mechanism allows building robust MOEMS-based Fourier-transform infrared (FTIR) spectrometers with large mechanical amplitudes and thus good spectral resolutions. The MOEMS mirror device, a rectangular 1.65 mm² metalized plate mirror suspended on bearing springs and driven by comb-structured electrodes, is driven by a rectangular signal with a duty cycle of 50% and high voltage levels up to 140 V at a frequency near twice its mechanical resonance frequency. Out-of-plane mirror displacements of up to ±100 μm have thus been achieved. To handle the high bandwidth of the sinusoidal mirror position reference signal, which is generated by a laser reference interferometer, an analog position detection circuit is necessary. This dedicated circuit demodulates the reference signal and generates a highly accurate control signal returning the zerocrossing position of the mirror. This permits the implementation of a closed-loop control, which ensures optimally stable MOEMS mirror movement and maximal mechanical amplitude, even under varying environmental conditions. While this solution has been developed for a specific MOEMS device, the principle is widely applicable to related components.

Paper Details

Date Published: 18 May 2009
PDF: 9 pages
Proc. SPIE 7362, Smart Sensors, Actuators, and MEMS IV, 736212 (18 May 2009); doi: 10.1117/12.820335
Show Author Affiliations
M. Lenzhofer, Carinthian Tech Research AG (Austria)
A. Tortschanoff, Carinthian Tech Research AG (Austria)
A. Frank, Carinthian Tech Research AG (Austria)
T. Sandner, Fraunhofer Institute for Photonic Microsystems (Germany)
H. Schenk, Fraunhofer Institute for Photonic Microsystems (Germany)
M. Kraft, Carinthian Tech Research AG (Austria)
A. Kenda, Carinthian Tech Research AG (Austria)

Published in SPIE Proceedings Vol. 7362:
Smart Sensors, Actuators, and MEMS IV
Ulrich Schmid, Editor(s)

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