Abstract
A novel dynamic excitation of an S-shaped PZT piezoelectric actuator, which is conceptualized by having two superimposed AC voltages, is characterized in this paper through the evaluation of the 2-D scanning characteristics of an integrated silicon micromirror. The device is micromachined from a SOI wafer with a 5 μm thick Si device layer and multilayers of Pt/Ti/PZT//Pt/Ti deposited as electrode and actuation materials. A large mirror (1.65 mm x 2mm) and an S-shaped PZT actuator are formed after the backside release process. Three modes of operation are investigated: bending, torsional and mixed. The resonant frequencies obtained for bending and torsional modes are 27Hz and 70Hz respectively. The maximum measured optical deflection angles obtained at 3Vpp are ± 38.9° and ± 2.1° respectively for bending and torsional modes. Various 2-D Lissajous patterns are demonstrated by superimposing two ac sinusoidal electrical signals of different frequencies (27 Hz and 70 Hz) into one signal to be used to actuate the mirror.
Highlights
Optical microelectromechanical systems technology has demonstrated enormous promises in numerous key commercial applications [1,2,3,4]
Piezoelectric actuator made of a number of bars of piezoelectric thin film (PZT) electrically connected in parallel and mechanically connected together in series in a meander line configuration was first conceptualized by W
The mirror plate is driven by a S-shaped PZT actuator, which is capable of 6 degrees of freedom of movement
Summary
Optical microelectromechanical systems (optical MEMS) technology has demonstrated enormous promises in numerous key commercial applications [1,2,3,4]. Isikman et al, where magnetic permalloy NiFe was electrodeposited on a mirror plate supported by a straight, narrow cantilever beam [11] This single cantilever actuated mirror allows for 2-D scanning by using superimposed ac currents corresponding to the frequency of bending and torsional mode to excite the external electro-coil. Various gimbaled electromagnetic actuated 2-D scanning mirrors using the same actuation mechanism i.e. superimposed current carrying different excitation frequencies were reported previously [7,10] Such electromagnetic actuated 2-D MEMS scanning mirrors require the presence of either an external permanent magnet or electromagnetic, resulting in bulky packaging
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