title: A 2-D MEMS scanning mirror based on dynamic mixed mode excitation of a piezoelectric PZT thin film S-shaped actuator.
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.
authors.affiliation: Department of Electrical & Computer Engineering, National University of Singapore 117576 Singapore.
authors.forename: Kah How
authors.initials: KH
authors.lastname: Koh
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Chengkuo
authors.initials: C
authors.lastname: Lee