Design and Optimization of Piezoelectric-Actuated Torsion Mirror With Lever Mechanisms

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Considering with high frequency response and self-detection function, a torsion mirror is designed by using piezoelectric material. For large rotating angle requirement, the torsion mirror contains a mechanism with four levers. The torsion mirror is rotating due to actuated by reflection of a piezoelectric beam deposing on the structure layer. The structure layer connects to the lever mechanism. The lever mechanism has four levers. Three levers enlarge the rotating angles by the different ratio of apply and resist moment arms lengths. The fourth lever has the same apply and resist moment arms lengths to adjust the rotating direction the same as deflection of piezoelectric-actuated beam. For self-detecting rotating angle, another additional beam with piezoelectric material depositing is attached to the mirror plate. Finite element method is used to analyze. To investigate the effect of piezoelectric actuated beam on rotating angle, the results show when the actuated beam has length and width of 300 and 24 μm, the thickness structure and piezoelectric actuation layers are both 1 μm, and the applied voltage is 10 volts, the maximum rotating angles could be 50.4 degree. In this rotating angle, the sensing voltage is 170 volts by the piezoelectric material beam attached to mirror plate. Therefore, the torsion mirror can rotate to large angle and have high resolution of angle sensing. To investigate the effect of ratio of apply and resist moment arms lengths on rotating angle. A maximum value is obtained. To optimize the ratio of apply and resist moment arms lengths, the structure of the torsion mirror with piezoelectric actuated beam being 100 and 8 μm long and wide is investigated. The thickness of structure and piezoelectric actuation layers are both 1 μm. And the applied voltage is 10 volts. It shows that the rotating angle increases nonlinearly as the ratio of apply and resist moment arms lengths increasing. And when the rotating angle reaches the maximum values, the rotating angle decreases fast as the ratio of apply and resist moment arms lengths increasing to 1. The maximum rotating angle is 22.71 degrees and the corresponding ratio of apply and resist moment arms lengths is 46/54. Theoretical analysis is derived and has similar tendency.