Piezoelectric optical micro scanner with built-in torsion sensors

The present study describes the design, fabrication and demonstration of the piezoelectric optical micro scanners (piezoelectric scanners) with built-in torsion sensors. We have developed the piezoelectric scanners with piezoelectric torsion sensors utilizing Pb(Zr,Ti)P₃ (PZT) thin films. A mirror (1 × 1 mm²) is supported by hinges, and the hinges are connected to resonators. The torsion sensors are formed on the hinges, which detect the rotation of the mirror through the direct piezoelectric effect of the PZT thin films. The micro scanners were fabricated from a multilayer of Pt/Ti/PZT/Pt/Ti/SiO₂ deposited on a silicon-on-insulator wafer using microelectromechanical systems bulk micromachining. The output voltage and phase of the torsion sensor showed the resonant peak compatible with the data measured by a laser Doppler vibrometer. The gain of the torsion sensor was measured to be 0.0012. We compared the scanning angle of the reflected light and output voltage of the torsion sensor as a function of the voltage applied to the resonators. The torsion sensor showed a nonlinear increase in the output voltage, which is in good agreement with that in the scanning angle.