Development of piezoelectric MEMS deformable mirror

This paper reports on piezoelectric micro-electro-mechanical systems deformable mirrors with high-density actuator array for low-voltage and high-resolution retinal imaging with adaptive optics. The deformable mirror was composed of unimorph structure of lead zirconate titanate (PZT) thin film deposited on Pt-coated silicon on insulator substrate and a diaphragm of 10 mm in diameter formed by backside-etching the Si handle wafer. 61 hexagonal electrodes were laid out on the PZT thin film for the high-density actuator array. In order to reduce the dead space for the lead lines between the electrodes and connecting pads, a polyimide layer with through holes on the electrodes was patterned as an electrical insulator. To confirm the application feasibility of the fabricated DMs, displacement profiles of the actuators were measured by a laser Doppler vibrometer. Independent applications of voltages on individual actuators were confirmed.