High-density piezoelectric actuator array for MEMS deformable mirrors composed of PZT thin films

In this paper, we report a piezoelectric deformable mirror composed of high-density actuator array for low-voltage adaptive optics. A piezoelectric Pb(Zr,Ti)O₃ (PZT) film was deposited on a Pt-coated silicon on insulator (SOI) substrate, and a diaphragm structure of 15 mm in diameter was fabricated by etching a Si handle wafer. A hexagonal 61-element unimorph actuator array was produced with an Al or Au reflective layer over the backside of the diaphragm. In order to reduce the dead space for the lead lines between the actuators, they were prepared on the polyimide insulating layer. The displacement of each actuator was measure by using a laser Doppler vibrometer and we confirmed a relatively large displacement of more than 1 mum by applying a voltage of 10 V_pp.