A Piezo-Hydraulic actuator design supporting fast steering mirror

Micro-displacement amplifiers play a crucial role for enhancing the output displacement of piezoelectric ceramic stack actuators. However, it remains a significant challenge to design a compact system with large load capacity that achieves both a high amplification ratio and high first-order resonant frequency. This article introduces a design methodology for a micro-displacement amplifier featuring a large amplification ratio, high resonance frequency, and a customizable axis angle between the input and output displacement directions, while effectively eliminating parasitic displacement. A compact Piezo-Hydraulic actuator with dimensions of Φ44mm×71mm is designed. The small deflection theory for the flexure piston is refined, resulting in a novel theoretical model for the Piezo-Hydraulic actuator's amplification ratio based on mass conservation principles. The influence of structural parameters on the actuator's performance is investigated through sensitivity analysis. The FEA results closely align with the theoretical model, exhibiting a deviation of only 0.76%. A prototype Piezo-Hydraulic actuator is fabricated and experimentally validated, achieving an amplification ratio of 12.61 with a relative error of 6.17%. The Piezo-Hydraulic actuator achieves a maximum output displacement of 104.9 μm, with the PZT-stack displacement measuring 8.32 μm at 150 V and a first-order resonant frequency of 1356 Hz. The Piezo-Hydraulic actuator is integrated into a fast steering mirror prototype, where its beam adjustment capabilities are experimentally demonstrated. This study proposes a novel evaluation methodology for Piezo-Hydraulic actuators and underscores their potential in precision optical systems.