Development of a nanoprecision 3-DOF vertical positioning system with a flexure hinge

This paper describes the conceptual design of an ultraprecision 3-DOF (Z, θx, θy) vertical positioning system with nanometer precision. The vertical out-of-plane positioning system can be used for various nanoalignment applications, such as optical instrument alignment. The proposed vertical positioning system is driven by three piezoelectric (PZT) actuators and is guided by three rotationally symmetric hinges. Because the displacement generated by a PZT actuator is very small, the proposed system also includes an amplification hinge mechanism. Because the relationships between the variables of the hinge parameters and system performance levels are complicated, an optimization procedure to obtain optimal design parameters, which maximize the system bandwidth, is developed. Based on the solution to the optimization problem, the design of a vertical positioning system and finite-element-method simulation results are presented. Finally, the stage is manufactured and tested for verification. The stroke of the translational movement is 190 mm, and the stroke of the rotational movement is 0.5 mrad, whereas their in-position stability levels are ±2 nm and ±20 nrad and resolutions are 5 nm and 80 nrad, respectively. The settling time is less than 45 ms.