Hybrid linear microactuators and their control models for mirror shape correction

Abstract

Future space-based imaging systems demand ultra-lightweight mirrors, which would involve a large number of actuators to provide the needed surface correction. These lightweight actuators are required to be integrated with the mirrors to avoid a significant increase in overall areal mass density. This paper presents the fabrication and testing of a linear microactuator and the modeling of an actuated mirror composed of such lightweight actuators. The linear microactuator is driven by a combination of a piezoelectric actuator block and electrostatic comb drive units. A full nonlinear optimization model of a mirror lattice was developed to simulate a lightweight primary with embedded microactuators, which allows for an arbitrarily connected lattice with connector elements having an arbitrary stiffness and actuation response. The modeling yielded a high precision estimation of the mirror shape correction.