A Fast Piezo Actuated Tip/Tilt Mirror for raster scan applications

摘要

This paper presents the system and control design of a novel high performance piezo-actuated fast steering mirror (FSM) for high speed optical scanning which is centered around an easy-to-manufacture membrane-like mechanical flexure and uses an optical sensor system for position measurement. With the membrane flexure the first fundamental resonance mode of the actuator is placed as high as 6.7 kHz, while still enabling an optical angular range of ±4.8 mrad. Using a PI controller together with three notch filters designed in a loop shaping approach for maximizing the system bandwidth and tracking of high resolution raster trajectories, a closed-loop bandwidth as high as 2.7 kHz and a positioning uncertainty of 3.8μrad rms is obtained. The obtained tracking error when tracking a 250 Hz raster scanning trajectory with a scan amplitude of 2.2 mrad is as small as 73.8μrad rms (3.6% of scan amplitude).