Control of a surface micromachined repulsive-force driven 2D micromirror

A two-axis micromirror is used in high-speed laser beam steering for vector-based display. The micromirror exhibits rotational motion around two axes as well as translational motion through four repulsive-force rotation electrostatic actuating units, positioned orthogonally from each other around the mirror. Measured data shows that the micromirror can achieve optical scanning angles of ±1.6° in one axis and ±2.4° in the other. The measured bandwidth (-3 dB) for each driving unit is about 2800 Hz operating at a sinusoidal input voltage between 50 V ~ 200 V. With the system being used in an open-loop configuration, the settling time of each driving unit is 4 ms with an overshoot of 80% for a step input of 0 V to 200 V.