초록
Micromirrors supported by S-shape girders were fabricated and their angular deflections were measured using a laser-based system. A micromirror consists of a $50\mum\times50\mum$ aluminum plate, posts and an S-shape girder. Two electrodes were deposited on two corners of the substrate beneath the mirror plate. $50\times50$micromirror array were fabricated using the Al-MEMS process. The electrostatic force caused by the voltage difference between the mirror plate and one of the electrodes causes the mirror plate to tilt until the girder touches the substrate. Bial voltage of the mirror plate is between 25~35V and signal pulse voltage on both electrodes is $\pm5V$. A laser-based system capable of real-time two-dimensional angular deflection measurement of the micromirror was developed. The operation of the system is based on measuring the displacement of a HeNe laser beam reflecting off the micromirror. The resonant frequency of the micromirror is 50kHz when the girder touches the substrate and it is 25 when the micromirror goes back to flat position, since the moving mass is about twice of the former case. The measurement results also revealed that the micromirror slants to the other direction even after the girder touches the substrate.