2D Asymmetric Silicon Micro-Mirrors for Electrostatic Field Distribution Measurement Using Optical Level Method

抄録

We developed silicon micro-mirrors with two asymmetric axes for electrostatic field distribution measurements using a single external piezoelectric ceramic vibrating element. The 2D asymmetric silicon micro-mirrors were fabricated by using an SOI-MEMS process. The vibration transmissibility of the proposed mirror under a vacuum atmosphere was evaluated by dynamic analysis. We obtained the resonant frequency in the low-speed axis of 23.3 Hz and in the high-speed axis of 556.8 Hz respectively. To prevent a reduction in the amplitude width, we induced a 90° phase shift between the low- and high-speed axes at the resonance frequency. The ratio of the deformation between the low-speed axis of 30 Hz and the high-speed axis of 604 Hz was simulated to be 4.04. In measurement, the ratio of the deformation between the low-speed axis of 23.3 Hz and the high-speed axis of 556.8 Hz was 6.48. The difference between the calculated and experiment values were apparently due to the fabrication errors and frequency characteristics of piezoelectric ceramic vibrating element. A Lissajous pattern projected onto the screen. The scanning angle was a degree of 7.6 (total angle) in the low- and high-speed axis. We subsequently measured the electrostatic field distribution using the 2D asymmetric silicon micro-mirrors by means of the optical level method.