一种新型微机电系统扫描镜的谐振频率研究

Study on Resonant Frequency for a Novel MEMS Micro Scanning Mirror

在微光机电系统(MOEMS)技术的基础上,采用绝缘体上硅(SOI)的体硅加工工艺,设计并加工制作了一种新型的静电驱动的谐振式微机电系统(MEMS)扫描镜。介绍了其基本工作原理及结构设计特点;理论计算了圆形和方形两种结构的尺寸扫描镜的谐振频率,并利用ANSYS有限元软件进行仿真;设计并搭建了一个简单易操作的光学测试系统,对研制出的MEMS扫描镜(7.1mm×5.2mm)进行扫描角度测试。利用该器件参数激励的迟滞频率特性,对其谐振频率进行实际测量。同时,为验证其所测谐振频率的准确性,利用激光多普勒测振(LDV)系统对其进行测试。在工作电压10V,方形和圆形扫描镜的驱动频率分别为556Hz和596Hz时,机械扫描角度分别可达到约6°和5°,谐振频率分别约为300Hz和277Hz。并分析误差产生的原因及其结果。

Based on the micro-opto-electro-mechanical systems（MOEMS） technology,a new resonant micro scanning mirror using silicion-on-insulator（SOI） process is designed and fabricated.Its basic operational principle and structural characterizations are briefly introduced.The resonant frequency considered to be its most important mechanical parameter is theoretically computed according to the two designed structural dimensions and numerically simulated by combining the finite element simulation tool of ANSYS.A simple but efficient optical system is set up for practically measuring their scanning angle of the designed micro scanning mirror.According to the characteristic of hysteretic frequency responses of parametric excitation of the designed micro scanning mirror,the resonant frequency is measured.To verify the accuracy of the testing results,the resonant frequency is achieved by the laser Doppler vibrometer（LDV）.With the driving voltage of 10 V,the mechanical scanning angles for the square and circular scanning mirror reach to about 6° and 5° respectively while the drive frequencies are 556 Hz and 596 Hz.Furthermore,the resonant frequency approximately reaches to 300 Hz and 277 Hz.All the derived results are comparised and very error cause is analyzed.