胡晓东,杨 媛,常新宇,卢钧胜
AuthorsHTML:胡晓东，杨 媛，常新宇，卢钧胜
AuthorsListE:Hu Xiaodong,Yang Yuan,Chang Xinyu,Lu Junsheng
AuthorsHTMLE:Hu Xiaodong，Yang Yuan，Chang Xinyu，Lu Junsheng
Unit:天津大学精密仪器与光电子工程学院，天津 300072
Unit_EngLish:School of Precision Instruments and Optoelectronics Engineering，Tianjin University，Tianjin 300072，China
Abstract_Chinese:针对微机电系统等微纳米尺度器件的振幅测量，基于外差干涉原理设计开发一种微振动模态测试系统，由 光路和解析电路两部分构成，在光路中利用载波技术将被测样品的振幅信息加载到被测光信号上，被测光信号与参 考光信号之间原本存在一个由声光调制器产生的频率差，当被测信号与参考信号经光电探测器混频后，可得到一个 参考差频信号及一个载有被测物理量信息的差频信号，之后在电路中对这两个信号进行电路解调即可得到被测样品 的振幅信息．该测量方式降低了测量过程对光强的要求，降低了样品所需的激励电压，避免了对样品表面的破坏， 同时测量不会受到光程波动和电磁反馈的影响，提高了测量速度，降低了测量误差．通过实验测试了谐振频率为 2.188 9 GHz 的薄膜体声波谐振器的振幅和原子力显微镜微悬臂梁探针前三阶谐振动模态的振幅，实验表明该系统可 以测量的振动频率范围约为几十 Hz 到数 GHz，振幅范围约为 1 pm～10 nm，因此本振动模态测量系统可以同时满 足高测量带宽和高测试灵敏度的测试需求．
Abstract_English:In this paper，we introduce a heterodyne interferometer for measuring the amplitudes of the highly sensitive vibrations of microstructures such as micro electro mechanical systems(MEMS)devices. The interferometer consists of an optical setup and a signal extraction circuit. The amplitude information of the sample is loaded onto the object beam using carrier technology. There is a frequency difference between the object beam and the reference beam produced by the acousto-optic modulator，and these two beams are combined in the mixer. The mixer outputs contain the original difference frequency signal and the difference frequency of the measurement information. The mixer outputs are demodulated via a signal extraction circuit and the amplitude information is subsequently calculated. This process requires low light intensity and effectively reduces the necessary excitation voltage，thus enabling less invasive measurements. It is also less vulnerable to slow but large flfluctuations in the optical path length and magnetic feedback. To demonstrate the effectiveness of the interferometer，we performed measurements on a film bulk acoustic resonator with a 2.188 9 GHz resonant frequency and a microcantilever probe of an atomic force microscope. The experimental results show that the heterodyne interferometer features measurement frequencies ranging from several tens of Hertz to 12 GHz and amplitudes ranging from about 1 pm to 10 nm. Thus，the heterodyne interferometer meets the demands for vibration measurements with wide ranges of frequency and amplitude.
Keyword_Chinese:微机电系统；外差干涉测量；薄膜体声波谐振器；微悬臂梁；振幅
Keywords_English:micro electro mechanical systems ； heterodyne interferometry ； film bulk acoustic resonator ； microcantilever；amplitude

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