A optical measurement system of Micro-electro-mechanical system (MEMS) motion is demonstrated to increase the efficiency of MEMS design and manufacturing. The system is developed based on the heterodyne laser Doppler technology, and frequency shift of 40MHz is introduced by a Bragg cell. The paper introduced MEMS vibration theory, designed optical structure and electronic circuit, and obtained the linear relation between the Doppler shift and the target velocity. Experiments on driving and measuring double-ended tuning fork resonator were carried out. The resonator is driven by using electrostatic force at its natural frequency 2.4KHz. Experimental results indicate that the measure system can be used to measure MEMS motion with high accuracy.
To provide useful insight into the reliability of silicon micromachined resonator, a measurement system of resonator vibration is presented to check the dynamic characteristics of resonator. The system utilizes heterodyne laser Doppler techniques and acquires the relation between resonator motion and Doppler shift of scatter beam. The vibration principle of resonator was expatiated detailedly and a special driving control circuit was also designed. Experiments on driving and measuring double-ended tuning fork vibration were carried out. The frequency of driving signal is 2.4 kHz and the peak-to-peak value of driving voltage is 140 V. Experimental results indicate that the system can measure dynamic characteristics of Micro-electro-mechanical system (MEMS) well.