The Design Of Electric Circuits And Software Of A MEMS Motion Measuring System Based On Laser Doppler Technology

Micro-electro-mechanical system (MEMS) is a integrated system which is composed of micro mechanisms, micro sensors, micro actuators, signal processing and intelligent control modules. It is widely used in national defense, communication, automobile, and life science. With the rapid development of MEMS, the demand for characterizations of the dynamic performance of MEMS device is increased.An investigation on MEMS motion measurements based on differential laser Doppler principle is made in this thesis. A method for measuring dynamic parameters, such as velocity, acceleration,displacement, of the MEMS resonator and the micro motor etc. is discussed. Based on the early work, the optical diagram, especially the signal processing module and hardware of the measurement system, has been improved.Based on the early work, the measurement system, including optical diagram, signal processing module and hardware design has been improved.The optical diagram of the former system is improved, and a micro optical spot with tens of micrometers diameter is obtained, and the gradient of the velocity in the spot is declined. The time-frequency analysis method is used in the signal processing module to improve the precision of the system. The signal sampling and processing circuits are designed to substitute for the DAQ card, and the cost of the system is reduced. It also provides a foundation for portability and high efficiency of the system for further MEMS research and exploration.On the basis of the MEMS resonators measurement, the vibration shape of the MEMS can be also analized by the system.Experiments on measuring the motion characteristics of the MEMS resonators, micro motor and acceleration calibrating device have been conducted successfully. Experimental results show that the system can be used to measure MEMS motion.