Measurement of MEMS mechanical parameters by injection interferometry

In testing MEMS and MOEMS, one can use the direct observation of the device under a microscope and the functionality test in the intended mode of operation. A new diagnostic tool, also useful since the initial design phases, is presented in this paper. It is based on injection interferometry and provides the actual amplitude of displacement and related parameters, e.g. the maximum frequency of operation and the mechanical quality-factor of the structure. We present the basic idea and the measurements (vibration amplitude, resonant frequency, Q and hysteresis effects) performed on a MEMS gyro structure with the aid of the injection interferometer.