Measuring in-plane operational deflection shapes at ultra-high frequencies

This paper reports the proof of concept of a novel sensor technique to measure the in-plane, contour modes of Radio Frequency Micro-Electro-Mechanical (RF-MEM) resonators at frequencies above 100 MHz with accurate vibration amplitudes. We have achieved this goal for the first time to our knowledge and we demonstrate our first measurement. RF-MEM resonators are designed to perform mainly an in-plane vibration and, thus, it is substantially for the designer to get an experimental feedback of the in-plane contour modes. In order to accomplish accurate in-plane-vibration measurements we have combined heterodyne interferometry, scanning vibrometry, amplitude demodulation, and optical flow. The results presented in this paper allow, for the first time, the analysis of the in-plane vibration behavior of MEM resonators.