MEMS Out-of-plane Test Based On Phase-stepping Microscopic Interferometry Microscope And In-plane Motion Compensation

MEMS dynamic testing technology is an important part of MEMS testing technologies,and it is one of the hotest research points at home and abroad. Commonly,MEMS dynamic testing systems are based on optical-interferometry or laser-Dopplertechnique. In optical-interferometry techniques, the stroboscopic imaging technologyhas advantages of wider measuring range and high accuracy, so it is widely used.Phase-stepping microscopic interferometry technology is commonly used in MEMSin-plane motion tests, thus, how to combine it with stroboscopic imaging technologyto complete MEMS integrated testing is a problem remains to be resolved.In this paper, based on stroboscopic imaging technique and phase-stepping microscopicinterferometry, we promote a new technology called optimal interferenceelimination, which uses phase-shifting interferometry images to get bright-field images.The new technology has implemented integration measurement of in-plane motionand out-of-plane motion. Major works in this paper include:�'�By analyzing research progress of MEMS dynamic testing techniques athome and abroad, especially in our State Key Laboratory, I established my major researchtopics.�'�Based on MEMS motion characteristics, we analyze the principles ofphase-stepping microscopic interferometry and block-matching technologies, thenpromote an integrated measuring scheme of MEMS devices’in-plane andout-of-plane motions based on phase-stepping microscopic interferometry technique.Thus, the scheme greatly reduces the introduction of errors from a second measurement.�'�Advancing a new technique named optimal interference elimination used inMEMS devices in-plane motion test. In this technology, we use phase-shifting interferometryimages to get bright-field images, and all the registrated images meet thetesting requirements. MATLAB is used to complete the whole data processing part ofthe preparation.�'�Advancing a method called in-plane motion compensation used in MEMSdevices ut-of-plane motion test. The method is used to identify surface points’spatial locations of the device in the view field, and ensures the correctness of thetime-domain phase unwrapping.�'�Improving the existing testing system. The subsystem of signal generationand synchronized control is completed by NI PXI chassis and signal cards, and itmainly controls the excitation signal and the signal waveform configuration. Hardwareportion of the light source drive circuit has also been built.�'�Testing the algorithm newly promoted. MEMS micro-resonator devices areused under out-of-plane motion test. After using stroboscopic imaging technology toget phase-shifting interferometry images of the devices, we further process the imagesby software algorithms. Then, motion information of the comb is accessed, such asin-plane motion, three-dimensional topography image of out-of-plane motion and theout-of-plane trajectory of points on the comb surface. Law of motion of the devices iswell revealed by analyzing the datas.