Measurement of microstructure in micro electro mechanical systems using optical interferometric microscope

An automatic measurement system for micro electro mechanical element with optical interferometric microscope is presented in the paper. The system introduces a novel method to calculate the central dark fringe (intensity minimum) and central bright fringe (intensity maximum) in the image. The changing of height in asymmetric micro-structure, based on the phase definition of interference fringe can be calculated. Interferometric image information is derived through image processing method, and innovated contour line algorithm is used to build up micro-structure 3D profile. In the experiments, the total processing time for five parts of element could be reduced to less than 5 s and the system error is less than 0.02 mu m.