White-light Spectral Scanning Interferometry for Surface Measurement System

The paper introduces the white-light spectral scanning interferometry for surface measurement. This interferometry can be used to measure the roughness of both smooth surfaces and those with large step heights. This real-time surface measurement can be achieved using acousto-optic tuneable filtering (AOTF) technique without mechanical scanning. At first, the structure and principle of this interferometry is introduced. Then the algorithm of the surface roughness measurement is proposed. What's more, the experiment with standard test piece is conducted. Compared with the traditional laser-light interferometry, the data shows that the proposed method has a higher accuracy which is proved to be nano-scale. A conclusion is given at last in which the superiorities and the limitations of the proposed system were discussed.