| With the development of micro-fabrication technology, it is necessary for micro-three-dimensional surface measurement. Phase-shifting interferometry has been widely used in micro-surface topography measurement with the advantages of high precision and non-contact. In this paper, a dual-wavelength interferometry algorithm which can get the real phase distribution directly without unwrapping is presented. Theoretical and experimental studies of the algorithm based on the dual wavelength interferometry are the focus on this research. The main work as follows has been done according to this main content.1. Based on the interference theory, the principle of dual-wavelength interfere was introduced. And the phase extraction algorithm based on two-wavelength interferometry was presented. This algorithm not only got rid of unwrapping but also avoided the additional errors from phase shifter.2. The process of surface reconstruction was simulated. Firstly, the ideal model of a three-dimensional object was established, and its interferograms were made based on the dual-wavelength interference theory. Then, the value of the phase can be obtained using the algorithm mentioned above. Additionally, different levels of Gaussian noise, salt and pepper noise were added in the interferograms to analyze the noise insensitive of the algorithm, and the results showed that the algorithm was insensitive to these kinds of noise which proved the feasibility of the algorithm.3. The surface morphology reconstruction system with dual-wavelength interferometry was designed. According to the actual requirements of the system, the parameters of the pinhole filter, the collimated beam expander, the interferometer and the data receiving system were calculated.4. An experimental system was carried out to get the interferograms of flat mirror and concave mirror, and further more got the true values of the phases. The results show that the dual wavelength interference theory and algorithm was correct. |
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