| Phase-shifting interferometry has been considered as a type of opto-electrical measuring interferometry and it has many advantages, such as simple structure, easily modulated, fast and real time, high accuracy and whole field automatic measurement. It has been widely used to test optical element, optical system, and to detect optical surface as well as some physical parameter (such as temperature field, density field) related with optical path difference.In this thesis, the author comprehensively described the research results on the theory and algorithms of phase-shifting interferometry. The study is concentrated on the key problem of phase-shifting interferometry: phase-extracting algorithms. By analyzing different phase-stepping algorithms, the phase error due to inaccurate phase-shift between data frames and image-detector nonlinearity were modeled and calculated, the best method was choosed. Accordingly, the system performance was improved. Because the method of phase-shifting has excessive demand and has to accept accurate steps, we adopted PZT as driving apparatus and choosed the area that it's characteristic of linearity is better. Based on this area, we designed power supply that drives the PZT and completed the precision phase stepping system, then the precision in measuring is improved. Based on the research on the processing of method of interferograms, an improved algoritlim is proposed. These methods are used to process the interferograms in Matlab, and the experimental results show that these methods can improve the quality of interferograms and the accury of interferometric testing effectively.At last, we refited the quondam interferometer, used the laser as the light resource, CCD as the sensor and PZT to provide microscopic translating, the computer sampled image and processed data with high speed. Based on this system, the 3-D surface topography of standard specimen was carried out. Finally, we analyed all measuring results and the further experiment was conceived. |
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