| The Digital Sharing Speckle Pattern Interferometry (DSSPI) is an important part of the speckle measurement. Not only does it has the advantages of non-contact, high accuracy, high sensibility and full-field, it could also measure strain directly and has a compact structure. The DSSPI has become a powerful tool in measuring the displacement, strain, defect, vibration and roughness. The DSSPI system which is based on the Wollaston prism is strongly immune to disturbance, and, thus, become a widely used type. Besides, the Temporal Speckle Pattern Interferometry (TSPI) has been recognized as a useful tool to retrieve phase information to realize quantitative measurement.In this paper, with the combination of the DSSPI and the TSPI, a measuring system is built. The experiment of the measurement of the displacement-derivative and the non-contact testing of defect are conducted, respectively. Preliminary experimental results are obtained.The main work of this paper is as follows:(1) A DSSPI system based on the Wollaston prism is built. The phase information is extracted by the TSPI instead of the widely-used phase-shifting devices in traditional DSSPI systems. Real-time measurement of the displacement-derivatives is realized.(2) Key factors such as the shearing distance and the polarization state are analyzed to better the fringe patterns. Experiments are conducted accordingly and fringe patterns of high quality are acquired.(3) Algorithms to retrieve phase information are compiled based on the Fourier Transformation and the Wavelet Transformation, respectively. With the phase-unwrapping program, the displacement-derivatives are obtained. The theoretical results are provided with the simulation of the Finite Element Method (FEM). The comparison of the experimental and simulation results shows that quantitative measurement of displacement-derivative is realized.(4) A non-destructive test is conducted with the system, and the location of inside defect of the material is identified. |
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