Experimental Study Of Speckle Pattern Interferometry Technique And Application Of Non-destructive Testing

Speckle testing technology is a full-field, high sensitivity and non-contact optical measurement mechanics method to measure the displacement and the strain, mainly contains electronic speckle pattern interferometry (ESPI),the digital speckle correlation methods (DSCM) and the temporal speckle pattern interferometry (TSPI), in recent years it has been developed widely, and its application domain continues to expand. On the basis of present research current situation, experimental researches were carried out on three aspects: in-plane displacement measurement speckle-shearing nondestructive testing and de-noising of wavelet analysis in this article.First, experimental study of the in-plane displacement measurement using ESPI is carried out. Based on the phase-shifting technology of the four-step phase shift, the in-plane displacement of the aluminum plate slightly rotated was measured, and also the three-point bending test was performed on marble to measure the surface displacement, in comparison with the results of FEM and the result is satisfied, the study result provides a new research ideas and methods for mechanical property study of the Stone. Second, experimental study of speckle-shearing interferometry is applied. The change of fringes of speckle-shearing interferometry is obtained; and then the speckle-shearing interferometry experiments is applied to wood with surface defect, finding that the change of shearing value has some impact on speckle-shearing interferometry; At the same time, this paper uses the speckle-shearing interferometry to detect hidden defects in wood, in order to apply speckle-shearing nondestructive testing to fault detection of the wood, and the result is much better by joining phase-shifting technology in the experiment. Finally, de-noising treatment using wavelet analysis on the map of speckle test is carried out. Using different wavelet functions and different parameters deals with the noise of map; the paper deals with the speckle-shearing phase shift maps by wavelet analysis de-noising method, then compare the phase map from these with unsettled phase map, found that wavelet analysis method is satisfying, this proved the method of wavelet analysis can be applied to the speckle-shearing interferometry technology.Based on the experimental study in this paper, ESPI technology can be applied to test the mechanical property of stone, also can be applied to the non-destructive testing of wood, and the processing of the map using wavelet analysis method can obtain satisfactory results in speckle interferometry technology.