Research In Oriented Partial Differential Equation Filter Methods And Their Applications

Based on modern high technologies such as laser, video, electronics, image processing and holography,Electronic speckle pattern interferometry (ESPI) is a well-known technique for non-contact nondestructive measurement of optical coarse surface. With the advantages of high precision, high sensitivity, whole-field and real-time testing,it has been applied in measuring object vibration, displacement, deformation and some medical diagnosis. Analysis ESPI fringe patterns and ESPI phase patterns is one of the major ways we obtain the information about object. But the ESPI fringe patterns and phase patterns got from experiments have strong noises, for getting accurate information about the object from the ESPI fringe patterns and phase patterns, we should reduce the noises of the patterns. So finding a good filtering method is very important to the ESPI.Directivity is a very important characteristic of ESPI fringe patterns and phase patterns, and it plays a very important role in directing the filtering process. To the ESPI fringe patterns and phase patterns, always we could get better effects with partial differential equation (PDE) filter methods. According to ESPI patterns'directivity, we propose the oriented PDE filtering methods, and apply them in the ESPI fringe patterns and phase patterns. After comparing with the experimental results which are got from the related PDE filter methods, we find the new methods can improve the pattern quality effectively: (1) With the new methods, the close ESPI fringe features can be preserved well after being filtered to the ESPI fringe patterns; (2) With the new methods, the close phase fringes can be reduced noise as well as be preserved the phase jump after being filtered. The adoption of the filtering methods can make a good base for the following processing. The validity of these methods has been demonstrated.