The Research Of Electronic Speckle Pattern Interferometry Technology And Fringe Pattern Information Extraction

Electronic Speckle Pattern Interferometry technology(ESPI)is a modern optical measurement technology which combines laser technology, video technology, computer technology, image processing technology, speckle interferometry technology. It has the merits of whole field, non-contact, high precision, so it is widely used optical rough surface deformation and displacement measurement, comparatively regarded in Nondestructive Testing, gradually developed in different application fields.This master's thesis studies the speckle interferometry and fringe information extraction, where information extraction for speckle fringes is the important step of optical measurements using of ESPI.First we introduced speckle interferometry technology development and application profiles, and then introduced the principle of speckle interferometry, fringe pattern generation mode, and disposal methods, made analysis and comparison of three fringe pattern generation mode and using correlation mode to generate fringe pattern of non-multiplicative noise. We study filtering techniques of fringes, and make comparison of fringes' filtering effect with different noise filtering algorithm for subsequent information extraction. We studied fringe center for the extraction of phase, focused on fringe skeleton extraction, made comparison and analysis of different thining methods, we made an improvement of speed and accuracy combining the two thining methods, and used the improved thining method to obtain skeleton from single speckle fringe pattern of deformation measurement experiment, and recovered the phase of deformation with back propagation neural networks. We used the method of phase shifting to get wrapped phase map of the deformation, made comparison and analysis of phase unwrapping results with several typical unwrapping algorithm, and improved the accuracy of phase unwrapping with the introduction of quality map phase unwrapping method by identifying residual, and finally got the phase information of specimen deformation.With the effective extraction of speckle fringe information, we got the phase field of the deformation of the specimen, reflected the real deformation of the specimen, and then we obtained the displacement or deformation information, and improved the accuracy and automation of speckle interferometry measurement.