Study On The Electronic Speckle Pattern Interferometry For Full-field Three-dimensional Deformation Measurement

Owing to their advantages,such as non-destructive,full-field,non-contact,and high-accuracy,speckle pattern interferometry(SPI)methods are widely used by academics and industries.With the advancement of technologies,the shapes and working conditions of components that constitute buildings,vehicles,ships,aircraft,etc.are being complicated.This requires the measurement/testing equipment possess greater performance,i.e.,higher accuracy and multi-dimensional measurements.The one-/ two-dimensional speckle pattern interferometers for the deformation of meso-scale objects have been fully developed.However,the SPI for three-dimensional deformation measurement and defect inspection have not been well developed yet.To meet the aforementioned requirements,the three-dimensional speckle pattern interferometer,which can simultaneously and independently determine three deformation components for objects to be tested,is studied here.The hardware of the interferometer is developed,and the image recording and processing software is programed.In addition,two de-noising algorithms for the noisy wrapped phase maps are proposed.This dissertation mainly includes the following aspects of the work concerning three-dimensional measurements:1.An electronic speckle pattern interferometer system is designed to determine three deformation components for objects to be tested.By optimizing optical configuration,only a piezoelectric ceramic(PZT)is used to achieve the phase-shifting for the three interferometers in the system.Because of the interferometers are independent from each other,the system is more robust to environment perturbation.The reliability and accuracy of the system is validated through experiments.2.A panoramic dual-directional shearography system,which can simultaneously determine outof-plane deformation derivatives in two directions and globally inspect the object to be tested,is proposed.A dual-wavelength shearographic method is presented to achieve dual-directional deformation gradients measurement.Using the auxiliary mirrors surrounding the object.By setting an auxiliary mirror around the object to be tested,the surface of the object is "unfolded" to allow global defect detection.The results of the experiments confirmed the utility of the system.3.Two denoising methods based on the features of wrapped phase maps are proposed.Using the orientations of the fringes of wrapped phase maps,an adaptive filtering method that can automatically adjust filter window size is presented.Considering the curvatures of the fringes of wrapped phase maps as the secondary control factor,another denoising algorithm is created.The experimental results demonstrate that the proposed method can effectively remove the noise of a varied fringe density pattern with non-uniform noise distribution and maintain a good orientation fidelity of the phase patterns,even for complicated fringe distributions.