Year

2005

Degree Name

Doctor of Philosophy

Department

Faculty of Engineering

Abstract

Mask-rotating speckle metrology for investigating low-speed dynamic problems has been discussed in detail in this thesis. All the dynamic information for the duration of exposure can be recorded onto one photographic plate and can be continuously reconstructed by the whole-field filtering. The dynamic thermal, flexural and residual deformations, as well as the dynamic out-of-plane displacements, of continuously deformed objects have been successfully measured by using the method proposed in this thesis. The proposed method has also been successfully used for measuring the dynamic slopes of a continuously deformed object. The influence of displacements on slope fringe formation in speckle aperture-shearing metrology has been systematically discussed in this thesis. It has been shown that the in-plane displacement, aperture orientation and shearing direction have a significant influence on slope fringe formation in photographic speckle aperture-shearing metrology. It has also been shown that the in-plane displacement and object-to-wedge distance have an important influence on slope fringe formation in digital speckle aperture-shearing metrology and that the influence is increased with an increase of the in-plane displacement and with a decrease of the object-to-wedge distance. Speckle aperture-shearing metrology, including digital speckle aperture-shearing metrology, for obtaining pure curvature and twist fringes has been studied in this thesis. The slope fringes influencing the contrast of curvature and twist fringes can be completely removed from the patterns of curvature and twist fringes and thus the patterns of pure curvature and twist fringes with high contrast can be obtained. The influence of displacements and strains on pure curvature and twist fringes in speckle aperture-shearing metrology has also been discussed. It has been shown that the in-plane displacements have no direct influence on fringe formation and that the in-plane strains have an important influence on fringe formation. Partially coherent speckle metrology, as well as the factors influencing the quality of speckle fringes, is investigated. It has been successfully used for measurement of slopes. In this thesis, the phase-shifting technique has also been successfully combined with conventional digital speckle aperture-shearing metrology to quantitatively evaluate slopes and strains and applied in digital speckle metrology to determine residual deformations. Volume grating digital speckle metrology has been proposed for measuring the out-of-plane displacement in this thesis. It can be employed to quantitatively evaluate the out-of-plane displacement of deformed objects when combined with the carrier and phase-shifting techniques. It can also be employed for measuring the amplitude distribution of vibrating objects, in which a Bessel fringe pattern with unit contrast can be obtained.

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