Based On Fringe Projection And Stripe Three-dimensional Topography Measurement Of Reflection

Fringe projection profilometry and fringe reflection profilometry are two importantnon-coherent optical3D sensing techniques for the measurement of diffuse and specularobjects, respectively. They have always been the focus of optical measurementtechnology because of the merits of non-contact, high speed and high accuracy.Phase analysis is the important and difficult part of these techniques. Firstly, thisdissertation investigates the phase analysis techniques, including typical phaseevaluation algorithms, phase shifting calibration techniques and phase unwrappingmethods. For the first time the interframe intensity correlation (IIC) matrix method,oriented from phase shifting calibration techniques, is introduced into characterizationof a LiNbO3Electro-optic Modulator and the reliability and flexibility of this strategy isdemonstrated by experimental results. Accurate phase unwrapping of objects havingspatially isolated surfaces is one of the most challenging problems in fringe projectionprofilometry. A colorful composite grating based on point array projection is describedin the dissertation. Furthermore, a novel phase unwrapping method based on reliabilityand digital point array has been proposed. Demonstrations of computer simulation andexperiments show validity of this strategy for unambiguous phase unwrapping ofspatially discontinued objects.Amounts of well developed techniques for3D measurement of diffuse objects arenot applicable to specular objects with high reflectivity. Limitations of conventionaltechniques for specular objects make it difficult to investigate topography of free formsurfaces fast and accurately.3D shape reconstruction algorithms, system error andanalysis method for large dynamic data of fringe reflection profilometry have beenresearched in the dissertation by simulation and experiments. The measured radius of astandard convex spherical mirror is15.818m and the nominal radius is15.360m. Bybandpass filtering, topography of cell phone cases has been investigated under thelateral resolution of300~1000μm and1000~3000μm for orange skin effect andmanufacturing defects, respectively. And sub-micron scratches on the lacquer surfaceare detected. Reference phase of carrier fringe has been removed by measuring an extra reference plane. Shape reconstruction error caused by position deviation of referenceplane has also been discussed with actual experiments. Distortion of reference phase ofcarrier fringe in non-telecentric system has been investigated by theoretical derivationand computer simulation. Appropriate carrier fringe removal technique can helpeliminating the effect of nonlinear phase distortion. For the first time, accuracy of theanalytical model for planar like specular surface is investigated in the dissertation bycomputer simulation. The results show a high accuracy of this model for themeasurement of planar like specular surface.