| The phase-shifting projected fringe profilometry (PSPFP) technique is a powerful tool in the profile measurements of rough engineering surfaces.; Despite previous efforts, two important problems, uncertainties in phase-to-depth conversion and accuracy in object lateral geometry, have not been thoroughly studied in the literature. The main purpose of this dissertation is to tackle these problems with some new approaches.; Chapter 1 provides an overview of profile measurements. The objectives and organization of the thesis are also outlined. In chapter 2, some background information of the PSPFP technique including the measurement principles, basic features, and related techniques is briefly introduced.; Chapter 3 describes the experimental verification of the proposed absolute PSPFP technique. The main advantages of using digital sinusoidal grating are (1) high geometrical accuracy (<1 μm); (2) high contrast ratio; and (3) very low high order harmonic distortions. And, the high-quality diffusive flat with precisely controlled lateral correlation length, fabricated by VLSI process, also offers a good calibration standard. It is found that, by applying these two components to the calibration-based phase-shifting projected fringe profilometry, an absolute 3D surface profile measurement accuracy in the order of micron can be achieved.; Chapter 4 provides a theoretical treatment of the absolute PSPFP measurement. The mathematical formulations and basic requirements of the absolute PSPFP measurement and its supporting techniques are discussed in detail. By comparing the experimental results from this technique with the data from Zeiss Universal Precision Measuring Center (Model UPMC 550), it is found that the absolute measurement accuracy for a bowl size object (about 160 mm in diameter and 40 mm in depth) is about 10 μm. This experimental result proves that, indeed, this calibration-based phase-shifting measurement technique has a good enough accuracy for precise engineering surface (such as gear gauge surface) measurement.; Chapter 5 presents a unique image registration technique based on PSPFP and its application to the integration of segmented 3D profiles, measured by the highly accurate calibration-based phase-shifting projected fringe profilometry. The experimental results shown that, for a medium size bowl object which has been tested in Chapter 4 (e.g., 160 mm in diameter and 45 mm in depth), a good accuracy of 20 micron in transversal plane and 13 micron in depth for the integrated 3D profile can be achieved. (Abstract shortened by UMI.)... |
