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Three--dimensional mapping has many applications including robot navigation, medical diagnosis and industrial inspection. However, many applications remain unfilled due to the large size and complex nature of typical 3--D mapping systems. The use of fiber optics allows the miniaturization and simplification of many optical systems. This research used a fiber optic coupler to project a fringe pattern onto an object to be profiled. The two outputs fibers of the coupler were brought close together to form the pinholes of a Young's Double Pinhole Interferometer. This provides the advantages of this simple interferometer without the disadvantage of power loss by the customary method of spatially filtering a collimated laser beam with a pair of pinholes. The shape of the object is determined by analyzing the fringe pattern. The system developed has a resolution of 0.1mm and a measurement error less than 1.5\% of the object's depth. The use of fiber optics provides many advantages including: remote location of the laser source (which also means remote location of heat sources, a critical requirement for many applications); easy accommodation of several laser sources, including gas lasers and high--power, low--cost fiber pigtailed laser diodes; and variation of source wavelength without disturbing the pinholes. The principal advantages of this mapping system over existing methods are its small size, minimum number of critically aligned components, and remote location of the laser sources. / Ph. D.

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Phase-shifting projected fringe profilometry (PSPFP) is powerful for 3D profile measurements. Test and analysis for accuracy of PSPFP is presented. A novel scheme to identify the accuracy of evaluated phases is propsed as well. This test scheme can be applied to any kind of measurements which use fringe projection techniques.

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A novel accurate calibration-based phase-shifting projected fringe profilometry (Calibration-based PSPFP) for finding the absolute shape of objects is proposed. In addition to a tremendous savings in time, the benefits of using Calibration-based PSPFP also include greatly reduced environmental vulnerability. Since Calibration-based PSPFP employs a sinusoidal fringe pattern to perform the phase-shifting algorithm, the quality and accuracy of the sinusoidal fringe pattern becomes critical. To evaluate the performance of this measurement scheme and reduce the phase error caused by projected fringes, fabrication of various digital sinusoidal fringe patterns is necessary. Thus, we propose a method to fabricate various digital patterns. Application of a 2-D fringe pattern for Calibration-based PSPFP is proposed as well.

This paper proposes a miniature gauging system for objects inside a body cavity using the projected fringe profilometry (PSPFP) combined with the endoscope. The fringe pattern is formed by launching a reading bean into a diffraction element . The diffraction element can avoid the influence of projected aberrations by lens and largely reduce the size of projected system. This system has the following properrties: 1. It is a noon-contact, and full field measurement. Only one-shot measurement is needed. It is able to carry on the immediate gauging to the dynamic object. 2. Arrangement of the projected fringe is unique due to the procedure of specific coding. It is easy to revise the errors when undergo phase unwrapping. 3. The double projection scheme compensates the defects of one-shot measurements.

A projected fringe profilometry (PFP) is an optical measurements technology which is widely used at present in gauging the object's three dimensional appearance. PFP is frequently used in detecting the quality of products in the industry due to the specialty of non-contact type, the short retrieve time and low environmental effect. As a result of the development for many years, PFP treats in the gauging static state of the object's three dimensional appearance has had the extremely fine gauging efficiency and the precision in , however in the dynamic inspected object in the gauging , not yet was still mature. If could to develop a set of gauging way in the dynamic inspected object , the application would be more widespread. Taking PFP as the gauging principle, analyzing the changes between the dynamic treat measured object and the fringe. Using the simple mathematics to describe the interaction relations between the fringe and the inspected the object. Finally, reconstructed the inspected object' three dimensional appearance. May know biggest superiority by the experimental process, in the situation of without losing the information of fringe, PFP can reconstruct the inspected object' three dimensional appearance and do not need the motion condition information.

Thermal Barrier Coatings (TBCs), and plasma spray coatings in general, require critical control over the deposited thickness to achieve reliable coating performance. Currently, the plasma spray industry quantifies thickness by sampling the part before and after TBC deposition. Approximate thickness is thus inferred from previous runs. However, process variability can allow errors to propagate in this result that leads to wasted time and resources, and can ultimately lead to non-reliant coatings. To this end, an in situ optical fringe profilometer is developed that enables coating thickness measurements across a 2-dimensional surface. The initial profilometer concept is explored through requirements and trade studies, leading to a hardware and algorithm design family and prototype build to capture and compare real-world data to simulation and model predictions. This initial result shows a viable path-forward and the ability to achieve micrometer-scale depth resolution. Modifications and alterations to the in situ profilometer are then explored to improve the performance limits achievable. In specific, industrial spray coatings operate by dropping fine-grain media into a high pressure gas line aimed through a plasma torch to impart enough thermal and kinetic energy to stick to the part surface. This presents a challenging operational environment for an optical depth measurement sensor, working with a variable high-temperature blackbody stray light source; constant part rotation and plasma gun movement; and a non-isolated vibration environment. As such, the concept of the profilometer is further adapted specific to this end-purpose, by developing and reviewing both dual-fringe projection and plenoptic imaging. These techniques allow an improvement to both the system micro- and macroscopic depth retrieval limits, allowing a method to solve for an extended range of phase ambiguities and relax object focus requirements (respectively). The end result is a system concept and algorithm design that presents a feasible manner for automated in situ geometry and depth measurements in the plasma spray industry. The in situ fringe profilometer work described herein allows a flexible path to recover object depth information remotely, and is especially relevant for asymmetric and complex non-planar geometries, which are experiencing renewed interest with additive manufacturing processes and generally quite common to the thermal spray industry.

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