Three-dimensional Surface Reconstruction And Visual Measurement Based On Parallel Astigmatic Confocal Detection System

Owings to the advantages of high accuracy, high resolution and the uniqueability of axial tomography, the confocal technology is used in the fields ofmedicine, materials science, semiconductor proceeding, and precision industry andso on. In recent years, the parallel confocal technology attracts the attention ofscholars around the world. Extensive researches by applying this technology haveyielded results. This thesis roots in the project sponsored by the National NaturalScience Foundation of China. Based on three-dimensional coordinate informationcollected by the parallel astigmatic confocal detection system, the study uses thespline interpolation function to reconstruct the measured micro-structure surface,and to achieve the visual measurement for measured micro-structure. Through thestudy of the mathematical model of profiles measurement parameter, the softwareinteraction during the measurement process has been programmed and thevisualized measurement of the profile parameters of micro-structure has beenrealized. The research has made some useful attempts to promote the practicalapplication of the parallel confocal detection system in the precision machiningindustry and IC industry and to meet the requirements of precision profilemeasurement of the micro-structure.First of all, this paper introduces the principle, methods and steps of collectingthe3D coordinates data of the measured micro-structure based on the parallelastigmatic detection system. According to the data characteristics and theadaptability of the micro-structure surface, the cumulative chord length bi-cubicparameter spline function with the characters of convexity preserving, conformaland reconstruction of surface through the data is selected to reconstruct themeasured surface in order to meet high precision requirements. Through studyingthe influence of the reconstruction parameters and the characteristics ofmicro-structure surface on the reconstruction accuracy, it is proposed that thehigher subdivision rate is beneficial to improve the reconstruction precision, geometry characters of the measured micro-structure surface decides to thereconstruction precision. Second, based on the visualization of the reconstructedsurface, two kinds of pickup ways, including points pickup and elements pickup,are proposed to achieve the measurement of the profile parameters. The directpickup to the cumulative chord length cubic parameter spline surface points wasdesigned and has been realized, which avoids the errors between the triangularfacets and reconstructed surface, improves the pickup accuracy based on the spacesystem defined by the OpenGL. Third, with the VC++, MFC and OpenGL softwaredevelopment environment, the reconstruction and visualization of the measuredmicro-structure surface was finished, the profile parameters calculation model ofthe elements pickup was designed and the interaction during the measurementprocess was achieved, finally the visual measurement for micro-structure profileparameters was implemented.