Based On High-magnification Telecentric Objectives High-precision Fringe Projection 3D Reconstruction Technology

With the intelligent upgrading of the core industries of modern industrial systems,non-contact optical three-dimensional measurement technology has received popular attention from industry and academia.fringe projection structured light technology which has the advantages of non-contact measurement,high measurement accuracy,fast measurement speed,and low system cost,is one of the most promising technologies for industrialization among many three-dimensional measurement technologies.Currently,the fringe projection three-dimensional measurement technology in China is mainly concentrated in the accuracy range of millimeter scale,which is difficult to meet the further requirements of modern manufacturing industry towards intelligent manufacturing.Starting with the principle of optical threedimensional imaging technology,this paper first configures a structured light prototype system based on conventional projection equipment and cameras;Secondly,based on the experimental data obtained by the system,the hardware and algorithm factors that affect the reconstruction accuracy are analyzed;Finally,a high-precision fringe projection system based on a high-power telecentric objective lens was built.The specific content is as follows:(1)Based on the structured light prototype system,systematic research and algorithm implementation were conducted on the calibration,pattern encoding,pattern decoding,and phase unwrapping algorithms of the structured light system.The performance of the spatial phase unwrapping algorithm and the temporal phase unwrapping algorithm were compared Horizontally through experimental data.(2)Starting with the optical imaging models of cameras and projectors,and based on the calibration experiments and data analysis of existing structured light system calibration algorithms,an improved phase depth mapping algorithm is proposed,which effectively overcomes the limitations of low accuracy calibration plates and can further optimize the linear mapping relationship of phase depth data over the full field of view.(3)By analyzing the error incentives of the structured light prototype system,the hardware selection of a high-precision fringe projection system is determined.The error analysis of the system’s discrete imaging,overexposure imaging,defocus imaging,and nonlinear response imaging is performed.The above errors are compensated and corrected using controlled variable experimental methods,improving the flatness of the absolute phase distribution.(4)A high-precision fringe projection system was built using a designed firmware fixture.With a single coin as the target to be tested,three-dimensional texture reconstruction at the high-precision was achieved while suppressing the specular reflection effect on its surface.Supported by the development of a software client,the efficiency of data collection was further improved.