Research On Multi-spectral Defocusing 3D Projection Measurement Technique

With the development of science and technology,people have more and more urgent demand for the acquisition of three-dimensional spatial coordinate information of the objects.The demanding especially expressed at the field of vibration analysis and motion detection,and there is a great significance in the field of engineering.However the dynamic test has more strict requirements about the measurement speed ability.Fortunately,the digital defocusing fringe projection technology has the ultra-fast three-dimensional information measurement capabilities,therefore,this kinds of techniques provides a new way for dynamic measurement.The defocusing fringe projection measurement technique takes the binary fringe patterns as the object for study.The high frequency components of the binary fringe patterns are eliminated by lens defocusing,therefore,the binary fringe patterns shows strong sinusoidal structure,and this kinds of patterns is suitable for measurement.This kind of measurement method has been extensively studied for it's non-linear ability and ultra-fast ability.However,the study of the defocusing fringe projection technology only takes advantages of the single color channel,therefore,this kind of method did not takes fully use of the multi-dimensional information for measurement speed enhancement.Multi-spectral technology is the technology using different channels information for auxiliary information increasing,Combining this technology with the defocusing projection technology has the potential for further speed enhancement.However,multi-spectral technique often influenced by the channel crosstalk phenomenon and the fringe defocusing projection measurement has weak robustness and is susceptible to the ambient light.This paper proposes the corresponding solutions to realize multi-spectral defocusing projection measurement technology.The main work of the thesis is embodied in four aspects:(1)This thesis has found that the fringe projection profilometry measurement system has the direction-determined properties.According to the direction-determined properties of the fringe projection profilometry system,this thesis modified the existing unwrapping algorithm,and improved the robustness of the fringe projection profilometry system..(2)This thesis developed the Multi-code technology based on the Quantized phase-coding method.Multi-code technology has the ability to be applied in the defocusing projection measurement system without code distortion,and the technology also has the technical advantages of striped high frequency.Thus,the????????technology provides a method for high-frequency implementation of defocusing projection measurement techniques.(3)On the basis of Multi-code,the Area-determined Multi-code technology is proposed.Compared with the Multi-code technology,the unwrapping method has higher fringe frequency and therefore,higher robustness.(4)This thesis also build a multi-spectral defocusing 3D projection system platform and using this platform verified the validation of the multi-spectral defocusing 3D projection measurement technology.The core technology if the multi-spectral defocusing 3D projection technology is Area-determined Multi-code technology and the different color channels selection.The realization of multi-spectral defocusing projection measurement technology makes the fringe projection measurement system have the potential to improve the measurement speed and reduce the high-speed hardware cost.