3D Shape Measurement By Using Polarization Analysis And Phase Measuring Deflectometry

With the rapid development of information technology and industrial inspection,three-dimensional perception and depth measurement of objects have become the focus of attention.At present,most of the components in the 3C industry are specular highreflective materials and transparent material objects with similar specular reflection characteristics.For some components with metal film on the surface,the traditional three-dimensional inspection method is to spray materials on the surface of the object to reduce the impact of high reflection,but reduce to improve the detection accuracy;use the mechanical probe to touch the surface of the object,which is easy to damage the object to be tested.The three-dimensional imaging technology based on structured light is a non-destructive,high-precision surface detection method,in which the phase measuring deflectometry(PMD)based on fringe reflection has good detection results for objects with specular reflection characteristics,but this technology faces the inherent problem of measurement ambiguity error,which limits the measurement accuracy.Based on the above,this paper combines the phase polarization measurement technology with the surface 3D reconstruction method based on polarized light to build a set of phase deflection measurement experimental system based on polarized light illumination,aiming to solve the ambiguity error in PMD technology Problem,improve the reconstruction accuracy.This paper mainly includes the following research work:(1)Analyze and introduce several surface 3D reconstruction methods for mirrorlike or mirror-like objects,compare their advantages and disadvantages,choose phase deflection measurement technology and polarized light-based 3D reconstruction technology as 3D measurement methods for mirror-like objects.(2)The basic principles of phase deflection measurement technology are theoretically analyzed,including monocular camera calibration,structured light encoding method,phase extraction of deformed fringes,mathematical relationship between phase deflection and object gradient and height,and subsequent integral reconstruction algorithms.(3)The sources of ambiguity errors in the measurement of phase deflection are analyzed;the principle of the three-dimensional imaging method based on polarized light is analyzed and introduced.In order to solve the problem of ambiguity error in phase measurement deflection technology,based on fringe reflection,a surface depth calculation model with light incident plane triangle as a constraint condition is proposed:the zenith angle information of the object obtained by polarization analysis is introduced,And combined with light geometric constraints to obtain the surface roughness depth distribution of the object,which is used to improve the calculation accuracy of the object gradient.(4)The phase unwrapping method based on Gray code decoding is used to extract the absolute phase distribution corresponding to the reflection fringe;two reconstruction algorithms based on the southwell model are simulated and analyzed;the LCD display pose calculation method based on the plane mirror is used to complete the system calibration and integration The conversion matrix between different coordinate systems in the experimental system was obtained;in the polarization PMD experimental system built,the concave spherical mirror and the transparent plastic cover of the mobile phone were used as the detection object to carry out the traditional PMD method and the polarization PMD method experiment.It was verified that the three-dimensional shape of the object was restored.