| With the wide application of precision optical components,more and more attention is paid to the detection and identification of nano-level surface defects.The repair techniques corresponding to different surface defects are very different.Therefore,the classification of surface defects will affect their subsequent operations.The traditional surface defect detection and recognition scheme mainly based on machine vision is limited to collecting the light intensity information of the target,and the development of polarization detection technology has opened up a new way for the surface defect recognition technology.This paper mainly uses polarization scattering theory to study the principles and methods of two different types of surface defect identification,and designs a set of classification identification system.First,the principle of bidirectional reflection distribution function and related basic knowledge of polarization measurement are introduced to understand the polarization phenomenon,polarization state and description method of light.Then the polarization information is added on the basis of bidirectional reflection distribution function to obtain the coordinates of polarization bidirectional reflection distribution function The definition and matrix description provide a theoretical basis for the study of polarization scattering characteristics of standard components and components with defects.Then,based on the different physical characteristics of the standard component and the two surface defects,the theoretical analysis of the polarization information of scattered light can be used as the discrimination standard from the essence.Then,under certain model conditions,the existence forms of particulate dust particles above the surface and bubble particles below the surface are discussed respectively,and their polarization scattering mathematical models are established according to the classic electromagnetic theory,Fresnel catadioptric theory and Rayleigh approximation.Subsequently,the two mathematical models of surface scattering polarization scattering are analyzed in depth.First,the model established in this paper is compared with the model established by foreign scholar Thomas A Germer to verify the correctness of the model.It is proposed that the BRDFpp term in the mathematical model can be used to distinguish the two surface defects with the change trend of the scattering azimuth.After analyzing the effects of different environments and different detection conditions on the polarization scattering model of the two surface defects,the results are as follows: the position of the particles below the surface does not affect the final detection results;different component surface materials,defect particle types and defect particle sizes are used for measurement The results have a certain impact,but will not affect the overall trend conclusion;for the experimental design of the identification scheme,the size of the incident light wavelength can be selected according to other factors such as the price and stability of the incident light source in the visible light range;the experiment recommends that the incident zenith angle is 45°,Observation conditions of the scattering zenith angle of 45°;and some of the conclusions obtained during the analysis can also verify the correctness of the model.This provides a theoretical reference for the design of the surface defect detection and recognition system of high-precision optical components.Finally,a set of two surface defect identification systems was designed.Starting from the mathematical model and analysis of surface defect particle polarization scattering,the conclusions obtained from the simulation are used to formulate the best plan,design the experimental optical path diagram,select the experimental device and introduce the specific steps to provide the experimental theoretical basis for high-precision surface defect detection and identification in engineering. |
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