Study Of Linear Scanning Computed Laminography Imaging And Experimental System Design

X-ray computed laminography(CL)imaging,which mainly detects plate-like structural components,has become one of the hotspots in X-ray imaging research in recent years.Its characteristic is that X-ray penetrates the object only in the thickness direction of the plate part,and the hierarchical image of the object can be obtained by a specific image reconstruction algorithm.This method can be used for nondestructive testing of multi-layer printed circuit boards,new material boards,solar panels,biofossils,aircraft wings,etc.This paper studies a new CL imaging method and system with simple and practical structure,which has important theoretical and application value.In 2014,Professor Fenglin Liu of Chongqing University of China and Professor Ge Wang of Rensselaer Polytechnic Institute of the United States proposed a linear scanning CT imaging scheme,which uses the ray source and detector to scan around the detection object in reverse parallel to obtain projection data.Based on this theory,the research and experiment of linear scanning CL imaging method are proposed.The main research work of this paper is as follows:(1)Based on the theory of linear scanning CT,the linear scanning CL imaging method is studied.The composition and geometric model of linear scanning CL system are analyzed.The filtering back projection image reconstruction algorithm(FDK)and algebraic iterative reconstruction algorithm(SART)for linear scanning CL imaging are studied.(2)The overall function design of the linear scanning CL test system and the selection design of each subsystem are carried out.The structure design,external processing,assembly and debugging of the mechanical system have been completed.The hardware design,software design and installation debugging of the control system have been completed.The CL scanning acquisition program has been compiled and the system debugging has been carried out.(3)The simulation experiment is carried out on the platform of Matlab.The image reconstruction is carried out by using FDK and SART algorithms for different projection angles.The results show that the SART algorithm has good adaptability.Scanning experiments are carried out on the experimental platform,and printed circuit boards and chips are used as experimental detection objects.The results of image reconstruction prove the effectiveness of the method.In order to improve the quality of reconstructed image,an iterative image reconstruction algorithm based on total variation minimization(TV)optimization is introduced.The results show that the quality of reconstructed image is significantly improved.This paper studies the theory of linear scanning CL,designs and manufactures the experimental system,and carries out the scanning imaging experiment.The experimental results show that the linear scanning CL imaging method can be applied to the imaging detection of flat parts.