Target Image Reconstruction Method Based On Laser Reflected Tomography

Laser Reflection Tomography Imaging(LRT)is a multi-angle echo signal detection technology that reconstructs the target's two-dimensional contour image from the target's projection data to achieve high-precision imaging of the target.Compared with other long-distance detection methods,laser imaging has advantages such as high imaging resolution,strong anti-interference ability,and small device size.It has a good application in long-distance detection of space-sensitive targets,especially satellite-to-satellite reconnaissance.prospect.This thesis mainly studies the basic principles of laser reflection tomography(including CT imaging principle),experimental system design,tomographic modeling and simulation,and image quality improvement.mainly includes the following aspects:(1).A set of LRT experimental system was built,and the selected experimental equipment was selected and introduced according to the experimental needs.The imaging model of the target model was studied by the system,and the imaging capability of the experimental system was verified.(2).There are vacancies in the research of laser reflection tomography simulation system,and the theory and software are implemented.Aiming at the problem of large computational complexity when sub-rays and bins are successively intersected,a fast algorithm based on laser beam boundary surface is proposed to improve the computational efficiency.Based on the spatio-temporal distribution characteristics of the lidar signal,the response function of the detection target to the signal is derived,and the action process model of the two is established.Based on the above key technologies,a target reconstruction simulation system based on laser reflection tomography is constructed.(3).Aiming at the problem that the rotation center deviation caused by the translation and the jitter of the target in the laser reflection tomography process leads to the formation of artifacts caused by the reconstructed image misalignment,an improved error reduction algorithm based on phase recovery technique is proposed.The method obtains the phase distribution by repeated iteration of light intensity,obtains the phase information of the reconstructed target,and improves the convergence of the algorithm by increasing the initial constraints and the constraints of the spatial domain and the frequency domain.The improved error reduction algorithm is used to effectively improve the convergence.The phase recovery method is easy to fall into the problem of local minimal solution,and an optimized reconstructed image is obtained.(4).In order to improve the image quality of laser reflection tomography target reconstruction,the current iterative reconstruction algorithm commonly used in CT imaging is introduced into the image of laser reflection tomography based on the current image reconstruction using laser back tomography.During the refactoring process.The performance characteristics of direct back projection,R-L and S-L filtered back projection and iterative reconstruction algorithm in image reconstruction are analyzed.The simulation and field experiments are carried out.The results show that the algebraic iterative reconstruction algorithm shows that compared with the back projection algorithm.Better reconstruction quality and stronger noise suppression performance.The innovations of this paper are as follows: 1.In the simulation process of reflective tomography system,a fast intersection point algorithm is proposed to solve the problem of the large amount of calculation of the intersection between the traditional ray and the panel,which improves the operation efficiency;2.To solve the problem of the deviation of projection data caused by the deviation of the rotation center,an error reduction calculation based on phase recovery is proposed.The method can effectively eliminate the artifacts of image reconstruction and greatly improve the quality of reconstructed image.3.On the basis of the filter back projection algorithm currently used in laser reflection tomography,the algebraic iteration reconstruction idea is introduced into the image reconstruction process of reflection tomography,which shows better reconstruction quality and noise suppression performance.