Research On Near-field Millimeter Wave 3D Holographic Imaging Algorithm

In recent years,the threat of international and domestic terrorism has increased dramatically.In order to protect public safety,security inspections in public places such as airports,subways,customs,and other major traffic hubs and large gatherings are essential links.It also puts forward higher requirements for its accuracy and timeliness.Hand-held metal detectors,X-ray security inspection machines and other traditional security inspection methods cannot meet the needs of human security inspections due to their respective limitations,so there is an urgent need for more efficient and safe security inspection methods.The millimeter wave is located between the microwave and the far infrared wave,and has the characteristics of both,especially the two advantages of not having the characteristics of ionizing radiation and a certain degree of penetration,making millimeter wave imaging technology in the detection and prohibition of targets Items inspection and other security precautions are becoming more and more widely used,and are also of great significance for responding to the current terrorist crisis.In this paper,with near-field target detection as the background,the active millimeter-wave stepping frequency pulse signal short-range plane scanning imaging algorithm is studied,and the focus is on the research of a high-resolution 3D millimeter wave algorithm with good imaging precision and short imaging time The main research contents are as follows:Firstly,the basic theoretical knowledge of near-field millimeter wave imaging is introduced,and the traditional phase compensation algorithm in active millimeter wave imaging is analyzed in detail,including the algorithm principles and processes of 2D coronal imaging,cross-sectional imaging,and 3D imaging.The spectral transformation process of 2D imaging is analyzed,and the internal relationship between 2D imaging and 3D imaging is pointed out,and the advantage of 3D imaging is more suitable for observing the details of the target.Secondly,under the near-field conditions,in the traditional wavenumber domain phase compensation algorithm,the phase compensation factor of the fixed compensation distance and the phase error due to Stolt approximate interpolation are improved,and an imaging algorithm based on iterative phase compensation is proposed.And reconstruct imaging of point targets,and analyze in detail the imaging effect of the improved algorithm relative to the traditional wavenumber domain phase compensation algorithm under close range conditions.Its focusing performance is greatly improved,ensuring the accuracy requirements of security imaging.Finally,for the problems of large data volume and long running time of the traditional wavenumber domain phase compensation algorithm,compressed sensing technology is applied to near-field imaging to improve imaging efficiency.Focus on the reconstruction algorithm.On the basis of the sparse prior characteristics of the scene,the down-sampling scheme is used for near-field imaging,and the imaging experiments are performed on the point target and the complex target model constructed by FEKO.The performance of the algorithm is analyzed in all aspects,and the practical engineering application value of the algorithm is verified.