高精度毫米波柱面孔径全息成像算法研究

Research on High Precision Millimeter Wave Cylindrical Aperture Holographic Imaging Algorithm

  • 摘要: 近年来,国际恐怖袭击事件时有发生,使得安全形势变得极为严峻,因此迫切需要引入新型的安全检查手段,防范和应对重大安全事故的发生。在此背景下,毫米波全息三维成像凭借其安全性、穿透性和高分辨率成像等优势,被广泛地应用在安检领域。由于人体安检需要在短时间内对目标进行精确的检测,具有实时性的特点,即需要在实时情况下快速做出判断和决策,因此对成像精度有着更高的要求。本文提出了一种高精度毫米波柱面孔径全息成像算法,给出了柱面孔径三维成像所需要满足的采样准则;首先,将成像区域划分为序列不同半径的成像柱面,依据成像精度和相位误差控制范围设置成像参考柱面,简化重复计算匹配滤波函数的过程;然后,将回波信号变换至三维波数域中,并与匹配滤波函数相乘;接着,沿距离向对匹配滤波的结果进行积分,聚焦获得相应半径柱面上目标的散射信息;最后,对不同半径柱面上的目标进行聚焦,获取目标的全部散射信息,进而完成对整个观测区域的三维图像重建。本文给出了参考面最佳分配策略和算法成像复杂度分析,并通过点目标仿真详细地分析了相位误差对成像质量的影响,并与现有的方法进行了比较,以及在同样的系统参数下对人体模特进行成像实验,仿真和实验的结果表明本文方法的有效性、精确性和正确性。

     

    Abstract: ‍ ‍In recent years, international terrorist attacks have occurred frequently, making the security situation extremely severe. Therefore, there is an urgent need to introduce new security screening methods to prevent and respond to major security incidents. Consequently, millimeter wave holographic three-dimensional (3D) imaging has been widely used in the security-screening field because of its security, penetration, and high-resolution imaging advantages. Because human body security screening requires accurate detection of targets within a short period, it has the characteristics of real-time, requiring quick judgments and decisions in real-time; therefore, it has higher requirements for imaging precision. In this paper, a high precision millimeter wave cylindrical aperture holographic imaging algorithm is proposed, and the sampling criteria for 3D imaging of cylindrical aperture are presented. First, the imaging region is divided into imaging cylindrical surfaces with different radii, and the imaging reference cylindrical surfaces are set according to the imaging accuracy and phase error control range to simplify the process of repeated calculation of the matching filter function. Then, the echo signal is transformed into the 3D wavenumber domain and multiplied with the matching filter function. Next, the results of matched filtering are integrated along the range direction, and the scattering information of the target on the corresponding radius cylindrical surface is obtained by focusing. Finally, the target on the cylindrical surface with a different radius is focused to obtain all the scattering information of the target, and then, the complete 3-D image reconstruction of the entire observation area is achieved. Moreover, the optimal allocation strategy of reference surface and the algorithm imaging complexity analysis are presented. The effect of phase error on imaging quality is analyzed in detail through point target simulation and compared with existing methods. Additionally, imaging experiments on human body models under the same system parameters are conducted. The simulation and experiment results show that the proposed method is effective, accurate, and correct.

     

/

返回文章
返回