提高0.14 THz 雷达成像质量的新方法

目前，国际上多个科研小组相继开展了太赫兹逆散射成像方面的研究，已开发出多个太赫兹逆散射成像系统。其电磁散射模型及成像处理方式多借鉴于其他辐射源已经成熟的研究成果，例如:雷达目标散射中心模型及ISAR/SAR, Born/Rytov 近似模型及层析成像。但上述方法直接应用于太赫兹波段将导致成像质量的下降。首先简要介绍了太赫兹雷达成像和太赫兹层析成像之间的关系，在分析两种成像方法特点的基础上，重点研究了大孔径、大带宽条件下的太赫兹逆散射成像，提出了一种基于Range-Doppler 算法的改进成像方法。最后，利用该方法对中物院研制的0.14 THz 雷达样机实验数据进行成像，并给出了典型目标的成像结果，验证了新成像方法的有效性。

Method for improving quality of 0.14 THz radar imaging

Terahertz (THz) frequency range provides information which are generally absent in microwave and optical images, so there are unique advantages with THz imaging for applications, both in science and beyond, such as military, security and safety screening, biological and medical analysis, non-contact materials testing, etc. However, compared with visible light, X-ray, infrared, laser, ultrasonic, etc, THz imaging is the latest development in the imaging field. Moreover, the terahertz electromagnetic scattering model and terahertz inverse scattering imaging method are mostly from well-studied fields: the Geometrical Theory of Diffraction (GTD) and Inverse Synthesis Aperture Radar (ISAR), Born/Rytov Approximation and Computer Tomography (CT), for example. Recent studies show that the mechanism of THz inverse scattering imaging cannot be accurately described by radar or tomography respectively. It may be said that there is a terahertz gap in inverse scattering imaging. In this paper, the relationship between radar imaging and tomography are briefly presented. The radar images have a response in which a few bright points dominate the image, because of isotropic point scattering mechanism. In contrast, tomography contains significant diffuse scattering components, providing fill to the images. In order to get more of a diffuse-like image that is more readily recognized and interpreted by humans, the improved method based on Range-Doppler(RD) algorithm is investigated. Finally, the 0.14 THz radar initial results are presented.