基于准光技术的太赫兹孔径编码高分辨成像方法

Coded-aperture imaging is an imaging technique that obtains the scattering coefficient by modulating the electromagnetic-wave spatial distribution over the illuminated area and is now mainly studied in optical and microwave band. It has been paid less attention to in the terahertz band since it faces several challenges. For example, the imaging model and the coding method are too simple, the system link loss is very high, and the imaging of complex area targets is difficult to realize. Therefore, this project proposes a terahertz coded-aperture imaging technique with high resolution based on quasi-optical technology. Firstly, the mathematical model will be studied in depth and different types of coding methods will be comprehensively analyzed. Secondly, the quasi-optical technology will be introduced to optimize the imaging system and improve the signal to noise ratio. Also, the quasi-optical beam scanning technique and the sparse representation technique will be studied to reduce the imaging difficulty of complex area targets. Finally, three dimensional coded-aperture imaging simulation in near field will be performed to verify the feasibility of the proposed method. The proposed method has many significant advantages such as high resolution, high frame rate, all-time and all-weather, and the ability of forward looking while it doesn’t rely on the relative movement which is necessary for conventional SAR/ISAR. The corresponding results of this project can provide substantial technical supports and promote the significant development of radar imaging technology.

孔径编码成像技术通过改变目标区域电磁波空间幅相分布来获取目标散射系数分布。目前的研究主要集中光学与微波频段，太赫兹频段虽有所涉及，但多采用固定或机械编码方式，且面临成像模型过于简单、编码方案单一、系统损耗严重以及复杂面目标成像难以实现等诸多难题。对此，本项目提出基于准光技术的太赫兹孔径编码高分辨成像方法，首先对太赫兹孔径编码成像数学模型进行深入研究，并对不同编码方案展开全面探索；然后引入准光波束扫描技术对太赫兹波进行聚束与指向控制，降低链路损耗，提高信噪比，结合稀疏表征降低复杂面目标成像处理难度，实现高分辨成像；最后通过近场条件下三维孔径编码成像仿真对建立的模型与算法进行验证。本方案不依赖传统SAR/ISAR所必需的相对运动，具有高分辨、高帧频、全天时全天候、前视成像等诸多优势，研究成果将为雷达高分辨前视成像等重大应用需求提供技术支撑，与传统成像方式形成互补，促进雷达成像技术的跨越式发展。

本项目围绕末制导与近炸引信、战场侦察以及反恐安检等领域对高分辨、高帧频、前视成像的迫切需求，开展了基于准光技术的太赫兹孔径编码高分辨成像方法研究，重点突破了有相位与无相位太赫兹孔径编码成像的高精度数学建模、高分辨成像算法、系统方案设计等关键技术，取得的成果主要包括：建立了高分辨成像数学模型；对比研究了不同编码方案下的系统成像性能，可为孔径编码天线与系统优化设计提供指导；分别针对简单目标、复杂面目标以及三维目标，研究或提出了多种高分辨成像算法，实现了有相位和无相位条件下的目标精确重构；提出了一种孔径编码天线阵元相位误差补偿方法；提出了基于准光数字波束扫描技术的近距成像系统实现方案和基于准光透镜的作用距离延拓方案；提出了单通道接收与阵列探测两种无相位孔径编码成像系统实现方案；搭建了X波段的孔径编码成像系统并开展了成像实验，等效验证了所提成像模型的准确性和成像算法的有效性。以项目研究成果为基础，共发表论文24篇，其中SCI检索16篇，EI检索1篇，中文核心7篇，授权专利10项，受理待批2项，出版学术专著1部。