借助亚波长微结构阵列的目标远场超分辨率电磁成像研究

How to effectively obtain the fine structure information in far-field, carried by the near-field evanescent wave of object, to achieve a super-resolution electromagnetic imaging is a research hotspot in detection and imaging field. It is also a challenging research topic. In this project, aided by the far-field super-resolution focusing properties of subwavelength microstructured array, the evanescent wave, carried the super-resolution information of object, is converted into the propagation wave by the mode coupling in near-field and radiated to far-field. Then, the key inverse technology is investigated to realize the super-resolution electromagnetic imaging. The investigations are including: (1) the research on mode dispersion characteristics, mode coupling mechanism, and controlling method in subwavelength microstructured array, and getting the quantitative design method for the array with compact, broadband, high efficient radiation performance, (2) establishing the high efficiency and accuracy electromagnetic imaging method for the complex object constructed by the subwavelength microstructured array and test object, (3) based on the above achievements, completing the experimental verification of object’s far-field super-resolution imaging aided by the subwavelength microstructured array. The investigation of this project can establish important theoretical and technological foundations for future developments of novel electromagnetic super-resolution imaging application systems.

如何在远场有效获取目标近场倏逝波所携带的精细结构信息来实现超分辨率电磁成像是探测与成像领域的研究热点，也是极富挑战的研究课题。本项目旨在借助亚波长微结构阵列的远场超分辨率聚焦特性，通过近场模式耦合的方式将携带目标超分辨率信息的倏逝波转换成传播波并辐射至远场，进而研究反演计算的关键技术实现超分辨率电磁成像，包括：（1）深入研究亚波长微结构阵列中的模式色散特性、耦合机理及调控方法，完成具有小型化宽带高效辐射特性的结构可量化设计；（2）建立亚波长微结构阵列与待测目标复合的远场超分辨率高效、高精度电磁成像方法；（3）有机集成上述成果，完成借助亚波长微结构阵列的目标远场超分辨率电磁成像原理性实验验证。项目研究将为发展新型电磁超分辨率成像应用系统奠定坚实的理论与技术基础。

本项目旨在以目标电磁探测与成像为背景，系统深入地研究亚波长微结构阵列及其与待测目标相互作用实现超分辨率远场成像的基础理论及关键技术。主要研究包括：（1）亚波长微结构阵列超分辨率聚焦理论研究及宽带高效辐射结构实现，项目首先以亚波长金属小球阵列为对象，研究了电磁波的超分辨机理，建立了亚波长微结构阵列与空间超分辨率的对应关系；在此基础上将光学领域基于隧穿效应的金属丝阵列、模式调制特性的光栅、表面等离子体效应的分形槽、立体透镜等结构引入到微波频段来实现超分辨率电磁成像，完成了模式转换机理、调控方法和阵列结构的可量化设计研究，成功将目标近场超分辨率信息有效传播至远场接收设备。(2)借助亚波长微结构阵列完成了与待测目标复合情况下的远场超分辨率电磁成像方法研究。项目首先基于亚波长微结构阵列的结构特征，建立了含亚波长微结构阵列的复合目标高效高精度可计算建模方法，为电磁散射数据的获取奠定了基础；然后基于模式耦合理论，借助多种平面亚波长微结构金属丝阵列实现了扩展目标的远场超分辨率电磁成像；最后基于局域模谐振理论完成了目标的高效、高分辨率电磁成像。项目实现了最高1/25波长的分辨率。（3）对借助亚波长微结构阵列的目标超分辨率电磁成像原理性实验，项目分别基于时域和频域测试平台完成了两套试验系统的搭建、测试和验证。