基于超振荡现象的非浸入式散射超分辨成像研究

Scattering media have recently been shown to be capable of completely working as special optical elements in the applications of the multi-spectral imaging, three-dimensional imaging and holographic display. These breakthroughs have attracted much attention, and present an opposite viewpoint from the traditional understanding that scattering light is not beneficial for imaging and propagating. However, as the scattering imaging system is a diffraction-limited optical system, the resolution is suffering from the diffraction limit, and it is difficult to recover the sub-diffraction detail of an object non-invasively through a single-shot speckle. To overcome this obstacle, we plan to give a deep research into the optical super-oscillatory phenomenon in a scattering imaging system and develop the new far-field super-resolution method based on this phenomenon. We would like to construct various customized functional super-oscillatory elements based on the light modulation of the metasurface, which has the capability of tailoring light properties at subwavelength resolution. We will also design the recovery algorithm for the object through a single-shot speckle and build the mathematical and physical model of the super-resolution imaging. Moreover, we will carry out researches in the fabrication and characterization of the super-oscillatory element, and construction and performance analysis of the scattering imaging system. In this project, we make full use of the information from a single-shot speckle and realize the recovery of the super-resolution information. We expect the research can provide a new method and principle to enhance the resolution in scattering imaging and find applications in astronomical observation, biomedical and other fields.

近年来，散射介质作为一种特殊的光学元件，在多光谱成像、三维成像、全息显示等方面的应用，改变了散射光不利于成像和传播的传统认识，受到了科研人员的广泛关注。然而，由于散射成像系统属于衍射受限光学系统，其空间分辨率将受到衍射极限的限制，如何利用单帧散射光场，非浸入式地恢复比衍射极限更精细的目标，是散射成像方法亟待解决的重要科学问题。本项目拟针对此问题，研究散射成像系统光学超振荡现象及其实现远场超分辨成像的方法和途径；结合超构表面器件的相位、振幅调制机理，发展特定性能超振荡器件的设计方法；构建基于单帧散斑的图像逆向恢复算法及物面、像面之间超分辨成像的数理模型；完成相关器件的加工和表征及散射成像系统的搭建和性能分析。本项目旨在充分挖掘单帧散射光场信息，实现物体超分辨信息的恢复，为散射成像技术提供分辨率增强的全新原理和方法，推动其在天文观测、生物医学等领域的应用。

在实际光学成像过程中，我们不可避免地面临光散射问题，从而无法通过直接观测获得隐藏的目标信息。随着光散射理论和实验技术的发展，克服散射现象实现光学成像取得了一定的成果，但是无法恢复比衍射极限更精细的目标。本项目针对此问题，数值分析散射光学系统中光波的传输过程，以及不同波矢分量下，散射光场的变化规律，构建特定尺寸散斑所需的超振荡调制及其逆向设计方法；研究了不同类型微纳结构的光场调制特性，设计了多种相位型、复振幅型超振荡光场调制器件；针对单帧散斑，设计了合理的图像恢复算法提取物体的超分辨信息，完成了超振荡器件的加工和散射成像光路的搭建，实验上获得了0.8倍衍射极限的超分辨图像。最后，分析影响分辨率的因素，并提出增强分辨率的方法。基于本项目相关研究成果，申请人发表了多篇SCI论文和申请国家专利，并受邀在第十届国际先进光学制造与检测学术会议作特邀报告。相关研究结果将为散射光学系统超分辨信息的提取和恢复提供重要理论依据和方法指导。