体等离子体结构光场照明实现超分辨率显微成像研究

Structured illumination microscopy has been widely employed to high-speed biomedical imaging related areas, but its spatial resolution is just the two times of the diffraction limit, and the imaging resolution could be improved largely by utilizing the structured illumination field with higher spatial frequency. In this project, we planned to investigate the bulk plasmon polaritons (BPP) structured illumination super resolution imaging mechanism based on hyperbolic metamaterials, and the expected imaging resolution may be improved by 5 times of the diffraction limit. The early works have been done to study the mechanism of propogation of electromagnetic wave in optical frequencies through hyperbolic metamaterials (HMM), and the factors which effect the optical spatial spectrum filtering characteristics. By further studying the mechanism of coupling and transmission of surface plasmon (SP) in HMM, construct the physical modal of BPP mode, and custom design the BPP illumination imaging structure. Study the multiple BPP modes interference method with tunable parameters. Fabricate the imaging device and set up the steady experimental platform for fluorescence microscopy, acquire a series of images containing the higher frequency spectrum of object. Build the anti-noise and anti-distortion image reconstruction algorithm, achieve the super resolution images from original image finally.

结构光场照明显微镜现已广泛应用于高速生物医学成像领域，但其空间分辨率仅是衍射极限的两倍，可通过采用更高空间频率的结构照明场来大幅提高成像分辨率。本项目拟开展基于双曲超材料的体离子体（BPP）结构照明实现超分辨率显微成像原理方法研究，预期将分辨率提高至5倍衍射极限左右。项目课题组前期已经开展了双曲超材料中光频电磁波的传输行为及影响其空间频谱滤波特性因素的研究。通过进一步研究双曲超材料中SP场的耦合传输机理，构建BPP模式物理模型，从而定制化设计BPP照明成像结构；构建参数可调的多重BPP模式干涉场实现方法；加工BPP照明成像器件并搭建稳健的荧光显微成像平台，获取一系列包含有物体更高空间频率信息的原始图像；设计抗噪声抗畸变的图像重建算法并利用该算法从原始图像中恢复物体的超分辨率图像。

结构光照明显微镜( Structured Illumination Microscopy，SIM) 通过结构化光场照明实现突破衍射极限的超分辨光学显微成像。SIM凭借其较低的激发光强、对荧光染料的非特异性需求以及快速的宽场成像优势已成为活细胞超分辨光学显微成像方面应用最多的技术，但是传统SIM的成像分辨率仅能达到衍射极限的两倍，难以满足生物医学研究对更高成像分辨率的迫切需求。本项目通过研究超衍射倏逝光场的激发调控原理，提出了三种基于超衍射倏逝光场的结构光照明超分辨显微成像方法，即基于双曲超构材料体等离激元、光子晶体Bloch表面波以及平面波导倏逝波导模式的超分辨显微成像方法。优化设计了相应的光学超构材料以及亚波长激发光栅用以产生高频结构照明光场，并实现其参数的灵活调控。在现有算法基础了构建了适用于超衍射结构光场照明显微成像的超分辨图像重构算法，并从目标物体衍射受限子图中恢复得到了超分辨率图像，验证了成像分辨率。搭建了基于空间光调制器（SLM）的超衍射结构光照明显微成像系统，可实现光束入射角、偏振方向以及相位差的灵活调节，并基于初步制备的超衍射结构光照明显微器件进行了显微成像实验尝试。相比于传统荧光显微镜，三种方法的成像分辨率可增强至相应荧光显微镜的2.70倍、2.78倍以及3.84倍，明显超过了常规SIM的成像分辨率。这些超分辨成像方法有望用于活体研究细胞膜上蛋白质和标记生物分子的分子动力学行为，从而助于理解某些关键的生命过程。