应用于双光子成像的超表面透镜设计与制备

Miniature two-photon microscope plays an important role in neuron researching. But the conventionally used miniature objective cannot simultaneously achieve high numerical aperture and portable weight. This project propose using metalens as miniature objective to achieve high numerical aperture with ultra light weight. Firstly, simulation of light field regulating mechanism for nanodisk is carried out. When overlapping electric dipole and magnetic dipole scattering peak, nanodisk can realize maximum efficiency of regulation. Nanodisk can be used as light field regulating element, as 0-2π phase space can be realized when changing the radius of the nanodisk. According to the realized phase spectrum, full field doublet metalens is designed according to the geometric aberration correction. Finally, the scanning imaging property of the metalens is verified on a existing two-photon microscope. The project introduce metalens to two-photon microscope, and will set an usage example of metalens in microscopy.

微型双光子显微系统是神经元在体成像的重要工具，但是常规微型物镜无法在进步一提高数值孔径的同时获得更轻的装备重量。本项目将光场调控超表面引入双光子显微领域，有望在大数值孔径下获得近乎于零的物镜装备重量。项目首先开展圆盘微元相位调控机制的仿真研究。结果显示散射场中的电偶和磁偶极散射重合时，圆盘微元光场调控效率最高。改变圆盘半径时，散射相位图谱覆盖0-2π，满足二元光场调控器件的设计要求。依据获得的相位图谱，设计并加工基于全视场像差校正的两片式超表面透镜。最后将超表面透镜搭载入双光子显系统，以验证其扫描成像特性。项目在概念上将超表面透镜引入双光子成像领域，是超表面透镜应用在显微成像领域的研究范例。

本项目将近红外光场调控超表面引入双光子显微领域，以矩形纳米微元为相位调制器件，从相位调控机理、荧光收集效率等多个角度优化设计适用于双光子显微成像的超构表面透镜，并以常规的硅基半导体微纳加工工艺获得口径大于600μm的超构表面透镜。实验测试其光场聚焦和荧光收集特性显示，超构表面光学调控能力能够应用于显微成像。进一步构建以超构表面透镜为核心物镜的双光子成像系统并编写扫描成像控制程序，最终针对包括荧光小球、小鼠肾脏切片和U2OS细胞在内的多种荧光样品获得双光子二维和三维显微亚微米分辨图像，同时，超构表面的可见光宽谱透射特性，使得系统能够在多个荧光通道上获得共定位的特异性图像。项目在概念上将超表面透镜引入双光子成像领域，是超表面透镜应用在显微成像领域的研究范例。