基于光纤端面超表面的高数值孔径抗模间色散多模光纤高分辨率快速成像技术研究

In this project, we will theoretically and experimentally study the technology of high-resolution, real-time imaging based on multimode fiber and meta-surface. 1) A meta-lens is designed to increase the numerical aperture (NA) of multimode fiber. To minimize the sampling density of the meta-lens, a deep learning method is used to optimize the phase profile of the meta-lens. And a multimode fiber with high NA is obtained by fabricating the meta-lens in the fiber tip. 2) Adaptive optics method is introduced to measure the mode dispersion of multimode fiber. To make the multimode fiber image clearly, a meta-surface is designed to compensate the mode dispersion of multimode fiber. The meta-surface is also fabricated on the fiber end to miniaturize the fiber imaging system. 3) A set of fiber end processing technology is developed, which extends the application of meta-surface. 4) A quantitative method is proposed to evaluate the quality of multimode fiber imaging. The parameters, such as focus length, modulation transfer function (MTF), point spread function (PSF), are measured and optimized to make the reconstructed image more clearly using multimode optical fiber imaging systems. Finally, with the implementation of this project, the new physics of multimode fiber imaging are revealed. With the help of meta-surface, we pave the way to achieve high-resolution, real-time, miniaturized multimode fiber endoscope.

本项目拟从物理机制和实验探索两方面入手，围绕多模光纤成像技术，结合超表面结构，实现多模光纤高分辨率快速成像。拟通过深度学习方法，优化超透镜的相位分布，在光纤端面制备高数值孔径超透镜，提高多模光纤的数值孔径。拟研究补偿多模光纤模间色散的方法，通过自适应光学方法测量多模光纤模间色散的补偿相位分布，在光纤端面设计并制备超表面结构实现补偿相位分布，补偿多模光纤的模间色散，实现多模光纤无外部光学元件情况下的高分辨率快速成像。拟发展一套光纤端面超表面结构制备工艺流程，扩展超表面结构的应用范围，探索端面修饰的多模光纤应用前景，为多模光纤成像技术提供技术支撑。拟建立多模光纤系统成像质量的定量评价标准，为优化多模光纤成像系统提供新思路。通过本项目的实施，揭示多模光纤成像的新物理、新规律以及新应用，结合超表面结构，发展多模光纤高分辨率快速成像技术，为高分辨率、实时、微型化内窥镜技术奠定技术基础。

超表面能够独立调控光场空间分布上各点的振幅、相位以及偏振等，能够实现多种功能的光学元件。超透镜具有紧凑、轻便等特点，能够应用众多应用场景。本项目主要研究超表面对光场的调控行为，设计制备了高数值孔径超透镜，并将其集成在光纤端面，实现光纤高数值孔径聚焦，同时发展了基于真实场景的快速全息三维成像算法。本项目按照研究计划，基本完成了项目的研究内容，主要包括：1）利用氮化硅制备了偏振不敏感、接近衍射极限、高效的超透镜阵列，实现了宽带消色差的三维集成成像；2）结合面编码三维全息算法，利用Kinect发展了一套获取真实场景三维信息并用于全息三维成像的技术；3）利用紫外曝光固化等技术，装备光纤端面超透镜，实现对光纤的高数值孔径聚焦。本项目的研究成果主要围绕超透镜成像技术，将超透镜应用于光纤成像领域，丰富了超透镜的研究内容，对内窥镜的集成化、轻便化提供新途径、新思路。..项目执行期间，标注资助的研究论文基本达到预期目标，发表SCI论文2篇，授权专利1项。