紧聚焦光场的空间结构测量、调控和应用研究

The topic of this project is experimental study on optical tightly focused beam with multiple spatial light modulations. An accuracy measurement system for tightly focused beam will be designed and assembled. A setup for spatial light modulation with multiple adjustable parameters, including amplitude, phase, polarization etc, will be designed. Both instruments will be used to measure the traditional focus beams, develop new types of focus beams and real time control of focus beams. Minimal or special beams profiles will be self-searched with a self-adaptive algorithm and a servo control system. The probes of the measurement system will be fabricated by silicon wafer fragments with double knife-edges, which will extend the present knife-edge scanning method from 1-dimentional measurement into 2-dimentional. Hence the measurement for non axial symmetric focus beam will be realized. The setup for spatial light modulation will be combined with modulators, wave plates and optical masks. By uniting different devices, different parameters will be adjustable and the profiles of tightly focus beam will be studied. This is an experimental project combining with multiple high techniques, including electronics, computer control, photonic measurement, self-adaptive algorithm and optical-mechanical-electrical system. The expected outcome of this project will be applied for quantitative analysis of the confocal microscope, laser direct writing setup etc. Minimal or special beams will be applied for new type of optical tweezers and super resolution microscope. The results of this project will be good proofs for the focus theories, and the technique basis for further nano-photonics.

本项目拟实验研究调控光场的紧聚焦特性及其应用，开发可靠的紧聚焦光斑三维测量系统和多参量空间光调制（振幅、相位、偏振等）装置，以实现传统焦斑测量、新型焦斑开发和多样化焦斑实时可调。并结合自适应反馈控制算法和软件，尝试极小尺度光斑和特殊光斑自动寻找和逼近。本项目拟通过硅片破碎法制备双刀边探针，将现有刀边扫描法的一维测量发展至二维甚至三维，以满足非轴对称焦斑的测量需要。拟通过多个空间光调制器、波片和相位掩膜板的设计组合，将空间光调制的紧聚焦特性研究从柱对称矢量光场调制推广至多个参量的同时调制。本项目是集电子与计算机控制、光电测量、自适应算法优化和精密光机电系统等高新技术的综合实验技术。项目研究成果可应用于紧聚焦仪器装置的性能测试和定标，如共聚焦显微镜、激光直写仪等；也可应用于开发新型光学镊子，超分辨光学显微镜等。项目将为光场聚焦理论提供可靠的实验佐证，也为纳米光子学发展提供技术储备。

本项目拟实验研究调制光场的紧聚焦特性及其应用，开发可靠的紧聚焦光斑测量系统和多参量空间光调制（振幅、相位、偏振等）装置，以实现传统焦斑测量、新型焦斑开发和多样化焦斑实时可调。结合自适应反馈控制算法和软件，尝试极小尺度光斑和特殊光斑自动寻找的逼近。项目主要成果包括：1、发展了一种紧聚焦光斑的测量的方法，分辨率达10nm，用于定量描述矢量光场紧聚焦光斑的调控研究；2、获得了当前最小（在非高折射率环境下）的聚焦光斑0.0711λ2; 3、采用矢量衍射理论重新建立共焦系统的成像过程。得到了具有最高对称性的激发和探测点扩散函数，保证了系统不仅有1/6λ的分辨率（实验结果为1/5λ），而且有远优于近场扫描光学显微镜和普通共聚焦显微镜的成像质量。相关成果以“巧用点扩散函数实现高分辨远场光学显微镜”为题入选中国激光杂志社“2014中国光学重要成果”奖。