基于超表面的多光谱成像系统设计

超表面是一种人工制造的亚波长结构阵列平面，重量轻，易集成，可实现多种功能，被广泛应用于诸多领域。传统光谱成像系统依赖于色散元件及光程累积相位差实现不同波长的色散与聚焦，无法满足系统集成化需求。不同于传统光学元件依赖电磁波在介质中传播累积相位差，超表面依靠界面相位变化来进行相位调控，可实现十分轻薄的光学系统。研究传输相位型超表面，使用时域有限差分算法(FDTD算法)优化单元结构。将超表面引入光谱成像系统中，通过优化亚波长结构尺寸，进行结构排布，开展超表面光谱成像系统研究，实现多波长色散与聚焦独立调控。利用该方法，扫描不同单元结构参数对相位的影响，依照聚焦的相位分布针对不同波长设计对应的位相分布，仿真实现了一个波段范围为510～720 nm,焦距为2 mm,谱段数为八个的超表面多光谱成像系统。通过电磁仿真软件FDTD solutions和数据处理软件计算全模结构电场的远场分布，并分析了系统的成像性能。相比于传统光栅或棱镜分光结构，超表面光谱成像系统可有效减小系统体积，其超轻、超薄、便携特点解决了现有光谱成像系统的应用局限性，为小型化、轻量化光谱成像系统的研制提供了一种新的解决方案。

Design of Imaging Spectrometer Based on Metasurface

As an artificially manufactured sub-wavelength structure array plane, metasurface is widely used in many fields because of its light-weight, easy integration, and realization of multiple functions. Traditional spectral imaging systems rely on dispersive components and cumulative phase differences in the optical path to achieve dispersion and focusing of different wavelengths, which cannot meet system integration needs. Unlike traditional optical components relying on the transmission phase accumulated by electromagnetic waves propagating in the medium, the metasurfacerelies on the interface phase mutation for phase control, so a very thin and light optical system can be realized. In this paper, the transmission phase metasurface is studied. The finite difference time domain algorithm (FDTD algorithm) is used to optimize the cell structure. Introducing the metasurface into the spectral imaging systems, and the research on the metasurface spectral imaging system is carried out by optimizing the size, and structure arrangement of the sub-wavelength structure to realize the independent regulation of multi-wavelength dispersion and to focus. Using this method, scanning the influence of different structure on the phase,according to the phase distribution of the hyperbolic plane lens, several different focusing hyperlenses are designed for different wavelengths, achieving ametasurface multispectral imaging system with eight spectral segments in the visible band 510~710 nm. Electromagnetic and optical simulation software(FDTD solutions), the data processing software is used to analyze the far-field electric field intensity data to obtain spectral data of different wavelengths. Metasurfaces provide a new way for spectral imaging technology and have great application potential in miniaturized spectral remote sensing fields such as aerospace. Compared with traditional grating or prism spectroscopy structures, metasurface spectacle imaging systems can effectively reduce the system’s volume. Their ultra-light, ultra-thin, and portable characteristics solve the limitations of existing spectroscopy imaging systems and provide a theoretical basis for developing miniaturized and lightweight spectroscopy systems.