基于超表面的相位成像技术进展(特邀)

Advances in Phase Imaging Based on Metasurfaces(Invited)

相位是光场信息的重要组成部分。在光学显微成像领域,大部分生物细胞对光的吸收较弱,传统的亮场显微无法准确地表征细胞的结构特征,因此相位成像成为非标记细胞观测的重要方法。经典的相衬显微镜基于干涉成像原理,通常需要大块的折射棱镜或者复杂的成像系统,因而系统臃肿,易受环境扰动。超表面是一种特征尺寸在纳米或微米量级的光学元件,具有强大的光场调控能力,超表面集成在显微系统中可以实现方向无关、单摄式的定量相位成像,具有小型、轻便、易集成等优点。本综述回顾经典的相位成像技术原理,详细介绍基于剪切干涉、相位衬比和强度传输方程等3类超表面的相位成像技术原理,比较不同技术的优缺点和适用场景,指出超表面在相位成像领域面临的挑战,并对未来发展趋势进行展望。

Phase is an important component of optical field information.In optical microscopy imaging,most biological cells have weak light absorption.Consequently,traditional bright field microscopy cannot accurately characterize the structural characteristics of cells.Therefore,phase imaging has become an important method for non-labeled cell observations.The classic phase contrast microscope is based on the principle of interferometric imaging and typically requires large refractive prisms or complex imaging systems,resulting in a bulky system that is easily disturbed by the environment.Metasurfaces are optical elements with characteristic dimensions in the nanometer or micrometer scale and has strong light field regulation capability.The integration of metasurfaces in microscopic systems can achieve directionally independent single shot quantitative phase imaging,along with the advantages of having a small,lightweight,and easily integrated structure.This study reviews the principles of classic phase imaging techiques,and provides a detailed introduction to the principles of techniques based on three types of metasurfaces:shear interference,phase contrast,and transport of intensity equation.The advantages,disadvantages,and applicable scenarios of the different techniques are compared,and then the challenges faced by metasurfaces in the field of phase imaging are pointed out.Finally,future development trends are prospected.