光学薄膜广泛应用于光学仪器和测控技术中，充斥着我们生活的方方面面，使我们的生活更加丰富多彩。不同于常规的光学薄膜应用场景，本综述重点介绍如何将光学薄膜与光学显微成像结合起来。研究方案主要是：基于负载表面等离子体波的贵金属薄膜、具有光子带隙结构的介质多层薄膜，研制出应用于无标记显微探测的平面薄膜光子元件。得益于其平面结构特性与成熟的制作工艺，该类薄膜光子元件可兼容常规明场、宽场显微成像系统，可以作为被测样品的衬底或成像系统的插件。借助于薄膜与光波的近-远场相互作用特性，该器件可以调控系统的照明光场，如实现暗场照明、全内反射照明、边缘增强照明等。通过照明方式的改变，提升成像的对比度、探测灵敏度，进而发展出多模式、高灵敏度、高对比度、无标记光学显微成像与传感系统。为充分发挥该系统结构简单、宽场、高灵敏度、无标记成像的特点，将其应用于环境光子学领域，实现了真实大气环境中单个超细颗粒物吸湿增长过程的原位、实时、无损表征，有望为大气雾霾溯源与追因研究提供有力的科学支撑和技术工具。

Optical thin films are widely used in optical instruments and measurement and control technology, thereby affecting various aspects of our life and making it diverse and colorful. Unlike conventional applications of optical thin films, this review focuses on the combination of optical thin films with optical microscopy imaging techniques. The main research plan is to develop planar thin film photonic devices for unmarked microscopic detection based on noble metal thin films loaded with surface plasmon waves and dielectric multilayer thin films with photonic bandgap structures. Owing to its planar structure and mature manufacturing process, this type of photonic thin film element can be made compatible with conventional bright field and wide field microscopic imaging systems, which makes it an ideal substrate for a test sample or can be used as a plugin for the imaging system. Such devices can utilize the near-far field interaction characteristics of thin films and light waves to regulate the illumination field of the system for achieving dark field illumination, total internal reflection illumination, and edge enhanced illumination. The contrast and detection sensitivity of imaging can be improved by changing the lighting method, leading to the development of multimodal, unmarked optical microscopy imaging and sensing systems with high sensitivity and contrast. To utilize the characteristics of simple structure, wide field, high sensitivity, and unlabeled imaging of this system, it has been applied to the field of environmental photonics for in situ, real-time, and nondestructive investigation of the hygroscopic growth process of a single ultrafine particle in a real atmospheric environment. Thus, this imaging system is expected to provide strong scientific support and technical tools for tracing of and further research on atmospheric haze.