光学显微镜具有无损、样品友好、速度快等优点,一直是人类探索微观世界的主要手段。但是,由于受到衍射极限限制,长期以来,光学成像系统的分辨率最高仅能达到可见光半波长量级,逐渐成为科学技术发展的桎梏。对于荧光标记样品,可以利用荧光超分辨光学显微成像技术打破光学衍射极限,填补电子显微镜(约为1 nm)和普通可见光学显微镜(200~250 nm)之间的空缺。然而,对于大多数样品特别是非荧光标记样品而言,利用现有技术进行超分辨成像依旧存在相当难度。近年来,科研人员从合成孔径成像原理出发,提出了光学移频超分辨成像方法,开辟了光学超分辨成像的新思路。光学移频超分辨成像不拘泥于荧光非线性效应的限制,兼具非荧光标记样品以及荧光标记样品的超分辨成像能力,而且因为其成像速度快、样品普适性高和光毒性低等优点,在材料学、生物学和医学等领域展现了很好的应用前景。本文从原理和方法上详细综述了移频超分辨光学显微成像技术,并对未来发展方向进行了评述和展望。

Optical microscopy is non-invasive, sample-friendly, and fast, rendering itself the major approach for human beings to explore the microcosmic world. However, the diffraction limit has hindered the resolution of all optical imaging systems to approximately half the wavelength of visible light for over a century, until it was fundamentally broken by the development of super-resolution optical fluorescence microscopy. This technology bridges the gap between the electron microscopes (1 nm) and the ordinary optical microscopes (200 nm to 250 nm), but it is essentially useless for most samples, especially those non-fluorescent-labeled. In recent years, inspired by the synthetic aperture imaging, we have developed the optical super-resolution imaging based on frequency shift, providing a new approach to optical super-resolution imaging. As the technique is not limited by the nonlinear effects of fluorescence, it is applicable for both non-fluorescent-labeled and fluorescent-labeled samples. Besides, due to such advantages as fast imaging, high sample universality, and low phototoxicity, the technique shows good prospects in multiple fields, including materials science, biology, and medicine. In this paper, we deliver a detailed overview on both the principles and methods of optical super-resolution imaging based on frequency shift, as well as our prospects to the future development direction of this technique.