Since the 1990s, continuous technical and scientific advances have defied the diffraction limit in microscopy and enabled three-dimensional (3D) super-resolution imaging. An important milestone in this pursuit is the coherent utilization of two opposing objectives (4Pi geometry) and its combination with super-resolution microscopy. Herein, we review the recent progress in 4Pi nanoscopy, which provides a 3D, non-invasive, diffraction-unlimited, and isotropic resolution in transparent samples. This review includes both the targeted and stochastic switching modalities of 4Pi nanoscopy. The schematics, principles, applications, and future potential of 4Pi nanoscopy are discussed in detail.

自 1990 年代以来，技术和科学的不断进步已经突破了显微镜的衍射极限，并实现了三维 (3D) 超分辨率成像。这一追求的一个重要里程碑是一致地利用两个相反的目标（4Pi 几何）及其与超分辨率显微镜的结合。在这里，我们回顾了 4Pi 纳米技术的最新进展，它在透明样品中提供了 3D、非侵入性、衍射无限和各向同性的分辨率。这篇综述包括 4Pi 纳米镜的靶向和随机切换模式。详细讨论了 4Pi 纳米技术的原理图、原理、应用和未来潜力。