Terahertz radiation has become an important diagnostic tool in the development of new technologies. However, the diffraction limit prevents terahertz radiation (λ ≈ 0.01–3 mm) from being focused to the nanometre length scale of modern devices. In response to this challenge, terahertz scanning probe microscopy techniques based on coupling terahertz radiation to subwavelength probes such as sharp tips have been developed. These probes enhance and confine the light, improving the spatial resolution of terahertz experiments by up to six orders of magnitude. In this Review, we survey terahertz scanning probe microscopy techniques that achieve spatial resolution on the scale of micrometres to ångströms, with particular emphasis on their overarching approaches and underlying probing mechanisms. Finally, we forecast the next steps in the field.

太赫兹辐射已成为新技术发展的重要诊断工具。然而，衍射极限会阻止太赫兹辐射 ( λ ≈ 0.01–3 mm）从聚焦到现代设备的纳米长度尺度。为应对这一挑战，基于将太赫兹辐射耦合到亚波长探针（如尖头）的太赫兹扫描探针显微镜技术得到了开发。这些探头增强和限制光，将太赫兹实验的空间分辨率提高多达六个数量级。在这篇评论中，我们调查了在微米到 ångströms 尺度上实现空间分辨率的太赫兹扫描探针显微镜技术，特别强调了它们的总体方法和潜在的探测机制。最后，我们预测该领域的下一步。