Zhou Rong, Zhang Liying, Li Beibei, Xiao Jingtao, Xing Yiheng, Chen Chang, Shen Yuecheng, Shen Hao, Pan Deng, Xu Hongxing
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.
School of Physics and Technology, Wuhan University, Wuhan 430072, China.
Photoacoustics. 2025 Mar 29;43:100719. doi: 10.1016/j.pacs.2025.100719. eCollection 2025 Jun.
Photoacoustic microscopy (PAM) offers a non-invasive imaging method that overcomes the limitations of light scattering in biological tissues by visualizing optical contrast through the detection of photo-generated acoustic signals. While optical microscopy has significantly advanced through the exploration of optical evanescent waves, the potential of evanescent photoacoustic (PA) waves in PAM remains largely unexplored. In this work, we demonstrate the generation and detection of evanescent PA waves in PAM by positioning the sample near an interface, which directs these waves into the far-field beyond the supercritical angle (SA). These SA-PA signals exhibit distinct characteristics, including dependence of intensity on the source depths and symmetry in far-field angular patterns. Leveraging these features, we develop a proof-of-concept for supercritical angle photoacoustic microscopy (SA-PAM), which utilizes evanescent PA waves to enable new PAM functionalities, such as surface topography reconstruction and edge detection. This approach highlights the role of acoustic near-field exploration in advancing PA technology.
光声显微镜（PAM）提供了一种非侵入性成像方法，通过检测光生声信号来可视化光学对比度，从而克服了生物组织中光散射的局限性。虽然光学显微镜通过对光学倏逝波的探索取得了显著进展，但倏逝光声（PA）波在PAM中的潜力在很大程度上仍未得到探索。在这项工作中，我们通过将样品放置在界面附近，证明了在PAM中倏逝PA波的产生和检测，这将这些波引导到超临界角（SA）之外的远场。这些SA-PA信号表现出独特的特征，包括强度对源深度的依赖性以及远场角度模式中的对称性。利用这些特性，我们开发了超临界角光声显微镜（SA-PAM）的概念验证，它利用倏逝PA波实现新的PAM功能，如表面形貌重建和边缘检测。这种方法突出了声学近场探索在推进PA技术方面的作用。
