Abrupt Autofocusing Metasurface for High‐Resolution Confocal Fluorescence Microscopy

ABSTRACT Fluorescence‐guided tissue imaging plays a pivotal role in various biomedical applications. However, obtaining high‐resolution fluorescence images of biological tissues while overcoming obstacles remains a significant challenge. In this study, we address this issue by integrating an abrupt autofocusing (AAF) metasurface into a laser scanning confocal microscope to outperform resolution and bypass barriers for imaging tissues. The AAF metasurface, employing cubic phase modulation, serves as a unique light shaper for both illumination and detection. The cylindrically symmetric beam, generated by the metasurface, follows a parabolic trajectory, facilitating obstacle avoidance during excitation (i.e., illumination) as well as imaging (i.e., detection). Our experimental results demonstrate a remarkable 36% improvement in resolution by implementing the AAF metasurface in confocal microscopy. We conducted ex vivo confocal imaging of the fluorescently labeled mouse brain glymphatic system, successfully overcoming obstacles such as a mouse skull with a diameter of 2.5 mm. In addition, we highlight the self‐healing properties and deep imaging capabilities of our approach under ex vivo conditions, leveraging a deconvolution method to enhance image quality. Given superior resolution and improved imaging performance bypassing obstacles, the integration of the AAF metasurface across various imaging modalities holds great potential for a wide range of clinical imaging applications.