Lensed fiber-based photoacoustic endomicroscopy for microvascular mapping in small luminal organs.

Miniaturization is crucial for translating photoacoustic (PA) endomicroscopy (PAE) into luminal environments that are beyond the reach of conventional endoscopes. Existing PAE probes rely on discrete optical components, which not only constrain further miniaturization but also suffer from assembly complexity and inconsistent optical performance. Here, we present a 1.4-mm-diameter PAE catheter based on astigmatism-corrected (AC) lensed fiber (LF), integrating optical focusing and acoustic detection in a compact capsule. It achieves 28 μm lateral and 19 μm longitudinal resolution at a 1.1 mm working distance (WD), enabling three-dimensional (3D) microvascular imaging in multiple small luminal organs of live mice. This universal, high-resolution platform expands PAE to previously inaccessible small luminal environments.