发表机构
Penn State University; University of Washington（宾夕法尼亚州立大学; 华盛顿大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种结合超薄超透镜与透明超声换能器的扩展景深光声显微成像系统，实现紧凑架构下1.3 mm轴向范围与微米级分辨率，并在体模和活体小鼠中验证了其成像优势。
AI 中文摘要
光学分辨率光声显微成像（ORPAM）可在毫米级组织深度提供无标记的光吸收对比度，并具有微米级的横向分辨率。然而，其体积覆盖范围受限于传统光学透镜的短焦深，而系统的小型化则受限于笨重的光学元件和超声换能器。在此，我们提出了一种扩展景深ORPAM系统，该系统将用于光学激发的超薄超透镜与用于光声检测的平面透明超声换能器（TUT）相结合。该芯片级TUT由压电铌酸锂制成，提供约80%的光学透明度，并能在14.4 MHz中心频率下实现同轴光学激发与同步声学检测。这种架构消除了对笨重的声光组合器以及换能器与成像目标之间大体积声耦合布置的需求。我们评估了三种超薄超透镜设计，分别为双曲型、二次型和扩展景深（EDOF）型，它们分别提供0.3、0.8和1.3 mm的有效轴向范围，横向分辨率分别为：双曲型1.1微米，二次型1.2微米，EDOF在整个轴向范围内为1.5微米。体模实验表明，与其他两种超透镜相比，EDOF设计能改善对多层、倾斜、体积分布目标的可视化。对清醒、头部固定小鼠的无标记成像进一步证明，EDOF能提供皮层下微血管的扩展景深可视化，且不受麻醉引起的混淆影响。这种芯片级超透镜-TUT架构为开发紧凑型光声显微成像系统奠定了基础。
英文摘要
Optical-resolution photoacoustic microscopy (ORPAM) provides label-free optical-absorption contrast at millimeter-scale tissue depths with micrometer-scale lateral resolution. However, its volumetric coverage is limited by the short depth of focus of conventional optical lenses, whereas system miniaturization is constrained by bulky optics and ultrasound transducers. Here, we present an extended-depth ORPAM system that combines an ultra-thin metalens for optical excitation with a planar transparent ultrasound transducer (TUT) for photoacoustic detection. Fabricated from piezoelectric lithium niobate, the chip-scale TUT provides ~80% optical transparency and enables coaxial optical excitation with simultaneous acoustic detection at 14.4 MHz center frequency. This architecture eliminates the need for bulky acousto-optic combiners and large-volume acoustic coupling arrangements between the transducer and imaging target. We evaluate three ultra-thin metalens designs as hyperbolic, quadratic, and extended depth-of-focus (EDOF), which provide effective axial ranges of 0.3, 0.8, and 1.3 mm, respectively, with lateral resolutions of 1.1 micron for hyperbolic, 1.2 micron quadratic lenses, and 1.5 micron for EDOF across the full axial range. Phantom experiments demonstrate improved visualization of multilayered, inclined, volumetrically distributed targets with the EDOF design compared with the two other metalenses. Label-free imaging in awake, head-fixed mice further demonstrates that EDOF provides extended-depth visualization of subcortical microvasculature without being subjected to anesthesia-induced confounds. This chip-scale metalens-TUT architecture provides a foundation for developing compact photoacoustic microscopy systems.
