AI 中文总结
该研究开发了一款用于光声显微成像的高光谱能量密度全光纤纳秒脉冲1.7 μm光源，基于受激拉曼散射架构实现了高性能，经仿体与生物组织成像验证可用于脂质相关分子成像及临床诊断
AI 中文摘要
本文提出了一种专为光声显微成像（PAM）设计的高光谱能量密度全光纤纳秒脉冲1.7 μm光源。该系统瞄准近红外III区（NIR-III）窗口内1720 nm附近的C-H键第一泛音吸收峰，在此波段脂质表现出强光吸收特性，同时组织受散射影响更小且允许的能量通量更高。为实现窄线宽、高脉冲能量和高脉冲重复频率（PRR），本文开发了基于受激拉曼散射的主振荡器光纤放大器架构，采用1589.80 nm拉曼泵浦源和定制的窄线宽拉曼种子激光器，生成了光谱纯净的1719.44 nm脉冲，其线宽约为0.10 nm。该光源输出的纳秒脉冲持续时间约为5 ns，脉冲能量至少为2.2 μJ，脉冲重复频率可调至300 kHz，由此获得的光谱能量密度约为22 μJ/nm，显著高于传统1.7 μm光源。通过1951 USAF靶标的分辨率测试验证了近红外光声显微（NIR-PAM）系统的性能，其空间分辨率约为4.14 μm，轴向分辨率约为85.5 μm。对富CH₂聚合物膜的仿体成像以及离体富脂质生物组织成像，证实了该系统对脂质特异性结构具有高空间保真度和强对比度。这种紧凑、稳定且光谱精细的高光谱能量密度光源，可为高分辨率无标记分子成像提供有效解决方案，也为涉及脂质检测和代谢疾病诊断的临床光声成像应用提供了有前景的平台。
英文摘要
We present a high spectral energy density all-fiber nanosecond pulsed 1.7 $μ$m light source specifically designed for photoacoustic microscopy (PAM). The system targets the first overtone absorption of C-H bonds near 1720 nm within the near-infrared-III (NIR-III) window, where lipids exhibit strong optical absorption and tissues benefit from reduced scattering and high permissible fluence. To achieve narrow linewidth, high pulse energy, and high pulse repetition rate (PRR), we developed a master oscillator fiber amplifier architecture based on stimulated Raman scattering. A 1589.80 nm Raman pump and a custom-built narrow-linewidth Raman seed laser were employed to generate spectrally pure 1719.44 nm pulses with an approximately 0.10 nm linewidth. The proposed light source delivers nanosecond pulses of approximately 5 ns with high pulse energy of at least 2.2 $μ$J and tunable PRRs up to 300 kHz, resulting in a spectral energy density of approximately 22 $μ$J/nm, which is significantly higher than that of conventional 1.7 $μ$m light sources. The performance of the NIR-PAM system was validated through resolution testing with a 1951 USAF target, demonstrating a spatial resolution of approximately 4.14 $μ$m and an axial resolution of approximately 85.5 $μ$m. Phantom imaging of CH$_2$-rich polymer films and ex vivo lipid-rich biological tissues confirmed the system's high spatial fidelity and strong contrast for lipid-specific structures. This compact, stable, and spectrally refined light source with high spectral energy density can offer an effective solution for high-resolution, label-free molecular imaging and represents a promising platform for clinical photoacoustic imaging applications involving lipid detection and metabolic disease diagnostics.
Journal refPhotoacoustics 44 (2025) 100744
DOI：10.1016/j.pacs.2025.100744
