Gu M, Bao H, Kang H
Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, Australia.
J Microsc. 2014 Apr;254(1):13-18. doi: 10.1111/jmi.12119. Epub 2014 Mar 5.
Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high-quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro-scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one-photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two-photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre-optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner.
由于具有高质量成像性能、紧凑的尺寸和灵活的移动性，显微内窥镜一直是探索体内微观/纳米机制的重要工具。对光纤、微扫描器和微型透镜的研究提高了向样本部位远程传输光以及信号采集的效率。鉴于荧光成像模式下光与材料的相互作用，本文综述了基于单根光纤的两类紧凑型显微内窥镜：线性光学显微内窥镜和非线性光学显微内窥镜。由于荧光仅在焦体积内产生，非线性光学显微内窥镜比线性光学显微内窥镜具有更强的光学切片能力，是深部组织成像的理想选择。此外，作为线性光学显微内窥镜的单光子激发荧光显微内窥镜，由于光漂白速率与激发激光功率呈线性相关，存在严重的光漂白问题。相反，非线性光学显微内窥镜，包括双光子激发荧光显微内窥镜和二次谐波产生显微内窥镜，能够在高激发功率下将光漂白效应降至最低或避免光漂白效应，并产生高图像对比度。非线性光学显微内窥镜获得的各种非线性信号的组合为深入了解内部器官的生物现象提供了全面的视角。光纤显微内窥镜克服了传统显微镜的物理限制，为以微创和局部方式实现早期癌症诊断和显微手术开辟了一条新途径。
