Lefort Claire, Hamzeh Hussein, Louradour Frederic, Pain Frédéric, Haidar Darine Abi
Paris-Sud University, Orsay, IMNC Lab, UMR 8165, FrancebLimoges University, Limoges F-87060, France.
Paris-Sud University, Orsay, IMNC Lab, UMR 8165, France.
J Biomed Opt. 2014;19(7):076005. doi: 10.1117/1.JBO.19.7.076005.
Several endomicroscope prototypes for nonlinear optical imaging were developed in the last decade for in situ analysis of tissue with cellular resolution by using short infrared light pulses. Fourier-transform-limited pulses at the tissue site are necessary for optimal excitation of faint endogenous signals. However, obtaining these transform-limited short pulses remains a challenge, and previously proposed devices did not achieve an optimal pulse delivery. We present a study of fibered endomicroscope architecture with an efficient femtosecond pulse delivery and a high excitation level at the output of commercially available double-clad fibers (DCFs). The endomicroscope incorporates a module based on a grism line to compensate for linear and nonlinear effects inside the system. Simulations and experimental results are presented and compared to the literature. Experimentally, we obtained short pulses down to 24 fs at the fiber output, what represents to the best of our knowledge the shortest pulse duration ever obtained at the output of a nonlinear endoscopic system without postcompression. The choice of the optimal DCF among four possible commercial components is discussed and evaluated in regard to multiphoton excitation and fluorescence emission.
在过去十年中，人们开发了几种用于非线性光学成像的内窥显微镜原型，以便通过使用短红外光脉冲对组织进行具有细胞分辨率的原位分析。在组织部位获得傅里叶变换极限脉冲对于微弱内源性信号的最佳激发是必要的。然而，获得这些变换极限短脉冲仍然是一个挑战，并且先前提出的设备未能实现最佳的脉冲传输。我们展示了一项关于光纤内窥显微镜架构的研究，该架构具有高效的飞秒脉冲传输以及在商用双包层光纤（DCF）输出端的高激发水平。该内窥显微镜包含一个基于光栅线的模块，以补偿系统内部的线性和非线性效应。给出了模拟和实验结果，并与文献进行了比较。在实验中，我们在光纤输出端获得了低至24飞秒的短脉冲，据我们所知，这代表了在没有后压缩的非线性内窥系统输出端获得的最短脉冲持续时间。讨论并评估了在四种可能的商用组件中选择最佳DCF对于多光子激发和荧光发射的情况。
