Fiber delivered probe for efficient CARS imaging of tissues.
Fiber delivered probe for efficient CARS imaging of tissues.
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DOI：
10.1364/oe.18.002380
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发表时间：
2010-02-01
期刊：
影响因子：
3.8
通讯作者：
Potma EO
中科院分区：
文献类型：
--
作者：
Balu M;Liu G;Chen Z;Tromberg BJ;Potma EO
我们展示了一种基于光纤的探测器，用于最大限度地收集生物组织中的相干反斯托克斯拉曼散射(CARS)信号。我们讨论了设计挑战，包括捕获样本中的后向散射正向产生的CARS信号，以及光纤非线性对传输脉冲的影响。测试了三种不同的单模光纤(熔融石英光纤、光子晶体光纤和双包层光子晶体光纤)的探头设计。我们研究了光纤中的自相位调制、受激拉曼散射(SRS)和四波混频(FWM)：在基于双光束激励的探测器中预计会发生非线性过程。虽然SPM和SRS引起的光谱展宽可以忽略不计，但在与CARS组织显微镜相关的激发条件下，所有被测纤维中都存在很强的非相位匹配的FWM贡献。为了在光谱上抑制这种强烈的贡献，探头设计结合了独立的光纤，用于激发光传输和信号检测，并与二向色性光学相结合。通过多模光纤采集样品中反向散射的正向产生的CARS信号，记录样品的CARS图像。我们对不同的生物组织进行了体外成像，以评估我们用于CARS成像的纤维传递探针的性能，我们认为这是一种朝着无标记、体内探测表面组织的重要进步。
We demonstrate a fiber-based probe for maximum collection of the coherent anti-Stokes Raman scattering (CARS) signal in biological tissues. We discuss the design challenges including capturing the back-scattered forward generated CARS signal in the sample and the effects of fiber nonlinearities on the propagating pulses. Three different single mode fibers (fused silica fiber, photonic crystal fiber and double-clad photonic crystal fiber) were tested for the probe design. We investigated self-phase modulation, stimulated Raman scattering (SRS) and four-wave-mixing (FWM) generation in the fiber: nonlinear processes expected to occur in a two-beam excitation based probe. While SPM and SRS induced spectral broadening was negligible, a strong non phase-matched FWM contribution was found to be present in all the tested fibers for excitation conditions relevant to CARS microscopy of tissues. To spectrally suppress this strong contribution, the probe design incorporates separate fibers for excitation light delivery and for signal detection, in combination with dichroic optics. CARS images of the samples were recorded by collecting the back-scattered forward generated CARS signal in the sample through a multi-mode fiber. Different biological tissues were imaged ex vivo in order to assess the performance of our fiber-delivered probe for CARS imaging, a tool which we consider an important advance towards label-free, in vivo probing of superficial tissues.