Vibrational contrast imaging of the distribution of complex biological molecules requires the use of techniques that provide broadband spectra with sufficient resolution. Coherent anti-Stokes Raman scattering (CARS) microscopy is currently limited in meeting these requirements due to the presence of a nonresonant background and its inability to target multiple resonances simultaneously. We present nonlinear interferometric vibrational imaging (NIVI), a technique based on CARS that uses femtosecond pump and Stokes pulses to retrieve broadband vibrational spectra over 200 cm(-1) (full-width at half maximum). By chirping the pump and performing spectral interferometric detection, the anti-Stokes pulses are resolved in time. This phase-sensitive detection allows suppression of not only the nonresonant background, but also of the real part of the nonlinear susceptibility χ((3)), improving the spectral resolution and features to make them comparable to those acquired with spontaneous Raman microscopy, as shown for a material sample and mammary tissue.

中文翻译：

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生物组织的高速非线性干涉振动成像与拉曼显微镜的比较。


复杂生物分子分布的振动对比成像需要使用能够提供足够分辨率的宽带光谱的技术。由于存在非共振背景且无法同时瞄准多个共振，相干反斯托克斯拉曼散射（CARS）显微镜目前在满足这些要求方面受到限制。我们提出了非线性干涉振动成像（NIVI），这是一种基于 CARS 的技术，它使用飞秒泵浦和斯托克斯脉冲来检索超过 200 cm(-1)（半高全宽）的宽带振动光谱。通过对泵进行啁啾并执行光谱干涉检测，可以及时解析反斯托克斯脉冲。这种相敏检测不仅可以抑制非共振背景，还可以抑制非线性磁化率 χ((3)) 的实部，从而提高光谱分辨率和特征，使其与自发拉曼显微镜获得的光谱分辨率和特征相当，如显示的是材料样本和乳腺组织。