Sensing and imaging methods based on the dynamic scattering of coherent light (including laser speckle, laser Doppler, diffuse correlation spectroscopy, dynamic light scattering, and diffusing wave spectroscopy) quantify scatterer motion using light intensity fluctuations. The underlying optical field autocorrelation, rather than being measured directly, is typically inferred from the intensity autocorrelation through the Siegert relationship, assuming that the scattered field obeys Gaussian statistics. Here, we demonstrate interferometric near-infrared spectroscopy for measuring the time-of-flight (TOF) resolved field and intensity autocorrelations in turbid media. We find that the Siegert relationship breaks down for short TOFs due to static paths whose optical field does not decorrelate over experimental time scales. We also show that eliminating such paths by polarization gating restores the validity of the Siegert relationship. The unique capability of measuring optical field autocorrelations, as demonstrated here, enables the study of non-Gaussian and non-ergodic light scattering processes. Moreover, direct measurements of field autocorrelations are more efficient than indirect measurements based on intensity autocorrelations. Thus, optical field measurements may improve the quantiffcation of scatterer dynamics with coherent light.

中文翻译：

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干涉近红外光谱法直接量化了混浊介质中的光场动态。

基于相干光的动态散射（包括激光散斑，激光多普勒，扩散相关光谱，动态光散射和散射波光谱）的传感和成像方法可以利用光强度波动来量化散射体的运动。假设散射场服从高斯统计，则通常通过Siegert关系从强度自相关推断基础光场自相关，而不是直接测量。在这里，我们展示了用于测量飞行时间（TOF）分辨场和浊度介质中强度自相关的近红外干涉测量技术。我们发现，由于静态路径的光场在实验时间尺度上不去相关，Siegert关系对于短的TOF破裂。我们还表明，通过极化门控消除此类路径可恢复Siegert关系的有效性。如此处所示，测量光场自相关的独特功能使研究非高斯和非遍历光散射过程成为可能。此外，现场自相关的直接测量比基于强度自相关的间接测量更有效。因此，光场测量可以改善相干光对散射体动力学的量化。场自相关的直接测量比基于强度自相关的间接测量更有效。因此，光场测量可以改善相干光对散射体动力学的量化。场自相关的直接测量比基于强度自相关的间接测量更有效。因此，光场测量可以改善相干光对散射体动力学的量化。