The survival of time-reversal symmetry in the presence of strong multiple scattering lies at the heart of some of the most robust interference effects of light in complex media. Here, the use of time-reversed light paths for imaging in highly scattering environments is investigated. A common-path Sagnac interferometer is constructed that is able to detect objects behind a layer of strongly scattering material at up to 14 mean free paths of total attenuation length. A spatial offset between the two light paths is used to suppress non-specific scattering contributions, limiting the signal to the volume of overlap. Scaling of the specific signal intensity indicates a transition from ballistic to quasi-ballistic contributions as the scattering thickness is increased. The characteristic frequency dependence for the coherent modulation signal provides a path length dependent signature, while the spatial overlap requirement allows for short-range 3D imaging. The technique of common-path, bistatic interferometry offers a conceptually novel approach that could open new applications in diverse areas such as medical imaging, machine vision, sensors, and lidar.

中文翻译：

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在共路径Sagnac干涉仪中使用弹道和准弹道光在高度散射的环境中成像

在强多重散射的情况下，时间反转对称性的生存是复杂介质中光的一些最强大干扰效应的核心。在这里，研究了在高散射环境下使用时间反转光路进行成像。构造了一条共通路径的Sagnac干涉仪，该干涉仪能够以高达14条的总衰减长度平均自由程检测强散射材料层后面的物体。两个光路之间的空间偏移用于抑制非特定的散射影响，从而将信号限制在重叠的范围内。特定信号强度的缩放表明，随着散射厚度的增加，从弹道作用向准弹道作用的过渡。相干调制信号的特征频率相关性提供了路径长度相关的签名，而空间重叠要求则允许进行短距离3D成像。共径双基地干涉测量技术提供了一种概念上新颖的方法，可以在医学成像，机器视觉，传感器和激光雷达等不同领域打开新的应用。