Du Dongyu, Jin Xin, Deng Rujia, Kang Jinshi, Cao Hongkun, Fan Yihui, Li Zhiheng, Wang Haoqian, Ji Xiangyang, Song Jingyan
Shenzhen International Graduate School, Tsinghua University, 518055, Shenzhen, China.
Department of Automation, Tsinghua University, 100084, Beijing, China.
Nat Commun. 2022 Jun 9;13(1):3234. doi: 10.1038/s41467-022-30948-7.
Effectively imaging within volumetric scattering media is of great importance and challenging especially in macroscopic applications. Recent works have demonstrated the ability to image through scattering media or within the weak volumetric scattering media using spatial distribution or temporal characteristics of the scattered field. Here, we focus on imaging Lambertian objects embedded in highly scattering media, where signal photons are dramatically attenuated during propagation and highly coupled with background photons. We address these challenges by providing a time-to-space boundary migration model (BMM) of the scattered field to convert the scattered measurements in spectral form to the scene information in the temporal domain using all of the optical signals. The experiments are conducted under two typical scattering scenarios: 2D and 3D Lambertian objects embedded in the polyethylene foam and the fog, which demonstrate the effectiveness of the proposed algorithm. It outperforms related works including time gating in terms of reconstruction precision and scattering strength. Even though the proportion of signal photons is only 0.75%, Lambertian objects located at more than 25 transport mean free paths (TMFPs), corresponding to the round-trip scattering length of more than 50 TMFPs, can be reconstructed. Also, the proposed method provides low reconstruction complexity and millisecond-scale runtime, which significantly benefits its application.
在体散射介质中进行有效的成像非常重要且具有挑战性，尤其是在宏观应用中。最近的研究表明，利用散射场的空间分布或时间特性能够透过散射介质或在弱体散射介质内部进行成像。在此，我们聚焦于对嵌入高散射介质中的朗伯体进行成像，在这种情况下，信号光子在传播过程中会大幅衰减，并与背景光子高度耦合。我们通过提供散射场的时间 - 空间边界迁移模型（BMM）来应对这些挑战，该模型利用所有光信号将光谱形式的散射测量转换为时间域中的场景信息。实验在两种典型的散射场景下进行：嵌入聚乙烯泡沫和雾中的二维和三维朗伯体，实验结果证明了所提算法的有效性。在所提算法在重建精度和散射强度方面优于包括时间选通在内的相关研究。即便信号光子的比例仅为0.75%，位于超过25个输运平均自由程（TMFP）处的朗伯体（对应往返散射长度超过50个TMFP）仍可被重建。此外，所提方法具有较低的重建复杂度和毫秒级的运行时间，这极大地有利于其应用。
