In this paper, a controlled-laboratory experiment is carried out to evaluate the lidar depolarization ratio of freshly emitted soot aggregates in the exact backward scattering direction at 180.0°. The experiment is performed at two wavelengths simultaneously, namely 355 and 532 nm, often used in polarimetric lidar remote sensing. The soot aggregates are generated from a kerosene JET A-1 pool fire in laboratory ambient air and microscopic images confirm the fractal morphology of generated soot aggregates. Then, the Superposition T-Matrix (STM) method is applied to numerically simulate the soot aggregates backscattering properties for different soot particles refractive indices, monomer radii and monomer numbers. The range of these parameters which ensures the lowest discrepancy between the laboratory measurement and the STM-computations is discussed within experimental and numerical error bars. We find that the polydisperse monomers model gives an overall better evaluation of the ratio F₂₂(π)/F₁₁(π). In the polydisperse case, our numerical and laboratory experimental findings agree at both wavelengths for a refractive index m = 2.65 + i1.32 and monomer number N_m > 40 at a mean monomer radius of r_p = 30 nm (N_m > 160 at r_p = 27.5 nm). We believe this work may be useful for the light scattering and remote sensing communities and may also help future studies aimed at better understanding the impact of soot particle aggregates on the Earth's climate, which still needs to be precisely quantified.

在本文中，进行了一个控制实验室的实验，以评估在精确的反向散射方向（180.0°）上，新发射的烟尘聚集体的激光雷达去极化率。该实验同时在偏振激光雷达遥感中经常使用的两个波长（即355 nm和532 nm）上进行。烟灰聚集体是由实验室环境空气中的煤油JET A-1池火产生的，显微图像证实了所生成烟灰聚集体的分形形态。然后，采用叠加T矩阵（STM）方法对不同烟灰颗粒折射率，单体半径和单体数的烟灰聚集体反向散射特性进行数值模拟。在实验和数值误差条中讨论了确保实验室测量值与STM计算之间最小差异的这些参数范围。我们发现，多分散单体模型可以更好地评估比率F₂₂（π）/ F ₁₁（π）。在多分散的情况下，我们的数值和实验室实验结果在两种波长下均一致，即折射率m = 2.65 + i1.32和单体数N _m > 40，且平均单体半径r _p  = 30 nm（N _m > 160 at r _p  = 27.5 nm）。我们认为这项工作可能对光散射和遥感社区有用，也可能有助于未来的研究，以便更好地了解烟灰颗粒聚集体对地球气候的影响，但仍需要精确量化。