Ragweed or Ambrosia artemisiifolia pollen is an important atmospheric constituent affecting the Earth's climate and public health. The literature on light scattering by pollens embedded in ambient air is however rather sparse: polarization measurements are limited to the sole depolarization ratio and pollens are beyond the reach of numerically exact light scattering models mainly due to their tens of micrometre size. Also, ragweed pollen presents a very complex shape, with a small-scale external structure exhibiting spikes that bears some resemblance with coronavirus, but also apertures and micrometre holes. In this paper, to face such a complexity, a controlled-laboratory experiment is proposed to evaluate the scattering matrix of ragweed pollen embedded in ambient air. It is based on a newly-built polarimeter, operating in the infra-red spectral range, to account for the large size of ragweed pollen. Moreover, the ragweed scattering matrix is also evaluated in the visible spectral range to reveal the spectral dependence of the ragweed scattering matrix within experimental error bars. As an output, precise spectral and polarimetric fingerprints for large size and complex-shaped ragweed pollen particles are then provided. We believe our laboratory experiment may interest the light scattering community by complementing other light scattering experiments and proposing outlooks for numerical work on large and complex-shaped particles.

豚草或青蒿花粉是影响地球气候和公共健康的重要大气成分。然而，关于嵌入在环境空气中的花粉的光散射的文献很少，偏振测量仅限于唯一的去偏振比，而花粉却由于其数十微米的尺寸而在数值上精确的光散射模型无法达到。此外，豚草花粉呈现出非常复杂的形状，具有小规模的外部结构，呈现出与冠状病毒有些相似的尖峰，但还有孔和微米孔。针对这种复杂性，提出了一种控制实验室的实验来评价豚草花粉在环境空气中的散射矩阵。它基于在红外光谱范围内运行的新型偏振计，来解释豚草花粉的大尺寸。此外，豚草散射矩阵也在可见光谱范围内进行评估，以揭示豚草散射矩阵在实验误差条内的光谱依赖性。作为输出，然后提供了用于大尺寸和复杂形状的豚草花粉颗粒的精确光谱和极化指纹。我们相信我们的实验室实验可能会通过补充其他光散射实验并提出对大型和复杂形状的粒子进行数值工作的前景来引起光散射界的兴趣。然后提供了用于大尺寸和复杂形状的豚草花粉颗粒的精确光谱和极化指纹。我们相信我们的实验室实验可能会通过补充其他光散射实验并提出对大型和复杂形状的粒子进行数值工作的前景来引起光散射界的兴趣。然后提供了用于大尺寸和复杂形状的豚草花粉颗粒的精确光谱和极化指纹。我们相信我们的实验室实验可能会通过补充其他光散射实验并提出对大型和复杂形状的粒子进行数值工作的前景来引起光散射界的兴趣。