Theoretically, laser beam divergence can redistribute multiple scattering lights by spreading laser illumination and thus alter lidar polarization measurements. To study multiple scattering effects of laser divergence on lidar polarization signals, we apply the Monte Carlo polarized radiative transfer model MSCART to simulate lidar Stokes vector signals from a uniform water cloud with and without taking account of laser divergences. The comparison analysis shows that for lidar receiver footprints with roughly the same sizes of the multiple scattering regimes, laser divergence has almost no effect on ground-based lidar signals, but can have significantly large and much complex polarization effects on spaceborne lidar signals. An increase in laser divergence on one hand can greatly enhance spaceborne lidar multiple scattering depolarization when the divergence is larger than the FOV, and on the other hand can also weaken it slightly when the divergence less than the FOV. The weakest multiple scattering depolarization occurs at the divergence equal to the FOV. Furthermore, laser divergence can significantly reduce the sensitivity of FOV-resolved polarization measurement of spaceborne lidar to non-diagonal elements of phase matrix and make the measurement at different receiving polar angles only sensitive to diagonal elements of phase matrix at almost the same scattering angles. The spaceborne MFOV and CCD polarized lidar thus might not provide more information about phase matrix than the single FOV lidar does.

从理论上讲，激光束发散可以通过散布激光照度来重新分配多个散射光，从而改变激光雷达的偏振测量。为了研究激光发散对激光雷达偏振信号的多重散射效应，我们应用了蒙特卡洛偏振辐射传递模型MSCART来模拟均匀水云中的激光雷达斯托克斯矢量信号，并考虑和不考虑激光发散。比较分析表明，对于激光雷达接收器的足迹，其多个散射范围的大小大致相同，激光发散对地基激光雷达信号几乎没有影响，但对星载激光雷达信号却具有非常大且非常复杂的偏振影响。一方面，当激光散度大于FOV时，激光散度的增加可以大大增强星载激光雷达的多重散射去极化，另一方面，当散度小于FOV时，激光散度也会略微减弱。最弱的多重散射去极化发生在等于FOV的散度处。此外，激光发散会显着降低星载激光雷达的FOV分辨偏振测量对相矩阵的非对角元素的灵敏度，并使在不同接收极角下的测量仅对几乎相同的散射角下对相矩阵的对角元素敏感。因此，与单个FOV激光雷达相比，星载MFOV和CCD偏振激光雷达可能无法提供有关相位矩阵的更多信息。另一方面，当散度小于FOV时，也会稍微削弱它。最弱的多重散射去极化发生在等于FOV的散度处。此外，激光发散可以显着降低星载激光雷达的FOV分辨偏振测量对相矩阵的非对角元素的灵敏度，并使在不同接收极角下的测量仅对几乎相同的散射角下对相矩阵的对角元素敏感。因此，与单个FOV激光雷达相比，星载MFOV和CCD偏振激光雷达可能无法提供有关相位矩阵的更多信息。另一方面，当散度小于FOV时，也会稍微削弱它。最弱的多重散射去极化发生在等于FOV的散度处。此外，激光发散可以显着降低星载激光雷达的FOV分辨偏振测量对相矩阵的非对角元素的灵敏度，并使在不同接收极角下的测量仅对几乎相同的散射角下对相矩阵的对角元素敏感。因此，与单个FOV激光雷达相比，星载MFOV和CCD偏振激光雷达可能无法提供有关相位矩阵的更多信息。激光发散可以显着降低星载激光雷达的FOV分辨偏振测量对相矩阵非对角元素的灵敏度，并使在不同接收极角下的测量仅对几乎相同散射角的相矩阵对角元素敏感。因此，与单个FOV激光雷达相比，星载MFOV和CCD偏振激光雷达可能无法提供有关相位矩阵的更多信息。激光发散可以显着降低星载激光雷达的FOV分辨偏振测量对相矩阵非对角元素的灵敏度，并使在不同接收极角下的测量仅对几乎相同散射角的相矩阵对角元素敏感。因此，与单个FOV激光雷达相比，星载MFOV和CCD偏振激光雷达可能无法提供有关相位矩阵的更多信息。