Measuring cloud droplet effective radius and liquid water content using changes in degree of linear polarization along cloud depth

Water Cloud Detection with Circular Polarization Lidar: A Semianalytic Monte Carlo Simulation Approach

This work presents polarization property studies of water clouds using a circular polarization lidar through a simulation approach. The simulation approach is based on a polarized, semianalytic Monte Carlo method under multiple-scattering conditions and considers three types of water clouds (namely homogeneous, inhomogeneous and partially inhomogeneous). The simulation results indicate that the layer-integrated circular depolarization ratios show similar variation trends as those of layer-integrated linear depolarization ratios. The Mishchenko–Hovenier relationship is validated to correlate the simulated layer-integrated circular and linear depolarization ratios. In addition, the cloud droplet effective radius, extinction coefficient, lidar field-of-view (FOV) and height of the cloud bottom are all found to affect the layer-integrated depolarization ratio. The current work theoretically indicates that a circular polarization lidar can efficiently perform measurements of water clouds, enjoying the advantage of higher sensitivity compared to a traditional linear polarization lidar. Hence, it should be of interest to researchers in fields of polarization lidar applications.

Ghost imaging utilizing experimentally acquired degree of linear polarization with no prior information

Ghost imaging is developed to obtain images of the objects based on intensity correlation of illumination patterns. However, it can be hard to distinguish between objects if the difference between their reflectivities is small. Considering the difference between degrees of polarization in the reflected light from different points, we put forward a method to retrieve distribution of the degree of linear polarization, and obtain high quality image of the objects. With the illumination source being linearly polarized, two orthogonal polarization components of the reflected intensities are measured, from which we can get the distribution of the degree of linear polarization. Furthermore, for the case that the degree of linear polarization can be approximately described with two different values within the field of view, we demonstrate retrieving of the image with high contrast. Our method can be widely applied in different situations, such as extracting the image of target hidden behind disguise or getting higher contrast in bio-imaging.