Diffusion of the lidar beam seen from the receiver

We study the diffusion of the lidar laser beam in a cloud as it is seen from the receiver. We consider two different types of clouds: an aerosol cloud cosisting of randomly oriented oblate spheroids and an ice cloud consisting of randomly oriented oblate cylinders. We calculate the off-axis diffusion which could be a measured by multiple field of view lidar with circular field stops and the diffusion of the beam (projected) in the plane perpendicular to its direction (we call it planar diffusion) which could be measured by a CCD type device. The simulations were done with or our variance reduction multiple scattering Monte Carlo program PBS2. This programme is based on a stochastic process of corpuscular multiple scattering including polarization which is equivalent to a corresponding vector radiative transfer equation and a time continuous Markovian jump process (and not to its diffusion limit) for the description of the transport of light through the atmosphere. The results of these simulations of the off-axis and the planar diffusion are striking: they allow for a simple classification of scattering particles.