Research On The Depolarization Characteristics Of Nanosecond Pulsed Polarized Laser Scattering On Rough Surfaces

The theoretical basis and experimental research of target scattering have made great progress in target recognition,which has been widely used in target recognition,underwater detection,medical diagnosis,the detection of environmental and other areas.The polarization characteristics of target reflection has an important influence for measuring system.As a result of the low Signal to Noise Ratio,it is easy to be affected by the background light source.In order to put up with the problem,the laser radar and laser ranging system based on polarized light emerge as the times require.Nevertheless,in the process of target surface reflection,polarized light will produce a certain deflection,leading to polarization reduction.The targets with different surface characteristics have different depolarization characteristics,which affects the application of the system.Therefore,the research on polarization characteristics of rough surface reflected by narrow pulse laser is one of the nucleus of the question to be solved in the progresses of polarization lidar and laser ranging.Aiming at the problem of scattering deflection characteristics of the nanosecond pulse polarized laser on rough surfaces,the following works are carried out in this paper:In terms of theory,the basic concept of polarization light and the representation form of polarization state are analyzed,and the basis of judging random rough surfaces and the function description of the rough medium appearance are defined.At the same time,Analyzed the influence of deflection characteristics caused by the scattering of light by the rough surface,and the evaluation formula of Stokes combined with polarized light is derived.According to the grade of rough surface,the light field distribution of different roughness surfaces are numerically calculated.The relationship between the incident angle of polarization angle irradiated on the rough surface and the polarization angle of scattered light,polarization light and roughness is discussed.It is found that the higher surface roughness,the more obvious the deflection of scattered light and the stronger the de-biasing characteristics.When the surface of the target is extermely rough,the depolarization degree decreases more obviously,when it reaches a certain angle,and the depolarization significant debiasing effect.And as the incident angle increases,the polarization angle of scattered light increases gradually rises.In terms of experimentation,To overcome this question of experiencing the depolarization characteristics of light scattering from rough surface,in which the basis of Stokes parameter,the experimental test scheme is improved,and established a short-pulse polarization laser real-time polarization measurement system.Taking different types of sandpaper as the representative research on objects,the polarization phenomenon of60,100,180,600,and 2000 sandpaper under the action of 1064 nm narrow pulse polarized laser were analyzed.The refractive index and polarization angle characteristics of narrow pulse polarized laser scattering at different incident angle are obtained.It is found that due to the increase of the roughness of sandpaper,the slope between the surface particles is enlarged,so the probability of multiple scattering of scattered light on the target surface increases.The target with high roughness has a great influence on the depolarization of polarized light,and the depolarization is more obvious.The polarization angle increases with the increase of the incident angle.When the incident angle is-40 degrees,the light irradiates the surface particles and has secondary scattering or even multiple scattering,it interacts with the sandpaper particles and attenuates the intensity of scattered light,the correctness of the theoretical analysis is verified.