Depolarization Properties Of Polarized Laser Pulse Beams Scattering On Random Rough Surface

Because of the characteristics of high intensity,anti-interference and good directivity,laser is widely used in the field of military affairs,communication,medical treatment and other civilian fields.With the continuous development of pulsed laser,pulsed laser beam has become an important information carrier in satellite communication,high-precision ranging,target recognition and detection,laser spectral analysis and other systems.The research on scattering polarization properties of rough surface is of great importance to detect interested targets in complex background,which is an important research direction in remote reconnaissance,target recognition and other fields.Because the polarization information of light wave will change in scattering and reflection,in target detection and recognition,the target characteristics can be distinguished according to the variation of the polarization characteristics of reflected light waves of different targets.The use of polarization technology makes the performance of the coherent detection system greatly improve,which can obtain higher signal to noise ratio and better resolving power.In this paper,the polarization laser pulse beam is as a typical example to study the depolarization properties when the laser beam scattering on a random rough surface.The research results of this paper are listed as follows:(1)The one-dimensional and two-dimensional Gauss random rough surfaces are simulated using the method of spectral inversion.The surface roughness of Gauss rough surface is described by the ratio of the height fluctuation root mean square and the surface coherence length,so that the transverse and longitudinal characteristics information of rough surface can be included.(2)The backscattering coefficient of laser multiple scattering on rough surface is deducedstarting from the tangential field of the incident wave surface.Numerical analysis shows that the more rough the rough surface is,the more obvious the scattering phenomenon is,and when the roughness of the rough surface is large,there is a phenomenon of backward scattering enhancement.(3)We take the elliptically polarized spatially and spectrally partially coherent EGSMP beams as a typical example.Based on the coherent polarization principle of random electromagnetic wave and the generalized Stokes parameter,the electromagnetic cross spectral density function(CSDF)matrix element of polarized light at the incident plane is derived,which is used to represent the polarization state of incident light.Based on the polarized bidirectional reflectance distribution function(BRDF),and to consider the multiple scattering effect,the depolarization of the pulse beams after scattering on a random rough surface is derived.Finally,the effects of depolarization properties on interrelated factors are comparative analyzed.The results show that the influences of the parameters of the initial pulse width,beam width and other parameters of the beams,the roughness of the surface and the material complex refractive index and other rough surface parameters have significant influence on the depolarization properties of the elliptical polarized beam.