Studies On Scattering Characteristics Of Polarized Lasers From Typical Targets

Due to the good homochromatism and directionalism of laser beam,laser detection is well used in the field of proximity fuze.And laser fuze is widely applied in different kinds of tactical missile systems because of its high detecting precision,ability of anti electromagnetic interference and small volume.However,the semiconductor lasr fuzes adopt the energy-based detection mode,which identifies the target based on the energy level of the echo wave.This detection mode is highly affected by environmental interferences such as sunlight,cloud,smoke and background,especially by the cloud and smoke interferences.However,there is a lot of information contained in the echo wave laser,not only the energy,but also the frequency and phase.The states of polarization of targets and interferences are of most special type.The study results show that the polarizing state of the laser beams can be changed with different degrees after reflected or scattered by different objects or targets.First of all,the back scattering of laser beam by typical objects and aerosols are studied theoretically in this paper.The back-scattering characteristics of typical objects and aerosol particles are analyzed and the distributing models are obtained.After that,the concepts of polarized laser and degree of polarization are introduced.Then the calculations of the Mie scattering coefficient and the scattering angle fuction are derived by using the Mie scattering theory.Based on the derivation,the degree of polarization of the laser echo wave is calculated and simulated.The results show that the degree of polarization is strongly affected by the size of particles.The degree of polarization changes remarkably with the increasing of the size of particles.The degree of polarization changes slightly when the size of particels decreases.The detecting experiments are carried out by using polarized laser in different situations.And the anti-interference experiment is also executed in the smoke environment.The experimental results show that the state of polarization remains almost the same as that of the incoming light.The elimination of polarization by targets is slight.However,the elimination of polarization by smoke particals is remarkable which is happening with the scattering of polarized light,and the polarized incoming light becomes non-polarized laser.Therefore,the targets and the smoke can be distinguished effectively by examining the state of polarization.The study results of polarization detecting characteristics are valuable to the theories and applications of target identification and anti-interference.It is also significant to the progress of the study of laser fuze.