Study On The Characteristic Of Speckle For Laser Radar Imaging In The Slant Path Through The Atmospheric Turbulence

This thesis mainly focused on the characteristic of speckle for laser radar imaging in the slant path through the atmospheric turbulence. Firstly, the speckle characteristics of rough surface in free space are discussed, including the intensity,phase,and correlation function’s statistical characteristics.Secondly, the simplified index of refraction spectral density function with the effect of the inner and outer scale of the turbulence is presented, the phenomenons of intensity fluctuation, beam spreading and wandering, angle-of-arrival fluctuation of the laser beam under the effect of slant path in turbulence are discussed by using the slant modified Rytov theory and ITU-R turbulence structure constant model.According to the extended Huygens-Fresnel principle,the effect of the log-amplitude covariance function on the statistics of speckle propagation through the atmospheric turbulence are also analyzed, some formulas of monochromatic and polychromatic speckles are obtained respectively. The formulas of one-point and two-point probability-density function of the intensity for laser speckle field in the turbulence are presented and discussed in details by applying the compound distribution, the joint moments of the intensity and the experiment dates are compared. Finally, with the probability density distribution of beam scintillation in turbulence and probability density distribution of speckle in free space, the joint probability density distribution is alsoed obtained. Based on the noise of the turbulence and target’s speckle, the image of laser radar is simulated.