随机粗糙面激光脉冲散射四阶统计特征

依据基尔霍夫近似，推导出一维高斯随机粗糙面四阶统计特性解析式，并获得脉冲波入射下粗糙面双点双频四阶矩互相关函数.数值计算不同入射角，不同高度起伏和相干长度，随机粗糙面双点双频四阶矩互相关函数随相干频谱带宽频差，散射角的变化情况.计算结果表明，高度起伏和相干长度对粗糙面散射四阶统计特的影响很大，粗糙面越光滑，在镜反射方向有最大的四阶矩散射峰值和小的相关带宽.随着粗糙度增加，随机粗糙面脉冲散射的四阶矩的相干分量减弱，展宽现象明显；而相干带宽频差越大，四阶矩衰减越快. 关键词： 四阶矩统计特征 双点双频互相关函数 随机粗糙面 脉冲波散射

The fourth order moment statistical characteristic of the laser pulse scattering on random rough surface

According to Kirchhoffs approximation，the fourth order moment statistical characteristic of the pulsed wave scattering by random rough surfaces is investigated numerically. As a special application，the fourth order moment （FOM） is simplified to obtain mutual correlation functions of the the two positions and two frequencies of pulsed wave scattering by random rough surface. It is found that the distributions of FOM vary with the coherence bandwidth frequency difference and scattering angle for different incidence angles. The numerical results show that the mean of fluctuating heights and coherent length of random rough surfaces have also an important influence on FOM. Generally，the largest scattering value and smallest coherence bandwidth of the FOM occur at the specific directions. That is to say，the FOM will have a lower coherent component and its distributions of scattering angles will be broadened in relation to the rugged surface. Meanwhile，the FOM decreases rapidly when there is a bigger coherence bandwidth frequency difference.