高功率激光系统随机相位屏的特性研究

 高功率激光系统中随机相位屏的统计模型出发，分析了其相位噪声及梯度的一阶和二阶统计性质。研究了完全相干光与部分相干光通过随机相位屏后的传输性质，推导得出部分相干光在经过随机相位屏后，其交叉谱密度的期望等于随机相位屏透过率函数的期望与入射光交叉谱密度的乘积。对该模型下的远场分布进行了数值模拟。结果显示，能量对称分布的完全相干光通过相位干屏后,只有通过随机相位屏透过率函数期望的远场分布是对称的；部分相干光在传输通过随机相位屏后，其谢尔模光束性质不会改变，但光强分布不再具有对称性，且强度明显降低。

Characteristics of random phase screen used in high power laser system

According to the statistical model of the random phase screen,which is employed in the high power laser system,the phase noise and the first and second statistical characteristics of RMS gradient have been studied.The properties of the coherent and partially coherent lights after propagating through the random phase screen are discussed.Using the statistical model,the numerical simulation of the far-field distribution of the beams has worked out.The results show that the far-field distribution of the coherent light that propagates through the phase screen becomes unsymmetrical until the phase distribution satisfies the mathematical expectation.The partially coherent light will hold its Gussian-Schell-model charecter while propagating through the random screen.The character of the Schell-model beam would not change while propagating through the random phase screen.But the random phase noise makes the light intensity decrease and the intensity distribution become unsymmetrical.