激光通道传输热特性对远场光束质量的影响

 通过仿真计算分析了激光在光束控制系统通道内传输所产生的热效应及其对远场光束质量的影响。激光传播由近轴波方程描述，用快速傅里叶变换技术求解；激光热效应引起的流场密度变化采用完全Navier-Stokes方程计算。计算给出了不同波长、不同吸收系数条件下的远场光斑情况。计算结果表明，在典型的工作条件和状态下，较高能量激光在光束控制系统通道内产生的热效应影响不容忽视，它会明显降低远场目标处的能量集中度，增大光斑的发散。

Effect of thermal characteristics in laser transmitting channel on far-field beam quality

In this paper, the laser thermal effects, produced in the transmitting channel of a beam control system, are numerically analyzed. The laser propagation is governed by the paraxial wave equation, which is solved by the FFT method. The air density variation is calculated with the complete Navier-Stokes equations. The numerical tests are carried out for different wave length of laser and different absorption coefficients of air medium, in order to estimate the effects on the beam quality at far field. The results show that the laser thermal effects in the transmitting channel may largely reduce the concentration of laser energy at far field.