激光内通道传输气体热效应对光束质量的影响

针对内通道中的稳态热晕效应与气体的吸收系数,光束与气体的作用长度及光束自身强度分布的关系,从稳态条件下的热传导方程入手,建立了一套激光在内通道传输时气体热效应对光束质量影响的模型.利用该模型计算了环形光束在内通道传输时,光束横截面上的气体温度分布及其引起的最大光程差、波前相位均方根、远场Strehl 比等光束质量参数与激光自身遮拦比、轴向气体速度的关系.模型中对气体温度分布的近似计算与理论的结果基本一致.该模型能够为激光控制系统的设计和性能评估提供一个定性的参考.

Thermal Effects on Laser Beam Quality in the Inner Channel Propagation

According to the relationship between the thermal effects and absorption coefficient of the inner channel gas, reaction length and intensity distribution of the laser beam, a model of thermal effects on laser beam quality in the inner channel propagation is established based on the steady-state heat-conduction equation. The relationship among the temperature distribution, the optical path difference across the beam, RMS phase distortion, Strehl ratio in the far-field and the obscuration ratio, the axial flow velocity is calculated. The approximate calculation results of the temperature distribution are about the same as the theoretical results. The model provides a qualitative reference for the laser beam control system design and performance evaluation.