光学 精密工程, 2014, 22 (8): 2032, 网络出版: 2014-09-15
镜面热变形及吹气流场对光束的联合影响
Combined influence of mirror thermal deformation and blowing on beam prapagation
激光系统 光传输 镜面热变形 热弹性力学模型 N-S方程 标量波动方程 laser system laser propagation reflector surface deformation thermal elastic mechanics model N-S equation scalar wave equation
摘要
采用热弹性力学模型、可压缩流体力学模型和标量波动方程,通过数值模拟定量研究了激光系统中高功率密度光束在弹性支撑反射镜上的热沉积造成的镜面热变形以及镜面变形对光束的影响;同时分析了抑制热晕的对称多孔吹气方式在不同吹气速度下通道流场对光束的影响。然后,通过空间顺序耦合得到了两者对光束的联合影响。实验结果显示:在中心固定的弹性支撑条件下,反射镜的镜面变形有效作用面比较平滑,主要表现为镜面总体倾斜导致光束在远场产生的轻微角度偏转基本可忽略或可预调校正,吹气流场在较低吹速下对光束的影响也基本可以忽略;但在较高流速下,流场由于密度非均匀分布加剧,对光束的影响十分严重;二者耦合后对光束的联合影响基本与单独影响一致。
Abstract
On the basis of thermal elastic mechanic equations, N-S equations and scalar wave equation, the thermal deformation of a reflector in a laser system caused by absorbing beam's energy and its effect on beam propagation were researched. Meanwhile, how much the blowing flow field would affect the beam at different blowing speeds was studied too. Then, the two effects were compared and their combined influence with sequential coupling on the beam was studied. Results show when the thin column reflector is free in constraint and is fixed at center point of back side, its deformation is rather small even radiated with a quite high power density laser beam. The effect of the deformation on beam propagation just displays as making beam tilted slightly in the outgoing direction and it is eliminated by pre-checking the optical system or is neglected directly. The results also show that blowing flow field will affect the beam quiet little when its speed is lower than 30 m/s. However, the effect will grow rapidly when the speed increases to rather high. Finally, it gives the conclusion that the combined influence on the beam is not evident when the blowing speed is not high and it could be omitted simply in most cases.
柳建, 李树民, 赵杰, 王世庆. 镜面热变形及吹气流场对光束的联合影响[J]. 光学 精密工程, 2014, 22(8): 2032. LIU Jian, LI Shu-min, ZHAO Jie, WANG Shi-qing. Combined influence of mirror thermal deformation and blowing on beam prapagation[J]. Optics and Precision Engineering, 2014, 22(8): 2032.