论文部分内容阅读
激光非均匀加热效应严重影响着激光能量的远距离传输。对于矩形平顶光束,在有轴向流存在的情况下,采用光束旋转的方式,借助商用的计算流体力学(CFD)软件Fluent,对激光在内通道中传输的气体热效应问题进行了仿真分析。仿真结果表明,激光束在横截面内的旋转,并不改变光场与气体耦合热效应到达稳态的时间。但是光束旋转效应使得光强非均匀分布带来的二阶像散项基本消失,光程差中只包含沿光轴方向对称的离焦项和球差项。而离焦项是便于校正的,因此光束旋转能够改善激光在内通道中的传输特性。
Laser non-uniform heating effect seriously affects the long-distance laser energy transmission. For the rectangular flat-top beam, the gas thermal effect of the laser propagating in the inner channel was simulated and analyzed by the way of light beam rotation in the presence of axial flow and by the commercial computational fluid dynamics (CFD) software Fluent. The simulation results show that the rotation of the laser beam in the cross section does not change the time when the thermal effect between the light field and the gas reaches the steady state. However, the second-order astigmatic term caused by the non-uniform light intensity disappears substantially due to the beam rotation effect. The optical path difference only includes the defocus and the spherical aberration that are symmetric along the optical axis. The defocusing factor is easy to calibrate, so beam rotation can improve the laser’s transmission characteristics in the inner channel.