中国激光, 2014, 41 (4): 0402008, 网络出版: 2014-03-14
2 kW射频板条CO2激光器输出光束整形特性研究
Shaping Characteristics of Output Beam of 2 kW Radio Frequency Slab CO2 Laser
激光光学 射频板条CO2激光器 离轴负支非稳腔 简单象散光束 光束整形 空间滤波器 laser optics radio frequency slab CO2 laser off-axis negative-branch unstable resonator simple astigmatic beam beam shaping spatial filter
摘要
针对2 kW射频板条CO2激光器离轴负支非稳波导混合腔的近场分布存在较多高空间频率分量,导致聚焦后会产生不可忽略的旁瓣,无法直接应用于激光加工的问题,对谐振腔的近场分布使用特征向量法和矩形波导的解析表达式进行了数值模拟和实验研究。并结合Collins公式研究了输出光束整形过程中光场分布的变化和整形系统中空间滤波器的优化设计。理论和实验结果表明:激光器输出光束在整形前为有较多高空间频率振荡的长条形的简单象散光束。通过带空间滤波器的整形系统消除旁瓣,并将初始的长条形的简单象散光束整形成近圆形、近基模高斯分布的光束。整形后的光束非稳方向的光束质量因子M2为1.1,波导方向M2为1.08。
Abstract
For side lobes caused by the high spatial frequency oscillations in the output beam of off-axis negative-branch unstable-waveguide hybrid resonator of 2 kW radio frequency slab CO2 laser, the near-field distributions of the hybrid resonator are investigated by numerical simulation and experimental method. The eigenvector method and the analytical expression of the rectangular waveguide resonator are used for the numerical simulation. The variations of intensity profiles of the output beam in the beam shaping system and the spatial filter design of beam shaping system are also studied with Collins integral expression. The results show that the laser emits a simple astigmatic beam with a rectangular intensity distribution. The unshaped beam has severe high spatial frequency oscillations in the unstable direction. The side lobes of the unshaped beam are eliminated and the unshaped beam is changed into an approximately circular, nearly Gaussian-shaped beam beam by a beam shaping system with a spatial filter. The shaped beam propagation factor M2 is 1.10 in the unstable direction and M2 is 1.08 in the waveguide direction.
肖龙胜, 唐霞辉, 秦应雄, 周泳全, 杨卫红, 韩蒙蒙. 2 kW射频板条CO2激光器输出光束整形特性研究[J]. 中国激光, 2014, 41(4): 0402008. Xiao Longsheng, Tang Xiahui, Qin Yingxiong, Zhou Yongquan, Yang Weihong, Han Mengmeng. Shaping Characteristics of Output Beam of 2 kW Radio Frequency Slab CO2 Laser[J]. Chinese Journal of Lasers, 2014, 41(4): 0402008.