摘要
针对2kW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。
For side lobes caused by the high spatial frequency oscillations in the output beam of offaxis negative branch unstablewaveguide hybrid resonator of 2 kW radio frequency slab COz laser, the nearfield 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 Gaussianshaped beam beam by a beam shaping system with a spatial filter. The shaped beam tion factor is 1.10 in the unstable direction and M2 is 1.08 in the waveuide direction.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2014年第4期38-44,共7页
Chinese Journal of Lasers
基金
高等学校博士学科点专项科学研基金(20110142110046)
中央高校科研业务(HUST2013TS048)
武汉市晨光计划(2013070104010006)
关键词
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 simpleastigmatic beam
beam shaping
spatial filter
