同轴非稳腔凸镜的涡流管冷却及稳定性

A vortex tube cooling system of unstable resonator and its stability

关键词:  二氧化碳激光器  同轴非稳腔+  光腔稳定性+  涡流管+

Key words:  Carbon dioxide laser  Unstable resonator+  Resonator stability+  Vortex tube+

摘要:

横向激励大气压(Transversely excited atmospheric,TEA)CO2同轴非稳腔激光器凸镜因热积累发生变形,对输出光束质量影响显著。为了改善TEA CO2同轴非稳腔激光器输出光束质量,采用涡流管低温气流冷却凸镜。应用有限元方法模拟计算了涡流管低温气流冷却对凸镜镜面热变形的影响,计算结果表明,随着激光器工作时间的延续,涡流管冷却对TEACO2同轴非稳腔激光器凸镜热积累导致的变形有较为显著的改善。实验实时监测了单脉冲平均能量18.3 J,激光器工作频率3 Hz,连续运行300 s,的光束模式。没有涡流管冷却时衍付极限信数因子β值由3.52变化到6.94,采用涡流管冷却后,β值仅由3.50变化到3.88。结果表明,涡流管冷却对提高光束质量稳定性有明显效果。

Abstract:

The beam quality of the unstable resonator of TEA CO2(Transversely Excited Atmospheric Pressure CO2 Laser) coaxial output laser is deteriorated remarkably by the thermal accumulation of the convex mirror.In order to improve the beam quality,a vortex tube cooling system of convex mirror was adopted.The time-varying thermal deformation of convex mirror with a vortex tube cooling system in high energy laser is analyzed by finite element method.The results indicated that the vortex tube cooling system reduces the deformation remarkably with the continuous laser working.The divergence angle was measured experimentally at a average pulse energy of 18.3 J under condition of different frequency and using vortex tube cooling system or not at real time.And the value of β was studied,too.The results show that the value of β was changed from 3.52 to 6.4 without the vortex tube cooling system and from 3.50 to 3.88 with the cooling system under the work frequency of 3 Hz and lasting work time of 300 s.