高功率横流CO2激光横模随时间变化的测量

Measurement of Temporal Depending Lasing Modes of a High Power Transverse-Flow CO_2 Laser Processor

用激光光束分析仪实时在线测量了一台连续运转的高功率横流CO2激光器的激光横模,获得了较为完整的激光横模随时间的变化关系.测量结果表明,激光输出由两个分离的、非对称的高阶横模叠加组成("双模"),两横模中心相距约8 mm.形成"双模"的原因是串接式谐振腔的前腔和后腔两者的中心轴线不重合以及阴极铜管形变.横模随激光器运行时间的延长而逐步蜕化,呈更高阶和复杂化趋向.初步分析表明,横模的时间变化主要与激光器连续运转过程中腔内气体组分发生的变化有关.

The transverse modes of a high power transverse-flow CO2 laser are on-line measured by using a laser beam analyzer. The temporal evolution of the transverse modes is observed also. The output beams are characterized with ＂double mode＂, i. e. , two higher-order modes spacing 8 mm between the mode centers, and overlapping unsymmetrical configurations. There is evidence to whow that such ＂double mode＂ arises from a misaligned axes of the resonator consisting of two tandem resonators, and a distorted cathode-copper tube. The transverse mode are more degenerated into complicated shapes as the lasing operating duration increases. An initial investigation shows that the temporal evolution of the modes depends on the gaseous component varying in the resonator during the lasing operation.