【作者】 谭冰；

【导师】 左都罗；

【作者基本信息】 华中科技大学 ， 物理电子学， 2008， 硕士

【摘要】 高能激光是激光发展的重要方向之一,在工业加工,航天,国防等领域应用广泛。高能TEA CO2激光效率高,功率高,光束质量好,是高能激光研究的重要对象,最近国际上的热门研究领域激光推进,TEA CO2激光器被认为是最可选激光器。激光器光束模式是影响这种远距离传输应用的关键因素。本文主要针对TEA CO2激光器光束模式改进以及激光传输特性做了相关方面的工作。在总结了激光光束的评价方法的基础上,对实验室中不同结构谐振腔(平平腔,平凹腔,平面-角隅镜以及非稳腔)输出光束进行了测量和分析,发现M=4虚共焦非稳腔结构的高能量TEA CO2激光在单脉冲能量在12J,其衍射极限因子β在2～3之间,具有较好的光束质量。光束质量除了横模,谱线和纵模也是很重要的参数,而TEA CO2激光由于功率大,谐振腔长,所以一般为多纵模输出。我们用注入锁定的方法使激光器在横模和纵模匹配的条件下在一定概率下实现了单纵模运转。实验结果表明,在TEA CO2激光器注入锁定的情况下,TEA CO2激光器的输出激光脉冲宽度比自由运转时变宽,脉冲峰值功率降低,并且激光脉冲产生的时间提前。在实验室环境下进行了脉冲CO2激光束传输的初步实验,由于水气吸收和粉尘散射的影响,将脉冲激光传输至25m和50m,其传输效率为85%和55%,并对强激光在大气中的传播进行了理论上的分析,能比较好地解释实验结果。以上研究结果,为高品质TEA脉冲CO2激光器的研制和脉冲CO2激光束的远程应用作了初步的准备。更多还原

【Abstract】 High energy laser is the most important area of laser technology and it has wide application on industry, aerospace, military and so on. TEA CO2 laser which is characterized by high efficiency, good beam quality and high average power takes an important position in high energy laser. It is considered as the most favorable laser for the application of laser propulsion which is increasingly studied recently. Beam mode is a key factor that has significant influence on this kind of energy transportation application. The thesis mainly focuses on the control of beam mode of TEA CO2 laser and its propagation characteristics.First, the methods how to evaluate the beam quality of high power laser were summarized. Then we calculated and measured different cavities in laboratory including plano-plano cavity, plano-concave cavity and unstable cavity, then we made theoretical analysis. Theβfactor of unstable cavity of TEA CO2 laser with M=4 is between 2～3, and with single pulse energy of 12 Joules. Besides transverse mode, spectrum and longitude of the beam are important parameters of a laser, however TEA CO2 laser usually has a long resonator, and work on multi longitudinal mode. Single longitudinal mode operation can be realized in locking injection with traverse and longitudinal matching. The experimental results show that under injection locking the pulse appeared in advance, the temporal of laser pulse prolongs, and its peak power lowers. And we did primary high power pulsed laser transition experiments, the pulsed energy propagated to 25m and 50m with energy efficiency of 85% and 55% in conditions of high humidity and powder, and theoretical analysis agreed with the experimental results.The above results are useful for studying high quality of high power pulsed CO2 laser and make primary preparation for its long range applications.更多还原