【作者】 李荣；

【导师】 徐均琪；

【作者基本信息】 西安工业大学 ， 光学工程， 2010， 硕士

【摘要】 光学薄膜元件是激光系统中极其重要的组成部分,对于大功率高能量激光系统来说,激光薄膜的性能一直是限制其向更高能量或更高功率发展的瓶颈之一。同时,薄膜元件也是红外窗口及导弹导引头等的重要组成部分,激光武器对薄膜元件的破坏可能造成光学系统的功能失效。因此,研究薄膜抗激光损伤特性,不断提高其损伤阈值,对改进激光系统,扩展其在科研及生产中的应用,具有重要的实际价值,同时也成为发展激光防卫武器的基础。本文从材料优化的角度入手,采用搭建的激光损伤阈值测试平台,对多种光学介质薄膜材料的激光损伤特性进行了研究。对光学薄膜损伤机理的研究表明：薄膜材料、厚度、激光波长和脉冲宽度均会影响薄膜的损伤阈值。基于文献分析和对比,结合材料自身的物理特性发现：材料的禁带宽度与激光损伤阈值密切相关,一般禁带宽度越大,损伤阈值越高；对于大多数材料,熔点、机械强度与损伤阈值具有正相关性。本文采用离子束辅助热蒸发技术,在K9玻璃上制备了单层HfO2、ZrO2和SiO2薄膜。基于1-on-1损伤测试方法、散射光强和相衬显微法损伤评判标准,利用1.064μm调QNd:YAG脉冲激光器,脉宽为10ns,对薄膜的激光损伤阈值和损伤形貌进行了测试,结果表明：沉积这三种薄膜时束流大小是影响损伤阈值的主要因素,HfO2的损伤阈值随着束流的增大先增大后减小；制备的HfO2损伤阈值最大为4.25J/cm2,退火后的损伤阈值明显提高；损伤形貌分析显示出,在同一激光能量下,HfO2比ZrO2的抗激光损伤能力强。论文还研究了MgF2、BaF2和YF3的激光损伤特性,结果表明：在同一激光能量下,三种氟化物中YF3抗激光损伤能力最强,BaF2薄膜次之,MgF2薄膜的抗激光损伤能力最弱。通过损伤阈值与薄膜镀制工艺关系的研究,得到了HfO2、SiO2、MgF2、BaF2和YF3的最优工艺参数。更多还原

【Abstract】 The optical thin film components are important parts of the laser systems. For large-power and high-energy laser systems, the laser damage resistance ability of films is also one of the bottlenecks of the development of these systems. Moreover, the thin film components are important parts of the infrared windows and the guide-heads of tactical missile. Once the thin film components are damaged by a high energy laser weapon, the whole optical system may be destroyed. Thus, it is important to improve the laser-induced damage threshold of the thin films for the development of high power laser systems and enlarging of the application of scientific research and production. Meanwhile it is of the theoretical principle to develop the high-energy laser weapon.In order to optimizing materials, laser damage characteristic of the various dielectric materials are investigated by using a set of laser-induced damage threshold (LIDT) testing system., The factors which are film materials, film thickness, and laser wavelength and pulse width influence the LIDT of thin films by studying damage mechanism. Base on literatures analyzing, material characteristics contrasting, it is showed that: a. the material with a higher band gap commonly has a higher LIDT; b. for most materials, the LIDT of films may be positive correlative with melting point and mechanical strength.Several single-layer dielectric thin films such as HfO2, ZrO2 and SiO2 are prepared by ion-beam-assisted deposition (IBAD) on K9 substrate. The damage threshold and damage morphology of these thin films are tested with 1-on-1 testing method, He-Ne laser scattering, phase contrast microscope damage checking method and 1.064μm Q switch Nd:YAG laser system with 10ns pulse width. The results are as following:the deposition rate is the major factor to damage threshold for HfO2, ZrO2 and SiO2. The damage threshold of HfO2 thin-film increases with the deposition rate first, and then decrease; the largest damage threshold prepared with HfO2 is 4.25J/cm2. After annealing, the damage threshold of these films significantly increases; damage morphology analysis shows that the laser damage resistance ability of HfO2 thin film is higher than that of ZrO2 under the same laser energy. In this paper, other materials such as MgF2, BaF2 and YF3 are also studied. The results indicate that for the same laser energy, the film materials are YF3, BaF2 and MgF2 according to their resistance capability to laser. Finally, the optimum process parameters of HfO2, SiO2, MgF2, BaF2 and YF3 are obtained through the relationship between damage threshold and experiment parameters.更多还原