| 题名 | 等离子体烧蚀对光学薄膜元件性能及传输光束影响研究 |
| 作者 | 郭猛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 李大伟 |
| 关键词 | 激光预处理 等离子体烧蚀 光束调制 功率谱密度 |
| 其他题名 | Influence of Plasma Scalds on the Performance of Optical Coatings and the Transmission Laser Beam |
| 中文摘要 | 光学薄膜元件是激光系统的重要组成部分，随着激光器输出能量的不断提高，对光学薄膜的抗激光损伤能力提出了越来越高的要求，激光预处理是提高基频反射膜抗激光损伤能力的最为有效方法之一。激光预处理技术为有损处理，在其过程中会对样品造成一定程度的损伤破坏，等离子体烧蚀是基频反射膜激光预处理中最为典型的损伤形貌。等离子体烧蚀形成后对薄膜元件光学特性影响有限，并且在后续脉冲作用下较为稳定，实际应用中光学元件表面允许一定程度的等离子体烧蚀存在，但等离子体烧蚀会对经过基频反射膜表面的传输光束产生一定程度的调制，同时也可能对薄膜元件的性能产生严重影响。因此，研究烧蚀对传输光束的调制及对薄膜元件性能的影响对于制定激光预处理工艺与指标、评价激光预处理成功与否以及激光预处理元件的合理充分使用都有一定的参考价值与实际意义。本文针对等离子体烧蚀对光束调制及对薄膜元件性能影响主要具体工作如下： （1）建立了光束质量测试系统并给出了其使用条件和使用方法，利用该系统分别记录了反射膜样品表面有、无等离子体烧蚀时传输光束的空间强度分布，分析了等离子体烧蚀对基频反射膜元件传输光束的调制特性，并总结了其随传输距离的变化规律； （2）提出了使用功率谱密度（PSD）的方法进行评价，并详细给出了受调制后的光束强度空间分布的一维和二维PSD计算方法；并分析了等离子体烧蚀产生前后基频光学薄膜元件传输光束的PSD曲线变化，证明了传输光束PSD变化与元件等离子体烧蚀特性之间的关联； （3）采用表面轮廓仪以及扫描电镜等多种手段分析了激光预处理过程中形成的等离子体烧蚀的结构及其尺寸，并根据测试结果构建模型，模拟分析在等离子体烧蚀对元件传输光束近场位相的调制和远场强度的影响； （4）介绍了面形表征的手段，常用的检测方法以及面形评价的一些参数，然后针对等离子体烧蚀对薄膜面形的影响，结合工程任务的需要实际测试了800×400mm以及φ50口径偏振片在预处理前后面形的参数的变化，以及预处理能量对面型参数变化的影响。 |
| 英文摘要 | Optical coatings are essential to high power laser systems. With the power of laser increasing rapidly, laser-induced damage threshold (LIDT) of optical coatings is urgent supposed to be improved. Laser conditioning is one of the most effective methods to improve laser damage resistance of optics, during which some damage will be created, and for high reflective thin film plasma scalds is one of the typical damage morphologies. In practical application, plasma scalds, which affect the function of optics slightly, are permited to exist in certain degree. However, plasma scalds could modulate transmission laser beam and affect the performance of optical coatings. So the research on influence of plasma scalds on laser beam modulation and the performance of optical coatings is quite significant for laser conditioning. Following are the main contents of the dissertation: （1）The laser beam modulation testing system is set and the operating procedure are also given. With the system, the spatial intensity of laser beam reflected by samples with and without plasma scalds is recorded. The transmitted beam is analyzed and the evolution of transmission of laser beam with distance is summarized. （2）The power spectral density is used to evaluate the downstream laser beam modulated by plasma scalds. Then the calculation of 1D-PSD and 2D-PSD is provided in detail. Through analyzing the PSD of the transmitted laser beam before and after laser conditioning, the relevance between plasma scalds and the PSD of transmitted laser beam is verified. （3）The plasma scalds are characterized by Surface Profiler and SEM, and model of plasma scalds is built. Then the near field phase modulation and the far field intensity modulation caused by plasma scalds are calculated and discussed. （4）The means and parameters of evaluating optical surface metrology are introduced, and some practical optics are measured and analyzed before and after laser conditioning. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16911]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 郭猛. 等离子体烧蚀对光学薄膜元件性能及传输光束影响研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
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