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题名	光学薄膜激光损伤光斑效应及激光预处理机制
作者	李笑
学位类别	博士
答辩日期	2010
授予单位	中国科学院上海光学精密机械研究所
导师	邵建达
关键词	激光预处理 小光斑扫描 缺陷特征 光斑效应 损伤几率
其他题名	Spot-size effect of laser-induced damage and laser conditioning mechanism of optical thin films
中文摘要	光学元件的损伤逐渐成为激光器向大能量高功率方向发展的瓶颈，尤其是光学薄膜的损伤行为，因为它是激光系统中最薄弱的环节之一。提高光学薄膜的抗激光损伤能力的研究日益重要。激光预处理技术是提高光学薄膜损伤阈值最有效的方法之一。研究激光预处理的机制和分析方法对激光预处理的工程应用具有重要的意义。 本文在光学薄膜损伤测试系统的基础上，建立了小光斑扫描激光预处理系统。以缺陷清除机制为基础，通过缺陷特征在光学薄膜预处理前后的变化来分析激光预处理机制。介绍了两种缺陷特征拟合方法，即光斑效应理论和损伤几率曲线理论。并利用这两种拟合方法对典型薄膜的预处理机制进行了研究。这些典型的薄膜包括HfO2单层膜、SiO2单层膜、HfO2/ SiO2高反射膜和ZrO2/SiO2高反射膜。 假设光学薄膜中引起损伤的缺陷具有确定的损伤阈值并且均匀分布，把缺陷阈值和缺陷密度作为表征缺陷特征的方法，利用光斑效应原理拟合分析光学薄膜多光斑损伤测试的阈值，可以得到预处理前后薄膜中缺陷的变化，进而可以确定光学薄膜激光预处理的机制。通过研究预处理能量密度与预处理增长因子的关系，得到了激光预处理能量选择方法。 假设光学薄膜中引起损伤的缺陷具有高斯分布形式，把缺陷的平均阈值、缺陷的密度以及缺陷的分布函数作为表征缺陷特征的方法，利用损伤几率曲线可以拟合出预处理前后光学薄膜中缺陷的变化，进而可以确定光学薄膜的激光预处理机制。 本文的研究表明，光学薄膜激光预处理对光学薄膜中缺陷的影响主要有两个方面，一方面是把低阈值的缺陷清除出薄膜或转化为高阈值的缺陷；另一方面是伴随着低阈值缺陷的清除和转化，把预处理前薄膜中存在的对光学薄膜损伤不产生影响的高阈值缺陷激活为对光学薄膜的损伤产生影响的缺陷。这两者之间的竞争影响着激光预处理效果。
英文摘要	The advance of large-energy and high-power laser system performance is being impeded by the limitation imposed by the optical components failure, especially by the failure of optical thin film for it is one of the most unsubstantial sections in the laser system. It is increasingly important to enhance the resistance to lasers of the thin films. The laser-conditioning technical is one of the most effectual methods to increase the LIDT (laser-induced damage threshold) of thin films. It is significance for engineer application to investigate the mechanisms and analysis methods of laser-conditioning. In this paper, the small spot scanning laser-conditioning system is founded on the the laser-induced damage threshold testing system. The mechanism of laser-conditioning is analysised by the comparison of defects characterizations before and after laser-conditioning based on the defects removal mode. Two theories including spot-size effect and laser-damage probability curve is introduced. And they are used to investigate the laser-conditioning mechanism of typical optical thin films including HfO2 mono-layer、SiO2 mono-layer、HfO2/ SiO2 HR multilayer coating and ZrO2/SiO2 HR multilayer coating. Supposed that he initiating defects in the film are distributed evenly and have a definite LIDT value, the defects threshold and density are used to characterize the defects. The spot-size effect is utilized to obtain the information of the changes of defects by analysizing the LIDTs of multi-spot tests. Consequently the laser-conditioning mechanisms of thin films are indicated. The choice method of laser-conditioning scanning energy density is obtained by the comparing the relationships between the laser-conditioning increasing factor and the scanning energy density. Supposed that he initiating defects in the film have a Gaussian distribution ensemble, three parameters and a functuon are used to characterize the defects including an average threshold, a threshold standard deviation and a defect density, and a defect ensemble function. The information of these mentioned defect characterization can be obtained by fitting the laser-induced damage probability before and after laser-conditioning. Consequently the laser-conditioning mechanisms of thin films are indicated. It is indicated in this paper that the laser-conditioning effect has two aspects. One is that the lower threshold defect are removed from the film or transformed to be higher threshold defects. Another is that the no-initiating defects with higher threshold before laser-conditioning are activated to be initiating defects after laser-conditioning going with together the removal and transformation of the lower threshold defect. The laser-conditioning effect is influenced by competition of these two aspects.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15636]
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	李笑. 光学薄膜激光损伤光斑效应及激光预处理机制[D]. 中国科学院上海光学精密机械研究所. 2010.

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