摘要本文从理论分析、数值模拟和实验方面研究了波长为1064nm脉宽分别为 1ms和10ns的单脉冲激光致K9玻璃的损伤机理。分析了激光作用材料的各种损伤机理，包括本征吸收、热应力损伤、雪崩电离、多光子吸收及杂质诱导损伤等。运用有限元法数值计算了两种脉宽激光辐照K9玻璃的温度场和热应力场分布，分析两种脉宽辐照K9玻璃的不同损伤机理。结果表明，毫秒脉宽激光辐照下K9玻璃的损伤由热应力造成，且表现为前后表面的共同损伤；纳秒脉宽激光辐照下K9玻璃的损伤主要由等离子体烧蚀及对材料表面的冲击造成，主要表现为前表面的熔融烧蚀斑。结合毫秒和纳秒量级脉宽激光辐照K9玻璃的实验损伤形貌，进一步明确了两种脉宽激光对K9玻璃的损伤机理。本文研究结果可为不同脉宽激光的应用提供理论参考，并帮助预知不同脉宽激光应用下脆性材料的损伤情况。65272

毕业论文关键词：激光损伤机理，有限元模拟，K9玻璃，毫秒激光，纳秒激光

毕业设计说明书（论文）外文摘要

Title    Research of pulsed laser-induced damage mechanism of K9-glass                     

Abstract

In this paper, we research  the laser-induced damage of K9-glass under the irradiation of laser beam with the wavelength of 1064nm and the pulse duriation 10ns 、1ms, through theoretical analysis, numerical simulation and experimental study methods. Analysis of the role of materials of all kinds of laser damage mechanisms, including the permit absorption, thermal stress damage, avalanche ionization, multiphoton absorption and impurity-induced damage. Through finite element method we compute the temperature field and thermal stress field distribution of K9 –glass under two different pulsed laser irradiation ,and then analysis their damage theories. The results indicate that under millisecond pulsed laser irradiation, both front and rear surfaces of K9-glass are damaged due to thermal stress theory; under nanosecond pulsed laser irradiation , K9-glass was damaged by the plasma ablation and shock to the material, which mainly for the front surface melting ablation spot. Combined with the laser-induced damage morphoiogy of K9-glass under millisecond and nanosecond pulse laser irradiation, we further clarify the mechanism of K9-glass of two kinds of pulsed laser. The research results can be applied for different pulsed laser applications to provide a theoretical reference and help predict different pulse laser applications of brittle material damage .

Keywords  laser damage mechanism, finite element method, K9-glass, millisecond laser, nanosecond laser

目   次

1 绪论 …   1

1.1 研究背景及意义   1

1.2 激光的发展与应用 …  2

1.3 脉冲激光致K9玻璃损伤的研究现状 …   3

1.4本文的主要工作    8

2 脉冲激光致K9玻璃损伤的理论模型   8

2.1 脉冲激光辐照K9玻璃的温升变化过程分析    8

2.2 脉冲激光辐照K9玻璃的热应力过程分析 …  13

2.3 本章小结 … 22

3 脉冲激光致K9玻璃损伤机理的实验研究  23

3.1 实验装置 … 23

3.2 损伤形貌 … 24

3.3 实验结果的讨论与分析 … 26

3.4 本章小结 … 28

4  总结与展望   29

4.1 总结    29

4.2 展望    30

致谢    31

参考文献    32