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题名:
高损伤阈值高重复频率DPL激光薄膜研究
作者: 代福
学位类别: 博士
答辩日期: 2008-06-06
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 熊胜明
关键词: 重复频率激光 ; 包裹物 ; 有限元 ; 温升 ; 损伤阈值 ; 损伤机理
其他题名: Study on high laser-induced damage threshold coatings at high repetition rate DPL laser
学位专业: 光学工程
中文摘要: 本文在理论上采用有限元ANSYS程序比较系统的模拟分析了激光辐照下光学元件表面的温度变化规律,实验上测试了重复频率10kHzDPL激光辐照下光学元件表面温升和损伤阈值。取得的研究成果主要有以下几点: (1)利用已有的实验数据,结合膜内包裹物热分析理论模型,得出了包裹物Au的吸收截面;计算了重复率激光辐照下膜内包裹物对激光损伤阈值的影响,得出随着重复频率的增加,激光损伤阈值单调下降,产生损伤所需的最小脉冲数则单调上升。 (2)有限元分析了光学元件在重复率激光或连续激光辐照下激光辐照点的温升。发现选取热导率大的基板镀膜可以大大降低激光辐照中心点的温度。空气对流系数在大光斑或长时间辐照时对激光辐照点温度影响较大,在小光斑或短时间辐照时对激光辐照点温度影响甚微,可忽略不计; (3)激光光斑尺寸对辐照点温升有很大的关系。样品表面激光辐照中心点温升与吸收功率密度呈线性关系。在单脉冲作用下,这种关系与光斑大小无关;在重复频率激光辐照下,光斑越大,相同功率密度激光辐照相同时间辐照点温升越高。 (4)实验得出,激光辐照中心点温升与薄膜表面吸收功率密度成正比;白宝石基板相比于石英和K9玻璃基板镀制的高反射薄膜在激光辐照下表面温升最低,激光损伤阈值最高;减小膜层中最外层高折射率膜层中的驻波场峰值可以提高重复频率激光辐照下薄膜的损伤阈值。 (5)分析了激光对光学薄膜的损伤过程,探讨了激光损伤机理。高重复频率脉冲激光辐照下,光学薄膜的损伤是薄膜表面的温升诱发微损伤,然后在后续脉冲的作用下微损伤产生累积,直到破坏薄膜的结构,出现宏观上的灾难性损伤。引发薄膜损伤的激光吸收功率密度存在一个临界值,只有大于该值,薄膜才会在多脉冲的 作用下产生损伤,小于该值,再多的脉冲数也不能使其损伤。
英文摘要: In this thesis, theoretically, we investigated the temperature varieties of optical component surface under laser irradiation by ANSYS program. Experimentally, we tested the temperature rises of optical component surface and laser-induced damage threshold at repetition rate of 10 kHz DPL laser irradiation. The main work and achievement are as following: (1)By the model of damage induced by inclusions in dielectric thin films, with the experiment done by S. papernov et al who deposited HfO2 thin films containing gold nanoparticles on a cleaved fused-silica by e-beam evaporation, the absorption cross-section of gold was obtained. Furthermore, the laser-induced damage threshold induced by inclusions with varies repetition rate was calculated, the result indicated that the relationship between damage threshold and the damage shot number both change near-linearly with the repetition rate increase, while the former is descending, and the latter is ascending. (2)By using ANSYS, the temperature rises of optical component surface at repetition rate or CW laser irradiation was calculated. The result indicated that, for substrate materials, the sapphire whose maximal temperature is lower than that of fused silica or K9, the temperature effect of cross-ventilation is neglectable at small laser facula or little time laser irradiation, but it must be considered when large laser facula or long time laser irradiation. (3)The laser facula is also affect the temperature rises of optical component surface. The relationship between temperature rises and absorption power density is almost linearly. When irradiated by single pulse laser, it is independent of laser facula, but when irradiated by repetition rate pulse laser, the temperature rises is large when irradiated by large laser facula. (4)From the experiment data, also, we know, the relationship between the temperature rises of optical component surface and the absorption power density is near-linearly. The sample whose films deposited on sapphire substrate, whose temperature rises of surface is lowermost, and it’s laser-induced damage threshold is upmost than that of fused silica or K9 substrate. Reducing the peak value of stationary wave field in the outset high refractive index coatings can enhance the laser-induced damage threshold at high repetition rate pulse laser irradiation. (5)Analyzing the laser-induced damage process of films and probing into the laser-induced damage mechanism, we know, under high repetition rate pulse laser irradiation, the temperature rises of component surface place a premium on tiny damage in films, then the tiny damage magnify under latter pulse irradiation, till destroy the configuration of films, the magnificent catastrophic damage appearing. There exist a critical power density that can induce the damage, only exceed the critical power density, the films will damage under latter more pulse laser, if less than it, the films will not damage even any more pulse.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/285
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
代福. 高损伤阈值高重复频率DPL激光薄膜研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2008.
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