高功率激光损伤阈值等效口径分析技术研究
文献类型：学位论文
| 作者 | 王巍 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 刘德安 |
| 关键词 | 高功率激光损伤，等效口径外推，损伤概率曲线，Monte Carlo方法, 功能性损伤阈值 |
| 其他题名 | Extrapolation of Laser damage threshold of different sizes optical component in high power laser system |
| 中文摘要 | 光学元器件的损伤阈值一直是制约高功率激光驱动器高通量负载能力的技术瓶颈，而实现大口径光学元件抗损伤性能的科学评估是提高损伤阈值的关键环节。美国劳伦兹利弗莫尔国家实验室在国家点火装置建造过程中不断将小口径激光损伤测试装置发展为大口径测试平台，为实质性提高光学元器件损伤阈值起到关键作用。目前，我国高功率激光装置还未达到聚变级高通量运行条件，中等通量以下的实验数据不足以支撑高通量运行环境中光损伤阈值的真实评估。同时，由于技术实现难度和经费的限制，国内将在很长一段时间内难以实现大口径光学元件损伤阈值测量实验平台。因此，如何充分利用现有小口径光损伤测量装置，通过一定的科学外推，实现大口径光学元件损伤性能的综合评估具有重要应用前景和科学意义。本文以光损伤概率为分析模型，探索性开展小口径光损伤外推预测大口径光损伤性能的研究方法，同时分析了光束时空分布特性对光损伤概率的影响关系。主要研究内容和结果为： 1.在现有损伤阈值分布模型的基础上，提出了用Weibull函数模型来描述缺陷损伤阈值分布的物理模型，从而更加准确的描述了缺陷损伤阈值分布特性，更为符合损伤概率实际分布情况。利用新提出的损伤阈值模型推导出光学元件损伤概率曲线表达式，为更加科学的评估光损伤阈值提供了新的物理模型 2.针对光束口径对光损伤概率分布特性的影响关系，建立了由小口径损伤阈值外推到大口径损伤阈值的普适性物理模型，为等效口径光损伤阈值评估提供了关键理论。在不同空间分布特性的光束辐照条件下，基于Monte Carlo方法仿真验证了等效口径外推方法的准确性与可靠性，并模拟分析了多种杂质缺陷类型下的等效外推结果。该研究对实际应用中大口径光损伤阈值的科学评估具有参考价值。 3.分析了光束质量对光损伤概率的影响，建立了多发次辐照下光学元件损伤概率的表达式，并数值模拟了光束空间与时间分布特性对损伤概率的影响，提出将元件损伤阈值的概率等效叠加到光束质量中的等效光场概念；基于等效光场概率，结合功能性损伤阈值的分析理论，得出了光束空间分布和时间分布特性对光学元件损伤概率的影响关系。该研究结果为光学元件损伤概率的综合评估提供了新的研究方法。 |
| 英文摘要 | The performance of high power laser system used for inertial confinement fusion is limited by the damage threshold of optical component under high fluence irradiation. To estimate the laser damage threshold is an important process in order to improve the laser damage resistance performance of optical component. Scientists in Lawrence Livermore National Laboratory are always improving the laser damage test equipment to test larger optical sample. This improvement is very important to increase the laser damage threshold of optical component. Now the high power laser system for inertial confinement fusion in our country is not capable to produce enough high fluence laser. Low fluence laser produced right now is not able to take the place of high power laser to test optical damage performance. The experiment result of laser damage threshold on the base of small diameter laser damage test is not able to predict the performance of large optical component under high fluence. Due to the limits of fund and technology, it is difficult to equip the laser damage equipment for large optical component in the near future. So it is important to estimate the performance of large optical element based on the small area sample damage threshold test facilities. In this paper, we make a progress to predict the damage performance of large optical component from the result of optical component damage test under small area laser irradiation and discuss the relationship between laser beam quality and damage probability curve. The main content and results are as follows: 1.Based on laser damage research, we develop a new defect damage model based on Weibull distribution to depict the defect damage performance under laser irradiation. The new model can overcome the disadvantage of old models such as degenerate, non-degenerate, normal and power model. We use the new model based on Weibull distribution to derive the damage probability curve and then give the extrapolation method both from small area laser damage to large area situation and different type of irradiation laser. This result provides a more scientific physical model to estimate the laser damage performance. 2.We propose a widely used physics model to extrapolate the damage threshold from small area test to large area component in practical use. It is an important step to predict laser damage performance of large area optical component. We use Monte Carlo method to simulate the reliability and accuracy of the extrapolation procedure under the irradiation of different laser beams. We give the simulation procedure based both on one kind of defect model and two kinds of defect model. This procedure is a guide for extrapolation of threshold in daily work. 3.We take the quality of laser fluence into consideration to predict the change of damage probability curve in normal case. We deduced the equation of damage probability curve under multiple irradiation case. By introducing the concept of equivalent optical field, we add the statistical property of laser damage threshold to the laser field for the purpose of simplify the statistical problem. We use Monte Carlo method to show the influence of laser fluence instability on the damage performance and give the relation between the irradiation number and damage probability. Based on the functional damage threshold concept, we also simulate the relation between the irradiation times and damage probability. This research result provides a new method to analyze the damage probability of optical component. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16732]  |
| 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 | 王巍. 高功率激光损伤阈值等效口径分析技术研究[D]. 中国科学院上海光学精密机械研究所. 2012. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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