研究熔石英光学元件亚表面纳米杂质粒子的特征和分布规律

项目名称： 研究熔石英光学元件亚表面纳米杂质粒子的特征和分布规律

项目编号： No.61505171

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 无线电电子学、电信技术

项目作者： 高翔

作者单位： 西南科技大学

项目金额： 21万元

中文摘要： 熔石英光学元件亚表面的纳米杂质粒子能够吸收激光能量，在远低于本征损伤阈值的激光辐照条件下引起损伤的发生，因而成为限制大口径高功率激光系统发展的一个关键因素。为了探索特定区域损伤的起源，有必要研究潜在纳米杂质粒子的特征和分布规律。建立联系杂质粒子物理特性和非线性吸收系数的阈值方程，结合损伤实验分析杂质粒子在热爆炸过程中吸收系数的非线性变化规律。采用光热偏转和暗场成像技术分别对熔石英光学元件表面特定区域的吸收和损伤阈值进行测量，并基于Mie理论和阈值方程分析该区域潜在杂质粒子的复折射率和尺寸，进而通过SIMS分析损伤区域的杂质种类以揭示潜在的杂质特征。测试不同能量密度辐照下熔石英光学元件表面损伤统计规律,建立通过损伤几率提取损伤密度的理论模型以获取各种杂质粒子的分布规律。本项目的研究有助于认识最易诱导损伤的杂质粒子的特征和分布，同时为提高光学元件的抗损伤能力提供了指导。

中文关键词： 熔石英光学元件；纳米杂质粒子；光热偏转技术；损伤密度

英文摘要： The nanoscale impurities on the subsurface of fused silica, absorbing the light, can initiate breakdown at fluences or intensities far below the intrinsic damage threshold，which remains a key limitation for large aperture, high-power laser systems. It is nesscessary to investigate the nature and distribution of potential impurities for indentifying the origin of damage. The threshold equation associated with the physical properties and nonlinear absorption coefficient has been development.According to damage test,the nonlinear absorption coefficients of different impuritities have been investigated during thermal explosion. The absorbtivity and damage threshold in a specific area on the suface of fused silica has been detected,respectively, with the technology of photothermal deflection and dark-field imaging.Furthmore, considering the Mie theory and threshold equation, the complex index and size of nanoscale impurities in the specific area can be analyzed. Furthermore,by the detection of species of impurities from SIMS, the nature of potential impurities can be acknowledged. The statistical behaviors of laser damage on the surface of fused silica have been test under the irraddiation of different fluences。Based on binomial distribution, the damage probability versus laser fluence can be fit. In order to obtain the distribution of nanoscale impurities, a model for extracting the damage density from the curve of damage probability has been present. The research for this project will provide a critical acknowlede of the nature and distribution of the most hazardous nanoscale impurities and also a important direction for improvement of damage resistance.

英文关键词： Fused silica;Nanoscale impurities;Photothermal deflection;Damage density