真空蒸镀光学元件面形变化机制研究
文献类型：学位论文
| 作者 | 祝沛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 朱健强 |
| 关键词 | 面形 基底应力 薄膜应力 水致应力 光学加工 |
| 其他题名 | Research on mechanism of optical surface deformation in vacuum evaporating deposition |
| 中文摘要 | 在惯性约束聚变（ICF）装置中，为了提高激光驱动系统的输出光束质量，需要对光学元件的面形进行严格控制。为了提高光学元件性能，元件表面需要镀制激光薄膜。然而镀膜后元件面形会发生改变。目前针对薄膜应力造成的形变的研究工作较多，通过调整沉积参数来减小薄膜应力，控制光学元件的面形变化。在实际的工艺研究中发现两个问题：首先，在真空蒸发镀膜之后，部分光学元件发生了与薄膜应力作用不符的无规则形变，面形难以控制；其次，在镀膜元件的存放过程中，面形受各种环境因素影响较大，其中的规律尚未得到明确。本文将结合这些难点，分别开展一系列基础性研究工作。 首先，对真空蒸镀过程中，基底自身应力的分布状态变化进行了分析。通过建模分析表明，由装夹产生的基底自重应力和温度梯度形成的热应力对镀膜元件的面形影响很小，可忽略不计。通过实验证明，基底在材料熔制和研磨加工中形成的残余应力是无规则形变的来源，并验证了在光学加工流程中加入精密退火工序，可有效消除基底残余应力，有效降低蒸镀热过程中基底的无规则形变。 针对镀膜后变形最严重的高反射光学元件，分析了激光高反膜的应力性质。实验结果表明激光高反膜应力通常表现出压应力，致使镀膜元件面形趋于突起。 研究了镀膜元件在存放过程中面形的变化机制，明确SiO2薄膜多孔的微结构吸附环境中水分子形成水致应力，使薄膜残余应力发生变迁。水致应力源于：水分子偶极矩相互排斥的物理机制和水合作用的化学机制。一系列跟踪实验被设置用于研究薄膜应力的变化趋势，结果表明随存放时间的延长，薄膜应力由压应力向张应力转变，镀膜元件面形向凹陷方向变化；随环境湿度的升高，水致压应力将增大，元件形变趋于凸起，反之亦然。 |
| 英文摘要 | In order to improve output beam quality in ICF device, the optical element figure must be controlled strictly. Laser films should be deposited on optical element surface to improve optical performance. However, the figure will be changed after deposition. Presently the deformation induced by film stress is investigated, and people attempt to reduce film stress by adjust deposition parameter to control optical element figure variation. However, two problems were found in technics research: firstly, irregular deformation was occurred on part optical element which is without film stress effect. Meanwhile, optical figure would be changed with environmental factor alternation during storing time, the regularity is under definition. we have carried out the fundamental research in the following respects: Substrate stress redistribution is analyzed in vacuum evaporating deposition, A model was built to confirm that the gravitational stress formed by sustain and thermal stress induced by temperature gradient influence little to optical element figure after deposition. The experimental results show that the irregular deformation of the substrate is caused by the residual stress and can be eliminated by fine annealing the substrate before polished. The stress nature of high-reflection film is analyzed, and the experimental results show that the compressive stress in high-reflection film will made optical element convex. The deformation mechanism during storing time is investigated，which shows that film stress is changed by water-induced stress formed by the adsorption of water vapor molecules on the porous SiO2 film. The water-induced stress is formed by two mechanism: electrostatic dipole interactions between the adsorbed water molecules and hydration of silica. A series of experiment is designed to investigate the transition tendency of film stress, and the results show that a compressive-tensile stress transition is observed during the storing time which made the figure concave progressively; and the water induced compressive stress will be changed with humidity with the same tendency. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16398]  |
| 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 | 祝沛. 真空蒸镀光学元件面形变化机制研究[D]. 中国科学院上海光学精密机械研究所. 2008. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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