光学薄膜的表面热透镜弱吸收测量及定标规范
文献类型：学位论文
| 作者 | 李霞 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 贺洪波 |
| 关键词 | 吸收测量 光学薄膜 表面热透镜 光热信号 激光损伤 |
| 其他题名 | Optical coating absorption measurement and its calibration based on Surface thermal lensing technique |
| 中文摘要 | 吸收损耗是衡量光学薄膜性能的重要指标，特别是对于强激光系统。在现有的光热测量技术中，表面热透镜技术用于光学薄膜吸收测量以其灵敏度高、调节方便、信号信息丰富等优点越来越受到人们的青睐。但是，在其向实用化迈进的过程中还有很多的技术问题有待解决。 论文首先综述了与吸收测量相关的基础知识和发展现状。包括吸收的定义及其与消光系数的关系，薄膜对激光能量吸收的强弱两种机制，薄膜中可能存在的吸收源，薄膜吸收测量方法，国内外发展现状以及表面热透镜技术的优点。 以三层体系模型为例，简要介绍了表面热透镜技术测量薄膜吸收的温度场理论、热形变理论和菲涅尔衍射检测理论，并介绍了自行建立的吸收测量装置。 定标规范和测量技术优化研究是本文的重点。对于定标方法，从泵浦光的衰减系统改进、信号响应线性区衍射环判定的提出、利用大吸收样品相互定标确定测量误差，到不同基底、不同膜厚对测量的影响，进行了详细的实验研究和分析，规范了定标测量。在测量技术方面，测定了装置中泵浦光和探测光的光斑，确定其直径比为1：2；测定了检测探测光直流分量的数字电压表的响应曲线，确定了其线性响应范围；提出定标测量时泵浦光与探测光的光强比问题，给出了光斑对准的微调与粗调的方法；优化了扫描测量参数（单点等待时间），使其能实际运用于常规测量。论文还讨论了调制频率与热波在样品中的扩散深度及与光热信号之间的关系，进行了变频率实验，为下一步的理论建模工作打下了基础。 结合采用离子束技术制备的薄膜样品的吸收扫描测量结果，分析了光热性质均匀性与激光损伤阈值的关系；探讨了吸收测量与激光损伤阈值测量中可能不同的吸收机制。利用吸收测量系统对大吸收样品进行了低调制频率下的变频率损伤实验，通过对破斑形貌的分析，研究了低调制频率下激光损伤的热力发展，并结合实时记录的光热信号，既分析了光热信号所表征的物理内涵，又对光热信号在损伤分析中的实际运用有重要促进作用。 论文最后重点总结了主要工作内容与创新点，并从热力物性分析、快速大面积成像检测、三维分辨测量和三倍频吸收测量四个方面，对薄膜吸收测量的今后发展、丰富和完善作了展望。 |
| 英文摘要 | Absorption is one of the significant characters to evaluate the performance of optical coatings, especially for high power laser related systems. Among modern photothermal techniques, surface thermal lens technique is becoming more and more popular, contributing to its high sensitivity, handleability, and plentiful information of signals. When it is becoming practical, there are still have many problems needed to settle down. At first, there is a briefly presentation about foundation and development of absorption measurement. It is including the definition of absorption and connection between it and extinction coefficient; strong and weak absorption two kinds of, mechanisms, absorptive sources in optical coatings, absorption measuring methods and the current progress of them in our nation and abroad, and the advantage of Surface Thermal Lensing (STL) technique. Taking three-layers model as an example, theories involved with STL technique are stated shortly and orderly, including temperature distribution, thermal expansion and Fresnel’s diffraction. After this, the absorption apparatus established by our research group is drawn briefly. Investigation of calibration and measuring techniques are the main parts of this paper. Calibrating measurement are descried in experiments and analysis from the improvement of pump light attenuation to diffraction pattern judgment of the linear response; from calibration of non-weak absorptive samples each other to the influence of different substructures and coating thickness on measuring outputs, finally, the rule of calibration is set. Diameters of pump and probe optical spots are measured-the ratio of them is 1:2; the curve of the digital voltage meter responding to the probe light DC signal is done to ascertain the linear ranges. The match problem of optical intensity between pump and probe is put forward in calibration. In addition, the optical spots alignment is described respectively for tiny and big displacement situations. One-point-waiting-time is changed in scanning for practical employment. Relationship between modulation frequency and thermal diffusion depth is developed, and the same thing is done between modulation frequency and photothermal signal. After the theory analysis, frequency variation experiments are performed, and the results set ground for further theory modeling work in this field. Based on the scanning results of a series of samples treated by ion technique, the uniformity of photothermal characters are connected to LIDT (Laser-Induced Damage Threshold), and the different absorption mechanisms between STL and LIDT measurement are figured out. There are a group of frequency variation damage experiments with the STL apparatus. The course of damage in low frequency from thermal to forceful characteristics is analyzed through observing the morphology of the damaged spots. Simultaneously, the employment of photothermal signals on analysis of LIDT is developed, depended on understanding the signals recorded during the experiments. At the end of this paper, whole contents and innovative points are summarized. The suggestions about the following work are given, including four promising aspects, namely: analysis of thermal and forceful characteristics of the optical coatings, time efficiency and wide area photothermal imaging detection, lengthways solution detection and measurement of absorption of 355nm optical energy. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16481]  |
| 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 | 李霞. 光学薄膜的表面热透镜弱吸收测量及定标规范[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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