激光波前检测与补偿技术研究
文献类型：学位论文
| 作者 | 姜有恩 |
| 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 | 李学春 |
| 关键词 | 波前检测和补偿，夏克-哈特曼波前传感器，质心计算，动态范围，波前重构，变形镜 |
| 其他题名 | Research on Wavefront Sensing and Compensation Technology for a Distorted Laser Beam |
| 中文摘要 | 惯性约束聚变及相关的单项物理实验，不仅需要ICF激光驱动装置有很高的输出能量，而且也需要该输出有良好的光束质量。激光的波前信息是光束质量最重要的参数之一，它不仅决定了光束的聚焦特性：焦斑的尺寸大小和焦斑的能量分布，而且也影响了波长为1053nm的基频光转换到波长为351nm的三倍频光的转换效率。因此实现激光波前检测与补偿是当今高功率激光驱动器中非常重要的研究课题。自适应光学技术发展于上世纪60年代末，目前该技术已经从传统的天文领域扩展到改进高功率激光装置的光束质量上。本文以自适应光学的重要组成器件夏克-哈特曼波前检测技术为核心，同时简单调研了变形镜技术，主要完成了以下几方面的工作： 1. 阐述了夏克-哈特曼波前传感技术, 包括：技术原理、质心计算法、波前重构算法，检测误差和测量动态范围等。并且分析讨论了一些技术细节，如基于Zernike多项式的模式法和Southwell模型的区域法作为波前重构算法的对比，矩阵方程求解方法的选择，以及消除装配误差对波前检测结果影响的方法等。 2. 提出了一种确定质心计算窗口的算法，并采用该算法分别与传统质心计算法、阈值法和权重一阶距法相结合来计算光斑的质心坐标。根据对实验数据进行的研究表明，权重一阶距法计算精度最高，阈值法次之，传统法最差。研究进一步表明，采用合适的Sinc2函数和高斯函数作为权重函数的权重一阶距法，在相对较小的质心计算窗口的情况下就可以获得较高的质心计算精度，因此可以显著提高夏克-哈特曼波前传感器的测量动态范围。 3. 首次提出了一种提高夏克-哈特曼波前传感器测量动态范围的方法，并申请了相关的专利。分析了限制夏克-哈特曼波前传感器测量动态范围的因素，给出了目前已有的提高测量动态范围方法。 4. 基于上述工作完成了一台夏克-哈特曼波前传感器的开发，包括硬件架构和软件设计，并且完成了传感器的参数校正和实验检测。硬件部分采用了适当的机械结构来耦合微透镜阵列和CCD相机。软件设计部分充分利用了1-3中对传感器算法分析和研究的结果，采用了C++编程语言实现图像采集与传输、光斑处理、波前重构和波前信息显示等四大模块的功能。已完成的软件可以输出激光波前轮廓三维分布图，同时可以输出波前PV值，RMS值和模式法多项式各阶的系数等参数。经过误差分析，本传感器测量误差的RMS值在0.07λ以内。 5. 分析了目前实用的波前补偿技术，并且采用Ansys软件对变形镜做了一个补偿能力的模拟，得出了有一定参考价值的数据。 |
| 英文摘要 | High beam quality, as important as high output energy, is required in inertial confinement fusion and other relative physics experiments. The wavefront, which determines the size of the beam’s focus and how the energy is distributed at the focus, is one of the most important parameters of a laser beam. In addition, the wavefront also impacts the conversion efficiency of the light from the fundamental wavelength at 1053 nm to the 3rd-harmonic wavelength at 351 nm. Therefore, the diagnosis and compensation of the distorted wavefront is a key issue in the research field of high power laser system. The practical development of adaptive optics started in the late 1960s. Its main applications have been to compensate for the effects of atmospheric turbulence in ground-based astronomical telescopes and to improve the beam quality of high-power lasers. In this paper, the Shack-Hartmann wavefront sensing method, one of the most widely used wavefront sensing technology, is fully investigated. We also did same research on the wavefront compensation by a simulation. The main research work can be summarized as follows: 1. A complete instruction to Shack-Hartmann wavefront sensing technology is presented, including the principle, centroiding, wavefront reconstruction, detection errors and dynamic range. Some details, such as the differences between zonal estimation and modal estimation, the best solution for a matrix equation and methods for eliminating misalignment effects, are also discussed. 2. A new center-of-mass with optimized detecting window is proposed. Combined with this new method, a full comparison of different centroiding algorithms such as center-of-mass with optimized detecting window, center-of-mass with thresholding, weighted center-of-Gravity, is depicted. We find that weighted center-of-Gravity has the highest precision. Moreover, even with much smaller calculation window, the centroiding precision of the weighted center-of-gravity ( with a Gasussian or a Sinc2 weighting function) is still reliable. Thus, the dynamic range could be improved by using the weighted center-of-gravity. 3. A new method for improving the dynamic range is proposed. Factors limiting the dynamic range are analyzed, and the current method that improves the dynamic range is presented . 4. A instruction to a developed Shack-Hartmann wavefront sensor is made, including the components, software design, calibration and detection results. We take advantage of the above research results to improve the accuracy and dynamic range of the sensor. The data processing software could be divided into four parts: frame grabbing and transmission, focal spots processing, wavefront reconstruction and wavefront information display. The software provides a three-dimension profile of the beam wavefront and some parameters such as PV, RMS, and coefficients of the polynomial in modal estimation. The error RMS of the sensor is no more than 0.07λ. 5. A deformable mirror simulation by using Ansys is presented. Some valuable parameters are obtained from the simulation for wavefront compensation. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16397]  |
| 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 | 姜有恩. 激光波前检测与补偿技术研究[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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