光学元件波前分布对光束质量的影响研究
文献类型：学位论文
| 作者 | 徐林波 |
| 文献子类 | 硕士 |
| 导师 | 卢兴强 |
| 关键词 | 波前畸变 Wavefront aberration 数值模拟 Simulation calculation 光束质量 Beam quality 光路设计 Optical layout design |
| 其他题名 | Influence of wavefront distribution of optical elements |
| 英文摘要 | 在惯性约束核聚变的极端物理实验中，高功率激光驱动装置的输出性能是影响物理实验能否成功的关键性因素。高功率激光束在驱动装置中传播时要经过几百个几何口径大小不一的光学元件，其中的大口径光学元件在光学加工和机械安装等过程中都会引入一系列的波前畸变，这些波前畸变累积到一定程度后会严重影响高功率激光的近场与远场光束质量，限制高功率激光驱动装置的负载能力。研究光学元件波前畸变对光束质量的影响特性对提升高功率激光装置的输出负载能力非常有必要。本文用光传输模拟仿真的计算方法研究了光束传输经过大口径光学元件后在不同空间位置上的光束质量变化，研究结论对指导光学元件加工波前控制以及优化驱动器末级光学元件的最佳排布有重要参考价值。 本论文首先从分段波前的角度研究了大口径光学元件透射波前对高功率激光装置末级输出激光近场质量的影响特性，并在基于小口径光学元件的验证实验平台上对研究结果进行了验证。其次模拟计算了大口径光学元件的波前畸变对神光II八路升级激光装置末级远场光束质量的影响，给出了神光II八路升级如果基于目前在线使用的大口径光学元件的波前加工特性，其激光远场输出指标在理论上可以达到的最好水平。最后，论文同时还完成了对光学元件波前数据处理软件的优化测试。下面具体对本论文研究取得的创新性工作进行描述： 基于衍射光学传播理论，模拟计算了理想光束经过大口径光学元件之后，不同频段波前畸变对近场光束质量的影响。研究结果表明大口径光学元件的波前PV值达到1.36λ时，中频段波前畸变最多会使光束填充因子下降约21%。波前分布特性不同的多片大口径光学元件的波前相消叠加能对光束填充因子最大提高约8%。驱动器末级光路的排布间隔如果控制在6m以上，相对宽松的驱动器末级光路设计可以进一步提高输出激光的平均通量水平。上述研究结果，在小口径光学实验系统中得到了进一步的验证。 研究波前畸变对远场焦斑形状的影响规律。理想情况下，基频光能在5倍衍射极限内包含95%的激光脉冲能量。由于部分光学元件波前数据的缺失，元件在装夹过程中引入的波前畸变情况不明，以及AO在运行期间提供的补偿波前分布特性未知等原因，模拟计算静态波前放大1.5倍情况下的远场光束质量，95%的输出能量集中度在8倍衍射极限左右。 根据本课题研究需要，测试优化了图像采集软件。可以处理计算得到的或者实际测量得到的光束近远场分布与光学元件波前数据，可计算能量集中度、空间能量分布曲线、光束填充因子和空间强度对比度等高功率激光参数，也可对光学元件波前信息进行匀滑、滤波等操作。是一款非常实用的图像数据采集、编辑、比对和分析的计算机软件。; In the extreme physics experiments of inertial confinement fusion, the output performance of the high power laser driving device is the key factor affecting the success of the physical experiment. When high power laser beams propagate in the driving device, hundreds of optical elements of different sizes are required. In the process of optical processing and mechanical installation, a series of wavefront aberrations are introduced in the process of optical processing and mechanical installation. These wavefront distortions will seriously affect the near field of high power laser. The far-field beam quality limits the output load capability of the high power laser driving device. It is necessary to study the influence of wavefront aberration on the beam quality for improving the output load capability of high power laser devices. In this paper, the light transmission simulation simulation method is used to study the beam quality changes in different space positions after beam transmission through large aperture optical elements. The conclusions are of great value for guiding the shape control of optical components and optimizing the optimal arrangement of optical elements at the last stage of the driver. In this paper, the influence of surface measurement data of large aperture optical elements on the near field quality of the last stage output laser of high power laser devices is studied from the point of view of the segmented wavefront, and the results are verified on the test platform based on the small aperture optical element. Secondly, the influence of the wavefront distortion of the large aperture optical element on the beam quality of the last stage of the SG II eight road upgrading laser device is simulated and calculated, and the best water of the laser far field output index can be achieved in theory if the surface machining characteristics of the large aperture optical element which is based on the current online use of the SG II eight path are given. Ping. Finally, the paper also completes the optimization test of the optical element surface data processing software. The following is a detailed description of the innovative work done in this paper. Based on the diffraction optical propagation theory, the effect of the wavefront distortion of different frequency bands on the near field beam quality is simulated and calculated after the ideal beam passes through a large aperture optical element. The results show that when the wavefront PV of large aperture optical elements reaches 1.36λ, the distortion of the mid frequency wavefront will reduce the beam quality by about 21%. The wavefront cancellation superposition of large aperture optical elements with different wavefront distribution characteristics can increase the beam quality by about 8%. If the spacing of the last stage of the driver is controlled above 6m, the design of the last stage light path of the relatively loose driver can further improve the average flux of the output laser. The above results are further verified in the small aperture optical experimental system. The influence of wavefront aberration on far-field focal spot shape is studied. In the ideal case, the fundamental frequency energy contains 95% laser pulse energy within the diffraction limit of 5 times. The results are in good agreement with the optimal experimental results of the SG II eight way upgrading device. Due to the lack of surface shape data of some optical elements, the surface distortion in the clamping process is unknown and the compensation surface distribution characteristic of AO is unknown during the operation. The far field beam quality under the 1.5 times magnification of static wave front is simulated, and the output energy concentration of 95% is 8 times the diffraction limit. According to the research needs of this subject, the test and optimization of the two-dimensional field map data processing software can deal with the calculated or actual measured beam near far field distribution and optical element surface data, and can calculate the high power laser parameters such as the energy concentration, the spatial energy distribution curve, the beam filling factor and the brightness contrast. It can also smooth and filter the wavefront information of optical elements. It is a very practical computer software for image data acquisition, editing, comparison and analysis. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31038]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 徐林波. 光学元件波前分布对光束质量的影响研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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