ICF装置光束自动准直系统研究
文献类型：学位论文
| 作者 | 刘代中 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 范滇元 |
| 关键词 | 惯性约束聚变 激光技术 光束准直 像传递 空间滤波器 近场 远场 多程放大器 |
| 其他题名 | Research on Beams Automatic Alignment System of ICF Facilities |
| 中文摘要 | 用于惯性约束聚变（ICF）的高功率固体激光驱动器，是当今脉冲功率最高、装置规模最大的激光系统。这些系统均包含有大量激光器件、光学元件和机械组件。为了确保从振荡器发出的激光束能够稳定、精确地穿过预放大器，主放大器、倍频器和靶室，传输百米以上距离，并准确地照射到微型靶丸上，无例外地配置了光束自动准直系统。光束自动准直系统是保证激光装置高效运行的必要手段，已成为大型激光装置必不可少的重要组成部分。近年发展的新型激光装置，具有超大规模和全新光路结构，如美国国家点火装置（NIF）、法国LMJ装置和我国神光一111装置，对自动准直系统提出了更新更高的要求。它们均采用了方形光束、远场注入和组合式多程放大加助推放大的光路结构，自动准直系统必需相应地发展新技术和新方案，才能满足准直精度、速度及工程可靠性的要求。本论文针对这一需求，系统地总结和完善了自动准直的理论基础，创新性地发展了相关的光、机、电关键技术，在此基础上提出了总体方案设计，并进行了集成演示实验，取得重要突破和满意结果。主要有以下几方面：第一、发展和完善了一套适用于光束自动准直系统的远、近场像传递理论。在总结前人近场像传递理论基础上，首次提出远场像传递概念。用几何光学、衍射光学和傅里叶变换三种分析方法，对多级空间滤波器的近场像传递和远场像传递进行了理论研究。通过自动准直系统的近场探测和远场探测实验，得到了与理论一致的满意验证。第二、创新性地发展了一系列自动准直单元技术，成功地进行了实验验证。针对新型光路结构，发展了一系列近场和远场准直新技术。包括：首次提出用双小光束来准直方形光束旋转的技术；用光栅取样的远场成像技术；用插入正透镜（或负透镜）照明并调整滤波小孔重叠的方法，对四程放大器腔镜进行准直，实现了不在腔镜后面取样的腔镜调整。在探测光束的图像处理方面，提出了在图像预处理的基础上利用椭圆拟合算法及其圆拟合算法来检测激光近场光斑和远场光斑中心，不但图像处理速度快而且中心定位精度高。在四程放大腔内空间滤波器准直方面，不同于NIF方案，创新地采用了近远场交替逐步逼近的调整技术，解决了滤波孔板需要移动和复位的难题，调整机构简化运行效率提高。以上新技术均经过实验考核，取得满意结果。第三、分析了激光靶定位误差，提出利用组合透镜成像系统来提高准直系统的探测精度和减小准直误差。把靶横向定位误差分解为打靶前的光束准直误差和光学元件的稳定性误差，利用均方根法设计了一种把总误差分解到装置各个光学元件的模型。设计了组合透镜成像系统，在不增加探测光路长度条件下，实现了高精度近场探测和远场探测，通过提高探测精度减少了光束准直误差。第四、在准直理论和单元技术研究基础上，对以神光m原型装置为目标的多种实际光路系统，进行了准直方案总体设计，并研制出自动准直系统，成功实现了联机应用。结果表明光束自动准直系统能够在30分钟内完成全光路准直，光束的角度调整精度优于±O.3"，光束中心调整精度优于光束直径的±0.5％，达到预定要求。 |
| 英文摘要 | High power solid-state lasers for application to Inertial Confinement Fusion are the largest laser systems with the highest pulse power today. These lasers all consist of many laser elements, optical components and mechanical assemblies. To ensure the laser pulses come from the oscillator pass through the preamplifier, the main amplifier, the frequency converter and the target chamber over a distance exceeding 100 meters stably and accurately, and irradiate the tine target accurately at last, beams automatic alignment systems have been installed on all of these facilities. The beams automatic alignment system is the necessary condition for laser facilities' running with high efficiency. It has become the important and absolutely necessary part of the kind of laser systems. The newly-built laser facilities developed recently, such as the NIF of America, the LMJ project of France and the SG-III facility of China, which has grand scale architecture and a fire-new optical path, demand newly and highly requirements with beams automatic alignment systems. These facilities have the optical structure with square beams in near field, beams injection in far field and combined amplification with a multi-pass amplifier and a booster amplifier. Beams automatic alignment systems must develop new technologies and schemes accordingly to meet the requirements in alignment precision, speed and engineering reliability. Aiming at these requirements, in this dissertation, we summarized and perfected the fundamental theories of beams automatic alignment, innovatively researched the related kernel technologies in optics, mechanics and electronics. We proposed the system scheme on base of those, made integrated demonstrate experiments, made great progresses and got content results. There are several main aspects as follows: 1. A series of image relaying theories of near field and far field suitable to beams automatic alignment systems are developed and perfected. On base of summarizing the preceding work on the near-field image relaying theory, the far-field image relaying is suggested firstly. Using the geometric optics, the diffractive optics and the Fourier transform, we research the theories on near-field image relaying and far-field relaying in spatial filters. With the experiments on near field detecting and far field detecting of beams automatic alignment system, we get the content verification consistent with theories. 2. A series of key technologies of automatic alignment are developed innovatively. The verification experiments are finished successfully. According the new type of optical paths, a series of novel alignment technologies on near field and far field are developed. These innovations include follows: firstly adjusting the square beams' rotation through a pair of small light sources, using insertable grating to sample and image far field, illuminating filter pinholes by use of insertable negative lenses or positive lenses, adjusting the cavity mirror of the four-pass amplifier through the overlap of filter pinholes, avoiding sampling at the back of the cavity mirror. In processing digital images of detected beams, we firstly propose fitting algorithms of circle and ellipse on base of image preprocess to detect the center of near-field beams and far-field light spots. The precision and speed of the detection algorithms are highly improved. In beams' passing through filter pinholes, we innovatively devised a method includes cross-coupled driving and stepwise moving of near field and far field. The method of beam's passing through filter pinholes is simpler and more efficient than that of NIF facility. The new technologies all above have been tested experimentally. The results are satisfied. 3. The target position error is analyzed in the paper. It is suggested to minimize the detection errors and improve the alignment precision by using the imaging system with combined lenses. We propose that the major contributors to the beam position on target are the accuracy of the alignment process and the stability of the laser system before and during a shot. We establish a model to decompose the total target position error to the single optical components by use of the square root method. Not longing the path of detection system, we design the imaging system with combined lenses to obtain near-field and far-field detection systems with high precision. The alignment error can be minimized through improve detection precision. 4. On base of the alignment theories and research of key technologies, to the multiple optical experiment systems aimed at the SG-III prototype facility, we designed the scheme of beams automatic alignment system, and manufactured the alignment systems which have been applied in experiments successfully with other subsystems. The experiment results indicate that all beams adjustment can be finished in 30 minutes. The precision of beams angle's adjusting was less than ±0.3". The precision of the beams center's adjusting was less than ±0.5% of beams diameter. All those have met the budgets. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15320]  |
| 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 | 刘代中. ICF装置光束自动准直系统研究[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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