全孔径背向散射诊断系统的设计与研究

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	全孔径背向散射诊断系统的设计与研究
	程亚东1,2
学位类型	硕士
导师	何俊华
	2015-06
学位授予单位	中国科学院大学
学位授予地点	北京
关键词	背向散射光学系统设计标定散射板匀化
摘要	在惯性约束试验中，对全孔径背向散射光参数诊断是研究激光等离子体相互作用的重要内容之一，全孔径背向散射光包括受激拉曼散射光和受激布里渊散射光，通过对其能量和光谱的测量能够有效分析激光靶丸耦合效率和激光等离子体相互作用区域内的电子密度、温度等。本文根据打靶试验的要求，对全孔径背向散射诊断系统进行了详细的光学设计和分析，实现了对打靶透镜内全孔径背向散射光的精密诊断。文中首先对受激拉曼散射光和受激布里渊散射光的产生机制进行了阐述，结合国内外全孔径背向散射诊断系统，将全孔径背向散射光诊断划分为四个过程：收光、滤波、诊断和标定。根据打靶试验要求，从光学系统设计角度出发，将全孔径背向散射诊断系统分为三个子系统：收光系统、滤波系统和诊断系统。在收光系统设计中，针对全孔径背向散射诊断系统空间要求和大口径折反透镜特性，采用离轴抛物镜与折叠反射镜相结合的收光结构，实现了收光和分离背向散射光与杂散光的目的；在滤波器系统设计中，针对杂散光及其引发的次生杂散光，设计了抛光倾斜小孔挡板真空滤波器，消除了杂散光对诊断的影响；在诊断包系统设计中，针对二向色镜分离后光束的光谱特性，设计了长波诊断包和短波诊断包，分析了诊断包内各个光学元件，设计了合理的准直镜、取样镜和耦合镜，同时在时间过程和时间光谱测量中，采用了散射板对耦合镜的光斑进行了匀化处理，匀化后光谱的不均匀性低于16%，满足系统测量的要求。其次介绍了标定系统和标定方法。在标定系统设计中，介绍了标定激光器选择、模拟镜设计与结果以及机械臂的原理。在标定方法研究中，分析了背向散射光能量传递过程，提出了线偏振光标定原理。标定时，对线偏振光振动方向进行等间隔旋转，测量相应的标定激光、标定系统出射光以及全孔径互相正交方向上出射光的能量，通过计算和拟合得到振动方向-透过率曲线，达到标定的目的。最后对全孔径背向散射诊断系统进行了综合分析。通过对六支诊断光路的误差分析，验证了系统的可行性；同时对分析了系统的精度，其中能量诊断的误差为7.62%，长波时间过程诊断误差为12.69%，短波时间过程诊断误差为4.92%，长波时间光谱诊断误差为0.134%，短波时间过程诊断误差为0.105%，结果表明全孔径背向散射诊断系统具有对背向散射光精确的诊断功能。
其他摘要	Diagnosing parameters of full-aperture backscattering light is an important way to study laser plasma interaction in inertial confinement experiments. The coupling efficiency of the laser capsule, electron density and temperature in laser plasma’s interaction region are obtained by measuring energy and spectral of backscattering light which conclude stimulated Brillouin scattering light (SBS) and Raman scattering light (SRS). According to the requirements of measurement, a full aperture backscattering system (FABS) was designed and analyzed, which realizes the diagnosis of backscatter light around the target. Generation mechanism of SBS and SRS light are introduced in the first part of paper. According to domestic and international full aperture backscatter diagnostic system, the diagnostic process of backscattering light always contains four parts: collection of light, filtering, diagnostics and calibration. From the aspect of optical design, the full aperture backscatter diagnosis system is composed of three subsystems: collection of light system, filter system and diagnostic system. In the design of the collection of light system, after investigating the characteristics of the current large diameter refraction and reflection lens, we proposes the off-axis parabola mirror which is combined with reflection lens, which realizes the purpose of collecting light and separates stray light from backscatter light; In the design of filter system, in view of the characteristic of stray light and the secondary stray light, the vacuum filter system with polishing inclined hole plate is researched, which eliminates stray light. In the diagnostic system, the long and short wave diagnostic systems are designed according to spectral separation characteristics of the dichroic splitter. In the measurement of time process and the time spectrum, the light speckle focused by coupling lens is smoothed by scatter plate. The spectral uniformity is less than 16%, which meets the requirements of measurement. In the second part of this paper, the calibration system and method are presented. In the design of calibration system, the choice of calibration laser, the design of analog lens and the principle of mechanical arm are analyzed. In the calibration method research, the principle of linearly polarized light calibration was analyzed on base of the energy transfer process of backscatter light. In calibration, the emergent light energy of calibration laser and two orthogonal directions of full aperture can be measured by rotating same angle for vibration direction of polarized light. This method can calculate and fit the curve of vibration-transmittance. Finally, analysis of error and accuracy of the diagnostic system is given. The analysis of six light paths’ error verifies feasibility of the system and analyzes the precision of system. The total error of energy is 7.62%; the error of time process of long wave is 12.69% and 4.92% for short wave; the error of time spectrum is 0.134% for long wave and 0.105% for short wave. So the system can measure the back-scattering lights accurately.
学科领域	工程光学
语种	中文
文献类型	学位论文
条目标识符	http://ir.opt.ac.cn/handle/181661/24006
专题	研究生部
作者单位	1.中国科学院西安光学精密机械研究所 2.中国科学院大学
第一作者单位	中国科学院西安光学精密机械研究所
推荐引用方式 GB/T 7714	程亚东. 全孔径背向散射诊断系统的设计与研究[D]. 北京. 中国科学院大学,2015.

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