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题名	基于多次全内反射的大口径光学元件缺陷三维检测技术研究
作者	杨菲菲
文献子类	硕士
导师	刘德安
关键词	大口径光学元件 large optics 缺陷检测 defect detection 多次全内反射 multiple total internal reflection 缺陷三维位置检测 defect three-dimensional 图像处理 position detection image processing
其他题名	Research on Three-Dimensional Detection Techniques of Large Optics Defects Based on Multiple Total Internal Reflection
英文摘要	为实现惯性约束聚变，高功率激光装置需要输出高能量激光，那么就要增大光束口径以减小光束能流密度，因此在高功率激光装置中常需要使用许多高质量的大口径光学元件。当大口径光学元件中存在缺陷时，光学元件本身就会对光束进行调制，产生波前畸变，影响输出光束的质量。在缺陷处产生的热效应和衍射效应很可能造成光学元件的损伤，从而降低系统的负载能力和抗激光损伤阈值，甚至破坏整个激光系统。因此有效检测大口径光学元件的缺陷至关重要。目前大口径光学元件的检测多集中在表面和亚表面，体内缺陷检测是大口径光学元件缺陷检测的一个重要组成部分也要重点研究，实现对大口径光学元件体内缺陷三维位置的快速检测对高功率激光装置具有重要指导作用。 本文围绕如何在大口径光学元件中实现缺陷深度位置信息的快速检测这一核心问题，提出了基于多次全内反射的大口径光学元件缺陷检测方法，本论文的主要工作如下： （1）提出了基于多次全内反射的大口径光学元件缺陷快速检测方法，分析了利用该方法检测光学元件体内缺陷深度位置的理论依据；讨论了光源耦合方式，依据检测对象和多次全内反射的检测方法确定了棱镜耦合方式；根据光束在大口径光学元件中传播时多次全内反射原理，给出了光学元件体内缺陷深度的换算公式；同时指出光学元件厚度、光束入射角和光束横截面宽度是确定扫描步距和扫描周期的决定性因素，并最终推导出了扫描次数的计算公式；指出了采用该方法检测光学元件缺陷时不但能够实现缺陷位置的三维定位，同时可以使检测时间缩短为传统方法的1/n，因此利用该方法进行缺陷检测时可大幅度提高检测效率。 （2）根据多次全内反射过程中缺陷图像的具体特征，针对多次扫描中图像处理的各个环节进行了重点分析。通过对比分析后确定采用灰度变换进行图像增强，利用Canny算子进行缺陷散射光斑的边缘检测。针对全反射线和缺陷的散射光斑包含像素个数较多、定位困难的问题，将基于最小二乘法的椭圆拟合算法和质心法应用到全反射线和缺陷的定位上，提高了缺陷深度位置定位的准确性，这对得到缺陷的三维位置并据此得到缺陷在光学元件中的相对位置分布奠定了基础。 （3）分析和讨论了采用多次全内反射检测方法进行缺陷深度位置定位的精度和分辨率。指出在实际测量中，系统误差、扫描时移动待测元件时的抖动误差及图像处理过程中带来的误差等外部因素是影响定位精度的主要原因，在本实验条件下深度方向的定位精度约为150 μm。在分辨率方面，提出检测系统的横向分辨率主要由成像系统的横向分辨率决定，二者正相关；同时说明了深度方向分辨率一方面与成像系统的横向分辨率和光束入射角有关，另一方面，当存在深度方向相同、深度位置不同且深度距离在光束横截面宽度范围内的两个缺陷点时，光束横截面宽度也是影响检测系统深度方向分辨率的一个重要原因。最后提出可以通过提高成像系统的横向分辨率和适当减小光束横截面宽度来提高检测系统的分辨率。; In order to achieve inertial confinement fusion, it requires high power laser facility to output high energy laser, then the beam aperture of the high power laser facility must be enlarged to reduce laser energy density. So there are many large optics with high quality used in high power laser facility. When there are defects in large optics, the optics will produce modulation to the beam resulting in wavefront distortion and affecting the quality of the output beam. The optics may be damaged due to thermal effect and diffraction effect produced by defects, thereby the load capacity and the anti-damaged threshold of the system may be reduced and the entire large high power laser system may even be destroyed. So it is important to detect defects effectively in large optics. At present, the defect detection of large optics is concentrated on the surface and subsurface. Bulk defects detection should be studied as an important component of large optics defects detection and the rapid detection of three-dimensional position of bulk defects in large optics has an important guiding role to high power laser facility. This paper focuses on the core problem that how to achieve the rapid detection of defects depth in large optics and proposes a defects detection method for large optics based on multiple total internal reflections. The main works of this paper are as follows: (1) A rapid defects detection method for large optics based on multiple total internal reflections is proposed. The theoretical basis for depth detection of the bulk defects in optics using this method is analyzed. The coupling method of light source is discussed. According to the detection object and the multiple total internal reflection detecting method, the prism coupling method is adopted. The conversion formula of the bulk defects depth is given according to the principle of multiple total internal reflections. At the same time, it is pointed out that the thickness of the optics, the beam incident angle and the cross-section width of laser beam are the decisive factors to determine the scanning step and the scanning period and the calculation formula of the scanning times is deduced finally. Not only can this method realize the three-dimensional position detection of defects, but also reduce the detection time to 1/n of the traditional method. Therefore, the detection efficiency can be improved greatly by the method. (2) On the basis of constructing optical path diagrams and principles of multiple total internal reflection detection, the paper analyzes the various aspects of image processing in multiple scanning emphatically. Through the contrast analysis, it is determined that the gray scale transform is used to enhance the image, and the Canny operator is used to detect the edge of the defect scattering spot. The elliptic fitting algorithm based on the least squares method and the centroid method are applied to the location of the total reflection line and the defect for the problem that the scattering spots of total reflection lines and the defects contain a lot of pixels and difficult to be positioned. It improves the accuracy of the location of the defects depth and it lays the foundation for getting three-dimensional position and relative distribution of defects in optics. (3) The accuracy and resolution of defect depth and plane position localization are analyzed and discussed by multiple total internal reflection detection method. It is indicated that the external factors such as the system error, the jitter error when the optics to be tested are moved and the error caused by the image processing are the main causes that influence the accuracy of positioning. The positioning accuracy in the depth direction is about 150 μm in this experiment. In terms of resolution, it is proposed that the lateral resolution of the detection system is mainly determined by the lateral resolution of the imaging system and they are positively related. It also shows that the depth direction resolution is related to the lateral resolution of the imaging system and the incident angle of the beam. On the other hand, for the case that there are two defects in the same depth direction, the depth of two defects is different and the distance between two defects in depth direction is within the width of the beam cross-section, the beam cross-section width is also an important reason for the resolution in depth direction of the detection system. Finally, it is proposed that the resolution of the detection system can be improved by enhancing the lateral resolution of the imaging system and by reducing the beam cross-sectional width appropriately.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30925]
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	杨菲菲. 基于多次全内反射的大口径光学元件缺陷三维检测技术研究[D].

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