| 题名 | 高精度靶定位图像处理技术研究 |
| 作者 | 李海涛 |
| 学位类别 | 硕士 |
| 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 | 朱健强 |
| 关键词 | 靶定位 数字图像处理 照明 分辨率 直边像锐度 |
| 其他题名 | The research on digital image processing technology of high precision target positioning |
| 中文摘要 | 在目前的ICF（惯性约束聚变）打靶中，驱动源束进入黑腔靶的腔内，聚变靶丸置于黑腔的中央，驱动源束辐照黑腔的内壁，驱动中心的靶丸内爆。为保证激光束正确地入射到黑腔的内部，要求分别调整激光束入射点和靶内孔中心到同一个基准点处，同时调整靶的姿态以适应光束入射的要求，调整光束入射点和调整靶这两个过程分别称为靶瞄准和靶定位。目前神光n装置靶定位的实现还是通过人眼判断，人为进行调整的，这样必然造成调整精度低、调整时间长，这些都将影响到最终的整体实验。基于上述问题，本文对靶定位的自动化实现进行了系统的研究，提出了采用数字图像处理技术实现靶自动定位的方案，并对此进行了实验验证。同时对于图像采集单元中图像质量的改善进行了较为全面的研究，得出了一些重要的结论和指导性的建议。这些都将有效的促进神光H以及将要建成的神光班靶定位自动控制工作的顺利进行。一、针对神光II装置靶定位的实际情况，提出了采用数字图像处理技术实现靶定位的闭环自控，及使用逐步逼近的方法确保定位精度的方案。1．提出利用数字图像处理技术及逐步逼近的方法实现靶自动定位并从实验上对该方案进行了验证。利用神光II靶定位装置中三台靶位CCD监视仪从三个方向对靶成像，并通过CCD和图像采集卡将图像存储到计算机中，再采用数字图像处理技术对采集到的图像进行处理和分析，分别提取出各方向上靶孔中心的数据，通过三个方向孔中心的数据进行藕合计算可确定靶的空间位置和姿态，将之与基准位置比较，确定要进行调整的偏移量和旋转量，再由控制系统驱动电机使靶移动至三台监视仪轴线交点所确定的基准区域内，这就是采用数字图像处理技术实现靶自动定位的方案。逐步逼近法就是实时提取靶图像，在靶移动完毕后，再提取靶所在位置的相应坐标，反馈给控制系统进行修正，如此反复直到最终靶位置满足定位要求。这样，在靶定位的过程存在的许多不利因素，如定位系统的机械分辨率、靶定位器的稳定性、监视系统的稳定性等，都可得到有效地弱化。我们对球靶采取上述方案进行了联机调试实验，实验的结果表明，在图像保证一定质量的情况下，采用该方案进行调整的复位精度是完全能够满足神光II装置靶定位的精度要求的。2．完成了靶定位软件的编制和完善。针对提出的利用数字图像处理技术实现靶自动定位的方案，编制了相应的软件系统。该软件包括了靶图像的提取、图像的处理以及驱动控制系统三个方面，是进行联机调试实验和靶定位的一个重要的工具。二、对成像系统和照明系统对靶图像像质影响进行了系统的研究，提出了一些重要的和指导性的观点。1．研究了成像系统对于图像分辨率的影响。分辨率是像质评价一个很重要的方面，同时它也影响到最终的定位精度，由于部分相干光成像是一个较普遍的成像方式，基于此，我们从两点分辨率出发，研究了通过改变成像系统光瞳函数来改善分辨率的方法，得到并通过实验验证了一些重要的结论：通过改变成像系统光瞳函数如采用环状光瞳、方形光瞳和四级相干光瞳都可以有效的改善成像分辨率，同时成像分辨率随环状光瞳中心遮挡系数的增大而提高，即对环状光瞳来说，中心被遮挡的越大，其分辨率越好。2．研究了照明系统对靶图像分辨率和图像边缘锐度的影响。以目前靶场实际的情况看，照明是阻碍靶图像提取的一个关键的因素，目前的靶图像局部反光严重、边缘模糊，须从照明的角度加以解决。我们从照明对于分辨率和直边像锐度的影响进行了系统的理论研究，研究表明通过改变照明光源的形状如采用环状照明、四级离轴照明都可以有效的改善图像的分辨率。而图像边缘的锐度随相干参数的增大而减小，对于环状照明来说，中心遮挡系数对边缘锐度的影响很微小。从照明对于分辨率和边缘锐度的影响综合考虑，即要求既要保证分辨率的有效提高，又要尽量增大边缘锐度，这样我们可根据研究结果对照明和成像系统进行优化和改善以提取到便于处理的靶图像。 |
| 英文摘要 | During the ICF(inertial confinement fusion) shot sequence, the drive source incident in the hollow of a hohlraum with a pellet placed on the hollow's center. The laser beams from the drive source illuminate the inwall of the hohlraum and drive the pellet to implode. The incident point and the center of hohlraum must be aligned individually into the same datum so that the beams can incident into the hohlraum rightly. At the same time, the pose of the target is aligned. The process of aligning the beams' incident point and aligning the target are called target pointing and target positioning. The target is positioned and aligned manually in ShenGuang II now. The low alignment precision and long adjust time will make against the whole experiment. Based on the problem mentioned above, the deep research on the automatic control of target positioning has been made and a plan for automatically positioning target using digital image process(DIP) technology is put forward. Finally some experiments are made to validate the feasibility of this plan. And several research on the influence of the imaging system and the illuminating system on the image quality is made. Some important conclusions are drawn and several useful suggest are given. These achievements will be beneficial to the research of automatically positioning target of ShenGuang II and ShenGuang III which is about to be finished. 1. The theoretical and experimental research work on target positioning that utilize DIP technology have been finished and the step-by step method has been put forward. (1). The research on target positioning using DIP technology and the step-by step method is made and is validated to be feasible through experiments. There are three target viewing system(TVS) which image the target in three different directions used for target viewing in the positioning system of ShenGuang II. The target image is saved in computer through CCD and image gathering card. Next, the image will be processed utilizing DIP technology and then we get the coordinates of the center of the target's hohlraum through computation, thus the spatial position and pose of the target can be confirmed. The offset between the center of the target's hohlraum and the datum can also be obtained, and then the control system drive the motor to position the target into the right area required. This method of positioning target is the plan of positioning target using DIP technology. The step-by step method here means that after the target is driven into one area, the image of the target at that locating spot is gathered again through TVS and the coordinates of the center of the target's hohlraum is supplied to the control system to position the target. This operation will be repeated again and again until the positioning precision satisfies the request of the system. In this way, we can ravel out availably even if there are some factors that make against the process of target positioning such as die mechanical resolution and the stability of the target positioner and the stability of the TVS. An online experiment on the automatically positioning of spherical target is implemented and the results indicate that the alignment precision meets the need of ShenGuang H (2). The target positioning software has been completed and perfected. Based on the plan we put forward above, the software concerned has been completed. The software consists of three parts as follows, the gathering of the target image, the process of the image and the control of the target, and it's an effective and important tool during the process of target positioning. 2. The deep research that how the imaging system and the illuminating system influence the quality of the target image has been finished and some important conclusions are drawn. (1). The s tudy o f t he i mpact o f t he i maging sy stem o n t he r esolve p ower o f t he image is made. The resolve power is one important aspect of image quality evaluation, and it also has an effect on the final target alignment precision. Based on the theory of partially coherent imaging and two point resolution, a study of resolution enhancement by changing the aperture function of the imaging system has been made and we get and validate through experiments some useful conclusions, as follows, the resolve power can be improved by using different kinds of apertures such as annular aperture, square-shaped aperture or quadrupole aperture. At the same time, the resolve power is improved with the central obstruction ratio of the annular aperture growing. That is to say, the more the aperture is obstructed, the more the resolve power improves. (2). The study of the impact of the illuminating system on the resolve power of the image and the acutance on the edge of image has been finished. Considering the actual situations in the target area, the illuminating is considered one of important factors that disturb the gathering of target image. Now there are some problems that make against the imaging of the target such as local scattering and blurring on the edge of the image, and these problems must be solved by improving on the illuminating system. So we make a study of the impact of the illuminating system on the resolve power of the image and the acutance on the edge of image. The research concerned indicates that the value of acutance on the image's edge decreases with the value of coherent parameter increasing, and in allusion to the illuminating system with a nnular s ource t here is little impact of central obstruction r atio on the acutance. Considering the resolution and the acutance, we must perfect the illuminating system and the imaging system according to the research findings to improve the resolve power and sharpen the edge of the image. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16659]  |
| 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 | 李海涛. 高精度靶定位图像处理技术研究[D]. 中国科学院上海光学精密机械研究所. 2004. |
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