| 题名 | 距离选通ICCD及其控制电路设计与实现 |
| 作者 | 何欢1 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015-05-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 田进寿 |
| 关键词 | 距离选通技术 增益控制 ICCD FPGA 分辨率 选通门宽 |
| 学位专业 | 物理电子学 |
| 中文摘要 | 自激光出现以来，距离选通激光主动成像技术能够有效克服大气中悬浮颗粒的后向散射以及背景光的影响，显著提高图像对比度，改善成像质量，与连续激光照明成像系统相比作用距离也更远，这些优势使得距离选通成像技术越来越受到各国军方重视，广泛应用于目标探测、精密追踪等诸多领域。 本文在全面分析距离选通成像技术的工作原理及其同步控制技术的基础上，首先对选通ICCD的结构及工作原理做出了分析，为了进一步提高ICCD的空间分辨率，获得研制高性能ICCD，通过分析ICCD各组成部件特性，分析像增强器结构及阴极灵敏度、MCP倍增特性、荧光屏余辉时间等对像增强器性能的影响，研制了一种短余辉、高分辨率、快时间响应的高速选通超二代像增强器，通过光纤锥与CCD耦合成高性能距离选通ICCD。理论分析了ICCD的调制传递函数及计算了ICCD的理论空间分辨率，为实验测试ICCD性能提供了理论依据。理论计算的ICCD空间分辨率可达32lp/mm。 ICCD在工作时，需与激光器协调配合以实现同步，此外还需配以必要的工作电压，并实现良好的增益控制，为此自主设计研制了基于FPGA现场可编程逻辑器件实现的距离选通控制电路，采用FPGA设计的电路控制系统可以产生出纳秒级的选通门宽，实现了对ICCD的数字控制，同时可以对选通脉冲宽度和延时时间进行调整，实现不同亮度以及距离目标的清晰成像，大大降低了背景噪声以及增大成像的动态范围。设计的增益监控和控制功能方便了增益的控制。本文完成了基于FPGA距离选通控制电路的软硬件设计和电路板的绘制及功能调试，实现了距离选通过程中对控制电路的要求，完成了数模、模数的转换功能，完整的实现了FPGA芯片与计算机的通讯。 本文最后搭建了相关实验测试平台，对ICCD性能进行了测试，测试结果显示选通门宽度3 ns~直流连续可调实现了对像增强器的选通，选通频率最高可达到300 kHz，高重频窄门宽的应用有效降低了图像噪声，提高成像质量。实验测试在微通道板电压为700 V、荧光屏电压为5000 V时增强器增益可达10718 cd/m2lx，ICCD系统空间分辨率达到29.7 lp/mm。 |
| 英文摘要 | Since the laser appears, the range gated imaging technology has a effect on distance , can effectively eliminate the influence of the backscatter of the floating particles in the atmosphere and the bias light. The technology can also improve the image contrast and the image quality significantly. Compared with continuous laser illumination imaging system，it has a further image distance. It is widely used in target detection, precision tracking and many other areas. Based on the range-gated imaging technology and its synchronous control technology, the structure of the range-gated ICCD and its operational principle has been analyzed. The components of the ICCD characteristics are also analyzed for improving the spatial resolution of ICCD, which can help develop high performance ICCD. The structure of image intensifier, the photocathode sensitivity, the characteristic of MCP and the delay time of the phosphor powder and there influences on the image intensifier has been analyzed. This paper designs a high-speed gated second generation image intensifier which is of short afterglow, high resolution and fast response time. A high performance range-gated ICCD was obtained by coupling a fiber taper to CCD. Theoretically analysis the coupling mode and coupling process, they also can make an effect on ICCD system. The MTF and system spatial resolution of the ICCD system are analyzed, which provide a theoretical basis for experimental test the performance of ICCD. The theoretical calculation of the ICCD spatial resolution is up to 32lp/mm. The ICCD need coordination and cooperation with the laser to achieve synchronization. In addition, the operating voltage and gain control are necessary. FPGA field programmable logic devices is employed to design the range-gated control circuit system, which can achieve digital control for ICCD by producing a nanosecond gating width. The system can also obtain clear images of objectives in different brightness and distance by adjusting the pulse width and delay time. In addition, the background noise is reduced and the dynamic range of imaging is increased. The gain of this system can be monitored and adjusted, which facilitate the gain control greatly. In this paper, the debugging of hardware and software of the FPGA control system are completed, and drawing the PCB board. Complete The functions of range gated control circuit, A/D, D/A are achieved. Also the design can achieve the FPGA chip communication with computer. A test platform has been built, the test result shows that a gating DC pulse which voltage is -200V and width is 3 ns ~DC continuously adjustable is applied to achieve image intensifier gating. The highest gating frequency can reach to 300kHz. The application of high frequency and narrow width pulse can effectively reduce image noise and improve image quality. The experimental test shows that the gain of the image intensifier is 10718cd/m2lx when MCP voltage is 700 V and phosphor screen voltage is 5000V and the system spatial resolution is 29.7 lp/mm |
| 语种 | 中文 |
| 学科主题 | 电子、电信技术 ; 变像管、像增强器 ; 夜视技术、夜视仪 |
| 公开日期 | 2015-06-30 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.opt.ac.cn/handle/181661/23015]  |
| 专题 | 西安光学精密机械研究所_研究生部 |
| 作者单位 | 1.西安光机所 2.中国科学院大学 |
| 推荐引用方式 GB/T 7714 | 何欢. 距离选通ICCD及其控制电路设计与实现[D]. 北京. 中国科学院研究生院. 2015. |
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