距离选通ICCD及其控制电路设计与实现

发布时间：2018-03-24 14:57

本文选题：距离选通技术　切入点：ICCD　出处：《中国科学院研究生院(西安光学精密机械研究所)》2015年硕士论文

【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10718cd/m2lx,ICCD系统空间分辨率达到29.7 lp/mm。
[Abstract]:Since the laser appeared, the range gated laser active imaging technology can effectively overcome the backscattering of suspended particles in the atmosphere and the influence of background light, improve the contrast of images and improve the imaging quality. Compared with the continuous laser illumination imaging system, the range gated imaging technology has been paid more and more attention by the military, and has been widely used in target detection. On the basis of analyzing the working principle of range-gated imaging technology and its synchronous control technology, the structure and working principle of gated ICCD are analyzed in this paper. In order to further improve the spatial resolution of ICCD and obtain the high performance ICCDs, the effects of the structure of image intensifier, cathode sensitivity, afterglow time and so on on the performance of image intensifier are analyzed by analyzing the characteristics of each component of ICCD. A high speed strobe supersecond generation image intensifier with short afterglow, high resolution and fast time response is developed. The optical fiber cone is coupled with CCD to form a high performance range-gated ICCD. The modulation transfer function of ICCD is theoretically analyzed and the theoretical spatial resolution of ICCD is calculated. The theoretical basis is provided for the experimental testing of ICCD performance. When the theoretically calculated ICCD spatial resolution can reach 32lp/mm.ICCD, it is necessary to coordinate with the laser to achieve synchronization, in addition, it is necessary to match the necessary working voltage and achieve good gain control. For this reason, the distance gating control circuit based on FPGA field programmable logic device is designed and developed independently. The circuit control system designed by FPGA can produce nanosecond gate width and realize the digital control of ICCD. At the same time, the width of the strobe pulse and the delay time can be adjusted to realize the clear imaging of the target with different brightness and distance. It greatly reduces the background noise and increases the dynamic range of imaging. The designed gain monitoring and control functions facilitate the gain control. In this paper, the hardware and software design of the distance gating control circuit based on FPGA and the drawing and function debugging of the circuit board are completed. The requirements of the control circuit in the distance gating process are realized, the conversion functions of digital to analog and analog-to-digital are completed, and the communication between the FPGA chip and the computer is completed. Finally, the related experimental test platform is built, and the performance of ICCD is tested. The test results show that the strobe width of the gate can be adjusted continuously from 3ns to DC, and the gating frequency of the image intensifier can be up to 300kHz. The application of high repetition frequency and narrow gate width can effectively reduce the image noise. When the voltage of microchannel plate is 700V and the voltage of phosphor screen is 5000 V, the gain of intensifier can reach 10718cd / m2lxICCD system spatial resolution of 29.7 lp / mmmm.
【学位授予单位】：中国科学院研究生院(西安光学精密机械研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN249

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