超小型条纹管的动态特性研究

基于条纹相机的非推扫式激光雷达可以实现三维多光谱荧光及偏振成像,克服了传统雷达技术中由于目标和搭载平台之间相对移动形成的图像畸变,图像刷新率高,也便于小型化.本文针对这一新技术发展的需求设计了一款大面积(阴极有效面积?25)、超小型(阴极到荧光屏净尺寸为100 mm)、无栅网、球面阴极、球面荧光屏的条纹管,利用电子轨迹追踪法理论分析了偏转板位置对偏转灵敏度和空间分辨率的影响.动态分析演示了从阴极面狭缝上同时出发的光电子在条纹管内部不同飞行阶段的时间畸变过程,给出了条纹管在扫描工作模式下狭缝像弯曲所对应的定量时间畸变值.该条纹管极限时间分辨率优于30 ps,在其阴极狭缝长28 mm的范围内,边缘动态空间分辨率大于10 lp/mm,阴极狭缝为30 mm×50μm时条纹管的动态时间分辨率优于50 ps,放大倍率为1.2.

Dynamic prop erties of a small-size streak tube

Scannerless (flash) lidar system based on streak camera is able to realize three-dimensional (3D) multi-spectral fluorescence imaging and 3D imaging polarimetry. Compared with conventional lidar system, the flash lidar system overcomes image distortions caused by the motion between the target and the sensor platform. Other advantages of the flash lidar system are higher image update rates and the potential for creating a miniaturized lidar system. To meet the requirements for developing this new technology, a super small-sized, large photocathode area and meshless streak tube with spherical cathode and screen is designed with the aid of computer simulation technology (CST) software. The tube with nearly 28 mm wide photocathode work area contains two electrostatic focusing lens, a pair of deflection plates, and a 50 mm diameter output screen. The external dimension of the tube is merely 50 mm×100 mm. And its electromagnetic fields are calculated in the CST Particle Studio based on the finite integration theory. Some dynamic properties of the tube are analyzed via observing different electron trajectories launched from a number of different points on the cathode. The influences of the deflector position on deflection sensitivity and spatial resolution are analyzed. Increasing the distance between the deflector and the anode pin hole leads to a worse deflection sensitivity but a better spatial resolution. As for the temporal resolution, three electron pulses separated by 30 ps can be well resolved by the streak tube in the dynamic mode. Thus, the dynamic temporal resolution of the streak tube is better than 30 ps. And a 10 lp/mm spatial resolution across the 28 mm long slit on the photocathode can be obtained by estimating modulation transfer functions of the electron trajectories. Temporal distortions at the entire photocathode working area are evaluated, and the data reveal that the larger the photocathode working area, the bigger the temporal distortions are. Also, the temporal distortion is present mainly in the photocathode-to-deflection plates region. In addition, the slit image of the streak tube working in the dynamic mode is simulated and presented. The phenomenon that the slit image is curved due to the temporal distortion is analyzed. Two rectangular electron pulses separated by 50 ps are well resolved by the streak tube. Therefore, the temporal resolution of this small-size steak tube is better than 50 ps with a rectangular slit dimension of 30 mm×50 μm on the photocathode, and its electron-optic magnification is 1.2.