变像管皮秒分幅和飞秒扫描相机的实验研究

EXPERIMENTAL STUDY OF PICOSECOND FRAMING AND FEMTOSECOND STREAK CAMERAS

本文将描述两种变像管皮秒分幅相机和一种飞秒扫描相机的设计特点、动态测试方法和实验结果。第一种变像管皮秒分幅相机采用了交叉点扫描多光栏分幅的方法,其变像管具有长加速电极和短阳极的静电弱聚焦系统与偏转灵敏度高、偏转像质好的偏转群体结构;其超快速控制电路只需一个光电开关斜坡电压脉冲发生器和一个特殊设计的脉冲成形网络即可送出具有合适时间关联的4对正负极性三角波和一对正负极性的单台阶液电压脉冲。实验表明,该相机在提供6幅分幅图像的情况下,每幅图像全曝光时间为80ps,除 3～4幅图像间的时间间隔为680ps外,其余均为160ps,动态空间分辨率达到5.51p/mm。第二种变像管皮秒分幅相机采用快门式分幅方法;其变像管采用行波偏转系统,内增强MCP做成带状线结构,并具有输入输出阻抗变换器,其三台阶波和快门脉冲序列均由光电开关电路和脉冲成形网络产生。该相机在提供三幅分幅图像的情况下,每幅图像全曝光时间为660ps,画幅之间的时间间隔均为4ns,动态空间分辨率为5.5lp/mm。飞秒扫描相机采用MCP内增强飞秒扫描变像管、具有负时间畸变的中继透镜和无触发晃动的光电开关扫描电路。实验证明,该相机在时间分辨率为500fs时,其动态范围为30;当时间分辨率为1.2ps时,其动态范围可达500;

The design features, dynamic measurement and experimental results of two kinds of picosecond framing cameras and one kind of femtosecond streak camera are described, A framing approach by sweeping electron beam across a multiplex aperture plate positioned at cross-over has been adopted for the first kind of picosecond framing camera. Its framing image tube possesses a weak electrostatic focusing system with a long accelerate electrode and a short anode and a group of deflection system with high sensitivity of defl -ection and good deflection image quality, The uitrafast control circuit consists of a ramp circuit with a photoconductive switch and a specially designed pulse forming network, which provides 4 pairs of triangle wave-form and a pair of single stair wave-form pulses. The experiments have shown that this camera can provide 6 frame images with full width of exposure time 80ps, interframe time of 160ps and dynamic spatial resolution of 5.5p/ mm, The second kind of picosecond framing camera is operated in gated mode, Atravelling wave deflection system and a strip line microchannel plate with impedance matching units has been used in this camera. The stair wave-form and gated pulses are generated by photoconductive switch circuits and pulse forming networks, 3 frame images with full width of exposure time 660ps, interframe time of 4ns and dynamic spatial resolution of 5.51p/ mm have been demonstrated by this camera. The femtosecond streak camera mainly consists of a microchannel plate internal intensified femtosecond streak image tube, a specially designed optical lens with negtive time distortion and a jitter free photoconductive switch sweep circuit, The experiments have shown that the dynamic ranges are greater than 30 and 500 for the subpicosecond and about 10ps pulses respectively. The experiments have also shown that this camera can provide streak image with jitter of less than ± 2ps and without slit image curvature.