为了补偿条纹变像管阴极和栅极之间的电子渡越时间弥散，提出了电子束时间聚焦和时间准直系统。系统中，时间聚焦器用来压缩补偿电子束团在加速过程中产生的时间宽度展宽，压缩补偿后的电子束团再通过时间准直器，时间准直器用来使输出的电子具有相同的能量，这样电子束团在后面的传输过程中就不会产生新的时间弥散。采用蒙特卡罗方法和有限差分法对系统进行了理论模拟。模拟结果表明，500 fs的电子脉冲经过时间聚焦器作用后，时间宽度变为131 fs，时间压缩比为3.8:1，此后由于时间准直器的作用，电子脉冲宽度保持在131 fs左右，时间准直性为16.8%。

In order to compensate the time dispersion between photocathode and anode in the streak tube, a time focus and time collimation system for electron bunch is presented. The time focus system is used to compensate the time dispersion in the process of accelerating. Then, the compensated electron pulse traverses the time collimation system. The energies of the electrons are equal as they emerge from the time collimation system. Therefore, the pulse width of the electron bunch is invariable in the latter transmission process. The system is simulated by using the Monte Carlo method and the finite difference method. The electron pulse with width of 500 fs is generated at the photo-cathode. The width of the electron pulse is shortened to 131 fs by using the time focus system. The time compression ratio is 3.8:1. Then, the pulse width maintains 131 fs by using the time collimation system. The time collimation ratio is 16.8%.