前近贴脉冲电压对三代微光像增强器halo效应的影响

Effect of pro-proximity pulse voltage on the third-generation low light level image intensifiers halo effect

为了探讨三代微光像增强器的合适工作电压,研究了前近贴脉冲电压对微光像增强器halo效应的影响.将脉冲电压信号加在光电阴极上,分别改变脉冲信号的高低电平电压幅值和占空比,利用高分辨率CCD采集了微光像增强器的halo图像,对比分析了halo图像中心线上各像素点对应的灰度值分布和光子计数.研究结果表明,随着高电平电压幅值和占空比的提高,灰度值为255的像素点数目变多,halo图像中背景和信号的边界越来越清晰.当前近贴电压增加到200V以上和占空比大于60%左右时,其对三代微光像增强器halo图像中心线上各像素点的灰度值分布影响不大.当低电平电压增加到2V以上时,光电子在低电平阶段无法克服阻滞场到达微通道板.此研究有利于探讨微光像增强器的最佳工作电压和光电子从阴极面出射时的能量分布,为提高三代微光像增强器的性能提供了实验支撑.

In order to explore the proper working voltage for the third-generation low light level image intensifier, the influence of pro- proximity pulse voltage on image intensifier halo effect is investigated. The pulse voltage is applied to photocathode of image intensi- fier. Respectively change the high and low level voltage and duty ratio, image intensifier halo images are collected by high-resolution charge-coupled device （CCD）. The gray distributions for pixel points on halo image central line are given and comparatively analyzed. The results show that as high level voltage and duty ratio increase, the number of pixel points whose gray value is 255 increases and the border between signal and background becomes clear. When high level voltage is above 200 V and duty ratio is above 60%, the pro-proximity voltage has not great influence on image intensifier halo effect. When low level voltage is above 2 V, photoelectrons escaping from photocathode cannot reach microchannel plate under low level voltage stage. The present investigation is beneficial to the exploration of the optimal working voltage for image intensifier and energy range of photoelectrons escaping from photocathode, and provides an experimental support for the improvement of the third-generation low light level image intensifier performance.