基于P31荧光粉的像增强器余辉测量方法研究

Research on afterglow measurement method of image intensifier based on P31 phosphor powder

荧光屏余辉在高帧频速光子计数等系统应用中起着决定性作用。GJB 7351-2011《超二代像增强器通用规范》荧光屏余辉试验方法中规定光脉冲作为激励源,该方法中光脉冲激励源停止后光源照度下降缓慢,造成在短余辉粉(μs级)和中余辉粉(ms级)的余辉时间测量中测试结果不准。针对该问题,提出了一种在光照持续工作状态下,用光电阴极电压脉冲信号作为激励源的荧光屏余辉测试方法,该方法中光电阴极超快响应时间(一般为1 ns左右)和脉冲电压信号的较短边沿时间(一般可控制在10 ns以内)特性改善了激励源自身时间响应对荧光屏余辉测试结果准确性带来的影响。基于该方法建立了一套微光像增强器荧光屏余晖测量装置,对P31荧光粉的国产三代微光像增强器余辉进行了重复性测量,对测量不确定度进行了误差分析,其扩展不确定度为3.2%,达到了传统光电测试仪器的准确度要求,可满足微光像增强管荧光屏余辉测量的要求。该研究成果为更高性能产品提供了一种检测手段。

The fluorescent screen afterglow of low-level-light(LLL)image intensifier plays a decisive role in the application of high frame rate photon counting system.According to the test method of fluorescent screen afterglow in the GJB 7351-2011 General Specification for Super Second Generation Image Intensifier,the light pulse was used as the excitation source.In this method,the illuminance of the light source dropped slowly when the light pulse excitation source stopped,which resulted in inaccurate test results in the measurement of afterglow time of short afterglow powder(μm level)and medium afterglow powder(ms level).Aiming at this problem,under the condition of continuous illumination,a test method of fluorescent screen afterglow with the voltage pulse signal of photocathode as the excitation source was proposed.In this method,the characteristics of the photocathode ultra fast response time(generally about 1 ns)and the shorter edge time(generally it can be controlled within 10 ns)of the voltage pulse signal improved the influence of excitation source time response on the accuracy of fluorescent screen afterglow test results.Based on this method,a set of fluorescent screen afterglow measuring device of LLL image intensifier was set up,and the repeatability measurement of domestic three generations LLL image intensifier afterglow of P31 phosphor powder was carried out.The error analysis of measurement uncertainty is carried out,and the expanded uncertainty is 3.2%,which reaches the accuracy requirements of traditional photpelectronic testing instrument,and can meet the requirements of afterglow measurement of LLL image intensifier fluorescent screen.The research results provide a detection method for higher performance products.