超二代与三代像增强器低照度分辨力的比较

Comparison of Resolution Between Super Gen.Ⅱand Gen.ⅢImage Intensifier

比较了超二代像增强器和三代像增强器在不同照度下的分辨力。结果表明,增益、极限分辨力、信噪比以及调制传递函数相同的超二代像增强器和三代像增强器,当照度大于4.3×10^(-3) lx时,分辨力均为常数,均不随照度的变化而变化;当照度小于4.3×10^(-3) lx时,分辨力均不为常数,均随照度的降低而降低,并且超二代像增强器的分辨力均低于三代像增强器的分辨力,照度越低,差别越大。此外,当采用品质因子来比较像增强器的综合性能时,只能在相同光电阴极的像增强器之间进行比较,而不能在不同光电阴极的像增强器之间进行比较,即品质因子不能用来比较超二代像增强器和三代像增强器的性能。

In this paper,the resolution of the super second generation image intensifier and the third generation image intensifier under different illuminations are studied.The results show that the resolution of the super second generation image intensifier and the third generation image intensifier with the same gain,limit resolution,signal to noise ratio and modulation transfer function is constant when the input illumination is above 4.3×10^(-3) lx,and does not change with the change of input illumination The resolution of the super second generation image intensifier is lower than that of the third generation image intensifier.The lower the input illumination,the greater the difference.The reason is that the third generation image intensifier has higher cathode sensitivity.The higher the sensitivity of the cathode,the higher the initial contrast of the photocathode,and the higher the contrast of the target image on the fluorescent screen,so the higher the resolution under low input illumination.Figure of Merit is an index to characterize the comprehensive performance of image intensifiers.However,when Figure of Merit is used to compare the comprehensive performance of image intensifiers,it can only be compared between the image intensifiers with the same photocathode,but not between the image intensifiers with different photocathode.Therefore,the Figure of Merit can not be used to compare the performance of super second generation and the third generation image intensifiers.