本文给出了逸出电子在最佳像面上落点的均方根半径值及直观图形表示;以实际管型为例,βeta分布取β_1,8至β_2,1,检验了均方根半径的变化状况,证明了理论分析的正确性;从数据上检验了均方根半径不仅可以表征系统鉴别率特性的好坏,而且和调制传递函数的优劣在像面上是一一对应的;证明了用指数形式表示系统的调制传递函数具有计算速度快、形式简洁、使用方便,并且在低频空间具有足够的精度.

In the paper,the value of RMS radius and the visual picture of escape electron dropped spots in optimum image plane has been given.The present paper has offered data to prove that when the βeta distribution changes from β_1,8 to β₂₁,the RMS radius value increases gradually,corresponding with theoretic analysis.It has offered data to check that the RMS radius not only can characterize the system resolution properties,but also does it correspond with the electron optical modulation transfer function (MTF) in image plane,and proved that expressing the system MTF by exponential function will have the properties of fast computation speed,succinct expression,convenient usage,and have enough accuracy in low frequency space.