中文摘要：

对工作于扫描状态下的飞秒电子衍射系统电子束偏转量的计算方法作了理论研究．讨论了超短电子脉冲宽度的测量方法，比较了相对论效应对电子束的偏转量及对电子束脉冲宽度的的影响，并做了相应的数值计算．计算结果显示，在忽略了电场的边缘效应等因素后，电子柬轴向速度的相对论修正与否对偏转距离和电子束脉冲宽度的影响分别达到20mm和65fs．

英文摘要：

The deflection-scan sub-system of the femtosecond electron diffraction system was theoretically studied and a more exact solution of the deflection distance was obtained. The numerical calculation under relativity correction and non-relativity correction both show that even more information of the scan system can be obtained by the dynamic analysis, of which the difference of the deflection distance is about 61.4 mm,and the difference of the electron pulse width is about 65 fs.