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对于不对称单场透镜的电子光学性质进行了系统的分析和计算。单场透镜的性质不仅决定于极靴的几何参数,而且决定于它的磁饱和程度。下极靴适当地强饱和时,不对称单场透镜可以产生低的球差系数。研究球差系数和色差系数的被积函数沿轴的分布,可以帮助设计者分析象差系数和极靴磁饱和的关系。D_1/D_2=4的不对称透镜是值得推荐的。不对称单场透镜在机械结构方面和电子光学性质方面都有其特点,值得加以注意和利用。
The electronic optical properties of asymmetric single field lens were systematically analyzed and calculated. The nature of a single lens depends not only on the geometric parameters of the pole piece, but also on the degree of magnetic saturation of it. As the lower pole boots are strongly saturated, an asymmetric one-field lens can produce a low spherical aberration coefficient. Studying the distribution of the integrand along the axis of the spherical aberration coefficient and the color difference coefficient helps the designer to analyze the relationship between the aberration coefficient and the magnetic saturation of the pole piece. Asymmetric lenses of D_1 / D_2 = 4 are recommended. Asymmetric single lens in the mechanical structure and electronic optical properties have their own characteristics, it is worth to pay attention to and use.