电子束聚焦和偏转系统中动态修正的计算
THE COMPUTATION OF DYNAMIC CORRECTION IN ELECTRON BEAM FOCUSING AND DEFLECTION SYSTEMS
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摘要: 在电子束聚焦和偏转系统中动态修正方法(即用场曲校正透镜和消象散器来消除偏转场曲和象散)可以相当显著地减小系统的总象差和提高系统的电子光学性能。本文讨论了动态修正的计算问题:包括场曲校正透镜和消象散器的工作原理;校正透镜和消象散器电磁场分布的计算;完全消除场曲和象散在校正透镜和消象散器上所加信号强度的计算;以及校正透镜和消象散器对畸变的影响。通过文章给出动态修正计算的实例可见动态修正对提高系统的电子光学性能起着很大的作用。
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Abstract: In electron focusing and deflection systems the method of dynamic correction (i.e. the application of field curvature correction lenses and stigmators) can significantly reduce the overall aberration and greatly improve the optical properties of systems. In this paper the following numerical computation problems of dynamic correction are described: (1) the principle of correction lenses and stigmators; (2) the computation of field distributions in electrostatic and magnetic correction lenses and stigmators;(3) the calculation of the signal strengths applied in correction lenses and stigmators which completely cancel field curvature and stigmatism; (4) the effect of correction lenses and stigmators on distortion. From the examples of computation of dynamic correction given in this paper it can be seen that the dynamic correction plays enormous role in improving the electron optical properties. -
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