Reduction of the focus hole diameter strongly affects the electrons with large emission angle but its influence on electron focusing is less markedly than the influence of the variations in potential.
减小聚焦极孔径对大发散角的电子有影响，但对聚焦作用的影响不如改变电位明显。
2
Magnetic coils focus the electron beams into fine spots.
磁线圈将电子束聚焦成细小的点。
《柯林斯英汉双解大词典》
3
Influence of focus electrode bias, focus hole size and grid electrode bias on the emission electron beams was discussed.