引言现今要求投影管具有明亮和清晰的图象。作为大屏幕电视用的投影管,需要以大电流来产生足够的亮度,然而在大电流范围内,电子束光点散焦是一个大问题。为了克服散焦,由两个同轴的双圆筒组成的高单电位电子枪(Hi-UPF)现已被开发出来。很多研究使我们清晰地看到,在电子束管(CRT)中,即使是最佳设计的简单双圆筒或三圆筒电透镜仍有球面像差。因此影响了图像质量。为此,我们研究了由两个分离的简单透镜组成的复合透镜。复合透镜的理论分析已由Hawkes 作出。可是他只给出直接用于实验性透镜设计的 Introduction Today’s projection tubes require bright and clear images. As a projection tube for a large-screen television, it is necessary to generate sufficient brightness with a large current. However, defocusing of the beam spot is a major problem in a large current range. To overcome the defocus, a high monopole electron gun (Hi-UPF) consisting of two coaxial double cylinders has now been developed. Many studies have made it clear that spherical aberration is still observed in even the best dual-cylinder or triple-tube lenses in electron beam tubes (CRT). Thus affecting the image quality. To this end, we have studied a compound lens consisting of two separate simple lenses. Theoretical analysis of the compound lens has been made by Hawkes. But he only gives direct use for experimental lens design