抄録
This paper deals with the focusing characteristics and image distortion of a quadrupole triplet lens under asymmetric operation, by which is meant that lenses of different lens strengths are used for the inlet and outlet quadrupole sections. When the ratio of the above two lens strengths is changed, the positions of the two principal planes become asymmetric, nevertheless the focal lengths on the object and image sides are symmetric. Then, the crosssectional multiplication factors can be changed and distortion becomes controllable, even if the object and image distances are given. By adjusting the above ratio and the lens strength of the central quadrupole section, an operation free or very nearly free from astigmatism can be realized under wide range of focal distances. These focusing characteristics are calculated using a digital computer and verified experimentally.
