Four-cylinder electrostatic lens. II. Energy scanning at constant image position and magnification

For pt.I see ibid., vol.16, no.7, p.625-30 (1983). A four-cylinder electrostatic lens can be used to keep both the position and magnification of the image of a fixed object constant while the energy of the image is varied. The required relationships that must be maintained between the variable voltage ratios of the lens have been determined using a new version of the charge-density method, and the spherical aberration of the resulting zoom-lens has been evaluated.