| 摘要 |
An improved particle lens has an axis that is shifted to follow the central ray of the beam as it is deflected through the lens creating, in effect, a variable curvilinear optical axis for the lens and introducing aberrations having depending on the object size and the distance off the lens symmetry axis. These aberrations are corrected by a set of correction elements generating compensating aberrations of the same type, comprising at least one wire pair perpendicular to the system axis and carrying fixed currents to introduce a gradient in the field, together with three coils centered on the system axis to cancel a bias field introduced by the wire pair.
|
