Electron optical correction system for lenses of electron microscope - has series of electric or magnetic and electromagnetic quadrupole elements located in optical path in astigmatic intermediate images.

摘要

The axial ray x and y components (1) passing through a circular lens are deflected by a quadrupole (2) which is followed by an electromagnetic quadrupole (3). A further quadrupole follows (4) and is located ahead of an octupole (5) on the centre axis (6). Further quadrupoles (7,8,9) complete the system. ADVANTAGE - For correction of third order aperture errors that occur in lens systems of electron microscope systems. Axial chromatic errors of first order are also corrected.