Corrector for the correction of chromatic aberrations in a particle-optical apparatus

摘要

The invention describes a corrector for the correction of chromatic aberrations in a particle lens, such as used in a SEM or a TEM. So as to reduce the stability demands on the power supplies of such a corrector, the energy with which the particle beam passes through the corrector is lower than the energy with which the beam passes through the lens to be corrected.

主权项

1. A particle-optical apparatus arranged to focus a beam of electrically charged particles, provided with:
a particle source for generating the beam, the particle source being maintained at a first electrical potential such that the electrically charged particles having a first nominal energy when exiting the particle source; a particle-optical lens for focusing the beam, the particle-optical lens being maintained at a second potential greater than the first potential such that electrically charged particles traversing the particle-optical lens at a second nominal energy greater than the first nominal energy; a corrector for correcting the chromatic lens errors occurring in the lens, the corrector being maintained at a third potential so that the electrically charged particles traversing the corrector with a nominal energy less than the second nominal energy; and transfer optics for accelerating the beam of electrically charged particles such that the electrically charged particles traverse the lens at said second nominal energy, wherein the beam traverses the transfer optics after traversing the corrector.