Method and system for automatically correcting aberrations of a beam of charged particles
AssigneeInternational Business Machines Corporation
InventorsSamuel K. Doran, Merlyn H. Perkins
Life of this patent
Estimating the term…
Abstract
The location of a beam of charged particles within a deflection field is determined by its orthogonal deflection voltages. With the location of the beam in the field, correction currents are supplied to a focus coil and to each of a pair of stigmator coils to correct for change of focal length and astigmatism due to the beam being deflected away from the center of its deflection field.
Claims57
A system for automatically correcting the aberration of a beam of charged particles as the beam moves from the center of a deflection field including:
- means to move the beam to any position within the field;
- means to determine any of the locations of the beam within the field to which the beam is moved by said moving means;
- said determining means including means to ascertain which sector of a plurality of sectors of the field that the beam is located with each of the sectors being defined by lines passing through the center of the field;
- and means to correct the aberration of the beam in accordance with the location of the beam in the field relative to the center of the field so that the beam has no aberration at its location in the field.
A method for automatically correcting the aberration of a beam of charged particles as the beam is moved from the center of a deflection field including:
- moving the beam to any position within the field;
- electronically dividing the field into a plurality of sectors by lines passing through the center of the field;
- electronically determining any of the locations of the beam within the field to which the beam is moved by electronically determining in which sector the beam is located;
- and correcting the aberration of the beam in accordance with the location of the beam in the field relative to the center of the field so that the beam has no aberration at its location in the field.
Dependencies are inferred from the claim text.