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US 6,633,040 B1Granted
Solenoid electron beam lenses with high demagnification and low aberrations
AssigneeInternational Business Machines Corporation
InventorsHans C. Pfeiffer, Maris A. Sturans
Life of this patent
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Abstract
A magnetic lens employs a solenoid field containing a passive pole piece that shapes the solenoid field to create a demagnifying lens that has very low geometrical aberrations by adjusting the field upstream and downstream of the gap between the pole pieces to create a negative term in the formula for spherical aberrations, subtracting a significant amount from the contribution to the aberrations that comes from the field in the gap.
Claims13
A magnetic lens comprising:
- means for generating a solenoid magnetic field along a first direction;
- and
- at least one magnetically permeable pole piece disposed within said solenoid magnetic field, said pole piece having a geometric axis parallel to said first direction and at least two beam-shaping pole tips disposed above and below a first transverse plane perpendicular to said geometric axis.
Dependencies are inferred from the claim text.