Objective lens arrangement usable in particle-optical systems
US10622184B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jun 26, 2017 |
| Grant date | Apr 14, 2020 |
| Priority date | — |
| Expiry date | Jan 6, 2038 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2817
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An objective lens arrangement includes a first, second and third pole pieces, each being substantially rotationally symmetric. The first, second and third pole pieces are disposed on a same side of an object plane. An end of the first pole piece is separated from an end of the second pole piece to form a first gap, and an end of the third pole piece is separated from an end of the second pole piece to form a second gap. A first excitation coil generates a focusing magnetic field in the first gap, and a second excitation coil generates a compensating magnetic field in the second gap. First and second power supplies supply current to the first and second excitation coils, respectively. A magnetic flux generated in the second pole piece is oriented in a same direction as a magnetic flux generated in the second pole piece.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.