Electron beam apparatus
US4315152A · kind A · utility
19Cited by
4References
12Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Oct 3, 1979 |
| Grant date | Feb 9, 1982 |
| Priority date | — |
| Expiry date | Oct 3, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J37/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In an electron-beam probe instrument such as a scanning electron microscope in which the electron gun employs a field-emission cathode the condenser lens is of the `snorkel` design. The term `snorkel` is used to denote a single-pole magnetic lens in which the pole-piece has an axially extending nose portion. The lens is positioned so that the cathode region is immersed in the radial field at the nose of the lens. Preferably the lens is placed closely behind the cathode but outside the vacuum envelope.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.