Electron microscope with annular illuminating aperture
US6797956B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 9, 2003 |
| Grant date | Sep 28, 2004 |
| Priority date | — |
| Expiry date | Jan 9, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2614
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a transmission electron microscope with phase contrast imaging, the illumination of the object to be imaged takes place with an annular illuminating aperture. An annular phase-shifting element with a central aperture is arranged in a plane Fourier transformed with respect to the object plane. The annular phase-shifting element confers a phase shift of &pgr;/2 on a null beam, while the radiation of higher diffraction orders diffracted at the object in the direction of the optical axis passes through the central aperture of the annular phase-shifting element and consequently is not affected, or only slightly affected, by the phase-shifting element. The annular illuminating aperture is preferably produced sequentially in time by a deflecting system, which produces a beam tilt in a plane conjugate to the object plane.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.