Electron microscope phase enhancement
US7737412B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 2005 |
| Grant date | Jun 15, 2010 |
| Priority date | — |
| Expiry date | May 13, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2614
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.