Topic
Contrast transfer function
About: Contrast transfer function is a research topic. Over the lifetime, 934 publications have been published within this topic receiving 26533 citations.
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TL;DR: This work shows how a thin, sculpted membrane is used as a phase-mask to induce specific aberrations into an electron beam probe in a standard high resolution TEM, and experimentally demonstrates beam splitting, two-fold astigmatism, three-foldAstigmatism and spherical aberration.
15 citations
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TL;DR: In this article, the authors studied the focusing of a singular beam by a lens in the presence of spherical aberration and defocusing by using Fresnel-Kirchhoff diffraction integral for two different values of topological charge.
15 citations
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TL;DR: In this paper, a quantitative discussion of the application of the strioscopic dark-field method to model biological objects was given, where the beam stopping apertures were constructed by microwelding fine platinum wires on to the platinum objective aperture.
Abstract: SUMMARY
Electron-optical methods of enhancing contrast are being investigated in order to eliminate the artifacts associated with heavy-metal contrasting procedures. This report gives a quantitative discussion of the application of the strioscopic dark-field method to model biological objects. Beam-stopping apertures were constructed by microwelding fine platinum wires on to platinum objective apertures. These were precisely located and centred in the back focal plane of the objective lens. Contrast was evaluated by a sensitive micro-Faraday cage system. Bright-field and strioscopic contrast of organic layers up to 557 nm thickness were investigated and related to the transition from single to plural scattering. The spherical-aberration phase-contrast contribution could be separated from the amplitude contrast in bright-field microscopy by extrapolation to zero object thickness. Strioscopic contrast of thin layers was found to be much greater than bright field aperture contrast and shown to be non-linear with respect to thickness in the region 0·7–10 nm. For diffraction patterns made up of a few discrete beams the resolution is high, but is considerably less for diffusely scattering and thick objects. Strioscopy may be the method of choice for obtaining contrast of unstained or weakly-stained objects at high acceleration voltage.
15 citations
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TL;DR: The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm and it is demonstrated that such a resolution can be achieved in practice at 200kV.
15 citations
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TL;DR: In this article, two different values of topological charge are selected compensation of aberration in the presence of appropriate value of defocusing is investigated Presence of spherical aberration results in an increase in the size of the dark core of the diffraction pattern.
15 citations