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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: The analysis of the spherical aberration coefficient within a waveoptical framework is presented in this article using several approaches: the naive, the multislice, the eikonal, and wide-angle parabolic equation.
Abstract: The analysis of the spherical aberration coefficient within a waveoptical framework is presented using several approaches: the naive, the multislice, the eikonal, and wide-angle parabolic equation. The effect of the spherical aberration as a phase plate is obtained and the Scherzer theorem for magnetic lenses derived. The amplitude transfer theory and its application to the scanning transmission electron microscope is presented.
TL;DR: A practical holography electron microscope was first developed in 1978 by the late Dr. Tonomura as mentioned in this paper, who developed bright and monochromatic field-emission electron beams over 35 years for observing quantum phenomena by utilizing the wave nature of electrons.
Abstract: A practical holography electron microscope was first developed in 1978 by the late Dr. Tonomura. After that, we (Tonomura’s group) developed bright and monochromatic field-emission electron beams over 35 years for observing quantum phenomena by utilizing the wave nature of electrons. As it turns out, every time we developed a brighter electron beam, electron interference experiments became easier to perform, and the precision in the phase measurements increased, thereby opening up new application fields.
Journal Article•
TL;DR: In this article, the authors compare the performance of COBS and TIE with TEM simulations and by using a new index, ITR, which was introduced in a previous paper for the comparison of principal aspects of microscopic schemes.
Abstract: A transmission electron microscopic (TEM) scheme to reconstitute wavefronts of electrons scattered from objects, which was termed as complex observation (COBS), has been successfully introduced. COBS is based on a complex combination of two orthogonal TEM experiments of the conventional (bright-field) and Zernike phase contrast method, both of which are relying on the interference phenomenon for the phase recovery. Recently, another class of phase recovery, the non-interference method often called as the Transport of Intensity Equation (TIE) method, has been proposed. TIE rather relies on the change of the optical energy or intensity in the direction of wave transfer. We report the methodological comparison between COBS and TIE, which has been carried out with TEM simulations and by using a new index, ITR, which was introduced in a previous paper for the comparison of principal aspects of microscopic schemes. TEM simulation has been clarified the preference of COBS in the image quality. This has been also confirmed quantitatively by using ITR, where the drawback of TIE comes to more visible. TIE inherently requests a differential operation to close the formulation, which is actually problematic for images including noise components. Signals in the low and high frequency regions are both seriously influenced by the noise, which results in a rather low resolution image for objects with a low dose limit such as biological samples.
01 Jan 1980
TL;DR: Two types of electron microscopes are capable of providing high-resolution information and it is only as the limit of resolution is approached that it is useful to discuss transfer theory as discussed by the authors.
Abstract: Two types of electron microscope are capable of providing high-resolution information and it is only as the limit of resolution is approached that it is useful to discuss transfer theory These are the conventional transmission electron microscope, in which an extended area of the specimen is illuminated with electrons, which subsequently form a magnified image of this area, and the scanning transmission electron microscope, in which a very small probe is scanned over the specimen in a regular raster and the image is formed point by point, all the incident electrons contributing to each image point (pixel) In the conventional instrument, the image contrast is generated by two mechanisms which, though not independent, may be conveniently treated separately In order to understand these, we briefly recapitulate some practical aspects of electron microscopes (See also the chapter by Wade in this volume)
01 Jan 1972
TL;DR: In this article, images reconstructed from long-wavelength holograms have aberrations as a result of large construction to reconstruction wavelength ratios, which may seriously degrade image resolution due to the large number of spherical aberrations.
Abstract: Images reconstructed from long wavelength holograms have aberrations as a result of large construction to reconstruction wavelength ratios. For many practical recording geometries, these aberrations of which spherical aberration is often the largest may seriously degrade image resolution.