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The effect of the contrast transfer function can be seen in the alternating light and dark rings (Thon rings), which show the relation between contrast and spatial frequency. The contrast transfer function (CTF) mathematically describes how aberrations in a transmission electron microscope (TEM) modify the image of a sample.
The phase-contrast microscope made it possible for biologists to study living cells and how they proliferate through cell division. It is one of the few methods available to quantify cellular structure and components without using fluorescence. [1] After its invention in the early 1930s, [2] phase-contrast microscopy proved to be such an ...
The use of diffraction patterns as a function of position dates back to the earliest days of STEM, for instance the early review of John M. Cowley and John C. H. Spence in 1978 [2] or the analysis in 1983 by Laurence D. Marks and David J. Smith of the orientation of different crystalline segments in nanoparticles. [3] Later work includes the ...
In the field of transmission electron microscopy, phase-contrast imaging may be employed to image columns of individual atoms; a more common name is high-resolution transmission electron microscopy. It is the highest resolution imaging technique ever developed, and can allow for resolutions of less than one angstrom (less than 0.1 nanometres).
A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen.
Often the contrast reduction is of most interest and the translation of the pattern can be ignored. The relative contrast is given by the absolute value of the optical transfer function, a function commonly referred to as the modulation transfer function (MTF). Its values indicate how much of the object's contrast is captured in the image as a ...
Contrary to conventional phase contrast images [citation needed], phase shift images of living cells are suitable to be processed by image analysis software. This has led to the development of non-invasive live cell imaging and automated cell culture analysis systems based on quantitative phase contrast microscopy. [6]
[20] [21] Quantitative phase-contrast microscopy has an advantage over fluorescent and phase-contrast microscopy in that it is both non-invasive and quantitative in its nature. Due to the narrow focal depth of conventional microscopy, live-cell imaging is to a large extent currently limited to observing cells on a single plane.