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Electron tomography is an extension of traditional transmission electron microscopy and uses a transmission electron microscope to collect the data. In the process, a beam of electrons is passed through the sample at incremental degrees of rotation around the center of the target sample.
In contrast to other electron tomography techniques, samples are imaged under cryogenic conditions (< −150 °C). For cellular material, the structure is immobilized in non-crystalline, vitreous ice , allowing them to be imaged without dehydration or chemical fixation , which would otherwise disrupt or distort biological structures.
For example, different elements in a sample result in different electron energies in the beam after the sample. This normally results in chromatic aberration – however this effect can, for example, be used to generate an image which provides information on elemental composition, based upon the atomic transition during electron-electron ...
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.
Electron beam computed tomography (EBCT) is a fifth generation computed tomography (CT) scanner in which the X-ray tube is not mechanically spun in order to rotate the source of X-ray photons. This different design was explicitly developed to better image heart structures that never stop moving, performing a complete cycle of movement with each ...
In conventional CT machines, an X-ray tube and detector are physically rotated behind a circular shroud (see the image above right). An alternative, short lived design, known as electron beam tomography (EBT), used electromagnetic deflection of an electron beam within a very large conical X-ray tube and a stationary array of detectors to achieve very high temporal resolution, for imaging of ...
The E-T secondary electron detector can be used in the SEM's back-scattered electron mode by either turning off the Faraday cage or by applying a negative voltage to the Faraday cage. However, better back-scattered electron images come from dedicated BSE detectors rather than from using the E–T detector as a BSE detector.
Tomography is imaging by sections or sectioning that uses any kind of penetrating wave. The method is used in radiology , archaeology , biology , atmospheric science , geophysics , oceanography , plasma physics , materials science , cosmochemistry , astrophysics , quantum information , and other areas of science .