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These pollen grains taken on an SEM show the characteristic depth of field of SEM micrographs.
M. von Ardenne's first SEM
SEM opened sample chamber
Analog type SEM

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that can be detected and that contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. SEM can achieve resolution better than 1 nanometer. Specimens can be observed in high vacuum, in low vacuum, in wet conditions (in environmental SEM), and at a wide range of cryogenic or elevated temperatures.

The most common SEM mode is detection of secondary electrons emitted by atoms excited by the electron beam. The number of secondary electrons that can be detected depends, among other things, on the angle at which beam meets surface of specimen,{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }} i.e. on specimen topography. By scanning the sample and collecting the secondary electrons with a special detector, an image displaying the topography of the surface is created.


Scanning electron microscope sections
Intro  History  Principles and capacities  Sample preparation  Scanning process and image formation  Detection of secondary electrons  Detection of backscattered electrons  Beam-injection analysis of semiconductors  Cathodoluminescence  X-ray microanalysis  Resolution of the SEM  Environmental SEM  3D in SEM  Transmission SEM  Gallery of SEM images  See also  References  External links  

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{{#invoke:Hatnote|hatnote}}

These pollen grains taken on an SEM show the characteristic depth of field of SEM micrographs.
M. von Ardenne's first SEM
SEM opened sample chamber
Analog type SEM

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that can be detected and that contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. SEM can achieve resolution better than 1 nanometer. Specimens can be observed in high vacuum, in low vacuum, in wet conditions (in environmental SEM), and at a wide range of cryogenic or elevated temperatures.

The most common SEM mode is detection of secondary electrons emitted by atoms excited by the electron beam. The number of secondary electrons that can be detected depends, among other things, on the angle at which beam meets surface of specimen,{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }} i.e. on specimen topography. By scanning the sample and collecting the secondary electrons with a special detector, an image displaying the topography of the surface is created.


Scanning electron microscope sections
Intro  History  Principles and capacities  Sample preparation  Scanning process and image formation  Detection of secondary electrons  Detection of backscattered electrons  Beam-injection analysis of semiconductors  Cathodoluminescence  X-ray microanalysis  Resolution of the SEM  Environmental SEM  3D in SEM  Transmission SEM  Gallery of SEM images  See also  References  External links  

PREVIOUS: IntroNEXT: History
<<>>