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Topic: Scanning electron microscope

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	Electron microscope - Wikipedia, the free encyclopedia
		The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons as the source of illumination, magnifying at levels up to 2,000,000 times.
		The first practical electron microscope was built at the University of Toronto in 1938, by Eli Franklin Burton and students Cecil Hall, James Hillier and Albert Prebus.
		Unlike the TEM, where electrons are detected by beam transmission, the Scanning Electron Microscope (SEM) produces images by detecting secondary electrons which are emitted from the surface due to excitation by the primary electron beam.
	en.wikipedia.org /wiki/Electron_microscope (1789 words)

	Scanning electron microscope - Wikipedia, the free encyclopedia
		The scanning electron microscope (SEM) is a type of electron microscope capable of producing high resolution images of a sample surface.
		The electron beam, which typically has an energy ranging from a few hundred eV to 50 keV, is focused by one or two condenser lenses into a beam with a very fine focal spot sized 1 nm to 5 nm.
		The high-energy electrons from the SEM beam will inject charge carriers into the semiconductor; that is, the beam electrons will loose energy by promoting electrons from the valence band into the conduction band, leaving behind holes.
	en.wikipedia.org /wiki/Scanning_electron_microscope (1180 words)

	Scanning electron microscope (Site not responding. Last check: 2007-09-20)
		electrons are detected by a scintillator - photomultiplier device and the resulting signal used modulate the intensity of a CRT that is rastered in conjunction with raster-scanned primary beam.
		Because the secondary electrons from the near surface region the brightness the signal depends on the surface area is exposed to the primary beam.
		Backscattered electrons may be used to both topological and compositional detail although due their much higher energy (approximately the same the primary beam) these electrons may be from fairly deep within the sample.
	www.freeglossary.com /Scanning_Electron_Microscope (533 words)

	[No title]
		The electron gun in a scanning electron microscope is the source for the electron beam used to probe the sample.
		Electrons are emitted from a cathode, accelerated by passage through electrical fields and focussed to a first optical image of the source.
		This beam of electrons will be focussed by the shape of the field gradient to a cross-over just before the anode, forming the first optical image of the source and ensuring that a larger percentage of the electrons will pass through the aperture of the anode.
	www.sem.com /analytic/sem.htm (4648 words)

	PHYS 319: The Scanning Electron Microscope
		Since the electron beams in the SEM column and in the CRT are scanning in synchronism, for every point on the specimen (within the raster-scanned area) there is a corresponding point on the display screen, in conformity with Maxwell's first rule for image formation.
		When a backscattered electron arrives at the detector and penetrates as far as the transition region (assumed within the electron range), it creates extra current carriers (electron and holes) which move under the influence of the internal field, causing a current pulse to flow through the circuit.
		Although the environmental SEM extends the range of materials which can be examined and avoids the need for coating the specimen to make it conducting, it has one drawback: electrons are deflected through scattering by gas molecules during the final phase of their journey.
	laser.phys.ualberta.ca /~egerton/SEM/sem.htm (5994 words)

	JUSTNET - Scanning Electron Microscopy (Site not responding. Last check: 2007-09-20)
		The scanning electron microscope (SEM) is, next to the optical microscope, one of the most important and versatile tools available to investigators not only in forensic science but in many other disciplines in the biological and physical sciences.
		SEMs may be classified into three generations according to the type of source used to produce the electron beam.
		SEMs are very often equipped with an energy-dispersive x-ray (EDX) analysis system for the elemental analysis of specimens.
	www.nlectc.org /assistance/sem.html (424 words)

	Scanning Electron Microscope
		The SEM is a microscope that uses electrons instead of light to form an image.
		Since their development in the early 1950's, scanning electron microscopes have developed new areas of study in the medical and physical science communities.
		The SEM is an instrument that produces a largely magnified image by using electrons instead of light to form an image.
	www.purdue.edu /rem/rs/sem.htm (789 words)

	Lesson Plans -- Virtual Electron Microscope -- (6-8, Microscopic World) (Site not responding. Last check: 2007-09-20)
		The microscope is able to create a picture of the specimen based on the way the electrons bounce off it.
		Compare the use of the compound microscope to the electron microscope.
		In addition to SEMs, there are other types of microscopes that are bringing us closer than ever to a previously invisible world: transmission electron microscopes, acoustic microscopes, and scanning tunneling microscopes, which enable scientists to see individual atoms.
	school.discovery.com /lessonplans/activities/electronmicroscope (1078 words)

	What are Electron Microscopes? (Site not responding. Last check: 2007-09-20)
		Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale.
		Electron Microscopes were developed due to the limitations of Light Microscopes which are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers.
		Electron Microscopes(EMs) function exactly as their optical counterparts except that they use a focused beam of electrons instead of light to "image" the specimen and gain information as to its structure and composition.
	www.unl.edu /CMRAcfem/em.htm (428 words)

	A Networked Scanning Electron Microscope
		The microscope image is carried to a television monitor at each remote station using an RS-170 video feed from the JEOL 6100 provided by the manufacturers, and hardcopy prints can be obtained using a thermal printer.
		Since the software-controlled concept allows the SEM to be operated from any suitably equipped computer on the Internet, links have been established with the local high school to provide students in physics, biology, and chemistry with the opportunity to see a sample in near-live time from the high school classroom.
		The SEM was acquired on a project funded by the Office of Naval Research with Mufit Akinc as the principal investigator.
	www.tms.org /pubs/journals/JOM/9509/Chumbley-9509.html (3102 words)

	math lessons - Scanning electron microscope
		X-rays, which are also produced by the interaction of electrons with the sample, may also be detected in an SEM equipped for Energy dispersive X-ray spectroscopy.
		The electrons are detected by a scintillator-photomultiplier device and the resulting signal used to modulate the intensity of a CRT that is rastered in conjunction with the raster-scanned primary beam.
		Because the secondary electrons come from the near surface region, the brightness of the signal depends on the surface area that is exposed to the primary beam.
	www.mathdaily.com /lessons/SEM (828 words)

	Tracing an image with electrons (Site not responding. Last check: 2007-09-20)
		Like a rapid-fire BB gun, it scans electrons across the target which reflect onto a fluorescent screen where the image is captured by a camera and enlarged.
		Electrons are much smaller than atoms, so a scanning electron microscope paints a razor-sharp image of the target.
		Second, the electron signals produced by the sample due to the electron beam must be seen by an electron detector.
	science.nasa.gov /newhome/headlines/ast05mar98_3.htm (745 words)

	The Scanning Tunneling Microscope
		The scanning tunneling microscope (STM) is a type of electron microscope that shows three-dimensional images of a sample.
		In the STM, the structure of a surface is studied using a stylus that scans the surface at a fixed distance from it.
		Electrons tunnel between the surface and the stylus, producing an electrical signal.
	nobelprize.org /educational_games/physics/microscopes/scanning (263 words)

	Petroglyph Manual Scanning Electron Microscope (Site not responding. Last check: 2007-09-20)
		Electron microscopy can be used to determine the shapes and sizes of small grains or even their chemical composition.
		The electron beam passes through several magnetic condensing "lenses" and spray apertures which narrow the beam and focus it on the sample.
		Electron backscattering can be the result of a single, high-angle deflection or several lower angle deflections.
	geologyindy.byu.edu /Petroglyph/ElectronMicro.html (670 words)

	SEM (Site not responding. Last check: 2007-09-20)
		The SEM has a large depth of field, which allows a large amount of the sample to be in focus at one time.
		A beam of electrons is produced at the top of the microscope by heating of a metallic filament.
		Detectors collect the secondary or backscattered electrons, and convert them to a signal that is sent to a viewing screen similar to the one in an ordinary television, producing an image.
	www.oardc.ohio-state.edu /atru/Research/sem.htm (227 words)

	Scanning Electron Microscope, and other Scanning Electron Microscope information (Site not responding. Last check: 2007-09-20)
		Scanning Electron Microscope Scanning Electron Microscope As part of the Science Learning Network, the Scanning Electron Microscope (SEM) Web site explores what an SEM is, how it's used, and what images it can produce.
		Scanning Electron Microscope - SEM Scanning Electron Microscope - SEM This website is from Boston Museum of Science and is an introduction to Scanning Electron Micrscope (SEM).
		The scanning electron microscope (SEM) is a type of electron microscope capable of producing high...
	www.maxiscopes.co.uk /directory/scanning-electron-microscope.html (425 words)

	High School (Site not responding. Last check: 2007-09-20)
		The development of the Scanning Electron Microscope in the early 1950's brought with it new areas of study in the medical and physical sciences because it allowed examination of a great variety of specimens.
		An optical microscope uses lenses to bend the light waves and the lenses are adjusted for focus.
		By scanning with an electron beam that has been generated and focused by the operation of the microscope, an image is formed in much the same way as a TV.
	www.mse.iastate.edu /microscopy/highschool.html (202 words)

	Scanning electron microscope Did You Mean scanning electron microscope
		The beam passes through pairs of scanning coils in the objective lens, wich deflect the beam in a raster fashion over a rectangular area of the sample surface.
		Backscattered electrons may be used to detect bothcontrast between areas with different chemical compositions can be observed especially when the average atomic number of the various regions is different.
		Additionaly, in contrast with the case with secondary electrons, the collection efficiency of backscattered electrons cannot be significantly improved by a positive bias common on Everhart-Thornley detectors.
	www.did-you-mean.com /Scanning_electron_microscope.html (923 words)

	Scanning Electron Microscopy Lab at NMNH
		The SEM Lab is a multi-user, biologic imaging facility available to all the researchers at NMNH.
		The Scanning Electron Microscope (SEM) scans a beam of electrons across the surface of a sample allowing researchers to visualize the microstructural details of their objects of study.
		The microscopic examination that was carried out prior to display of the Sikh artifacts served as a visual guide for conservators in their choices of conservation methods.
	www.nmnh.si.edu /highlight/sem/highlight/SEM_main.htm (564 words)

	Scanning Electron Microscope
		The major activity in electrical engineering after the war, was the development of the scanning electron microscope (SEM).
		Although the principles of the scanning electron microscope had already been established in Germany in the 1930s, there was a widely held belief that this technique had insufficient scientific merit and no commercial future.
		The first microscope (pictured on the left) was designed and built in the Department and it was operational in 1951.
	www-g.eng.cam.ac.uk /125/1950-1975/sem.html (142 words)

	Scanning Electron Microscope--Theory (Site not responding. Last check: 2007-09-20)
		However, the scanning electron microscope (SEM) does not actually view a true image of the specimen, but rather produces an electronic map of the specimen that is displayed on a cathode ray tube (CRT).
		Electrons from a filament in an electron gun are beamed at the specimen in a vacuum chamber.
		The signal produced by the secondary electrons is detected and sent to a CRT image.
	www.gmu.edu /departments/SRIF/tutorial/sem/sem.htm (205 words)

	Scanning Electron Microscope
		A set of coils then "scan" or "sweep" the beam in a grid fashion (like a television), dwelling on points for a period of time determined by the scan speed (usually in the microsecond range)
		The final lens, the Objective, focuses the scanning beam onto the part of the specimen desired.
		Before the beam moves to its next dwell point these instruments count the number of interactions and display a pixel on a CRT whose intensity is determined by this number (the more reactions the brighter the pixel).
	www.unl.edu /CMRAcfem/semoptic.htm (374 words)

	Scanning Electron Microscope
		A combination of light microscope and SEM views of certain female mosquitoes that have tried to obtain some of my bodily fluids over the last two years.
		Springtails or snow fleas are speck sized invertebrates that are particularly prevalent as numerous dust spots on the surface of the snow.
		These SEM views of a water strider are particularly good for showing how these insects are able to make use of the water's surface tension to move around.
	science.exeter.edu /jekstrom/SEM/SEM.html (1051 words)

	Scanning Electron Microscope - Large SEM
		The main advantage of scanning electron microscopy is the combination of a high lateral resolution with a large depth of focus.
		MIRA large SEM, is a new class in scanning electron microscopy: the X-tended View technology of MIRA scanning electron microscope, sets new standards in non-destructive measuring and testing techniques.
		In contrast to conventional solutions, the electron optics and the detector are positioned freely in the 2 m3 vacuum chamber, with the sample to be studied left unaffected.
	www.qualitest-inc.com /mira.htm (518 words)

	Scanning Electron Microscope (Site not responding. Last check: 2007-09-20)
		An electron microscope uses a focused beam of electrons to obtain much higher magnification than is possible on a conventional light microscopes (the image above has only 100x magnification, which is well within the reach of light microscopy, however, magnification of thousands of times is possible).
		A scanning electron microscope is similar to a light microscope being used in reflection.
		The major difference is that instead of imaging the entire specimen at once, the electron beam is scanned back and forth over the specimen, imaging only one point at a time (much like how a television works--there is only one electron beam, but it scans every spot on the screen).
	people.ccmr.cornell.edu /~mseugrad/micro/scane.html (273 words)

	Orlando Science Center - Scanning Electron Microscope
		The Scanning Electron Microscope here at the Orlando Science Center is a high tech system to examine objects at very high magnification.
		As opposed to an optical microscope which uses refraction of light, the SEM uses an electron beam to obtain visual magnification.
		The beam knocks electrons loose from the surface of the sample, where they are counted by a detector to create the image.
	www.osc.org /exhibits/sem.htm (386 words)

	Scanning Electron Microscope History
		The first SEM used to examine the surface of a solid specimen was described by Zworykin et al.
		The electron optics of the instrument consisted of three electrostatic lenses with scan coils placed between the second and third lenses The electron gun was located at the bottom so the specimen chamber was at a comfortable height for the operator.
		Oatley CW and Everhart TE (1957): The examination of p-n junctions in the scanning electron microscope.
	www2.eng.cam.ac.uk /~bcb/history.htm (1612 words)

	Scanning Electron Microscope Facility
		The core of the Electron Microscope Facility is a Hitachi S-4100 Field Emission Scanning Electron Microscope with X-ray analyser.
		The Scanning Microscope is available predominantly for research and teaching but also for commercial applications.
		Commercial applications include the imaging and elemental analysis of contaminants, which is particularly important for the food, dairy and water industries where quality assurance is important.
	sci.waikato.ac.nz /services/ScanningElectron.shtml (160 words)

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