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An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light, electron microscopes have a higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes. Electron microscope may refer to:
Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visible without a microscope. Although one may divide microscopic anatomy into organology, the study of organs, histology, the study of tissues, and cytology, the study of cells, modern usage places all of these topics under the field of histology. In medicine, histopathology is the branch of histology that includes the microscopic identification and study of diseased tissue. In the field of paleontology, the term paleohistology refers to the histology of fossil organisms.
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
A microscope is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope.
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector. The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer.
The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.
Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit.
Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures within an object. This technique is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection and materials science.
A microtome is a cutting tool used to produce extremely thin slices of material known as sections, with the process being termed microsectioning. Important in science, microtomes are used in microscopy for the preparation of samples for observation under transmitted light or electron radiation.
Two-photon excitation microscopy is a fluorescence imaging technique that is particularly well-suited to image scattering living tissue of up to about one millimeter in thickness. Unlike traditional fluorescence microscopy, where the excitation wavelength is shorter than the emission wavelength, two-photon excitation requires simultaneous excitation by two photons with longer wavelength than the emitted light. The laser is focused onto a specific location in the tissue and scanned across the sample to sequentially produce the image. Due to the non-linearity of two-photon excitation, mainly fluorophores in the micrometer-sized focus of the laser beam are excited, which results in the spatial resolution of the image. This contrasts with confocal microscopy, where the spatial resolution is produced by the interaction of excitation focus and the confined detection with a pinhole.
Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor industry, materials science and increasingly in the biological field for site-specific analysis, deposition, and ablation of materials. A FIB setup is a scientific instrument that resembles a scanning electron microscope (SEM). However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB setup uses a focused beam of ions instead. FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams. FIB should not be confused with using a beam of focused ions for direct write lithography. These are generally quite different systems where the material is modified by other mechanisms.
Electron cryotomography (cryo-ET) is an imaging technique used to produce high-resolution (~1–4 nm) three-dimensional views of samples, often biological macromolecules and cells. cryo-ET is a specialized application of transmission electron cryomicroscopy (CryoTEM) in which samples are imaged as they are tilted, resulting in a series of 2D images that can be combined to produce a 3D reconstruction, similar to a CT scan of the human body. In contrast to other electron tomography techniques, samples are imaged under cryogenic conditions. 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.
A scanning helium ion microscope is an imaging technology based on a scanning helium ion beam. Similar to other focused ion beam techniques, it allows to combine milling and cutting of samples with their observation at sub-nanometer resolution.
A scanning acoustic microscope (SAM) is a device which uses focused sound to investigate, measure, or image an object. It is commonly used in failure analysis and non-destructive evaluation. It also has applications in biological and medical research. The semiconductor industry has found the SAM useful in detecting voids, cracks, and delaminations within microelectronic packages.
Winfried Denk is a German physicist. He built the first two-photon microscope while he was a graduate student in Watt W. Webb's lab at Cornell University, in 1989.
Low-voltage electron microscope (LVEM) is an electron microscope which operates at accelerating voltages of a few kiloelectronvolts or less. Traditional electron microscopes use accelerating voltages in the range of 10-1000 keV.
Immunogold labeling or Immunogold staining (IGS) is a staining technique used in electron microscopy. This staining technique is an equivalent of the indirect immunofluorescence technique for visible light. Colloidal gold particles are most often attached to secondary antibodies which are in turn attached to primary antibodies designed to bind a specific antigen or other cell component. Gold is used for its high electron density which increases electron scatter to give high contrast 'dark spots'.
Neural circuit reconstruction is the reconstruction of the detailed circuitry of the nervous system of an animal. It is sometimes called EM reconstruction since the main method used is the electron microscope (EM). This field is a close relative of reverse engineering of human-made devices, and is part of the field of connectomics, which in turn is a sub-field of neuroanatomy.
Cryogenic electron microscopy (cryo-EM) is a cryomicroscopy technique applied on samples cooled to cryogenic temperatures. For biological specimens, the structure is preserved by embedding in an environment of vitreous ice. An aqueous sample solution is applied to a grid-mesh and plunge-frozen in liquid ethane or a mixture of liquid ethane and propane. While development of the technique began in the 1970s, recent advances in detector technology and software algorithms have allowed for the determination of biomolecular structures at near-atomic resolution. This has attracted wide attention to the approach as an alternative to X-ray crystallography or NMR spectroscopy for macromolecular structure determination without the need for crystallization.
References
- 1 2 Denk, W; Horstmann, H (2004). "Serial Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue Nanostructure". PLOS Biol. 2 (11): e329. doi:10.1371/journal.pbio.0020329. PMC 524270 . PMID 15514700.
- ↑ Mukherjee, Konark; Clark, Helen R.; Chavan, Vrushali; Benson, Emily K.; Kidd, Grahame J.; Srivastava, Sarika (2016-07-09). "Analysis of Brain Mitochondria Using Serial Block-Face Scanning Electron Microscopy". Journal of Visualized Experiments (113): e54214. doi:10.3791/54214. ISSN 1940-087X. PMC 4993410 . PMID 27501303.
- ↑ Hua, Yunfeng; Laserstein, Philip; Helmstaedter, Moritz (2015-08-03). "Large-volume en-bloc staining for electron microscopy-based connectomics". Nature Communications. 6: 7923. Bibcode:2015NatCo...6.7923H. doi:10.1038/ncomms8923. ISSN 2041-1723. PMC 4532871 . PMID 26235643.
- ↑ "3View System for Image Capture of 3D Ultrastructures | Gatan, Inc".
- ↑ "Teneo VolumeScope SEM for Life Sciences". www.fei.com. Mark Anderson. 2017-10-02. Retrieved 2017-10-09.
{{cite web}}: CS1 maint: others (link) - ↑ "Katana microtome".
- ↑ "Challenge << EyeWire". Archived from the original on April 14, 2012. Retrieved March 27, 2012.
- ↑ Holland, Nicholas (June 21, 2018). "Formation of the initial kidney and mouth opening in larval amphioxus studied with serial blockface scanning electron microscopy (SBSEM)". Evodevo. 9 (16): 16. doi:10.1186/s13227-018-0104-3. PMC 6013890 . PMID 29977493.
