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Three Photon Microscopy
Three-photon microscopy (3PEF) is a high-resolution fluorescence microscopy based on nonlinear excitation effect. Different from two photon excitation microscopy, it uses three exciting photons. It typically uses 1300 nm or longer wavelength lasers to excite the fluorescent dyes with three simultaneously absorbed photons. The fluorescent dyes then emit one photon whose energy is (slightly smaller than) three times the energy of each incident photon. Compared to two-photon microscopy, three-photon microscopy reduces the fluorescence away from the focal plane by 1/z^4, which is much faster than that of two-photon microscopy by 1/z^2. In addition, three-photon microscopy employs near-infrared light with less tissue scattering effect. This causes three photon microscopy to have higher resolution than conventional microscopy. Concept Three-photon excited fluorescence was first observed by Singh and Bradley in 1964 when they estimated the three-photon absorption cross section of n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, vacu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Scanning Microscopy
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light which is ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar (light detection and ranging). Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum. Alternatively, temporal coherence can be used to produce ultrashort pulses of light wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Equipment
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicians' offices, clinics, hospitals, and regional and national referral centers. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in which to observe behavior. In some laboratories, such as those commonly used by computer scientists, computers (sometimes supercomputers) are used for either simulations or the analysis of data. Scien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Imaging
Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery with only a few monks or nuns * Prison cell, a room used to hold people in prisons Groups of people * Cell, a group of people in a cell group, a form of Christian church organization * Cell, a unit of a clandestine cell system, a penetration-resistant form of a secret or outlawed organization * Cellular organizational structure, such as in business management Science, mathematics, and technology Computing and telecommunications * Cell (EDA), a term used in an electronic circuit design schematics * Cell (microprocessor), a microprocessor architecture developed by Sony, Toshiba, and IBM * Memory cell (computing) The memory cell is the fundamental building block of computer memory. The memory cell is an electronic circuit that stores on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence Techniques
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, vacuu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear Optics
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in ''nonlinear media'', that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds. History The first nonlinear optical effect to be predicted was two-photon absorption, by Maria Goeppert Mayer for her PhD in 1931, but it remained an unexplored theoretical curiosity until 1961 and the almost simultaneous observation of two-photon absorption at Bell Labs and the discovery of second-harmonic generation by Peter Franken ''et al.'' at University of Michigan, both shortly after the constru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Scanning
Laser scanning is the controlled deflection of laser beams, visible or invisible. Scanned laser beams are used in some 3-D printers, in rapid prototyping, in machines for material processing, in laser engraving machines, in ophthalmological laser systems for the treatment of presbyopia, in confocal microscopy, in laser printers, in laser shows, in Laser TV, and in barcode scanners. Applications specific to mapping and 3D object reconstruction are known as '' 3D laser scanner''. Technology Scanning mirrors Most laser scanners use moveable mirrors to steer the laser beam. The steering of the beam can be ''one-dimensional'', as inside a laser printer, or ''two-dimensional'', as in a laser show system. Additionally, the mirrors can lead to a ''periodic'' motion - like the rotating ''polygon mirrror'' in a barcode scanner or so-called ''resonant galvanometer'' scanners - or to a ''freely addressable'' motion, as in servo-controlled galvanometer scanners. One also uses the terms ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Of View
The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Humans and animals In the context of human and primate vision, the term "field of view" is typically only used in the sense of a restriction to what is visible by external apparatus, like when wearing spectacles or virtual reality goggles. Note that eye movements are allowed in the definition but do not change the field of view when understood this way. If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the visual field. It is defined as "the number of degrees of visual angle during stable fixation of the eyes".Strasburger, Hans; Pöppel, Ernst (2002). Visual Field. In G. Adelman & B.H. Smith (Eds): ''Encyclopedia of Neuroscience''; 3rd edition, on CD-ROM. El ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Full Width At Half Maximum
In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the ''y''-axis which are half the maximum amplitude. Half width at half maximum (HWHM) is half of the FWHM if the function is symmetric. The term full duration at half maximum (FDHM) is preferred when the independent variable is time. FWHM is applied to such phenomena as the duration of pulse waveforms and the spectral width of sources used for optical communications and the resolution of spectrometers. The convention of "width" meaning "half maximum" is also widely used in signal processing to define bandwidth as "width of frequency range where less than half the signal's power is attenuated", i.e., the power is at least half the maximum. In signal processing terms, this is at most −3 dB of attenuatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-photon Excitation Microscopy
Two-photon excitation microscopy (TPEF or 2PEF) is a fluorescence imaging technique that allows imaging of living tissue up to about one millimeter in thickness, with 0.64 μm lateral and 3.35 μm axial spatial resolution. Unlike traditional fluorescence microscopy, in which 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. Two-photon excitation microscopy typically uses near-infrared (NIR) excitation light which can also excite fluorescent dyes. However, for each excitation, two photons of NIR light are absorbed. Using infrared light minimizes scattering in the tissue. Due to the multiphoton absorption, the background signal is strongly suppressed. Both effects lead to an increased penetration depth for this technique. Two-photon excitation can be a superior alternative to confocal microscopy due to its deeper tissue penetration, efficient light d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mouse Brain
The mouse brain refers to the brain of Mus musculus. Various brain atlases exist. For reasons of reproducibility, genetically characterized, stable strains like C57BL/6 were chosen to produce high-resolution images and databases. Well known online resources include: *Allen Brain Atlas * Mouse Brain LibraryHigh resolution mouse brain atlas*BrainMaps High-Resolution Brain Maps and Brain Atlases of ''Mus musculus'' Despite superficial differences, especially in size and weight, the mouse brain and its function can serve as a powerful animal model for study of human brain diseases or mental disorders (see e.g. Reeler, Chakragati mouse). This is because the genes responsible for building and operating both mouse and human brain are 90% identical. Transgenic mouse lines also allow neuroscientists to specifically target the labeling of certain cell types to probe the neural basis of fundamental processes. Anatomy The cerebral cortex of a mouse has around 8–14 million neurons while in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromophores
A chromophore is the part of a molecule responsible for its color. The color that is seen by our eyes is the one not absorbed by the reflecting object within a certain wavelength spectrum of visible light. The chromophore is a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum. Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state. In biological molecules that serve to capture or detect light energy, the chromophore is the moiety that causes a conformational change in the molecule when hit by light. Conjugated pi-bond system chromophores Just like how two adjacent p-orbitals in a molecule will form a pi-bond, three or more adjacent p-orbitals in a molecule can form a conjugated pi-system. In a conjugated pi-system, electrons are able to capture certain photons as the electrons resonate along a certain distan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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