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Fiber Laser
A fiber laser (or fibre laser in British English) is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium. They are related to doped fiber amplifiers, which provide light amplification without lasing. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing can also provide gain and thus serve as gain media for a fiber laser. Advantages and applications An advantage of fiber lasers over other types of lasers is that the laser light is both generated and delivered by an inherently flexible medium, which allows easier delivery to the focusing location and target. This can be important for laser cutting, welding, and folding of metals and polymers. Another advantage is high output power compared to other types of laser. Fiber lasers can have active regions several kilometers long, and so can provide very high optical gain. They can support ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British English
British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in England, or, more broadly, to the collective dialects of English throughout the British Isles taken as a single umbrella variety, for instance additionally incorporating Scottish English, Welsh English, and Ulster English, Northern Irish English. Tom McArthur (linguist), Tom McArthur in the ''Oxford Guide to World English'' acknowledges that British English shares "all the ambiguities and tensions [with] the word 'British people, British' and as a result can be used and interpreted in two ways, more broadly or more narrowly, within a range of blurring and ambiguity". Variations exist in formal (both written and spoken) English in the United Kingdom. For example, the adjective ''wee'' is almost exclusively used in parts of Scotland, North E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Area
The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with flat polygonal faces), for which the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces. This definition of surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration. A general definition of surface area was sought by Henri Lebesgue and Hermann Minkowski at the turn of the twentieth century. Their work led to the development of geometric measure theory, which studies various notions of surface area for irregular objects of any dimension. An important example is the Minkowski cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiber Bragg Grating
A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. Hence a fiber Bragg grating can be used as an inline optical fiber to block certain wavelengths, can be used for sensing applications, or it can be used as wavelength-specific reflector. History The first in-fiber Bragg grating was demonstrated by Ken Hill in 1978. Initially, the gratings were fabricated using a visible laser propagating along the fiber core. In 1989, Gerald Meltz and colleagues demonstrated the much more flexible transverse holographic inscription technique where the laser illumination came from the side of the fiber. This technique uses the interference pattern of ultraviolet laser light to create the periodic structure of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusion Splicing
Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole. Fusion may also refer to: Science and technology Physics *Nuclear fusion, multiple atomic nuclei combining to form one or more different atomic nuclei and subatomic particles **Fusion power, power generation using controlled nuclear fusion reactions **Cold fusion, a hypothesized type of nuclear reaction that would occur at or near room temperature *Heat fusion, a welding process for joining two pieces of a thermoplastic material *Melting, or transitioning from solid to liquid form Biology and medicine * Binaural fusion, the cognitive process of combining the auditory information received by both ears * Binocular fusion, the cognitive process in binocular vision of combining the visual information received by both eyes * Cell fusion, a process in which several uninuclear cells combine to form a multinuclear cell * Gene fusion, a genetic event and molecular biology technique * Lipid b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Cavity
An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors or other optical elements that forms a cavity resonator for light waves. Optical cavities are a major component of lasers, surrounding the gain medium and providing feedback of the laser light. They are also used in optical parametric oscillators and some interferometers. Light confined in the cavity reflects multiple times, producing modes with certain resonance frequencies. Modes can be decomposed into longitudinal modes that differ only in frequency and transverse modes that have different intensity patterns across the cross-section of the beam. Many types of optical cavity produce standing wave modes. Different resonator types are distinguished by the focal lengths of the two mirrors and the distance between them. Flat mirrors are not often used because of the difficulty of aligning them to the needed precision. The geometry (resonator type) must be chosen so that the beam remains stable, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directed Energy Weapon
A directed-energy weapon (DEW) is a ranged weapon that damages its target with highly focused energy without a solid projectile, including lasers, microwaves, particle beams, and sound beams. Potential applications of this technology include weapons that target personnel, missiles, vehicles, and optical devices."Daily Telegraph, 12th September 2013" ''Golden Eye-style energy beam is developed by Nato scientists'', Oct. 08, 2013"Milsat Magazine, Satnews Daily, June 24th 2009" ''U.S. Navy Laser Versus UAVs... Laser Wins...'', Oct. 08, 2013 In t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medicine
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others. Medicine has been practiced since prehistoric times, and for most of this time it was an art (an area of skill and knowledge), frequently having connections to the religious and philosophical beliefs of local culture. For example, a medicine man would apply herbs and say prayers for healing, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopy
Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO) In simpler terms, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical structure and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cost Of Ownership
Total cost of ownership (TCO) is a financial estimate intended to help buyers and owners determine the direct and indirect costs of a product or service. It is a management accounting concept that can be used in full cost accounting or even ecological economics where it includes social costs. For manufacturing, as TCO is typically compared with doing business overseas, it goes beyond the initial manufacturing cycle time and cost to make parts. TCO includes a variety of cost of doing business items, for example, ship and re-ship, and opportunity costs, while it also considers incentives developed for an alternative approach. Incentives and other variables include tax credits, common language, expedited delivery, and customer-oriented supplier visits. Use of concept TCO, when incorporated in any financial benefit analysis, provides a cost basis for determining the total economic value of an investment. Examples include: return on investment, internal rate of return, economic value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Laser
A gas laser is a laser in which an electric current is discharged through a gas to produce coherent light. The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a laser light output. The first gas laser, the Helium–neon laser (HeNe), was co-invented by Iranian-American engineer and scientist Ali Javan and American physicist William R. Bennett, Jr., in 1960. It produced a coherent light beam in the infrared region of the spectrum at 1.15 micrometres. Types of gas laser Gas lasers using many gases have been built and used for many purposes. Carbon dioxide lasers, or CO2 lasers can emit hundreds of kilowatts at 9.6 µm and 10.6 µm, and are often used in industry for cutting and welding. The efficiency of a CO2 laser is over 10%. Carbon monoxide or "CO" lasers have the potential for very large outputs, but the use of this type of laser is limited by the toxicity of carbon monoxide g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Laser
A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers, called laser diodes. Solid-state media Generally, the active medium of a solid-state laser consists of a glass or crystalline "host" material, to which is added a "dopant" such as neodymium, chromium, erbium, thulium or ytterbium.Z. Su, J. D. Bradley, N. Li, E. S. Magden, Purnawirman, D. Coleman, N. Fahrenkopf, C. Baiocco, T. Adam, G. Leake, D. Coolbaugh, D. Vermeulen, and M. R. Watts (2016"Ultra-Compact CMOS-Compatible Ytterbium Microlaser" ''Integrated Photonics Research, Silicon and Nanophotonics 2016'', IW1A.3. Many of the common dopants are rare-earth elements, because the excited states of such ions are not strongly coupled with the thermal vibrations of their crystal lattices (phonons), and their operational t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
