Laser beam weldingLaser beam welding (LBW) is a welding technique used to join pieces of metal or thermoplastics through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume and precision requiring applications using automation, as in the automotive and aeronautics industries. It is based on keyhole or penetration mode welding.
LaserA 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 anacronym that originated as an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light that is coherent.
Laser diodeA laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. Driven by voltage, the doped p–n-transition allows for recombination of an electron with a hole. Due to the drop of the electron from a higher energy level to a lower one, radiation, in the form of an emitted photon is generated. This is spontaneous emission.
Laser pointerA laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light. The small width of the beam and low power of typical laser pointers make the beam itself invisible in a clean atmosphere, only showing a point of light when striking an opaque surface.
WeldingWelding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as brazing and soldering, which do not melt the base metal (parent metal). In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that, based on weld configuration (butt, full penetration, fillet, etc.
Laser safetyLaser radiation safety is the safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government regulations. Moderate and high-power lasers are potentially hazardous because they can burn the retina, or even the skin.
Laser beam machiningLaser beam machining (LBM) is a form of machining that uses heat directed from a laser beam. This process uses thermal energy to remove material from metallic or nonmetallic surfaces. The high frequency of monochromatic light will fall on the surface, thus heating, melting and vaporizing the material due to the impinge of photons (see Coulomb explosion). Laser beam machining is best suited for brittle materials with low conductivity, but can be used on most materials. Laser beam machining can be done on glass without melting the surface.
Helium–neon laserA helium–neon laser or He-Ne laser is a type of gas laser whose high energetic medium gain medium consists of a mixture of ratio(between 5:1 and 20:1) of helium and neon at a total pressure of about 1 torr inside of a small electrical discharge. The best-known and most widely used He-Ne laser operates at a wavelength of 632.8 nm, in the red part of the visible spectrum. The first He-Ne lasers emitted infrared at 1150 nm, and were the first gas lasers and the first lasers with continuous wave output.
Ion laserAn ion laser is a gas laser that uses an ionized gas as its lasing medium. Like other gas lasers, ion lasers feature a sealed cavity containing the laser medium and mirrors forming a Fabry–Pérot resonator. Unlike helium–neon lasers, the energy level transitions that contribute to laser action come from ions. Because of the large amount of energy required to excite the ionic transitions used in ion lasers, the required current is much greater, and as a result almost all except for the smallest ion lasers are water-cooled.
Gas metal arc weldingGas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) and metal active gas (MAG) is a welding process in which an electric arc forms between a consumable MIG wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to fuse (melt and join). Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from atmospheric contamination. The process can be semi-automatic or automatic.
Fiber laserA fiber laser (or fibre laser in Commonwealth 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.
Carbon-dioxide laserThe carbon-dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed. It was invented by Kumar Patel of Bell Labs in 1964 and is still one of the most useful types of laser. Carbon-dioxide lasers are the highest-power continuous-wave lasers that are currently available. They are also quite efficient: the ratio of output power to pump power can be as large as 20%. The CO2 laser produces a beam of infrared light with the principal wavelength bands centering on 9.6 and 10.6 micrometers (μm).
Oxy-fuel welding and cuttingOxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, bio diesel, kerosene, etc) and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localised melting of the workpiece material (e.
Gaussian beamIn optics, a Gaussian beam is a beam of electromagnetic radiation with high monochromaticity whose amplitude envelope in the transverse plane is given by a Gaussian function; this also implies a Gaussian intensity (irradiance) profile. This fundamental (or TEM00) transverse Gaussian mode describes the intended output of most (but not all) lasers, as such a beam can be focused into the most concentrated spot. When such a beam is refocused by a lens, the transverse phase dependence is altered; this results in a different Gaussian beam.
Beam divergenceIn electromagnetics, especially in optics, beam divergence is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the beam emerges. The term is relevant only in the "far field", away from any focus of the beam. Practically speaking, however, the far field can commence physically close to the radiating aperture, depending on aperture diameter and the operating wavelength.
BrazingBrazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from welding in that it does not involve melting the work pieces. Brazing differs from soldering through the use of a higher temperature and much more closely fitted parts than when soldering. During the brazing process, the filler metal flows into the gap between close-fitting parts by capillary action.
Thermal analysisThermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature.
Least developed countriesThe least developed countries (LDCs) are developing countries listed by the United Nations that exhibit the lowest indicators of socioeconomic development. The concept of LDCs originated in the late 1960s and the first group of LDCs was listed by the UN in its resolution 2768 (XXVI) on 18 November 1971. A country is classified among the Least Developed Countries if it meets three criteria: Poverty – adjustable criterion based on Gross national income (GNI) per capita averaged over three years.
InterferometryInterferometry is a technique which uses the interference of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy (and its applications to chemistry), quantum mechanics, nuclear and particle physics, plasma physics, biomolecular interactions, surface profiling, microfluidics, mechanical stress/strain measurement, velocimetry, optometry, and making holograms.
Developing countryA developing country is a sovereign state with a less developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreement on which countries fit this category. The terms low and middle-income country (LMIC) and newly emerging economy (NEE) are often used interchangeably but refers only to the economy of the countries.
