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Encyclopedia > Laser construction

A laser system generally consists of three important parts: The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...

  • An energy source (usually referred to as the pump or pump source);
  • A gain medium or laser medium;
  • A mirror, or system of mirrors, forming an optical resonator. These mirrors are often coated with a thin "layer" of metal to change the reflectivity of the mirrors. The coatings have two different refractive indices with an odd number of coatings. The higher refractive index is normally placed closer to the substrate. The layers are formed in a vacuum with alternating coatings being applied to the material.
Schematic diagram of a typical laser, showing the three major parts
Schematic diagram of a typical laser, showing the three major parts

The pump source is the part that provides energy to the laser system. Examples of pump sources include electrical discharges, flashlamps, arc lamps, light from another laser, chemical reactions and even explosive devices. The type of pump source used principally depends on the gain medium, and this also determines how the energy is transmitted to the medium. A helium-neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture, a Nd:YAG laser uses a light focussed from a Xenon flash lamp, and excimer lasers use a chemical reaction. Within a laser, the active laser medium is the material that exhibits optical gain. ... This page meets Wikipedias criteria for speedy deletion. ... Schematic diagram of a Nd:YAG laser, for laser construction. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... Xenon flash lamp being fired. ...


The gain medium is the major determining factor of the wavelength of operation, and other properties, of the laser. There are hundreds if not thousands of different gain media in which laser operation has been achieved. The gain medium is excited by the pump source to produce a population inversion, and it is in the gain medium that spontaneous and stimulated emission of photons takes place, leading to the phenomenon of optical gain, amplification. The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ... In physics, specifically statistical mechanics, the concept of population inversion is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a laser. ... In optics, stimulated emission is the process by which, when perturbed by a photon, matter may lose energy resulting in the creation of another photon. ...


Examples of different gain media include

  • Liquids, such as dye lasers. These are usually organic chemical solvents, such as methanol, ethanol or ethylene glycol, to which are added chemical dyes such as coumarin, rhodamine and fluorescein. The exact chemical configuration of the dye molecules determines the operation wavelength of the dye laser.
  • Gases, such as carbon dioxide, argon, krypton and mixtures such as helium-neon. These lasers are often pumped by electrical discharge.
  • Solids, such as crystals and glasses. The solid host materials are usually doped with an impurity such as chromium, neodymium, erbium or titanium ions. Typical hosts include YAG (yttrium aluminium garnet), YLF (yttrium lithium fluoride), sapphire (aluminium oxide) and various glasses. Examples of solid-state laser media include Nd:YAG, Ti:sapphire, Cr:sapphire (usually known as ruby), Cr:LiSAF (chromium-doped lithium strontium aluminium fluoride), Er:YLF, Nd:glass, and Er:glass. Solid-state lasers are usually pumped by flashlamps or light from another laser.
  • Semiconductors, a type of solid, in which the movement of electrons between material with differing dopant levels can cause laser action. Semiconductor lasers are typically very small, and can be pumped with a simple electric current, enabling them to be used in consumer devices such as compact disc players. See laser diode.

The optical resonator, or optical cavity, in its simplest form is two parallel mirrors placed around the gain medium. Light from the medium, produced by spontaneous emission, is reflected by the mirrors back into the medium, where it may be amplified by stimulated emission. The light may reflect from the mirrors and thus pass through the gain medium many hundreds of times before exiting the cavity. In more complex lasers, configurations with four or more mirrors forming the cavity are used. The design and alignment of the mirrors with respect to the medium is crucial to determining the exact operating wavelength and other attributes of the laser system. Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds that by definition contain carbon. ... A substance is soluble in a fluid if it dissolves in the fluid. ... Coumarin is a chemical compound. ... Rhodamine is a family of related chemical compounds. ... fluorescein isothiocyanate Fluorescein is a fluorophore commonly used in microscopy, in a type of dye laser as the gain medium, and in forensics and serology to detect latent blood stains. ... A dye laser is a laser that uses an organic dye as a lasing medium, usually as a liquid solution. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... General Name, Symbol, Number krypton, Kr, 36 Chemical series noble gases Group, Period, Block 18, 4, p Appearance colorless Atomic mass 83. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... Quartz crystal A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... For eyeglasses, see glasses. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ... General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white, yellowish tinge Atomic mass 144. ... General Name, Symbol, Number Erbium, Er, 68 Chemical series Lanthanides Group, Period, Block NA, 6, f Density, Hardness 9066 kg/m3, ND Appearance silvery white Atomic properties Atomic weight 167. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... An ion is an atom or group of atoms with a net electric charge. ... YAG Yttrium Aluminum Garnet Color: Wide range of colors Moh’s hardness: 8. ... General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Atomic mass 88. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... The Garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons. ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/gray Atomic mass 6. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ... Sapphire is the single-crystal form of aluminium oxide (Al2O3), a mineral known as corundum. ... Part of a Ti-sapphire oscillator. ... Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. ... General Name, Symbol, Number strontium, Sr, 38 Chemical series alkaline earth metals Group, Period, Block 2, 5, s Appearance silvery white metallic Atomic mass 87. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... Interference colors. ... A packaged laser diode with penny for scale. ... A cavity resonator uses resonance to amplify a wave. ... Spontaneous emission is the process by which a molecule in an excited state drops to the ground state, resulting in the creation of a photon. ... In optics, stimulated emission is the process by which, when perturbed by a photon, matter may lose energy resulting in the creation of another photon. ...


Other optical devices, such as spinning mirrors, modulators, filters and absorbers may be placed within the optical resonator, to produce a variety of effects on the laser output, such as altering the wavelength of operation or the production of pulses of laser light.


See also


  Results from FactBites:
 
Laser construction - Wikipedia, the free encyclopedia (561 words)
A helium-neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture, a Nd:YAG laser uses a light focussed from a Xenon flash lamp, and excimer lasers use a chemical reaction.
The gain medium is excited by the pump source to produce a population inversion, and it is in the gain medium that spontaneous and stimulated emission of photons takes place, leading to the phenomenon of optical gain, amplification.
Semiconductor lasers are typically very small, and can be pumped with a simple electric current, enabling them to be used in consumer devices such as compact disc players.
  More results at FactBites »

 
 

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