A test target is vaporized and bursts into flame upon irradiation by a high power continuous wave carbon dioxide laser emitting tens of kilowatts of infrared light.

The carbon dioxide laser (CO₂ laser) was one of the earliest gas lasers to be developed (invented by Kumar Patel of Bell Labs in 1964^[1]), and is still one of the most useful. 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%. Image File history File links Download high resolution version (1204x680, 228 KB) Summary continuous wave 50,000 watt carbon dioxide electric discharge coaxial laser [1]. Original caption: A sergeant operates a 15,000-watt laser. ... Image File history File links Download high resolution version (1204x680, 228 KB) Summary continuous wave 50,000 watt carbon dioxide electric discharge coaxial laser [1]. Original caption: A sergeant operates a 15,000-watt laser. ... Image of two girls in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The gas laser is a kind of laser in which some sort of gas (such as helium or neon) is discharged to produce the laser light. ... C. Kumar N. Patel developed the carbon dioxide laser in 1963[1]; it is now widely used in industry for cutting and welding, as a laser scalpel in surgery, and in laser skin resurfacing. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... A LASER (from the acronym of Light Amplification by Stimulated Emission of Radiation) is an optical source that emits photons in a coherent beam. ...

The CO₂ laser produces a beam of infrared light with the principal wavelength bands centering around 9.4 and 10.6 micrometers. Image of two girls in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength[1]. The elementary particle that defines light is the photon. ... The wavelength is the distance between repeating units of a wave pattern. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the size of a droplet of mist or fog. ...

Amplification

The active laser medium (laser gain/amplification medium) is a gas discharge which is air cooled (water cooled in higher power applications). The filling gas within the discharge tube consists primarily of: Within a laser, the active laser medium is the material that exhibits optical gain. ... Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ... -1...

• Carbon dioxide (CO₂) (around 10-20 %) CO₂ is a molecule with 3 atoms, the middle atom is carbon.
• Nitrogen (N₂) (around 10-20%)
• Hydrogen (H₂) and/or (Xe) (a few percent)
• Helium (He) (The remainder of the gas mixture)

The specific proportions vary according to the particular laser. Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ...

The population inversion in the laser is achieved by the following sequence: 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. ...

1. Electron impact excites vibrational motion of the nitrogen. Because nitrogen is a homonuclear molecule, it cannot lose this energy by photon emission, and its excited vibrational levels are therefore metastable and live for a long time.
2. Collisional energy transfer between the nitrogen and the carbon dioxide molecule causes vibrational excitation of the carbon dioxide, with sufficient efficiency to lead to the desired population inversion necessary for laser operation.

The electron is a fundamental subatomic particle that carries an electric charge. ... Homonuclear molecules, or homonuclear species, are molecules composed of only one type of element. ... The word light is defined here as electromagnetic radiation of any wavelength; thus, X-rays, gamma rays, ultraviolet light, microwaves, radio waves, and visible light are all forms of light. ... A metastable system with a weakly stable state (1), an unstable transition state (2) and a strongly stable state (3) Metastability is the ability of a non-equilibrium state to persist for some period of time. ...

Construction

Because CO₂ lasers operate in the infrared, special materials are necessary for their construction. Typically, the mirrors are made of coated silicon, molybdenum, or gold, while windows and lenses are made of either germanium or zinc selenide. For high power applications, gold mirrors and zinc selenide windows and lenses are preferred. Historically, lenses and windows were made out of salt (either sodium chloride or potassium chloride). While the material was inexpensive, the lenses and windows degraded slowly with exposure to atmospheric moisture. A mirror, reflecting a vase. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark gray with bluish tinge Atomic mass 28. ... General Name, Symbol, Number molybdenum, Mo, 42 Chemical series transition metals Group, Period, Block 6, 5, d Appearance gray metallic Atomic mass 95. ... General Name, Symbol, Number gold, Au, 79 Chemical series transition metals Group, Period, Block 11, 6, d Appearance metallic yellow Atomic mass 196. ... General Name, Symbol, Number germanium, Ge, 32 Chemical series metalloids Group, Period, Block 14, 4, p Appearance grayish white Atomic mass 72. ... Zinc selenide (ZnSe), is a light yellow binary solid compound. ... Sodium chloride, also known as common salt, table salt, or halite, is a chemical compound with the formula NaCl. ... The chemical compound potassium chloride (KCl) is a metal halide composed of potassium and chlorine. ...

The most basic form of a CO₂ laser consists of a gas discharge (with a mix close to that specified above) with a total reflector at one end, and an output coupler (usually a semi-reflective coated zinc selenide mirror) at the output end. The reflectivity of the output coupler is typically around 5-15%. The laser output may also be edge-coupled in higher power systems to reduce optical heating problems. Spheres reflecting the floor and each other. ...

The CO₂ laser can be constructed to have powers between milliwatts (mW) and gigawatts (GW). It is also very easy to actively Q-switch a CO₂ laser by means of a rotating mirror or an electro-optic switch, giving rise to Q-switched peak powers 100 to 1000 times higher than the equivalent continuous wave laser of any particular design. Milliwatt (SI symbol: mW) is a unit for measuring electrical power, equal to one-thousandth (10-3) of a watt. ... The gigawatt (symbol: GW) is a unit for measuring power corresponding to one billion (109) watts. ... Q-switching, sometimes known as giant pulse formation, is a technique discovered circa 1962 by R.W. Hellwarth and F.J. McClung using electrically switched Kerr cell shutters and is a technique by which a laser can be made to produce a pulsed output beam. ... A continuous wave (CW) is an electromagnetic wave of constant amplitude and frequency. ...

Because the laser transitions are actually on vibration-rotation bands of a linear triatomic molecule, the rotational structure of the P and R bands can be selected by a tuning element in the laser cavity. Because transmissive materials in the infrared are rather lossy, the frequency tuning element is almost always a diffraction grating. By rotating the diffraction grating, a particular rotational line of the vibrational transition can be selected. The finest frequency selection may also be obtained through the use of an etalon. In practice, together with isotopic substitution, this means that a continuous comb of frequencies separated by around 1 cm^-1 (30 GHz) can be used that extend from 880 to 1090 cm^-1. Such "line-tuneable" carbon dioxide lasers are principally of interest in research applications. An optical cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves. ... Sine waves of various frequencies; the bottom waves have higher frequencies than those above. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In optics, a Fabry-Perot interferometer or etalon is typically made of a transparent plate with two reflecting surfaces, or two parallel highly-reflecting mirrors. ...

Applications

Because of the high power levels available (combined with reasonable cost for the laser), CO₂ lasers are frequently used in industrial applications for cutting and welding. They are also very useful in surgical procedures because water (which makes up most biological tissue) absorbs this frequency of light very well. Some examples of medical uses are laser surgery, skin resurfacing ("laser facelifts") (which essentially consist of burning the skin to promote collagen formation), and dermabrasion. Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force. ... Laser beam welding is a technique in manufacturing whereby two or more pieces of material (usually metal) are joined by together through use of a laser beam. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... // The benefits of lasers in various applications stems from their properties such as coherency, high monochromaticity, and ability to reach extremely high powers. ... Laser resurfacing is a technique used during laser surgery wherein molecular bonds of a material are dissolved by a laser. ... Facelift has several meanings: Facelift is an album by Alice in Chains; facelift is a cosmetic surgery procedure; facelift is the revival of a product through cosmetic means. ... Dermabrasion involves the removal of the surface of the skin with specialist equipment and usually involves a general anaesthetic. ...

Because the atmosphere is quite transparent to infrared light, CO₂ lasers are also used for military rangefinding using LIDAR techniques. Layers of Atmosphere (NOAA) Air redirects here. ... A rangefinder is an optical device that allows distance to be estimated or measured using triangulation, laser, radar, or other method. ... This article or section does not cite its references or sources. ...

References

1. ^ Patel, C. K. N. (1964). "Continuous-Wave Laser Action on Vibrational-Rotational Transitions of CO₂". Physical Review 136 (5A): A1187–A1193. DOI:10.1103/PhysRev.136.A1187.

C. Kumar N. Patel developed the carbon dioxide laser in 1963[1]; it is now widely used in industry for cutting and welding, as a laser scalpel in surgery, and in laser skin resurfacing. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

• Home-built Carbon dioxide laser