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Laser

Specialty Definition: Laser

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Specialty Definition: Ford Laser

(From Wikipedia, the free Encyclopedia)

The Ford Laser is a small family car sold by Ford in Asia, Australasia, and parts of South America and Africa, as well as in North America where it is sold as the Escort, which is not to be confused with the model of the same name sold in Europe. It is also known as the Lidea in Japan, the Tierra in Taiwan and the Lynx in Malaysia.

It is generally available as a sedan or hatchback, although convertible and wagon versions have also been available.

The Ford Laser is, in fact, a restyled version of the 323 produced by Mazda in Japan since 1980. (Ford had acquired a 25 per cent stake in Mazda in 1979.) The Laser replaced the rear-wheel-drive Escort in Australasia in 1981, proving hugely popular as a hatchback, as well as a sedan (also known as the Meteor, and providing a worthy rival to Japanese models like the Toyota Corolla.

Many buyers in Australia and New Zealand were totally unaware that the Laser was Japanese at all, with Ford being seen as a 'local' brand. In those markets, the Laser outsold its Mazda twin, but in neighbouring Asian countries, such as Singapore, Malaysia and Thailand, as well as Japan itself, the reverse was the case. However, pooling resources with Mazda allowed Ford to maintain a footold in the region, which it would otherwise have lost. This was also the case in South America, Africa, and the Caribbean, where the Laser was also sold, in many cases being locally assembled.

In 1987, a version of the Laser built in Mexico was introduced in North America where it was known as the Mercury Tracer. In 1989, the US Ford Escort was replaced by a version of the Laser, although the Escort name was retained.

However, the Laser has been replaced in most markets around the world by the European-sourced Focus, designated as one of Ford's 'world cars'. The Mazda 323 replacement, the Mazda 3, is also based on the same platform as the new model Focus.

See also

• Ford Meteor
• Ford Telstar
• Ford Escort
• Ford Falcon

  Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Ford Laser."

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Helium-neon laser

(From Wikipedia, the free Encyclopedia)

A helium-neon laser, usually called a HeNe laser, is a small gas laser of a type often used in laboratory demonstrations of optics. Its usual operation wavelength is 632.8 nm, in the red portion of the visible spectrum.

Schematic diagram of a helium-neon laser

The gain medium of the laser, as suggested by its name, is a mixture of helium and neon gases, approximately in the ratio 5:1, contained at low pressure (typically ~300 Pa) in a glass envelope. The energy or pump source of the laser is provided by an electrical discharge of around 1000 V through an anode and cathode at each end of the glass tube. The cavity of the laser typically consists of a plane, high-reflecting mirror at one end of the laser tube, and a concave output coupler mirror of approximately 1% transmission at the other end.

HeNe lasers are typically small, with cavity lengths of around 15 cm up to 0.5 m, and optical output powers ranging from 1 mW to 100 mW.

Energy level diagram of a HeNe laser

The laser process in a HeNe laser starts with collision of electrons from the electrical discharge with the helium atoms in the gas. This excites helium from the ground state to the 2³S₁ and 2¹S₀ long-lived, metastable excited states. Collision of the excited helium atoms with the ground-state neon atoms results in transfer of energy to the neon atoms, exciting them into the 2s and 3s states. This is due to a coincidence of energy levels between the helium and neon atoms.

This process is given by the reaction equation:

He* + Ne → He + Ne* + ΔE

where (*) represents an excited state, and ΔE is the small energy difference between the energy states of the two atoms, of the order of 0.05 eV.

The number of neon atoms entering the excited states builds up as further collisions between helium and neon atoms occur, causing a population inversion between the neon 3s and 2s, and 3p and 3p states. Spontaneous emission between the 3s and 2p states results in emission of 632.8 nm wavelength light, the typical operating wavelength of a HeNe laser.

After this, fast radiative decay occurs from the 2p to the 1s energy levels, which then decay to the ground state via collisions of the neon atoms with the container walls. Because of this last required step, the bore size of the laser cannot be made very large and the HeNe laser is limited in size and power.

With the correct selection of cavity mirrors, other wavelengths of laser emission of the HeNe laser are possible. The 3s→3p and 2s→2p transitions give infrared operation at 3.39 μm and 1.15 μm wavelengths, and a variety of 2s→1s transitions are possible in the green (543.5 nm, the so-called GreeNe laser), the yellow (594 nm) and the orange (612 nm).

The gain bandwidth of the laser is dominated by Doppler broadening, and is quite narrow at around 1.5 GHz. This, along with the visible output and excellent beam quality possible from these lasers, makes the HeNe a useful source for holography and as a reference for spectroscopy. Other applications include use in barcode scanners.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Helium-neon laser."

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Laser

(From Wikipedia, the free Encyclopedia)

Laser is an acronym for "Light Amplification by Stimulated Emission of Radiation". It uses a quantum mechanical effect, stimulated emission, to generate a very collimated, monochromatic and coherent beam of light.

Laser (U.S. Air Force)

Common light sources, such as the electric light bulb emit photons in all directions, usually over a wide spectrum of wavelengths. Most light sources are also incoherent, i.e., there is no fixed phase relationship between the photons emitted by the light source.

By contrast, a laser emits photons in a narrow, well-defined beam of light. The light is often near-monochromatic, consisting of a single wavelength or color, is highly coherent and is often polarised. Some types of laser, such as dye lasers and vibronic solid-state lasers can produce light over a broad range of wavelengths; this property makes them suitable for the generation of extremely short pulses of light, on the order of a femtosecond (10^-15 seconds).

Laser light can be highly intense — able to cut steel and other metals. The beam emitted by a laser often has a very small divergence (i.e. it is highly collimated). The beam will eventually spread due to the effect of diffraction but much less so than a beam of light generated by other means. A beam generated by a small laboratory laser such as a helium-neon (HeNe) laser spreads to approximately 1 mile in diameter if shone from the Earth's surface to the Moon.

A laser can also function as an optical amplifier when seeded with light from another source. The amplified signal can be very similar to the input signal in terms wavelength, phase and polarisation; this is particularly important in optical communications.

Even low power lasers can be hazardous to a person's eyesight. The coherence and low divergence of laser light means that it can be focused by the eye into an extremely small spot on the retina, resulting in localised burning and permanent damage in seconds. Certain wavelengths of laser light can cause cataracts or even boiling of the vitreous humor, the fluid in the eyeball. Infrared and ultraviolet lasers are particularly dangerous, since the body's "blink reflex", which can protect an eye from excessively bright light, works only if the light is visible. Lasers are classified by wavelength and maximum output power into safety classes, from class I (inherently safe; no possibility of eye damage even from hours of direct exposure) to class IV (highly dangerous; even non-direct scattering of light from the beam can blind). Users of class III lasers and above must usually wear appropriate eye protection when operating the laser.

The output of a laser may be a continuous, constant-amplitude output (known as c.w. or continuous wave), or pulsed, by using the techniques of Q-switching or modelocking.

The basic physics of lasers centres around the idea of producing a population inversion in a laser medium. The medium may then amplify light by the process of stimulated emission, which if the light is fed back through the medium by means of a cavity resonator, will continue to be amplified into a high-intensity beam. A great deal of quantum mechanics and thermodynamics theory can be applied to laser action (see laser science), though in fact many laser types were discovered by trial and error.

Population inversion is also the concept behind the maser, which is similar in principle to a laser but works with microwaves. The first maser was built by Charles H. Townes in 1953. Townes later worked with Arthur L. Schawlow to describe the theory of the laser, or optical maser as it was then known.

The first maser, developed by Townes, was incapable of continuous output. Nikolai Basov and Alexander Prokhorov of the USSR worked independently on the quantum oscillator and solved the problem of continuous output systems by using more than two energy levels. These systems could release stimulated emission without falling to the ground state, thus maintaining a population inversion. In 1964, Charles Townes, Nikolai Basov and Alexandr Prokhorov shared a Nobel Prize in Physics "for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle."

The first working laser was made by Theodore H. Maiman in 1960 at Hughes Research Laboratories in Malibu, California, beating several research teams including those of Townes at Columbia University, and Schawlow at Bell laboratories. Maiman used a solid-state flashlamp-pumped ruby crystal to produce red laser light at 694 nanometeres wavelength.

Types of lasers include:

• Ruby lasers, producing red (694 nm) light. The first type invented, often used for medical purposes including the removal of tattoos and birthmarks.
• Semiconductor lasers, used in laser pointers, laser printers, and CD/DVD players;
• Dye lasers
• Carbon dioxide lasers - used in industry for cutting and welding
• Excimer lasers, producing ultraviolet light, used in semiconductor manufacturing;
• Neodymium-doped YAG lasers (Nd:YAG), a high-power laser operating in the infrared, used for cutting, welding and marking of metals and other materials;
• Holmium-doped glass, a high-power laser operating in the infrared, it is explosively absorbed by water-bearing tissues in sections less than a millimeter thick. It is usually operated in a pulsed mode, and passed through optic fiber surgical devices to resurface joints, remove rot from teeth, vaporize cancers, and to pulverize kidney and gall stones.
• Titanium-doped sapphire (Ti:sapphire) lasers, a highly tunable infrared laser, used for spectroscopy;
• Erbium-doped fiber lasers, a type of laser formed from a specially made optical fiber, which is used as an amplifier for optical communications.
• Random laser, different with conventional lasers, the necessary feedback is from strong scattering inside disordered media instead of end mirrors.

See also Laser applications, Laser construction, Laser science, LADAR, active laser medium, laser diode, Ring laser gyroscope

The verb "to lase" means to give off coherent light or possibly to cut or otherwise treat with coherent light, and is a back-formation of the term laser.

External Link

• Sam's Laser FAQ

Laser is a resin produced by the silphium plant, also called laserwort, and a genus of the family Apiaceae.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Laser."

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Abbreviations & Acronyms: Laser

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Modern Usage: Laser

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Commercial Usage: Laser

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Image Slideshow: Laser

Photos: Laser More pictures...

Computer Images: Laser More pictures...

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Photo Album: Laser

Thumbnail	Description & Credit	Thumbnail	Description & Credit
	Seen is a "beam of light" traveling along fiber optics for photodynamic therapy for use in an operating room. Its source is a laser beam which is split at two different stages to create the proper "therapeutic wavelength". The patient has been given a photo sensitive drug containing cancer killing substances which are absorbed by cancer cells. During the surgery, the light beam is positioned at the tumor site, which then activates the drug that kills the cancer cells, thus photodynamic therapy. Credit: John Crawford (photographer).		Shown is close up of surgeons' hands in an operating room with a "beam of light" traveling along fiber optics for photodynamic therapy. Its source is a laser beam which is split at two different stages to create the proper "therapeutic wavelength". A patient would be given a photo sensitive drug (photofrin) containing cancer killing substances which are absorbed by cancer cells. During the surgery, the light beam is positioned at the tumor site, which then activates the drug that kills the cancer cells, thus photodynamic therapy (PDT). Credit: John Crawford (photographer).
	Using laser light, CDC laboratory scientists sometimes work with a confocal microscope when diagnosing various pathogens. Credit: CDC.		This movie depicts the airborne laser altimeter collecting data.  In 1993 and 1994, NASA researchers surveyed the Greenland ice sheet using an airborne laser altimeter. Ten flight lines flown in 1993 in southern Greenland were resurveyed in 1998. Sci. Credit: NASA.
	Laser beam from Geodimeter Transcontinental traverse party of Woodrow Johnson. Credit: Coast & Geodetic Survey Historical Image Collection.		Laser light emitting from Geodimeter Transcontinental traverse party of Woodrow Johnson. Credit: Coast & Geodetic Survey Historical Image Collection.
	MiniRover equipped with video and laser scanning system. Credit: National Undersea Research Program (NURP).		A green laser water penetration system devised by Sylvania Electronic Systems in the late 1970's. Although advertised for fisheries use, this technology has evolved into LIDAR, a system for measuring shallow-water bathymetry and also for into a rapid terrain mapping technique. In: Farooq Hussain, 1970, "Living Underwater, " p. 87. Library Call Number GC65 H8 1970b. Credit: Sailing for Science - the NOAA Fleet Then and Now.
	Floating just above the water, a balloon representing the Airborne Laser program makes a practice flight in preparation for the Kodak Albuquerque International Balloon Fiesta, which begins Oct. 7. One of approximately 1,000 balloons attending this year's.		Laser-leveled land is irrigated in Southern California's Imperial Valley. Laser-leveling is done by earth movers equipped with laser receiving equipment. Levelling is done to optimally manage the flow of irrigation water across a field. Credit: Tim McCabe.
Source: pictures compiled by the editor from various references; see picture credits.

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Digital Photo Gallery: Laser
 

"DYE Laser 3" by Rodrigo Galindo Commentary: "Views of an Ar-Ion Pumped, Rhodamine 6G DYE Laser at work."	"Street laser" by Jim Robinson Commentary: "Playing with shutter speeds at night ."
Source: photographs selected by the editor, with permission from the photographers.

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Sounds Captioned with "Laser".

Play	Caption	Play	Caption
	Synthesized music with laser sounds.		Laser shooting sound effect.
	Laser gunshot sound effect.		Firing of a laser gun; phaser fire;.
	Laser gun shooting.
Source: compiled by the editor from various references; see credits.

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Non-Fiction Usage: Laser

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Spoken Usage: Laser

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Speeches: Laser

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Usage Frequency: Laser

Source: compiled by the editor from several corpora; see credits.

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Name Usage Frequency: Laser

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Usage in Company Names: Laser

Source: compiled by the editor from Icon Group International, Inc.

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Expressions: Laser

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Frequency of Internet Keywords: Laser

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Modern Translation: Laser

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Derivations & Misspellings: Laser

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Rhyming with "Laser"

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Anagrams: Laser

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