laser
[ ley-zer ]
/ ˈleɪ zər /
noun Physics.
a device that produces a nearly parallel, nearly monochromatic, and coherent beam of light by exciting atoms to a higher energy level and causing them to radiate their energy in phase.
Also called
optical maser.
Origin of laser
1955–60;
l(ightwave)
a(mplification by)
s(timulated)
e(mission of)
r(adiation)
Words nearby laser
lascaux,
lascaux cave,
lascivious,
lasdun,
lase,
laser,
laser beam,
laser card,
laser chemistry,
laser cooling,
laser diode
Example sentences from the Web for laser
British Dictionary definitions for laser (1 of 2)
laser
/ (ˈleɪzə) /
noun
a source of high-intensity optical, infrared, or ultraviolet radiation produced as a result of stimulated emission maintained within a solid, liquid, or gaseous medium. The photons involved in the emission process all have the same energy and phase so that the laser beam is monochromatic and coherent, allowing it to be brought to a fine focus
any similar source producing a beam of any electromagnetic radiation, such as infrared or microwave radiation
verb (tr)
to use a laser on (something), esp as part of medical treatment
(often foll by off)
to remove (a tattoo, fat, etc) with laser treatment
See also
maser
Word Origin for laser
C20: from
l ight
a mplification by
s timulated
e mission of
r adiation
British Dictionary definitions for laser (2 of 2)
Laser
/ (ˈleɪzə) /
noun
trademark
a type of dinghy, designed to be sailed by one person
Medical definitions for laser
laser
[ lā′zər ]
n.
Any of several devices that convert incident electromagnetic radiation of mixed frequencies to discrete frequencies of highly amplified and coherent ultraviolet, visible, or infrared radiation; used in surgery to cut and dissolve tissue.
Scientific definitions for laser
laser
[ lā′zər ]
Short for light amplification by stimulated emission of radiation. A device that creates and amplifies electromagnetic radiation of a specific frequency through the process of stimulated emission. The radiation emitted by a laser consists of a coherent beam of photons, all in phase and having the same polarization. Lasers have many uses, such as cutting hard or delicate substances, reading data from compact disks and other storage devices, and establishing straight lines in geographical surveying.
A Closer Look
A laser emits a thin, intense beam of nearly monochromatic visible or infrared light that can travel long distances without diffusing. Most light beams consist of many waves traveling in roughly the same direction, but the phases and polarizations of each individual wave (or photon) are randomly distributed. In laser light, the waves are all precisely in step, or in phase, with each other, and have the same polarization. Such light is called coherent. All of the photons that make up a laser beam are in the same quantum state. Lasers produce coherent light through a process called stimulated emission. The laser contains a chamber in which atoms of a medium such as a synthetic ruby rod or a gas are excited, bringing their electrons into higher orbits with higher energy states. When one of these electrons jumps down to a lower energy state (which can happen spontaneously), it gives off its extra energy as a photon with a specific frequency. But this photon, upon encountering another atom with an excited electron, will stimulate that electron to jump down as well, emitting another photon with the same frequency as the first and in phase with it. This effect cascades through the chamber, constantly stimulating other atoms to emit yet more coherent photons. Mirrors at both ends of the chamber cause the light to bounce back and forth in the chamber, sweeping across the entire medium. If a sufficient number of atoms in the medium are maintained by some external energy source in the higher energy state-a condition called population inversion-then emission is continuously stimulated, and a stream of coherent photons develops. One of the mirrors is partially transparent, allowing the laser beam to exit from that end of the chamber. Lasers have many industrial, military, and scientific uses, including welding, target detection, microscopic photography, fiber optics, surgery, and optical instrumentation for surveying.