Beams of light from multiple lasers.
An example of a laser is a tool for removing unwanted hairs.
Origin of laserl(ight) a(mplification by) s(timulated) e(mission of) r(adiation)
- a. Any of several devices that emit highly amplified and coherent radiation of one or more discrete wavelengths. One of the most common lasers makes use of atoms in a metastable energy state, which, as they decay to a lower energy level, stimulate others to decay, resulting in a cascade of emitted radiation.b. A beam of radiation emitted by a laser.
- Sports A ball or puck sent in a straight line at high speed: shot a laser into the upper right corner of the goal.
Origin of laserl(ight) a(mplification by) s(timulated) e(mission of) r(adiation).
top:lasers using argon, organic dye, and a crystal made of neodymuim and YAG as different media for exciting atoms
bottom:a ruby laser
- Abbreviation of light amplification by stimulated emission of radiation.
laser - Computer Definition
A device that produces an intense, coherent, collimated, focused, and nearly monochromatic beam of radiated optical energy by stimulating electronic, ionic, or molecular transitions to lower energy levels. A laser comprises an active medium, or gain medium, and a resonant cavity. An external power source, or pump, in the form of electricity or another laser, energizes the gain medium, which absorbs the energy. Some of the particles in the gain medium are excited into quantum high-energy states. When a critical level of energy is achieved, a light signal passing through the medium produces more optical energy than is absorbed, and the signal is greatly amplified.The resulting radiated optical signal is highly coherent, i.e., consistent in phase and polarization, and virtually monochromatic.Through a resonating cavity and either mirrors or a diffraction grating, the signal is narrowly channeled and collimated, i.e., the rays are lined up so that they are virtually parallel. Fiber optic transmission systems (FOTS) in long haul applications employ semiconductor diode lasers, generally Fabry-Perot lasers or distributed feedback (DFB) lasers. Short haul transmission systems such as those associated with local area networks (LANs) more commonly employ light-emitting diodes (LEDs) or vertical cavity surface-emitting lasers (VCSELs) as light sources. (Note: The laser was patented by AT&T Bell Telephones in 1960 as the optical maser.) See also coherence, collimation, DFB laser, Fabry-Perot laser, LED, maser, pump laser, radiation, and VCSEL.
(Light Amplification by the Stimulated Emission of Radiation) A device that creates a uniform and coherent light that is very different from an ordinary light bulb. Many lasers deliver light in an almost-perfectly parallel beam (collimated) that is very pure, approaching a single wavelength. Laser light can be focused down to a tiny spot as small as a single wavelength. Laser output can be continuous or pulsed and is used in myriad applications. Gas lasers are used to cut steel and perform delicate eye surgery, while solid state lasers create the ultra-high-speed, minuscule pulses traveling in optical fibers traversing the backbones of all major communications networks. Light traveling in an optical fiber is impervious to external interference, a constant problem with electrical pulses in copper wire. See optical fiber and saser. How Does It Work? A laser is an optical oscillator, which is made out of a solid, liquid or gas with mirrors at both ends. To make the laser work, the material is excited or "pumped," with light or electricity. The pumping excites the electrons in the atoms, causing them to jump to higher orbits, creating a "population inversion." A few of the electrons drop back to lower energy levels spontaneously, releasing a photon (quantum of light). The photons stimulate other excited electrons to emit more photons with the same energy and thus the same wavelength as the original. The light waves build in strength as they pass through the laser medium, and the mirrors at both ends keep reflecting the light back and forth creating a chain reaction and causing the laser to "lase." In simple laser cavities, one mirror has a small transparent area that lets the laser beam out. In semiconductor lasers, both mirrors often transmit a beam, the second one being used for monitoring purposes.