Laser is a device that stimulates atoms or molecules to emit light at particular wavelengths and amplifies that light, typically producing a really narrow beam of radiation. The emission generally covers an extremely limited range of visible, infrared, or ultraviolet wavelengths.
Applications:
1. Lasers are broadly used in manufacturing, e.g. for cutting, drilling, welding, cladding, soldering (brazing), hardening, ablating, surface treatment, marking, engraving, micromachining, pulsed laser deposition, lithography, etc.
2. Lasers are also used for surgery, exploiting the possibility to cut tissues while causing minimal bleeding and in vision correction dentistry, dermatology, various kinds of cosmetic treatment such as tattoo removal and hair removal.
3. Optical fiber communication, extensively used mainly for long-distance optical data transmission, typically relies on laser light in optical glass fibers. Free-space optical communications, e.g. for inter-satellite communications, is predicated on higher-power lasers, generating collimated laser beams which propagate over large distances with small beam divergence.
4. Laser scanners are scanning the direction of laser beams, which can read e.g. bar codes or other graphics over some distance. It is also possible to scan three-dimensional objects, e.g. in the context of crime scene investigation.
5. Solid materials can be analyzed with laser-induced breakdown spectroscopy. Laser microscopes and setups for optical coherence tomography (OCT) provide images of, e.g., biological samples with extremely high resolution, often in three dimensions. It is also possible to realize functional imaging.