A laser (from the acronym Light Amplification by Stimulated Emission of Radiation) is a device which produces a narrow, intense beam of electromagnetic radiation. A laser transfers energy to anything it strikes, and a sufficiently intense laser beam can burn through material.
Laser light has useful characteristics:
- A laser beam is "monochromatic", meaning that every photon of light in the beam has the same frequency. Consistent frequency is achieved by exciting atoms of a single element, stimulating them to release photons of light at a frequency specific to that element.
- A laser beam is "coherent", meaning that light waves in the beam are synchronized.
- A laser beam is "directional", meaning that all light rays in the beam are travelling in exactly the same direction.
Theodore H. Maiman invented the first laser in 1960 . Practical modern applications for lasers include reading and writing digital information, security systems, targeting devices on weapons, and precision cutting of certain materials. Several military organizations are researching laser weapons systems, but these are still in the R&D stage.
Lasers in Science Fiction
Weaponized lasers are common in science fiction, ranging from small arms to spacecraft-scale weapons. Sci-fi laser weapons do not always share the characteristics of real-life lasers, however. In many science fiction franchises, the term "laser" seems to have taken on a far more generic definition, encompassing any beam-style directed-energy weapon.
Often, one or more of the following attributes can be found in sci-fi lasers that are incompatible with real-life laser behavior:
- Visible in a vacuum
- Light is only visible when it reflects to a detector (an eye or camera, for example). Because the photons in a laser beam are all going in the same direction, the beam can only be made "visible" if the photons were to reflect off of something (such as dust).
- Slower-than-light propagation
- Because a laser beam is a type of light beam, a laser would naturally propagate at lightspeed.
- Theodore H. Maiman article at the IEEE Virtual Museum
- Lasers on How Stuff Works