Light is generated using devices such as the light emitting diode and the laser. It is transmitted through the atmosphere, through optical systems composed of lenses, mirrors, and crystals, or through light pipes -optical fibers. Light is detected using such devices as photodiodes, photocells, or the photoconducting surface of a vidicon camera. The amount of light generated or transmitted is controlled using electric devices, such as electrooptic and acoustooptic modulators, electronic shutters, scanners, and even by light itself.
Light is used as a carrier of information or energy.
In laser radar, light is used to detect the presence and properties of a target. In holography, laser light is used to record three-dimensional information on a photographic film, a hologram. In metrological applications, lasers are used to locate objects. Light may be used as a carrier of energy in applications ranging from surgery to nuclear fusion. Industrial, medical, and military applications of photonics are growing at a very rapid pace.