| Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography | A laser differs from other sources of light in that it emits light coherently |
|---|---|
| Among their many applications, lasers are used in optical disk drives, laser printers, and barcode scanners; DNA sequencing instruments, fiber-optic and free-space optical communication; laser surgery and skin treatments; cutting and welding materials; military and law enforcement devices for marking targets and measuring range and speed; and laser lighting displays in entertainment | Temporal coherence can be used to produce pulses of light as short as a femtosecond |
, they can emit a single color of light.
| Spatial coherence also allows a laser beam to stay narrow over great distances collimation , enabling applications such as laser pointers | Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range |
|---|---|
| Since the early period of laser history, laser research has produced a variety of improved and specialized laser types, optimized for different performance goals, including: new wavelength bands maximum average output power maximum peak pulse energy maximum peak pulse power minimum output pulse duration maximum power efficiency minimum cost and this research continues to this day |
The first laser was built in 1960 by Theodore H.