Laser: A timeline

Following is a timeline of the laser, which was born 50 years ago on May 16:

- 1917: Einstein proposes the theory of "stimulated emission," by which a photon, or light particle, induces an atom to emit an identical photon.

- 1953: American physicist Charles Townes builds forerunner of the laser, a "maser," for Microwave Amplification by Stimulated Emission of Radiation.

- 1957: Gordon Gould, a doctoral student under Townes, coins the term "laser," theorising that light could be used to excite atoms into making a coherent beam of light. Later files a patent; legal dispute lasts nearly three decades.

- 1960: First laser, built by Theodore Maiman of Hughes Research Laboratories in California, becomes operational.

- 1961: Laser used for first time in surgery, to destroy retinal tumour.

- 1962: Invention of the semi-conducting diode laser, the mainstay of small commercial lasers today.

- 1969: Laser's use in telemetry makes headlines. A beam bounced back by a mirror deployed by the Apollo 11 crew measures the distance between Earth and the Moon to within a few metres (yards).

- 1971: Lasers enter the arts, with light shows and the awarding of the Nobel Prize to Dennis Gabor, a British-Hungarian, for holography.

- 1974: First supermarket bar-code scanner.

- 1975: IBM introduces first commercial laser printer.

- 1978: First laser disc player, made by Philips, but high cost is a barrier to success.

- 1982: First Compact Disc player. First CD to be pressed is "52nd Street" by Billy Joel.

- 1983: President Ronald Reagan makes "Star Wars" speech, sketching vision of space-based laser weapons.

- 1988: North America and Europe are linked by first fibre-optic cable, which uses laser pulses to transport data.

- 1990s: Lasers become established in manufacturing processes, including integrated circuits and car manufacturing.

- 1991: First laser surgery to correct short-sightedness. Gulf War sees first use of laser-guided munitions.

- 1996: Toshiba sells first digital versatile disc (DVD) player.

- 2008: French neurosurgeons use fibre-optic laser and keyhole surgery to destroy brain cancer.

- 2010: US National Nuclear Security Administration says quest for nuclear fusion clears a key hurdle, with the use of 192 laser beams to compress tiny balls of fuel made from deuterium and tritium.