who discover the LASER light ?

Answer 1

History of lasers courtesy of wikipedia:

In 1917, Albert Einstein in his paper Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation), laid the foundation for the invention of the laser and its predecessor, the maser, in a ground-breaking rederivation of Max Planck's law of radiation based on the concepts of probability coefficients (later to be termed 'Einstein coefficients') for the absorption, spontaneous, and stimulated emission.

In 1928, Rudolph W. Landenburg confirmed the existence of stimulated emission and negative absorption.[3]

In 1939, Valentin A. Fabrikant (USSR) predicted the use of stimulated emission to amplify "short" waves.[4]

In 1947, Willis E. Lamb and R. C. Retherford found apparent stimulated emission in hydrogen spectra and made the first demonstration of stimulated emission.[5]

In 1950, Alfred Kastler (Nobel Prize for Physics 1966) proposed the method of optical pumping, which was experimentally confirmed by Brossel, Kastler and Winter two years later.[6]

Answer 2

Inventors: Gordon Gould, Charles Townes, Arthur Schawlow, Theodore Maiman

The name LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. In 1917, Albert Einstein first theorized about the process which makes lasers possible called "Stimulated Emission."
Maser
In 1954, Charles Townes and Arthur Schawlow invented the maser (microwave amplification by stimulated emission of radiation), using ammonia gas and microwave radiation - the maser was invented before the (optical) laser. The technology is very close but does not use a visible light.

On March 24, 1959, Charles Townes and Arthur Schawlow were granted a patent for the maser. The maser was used to amplify radio signals and as an ultrasensitive detector for space research.

Theory
In 1958, Charles Townes and Arthur Schawlow theorized about a visible laser, an invention that would use infrared and/or visible spectrum light.

Ruby Laser
Theodore Maiman invented the ruby laser considered to be the first successful optical or light laser. Many historians claim that Theodore Maiman invented the first optical laser, however, there is some controversy that Gordon Gould was the first.

Gordon Gould - Laser
Gordon Gould was the first person to use the word "laser". There is good reason to believe that Gordon Gould made the first light laser. Gould was a doctoral student at Columbia University under Charles Townes, the inventor of the maser. Gordon Gould was inspired to build his optical laser starting in 1958. He failed to file for a patent his invention until 1959. As a result, Gordon Gould's patent was refused and his technolgy was exploited by others. It took until 1977 for Gordon Gould to finally win his patent war and recieve his first patent for the laser.

Gas Laser
The first gas laser (helium neon) was invented by Ali Javan in 1960.

Robert Hall - Semiconductor Injection Laser
In 1962, Robert Hall created a revolutionary type of laser that is still used in many of the electronic appliances and communications systems that we use every day.

Kumar Patel - Carbon Dioxide Laser
The carbon dioxide laser was invented by Kumar Patel in 1964.

Hildreth "Hal" Walker - Laser Telemetry
Hildreth Walker invented laser telemetry and targeting systems.

Answer 3

Theodore Maiman
I think there's a Wicki article on him.

Doug