Lasers, as with many areas of physics, have a very rich history. The word laser is actually an acronym; LASER stands for Light Amplification by Stimulated Emission of Radiation. The origin of this somewhat complex sounding invention started with Einstein in 1917. Einstein was the first to theorize a concept called "Stimulated Emission". Essentially, stimulated emission is a process where an electron in an atom drops to a lower energy state due to interacting with an electromagnetic wave. This was the foundation for the laser. For more information on stimulated emission, see the "How a Laser Works" page.

Almost 40 years after Einstein came up with stimulated emission, two physicists names Charles Townes and Arthus Schawlow invented the MASER, or Microwave Amplification by Stimulated Emission of Radiation. The maser used ammonia gas and microwave radiation to create a beam that was close to visible light. The maser used the principle of stimulated emission to get a large amount of photons in a steady beam, which is the basis of all lasers today.

Six years after Townes and Schawlow and their maser, Theodore Maiman invented the Ruby Laser. This was the first truly optical laser, using a cylindrical ruby crystal encased in a quartz flash tube with a completely reflective mirror on one end and a partially reflective mirror on the other. Maiman's laser emitted a series of fast pulses, and was called a "pulse laser" because of it.

Maiman is usually credited with the first laser, but just like the origins of Calculus, there is a small bit of controversy. A man named Gordon Gould was a student of Townes, and was the first person to start using the world "laser". After seeing Townes's work with his maser, Gould began his own laser in 1958. He attempted to get a patent in 1959, but it was rejected, and his work was stolen and use over and over before he finally got his patent in 1977.

The next leap in laser technology was the gas laser, which used a gas as the medium instead of a crystal. Ali Javan used a helium-neon mixture to create the first continuous emitting laser, unlike Maiman's pulse laser. It was also the first laser to finally fit the category of a method of taking electrical energy and turning it into laser light.

Only two years later in 1962, the first semiconductor injection laser was invented by Robert Hall. This type of laser uses a method similar to a light emitting diode to produce the light, and is currently the most common laser on the open market. They are extremely easy and cheap to produce, and can be made very small easily. These lasers can be found in everything from CD players to bar code scanners.