What is a Laser?

Coherent laser light available in different wavelengths (colors)

What Is a Laser? A laser produces a very narrow beam of light that is useful in many technologies and instruments. The letters in the word laser stand for Light Amplification by Stimulated Emission of Radiation.

A laser is an unusual light source. It is quite different from a light bulb or a flash light. Lasers produce a very narrow beam of light. This type of light is useful for lots of technologies and instruments – even some that you might use at home! NASA

A laser is created when electrons in the atoms in optical materials like glass, crystal, or gas absorb the energy from an electrical current or a light. That extra energy “excites” the electrons enough to move from a lower-energy orbit to a higher-energy orbit around the atom’s nucleus.

Lasers have been around since 1960, although the idea goes back to 1900 (see “A Legacy of Lasers and Laser Fusion Pioneers”).

Today, lasers come in many sizes, shapes, colors, and levels of power, and are used for everything from surgery in hospitals, to bar code scanners at the grocery store, and even playing music, movies, and video games at home. You might have undergone LASIK surgery, which corrects your vision by using a tiny laser to reshape the cornea of your eye.

Some lasers, such as ruby lasers, emit short pulses of light. Others, like helium–neon gas lasers or liquid dye lasers, emit light that is continuous. NIF, like the ruby laser, emits pulses of light lasting only billionths of a second. Laser light does not need to be visible. NIF beams start out as invisible infrared light and then pass through special optics that convert them to visible green light and then to invisible, high-energy ultraviolet light for optimum interaction with the target.

Lasers can be tiny constituents of microchips or as immense as NIF, the world’s most energetic laser housed in a building 10 stories high and as wide as three football fields.

NIF&PS