What does LASER stand for?

The correct answer, "Light amplification by stimulated emission of radiation," accurately describes the fundamental process by which lasers operate. This phrase encapsulates the critical components of laser technology:

1. Light Amplification: Lasers intensify light. This is achieved through a process called stimulated emission, where an incoming photon stimulates excited atoms to emit additional photons of the same wavelength and phase, leading to an increased intensity of light.

2. Stimulated Emission: This occurs when an atom or molecule, which is in an excited state, is struck by a photon. The resulting interaction causes the emission of a second photon that is coherent with the first, meaning it has the same phase and direction.

3. Radiation: This term refers to the emitted light itself. In the context of lasers, the radiation produced is monochromatic (single wavelength), coherent (light waves are in phase), and directional (focused into a narrow beam).

Combining these aspects highlights why the correct choice effectively summarizes the core principles of how lasers function. The other options do not adequately capture this process, either by misunderstanding the role of stimulated emission or incorrectly describing the interaction of light and energy in a laser system.