What does the acronym LASER stand for?

The acronym LASER stands for "Light amplification by stimulated emission of radiation." This definition is foundational in understanding how lasers operate. The term describes a process in which the light is amplified through a specific mechanism known as stimulated emission, which occurs when an atom or molecule, after being excited by an external energy source, emits light as it returns to its ground state.

This mechanism is crucial as it differentiates lasers from other light sources; a laser emits coherent light, meaning that the light waves are in phase and have a fixed relationship in terms of frequency and direction. The aspect of amplification indicates that lasers can produce a highly focused beam of light that can be much more intense than ordinary light sources.

The other options do not accurately capture the essential scientific principles underlying laser technology. They either provide incorrect definitions or combine terms in ways that do not reflect the actual physics of how lasers function. By understanding the correct definition of laser, practitioners in fields such as electrology, laser, and IPL are better equipped to utilize laser technology effectively.