ââ¬ÅLaserââ¬Â is an acronym for light amplification by stimulated emission of radiation. A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become ââ¬Åexcited.ââ¬Â The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atomââ¬â¢s nucleus. When they return to their normal or ââ¬Ågroundââ¬Â state, the electrons emit photons particles of light. These photons are all at the same wavelength and are ââ¬Åcoherent,ââ¬Â meaning the crests and troughs of the light waves are all in lockstep. In contrast, ordinary visible light comprises multiple wavelengths and is not coherent.
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