LASER

Acronym for light amplification by stimulated emission of radiation . A device that produces a coherent beam of optical radiation by stimulating electronic, ionic, or molecular transitions to higher energy levels so that when they return to lower energy levels they emit energy. Note 1: Laser radiation may be either temporally coherent, spatially coherent, or both. Note 2: The degree of coherence of laser radiation exceeds 0.88. ( 188 )