这个词是什么意思？
An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D007834 · MeSH 2026。
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