- (noun) A device that generates an intense, narrow beam of light created by bombarding an active medium (CO2, Nd:YAG, argon), with energy in the form of high-voltage electricity, high-intensity light, or radio frequency waves. By passing through a mirrored tube, the photons are released as a nondivergent ("collimated"), monochromatic (all one wavelength), coherent (all in phase) beam. Lasers are used in microsurgery, for cauterization, excision, and for a variety of diagnostic purposes. The wavelength delivered depends on the active medium excited; targetted tissues ("chromophores") are determined by the laser wavelength that they absorb. Laser dosage, or fluence, delivered is derived by dividing the energy delivered by the cross-sectional area of the beam (Joules/CM2). Lasers can be based on numerous chemical sources, gas, liquid, and solid, some of which are listed in the chart on p. 1051. Lasers are widely used in printers of text or x-ray images.
- (verb) To treat a structure with a laser beam.
[acronym coined from light amplification by stimulated emission of radiation]
See Also: chromophore
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