The term laser is an acronym for "light amplification by stimulated emission of radiation".
Lasers have the following properties:
(1) Outstanding monochromaticity
The light waves in the laser beam are all the same color;
Ordinary light (such as the light emitted by fluorescent tubes) is generally a mixture of several colors of light that appear white.
(2) Excellent directionality
The laser emits a beam with high directivity, that is, the composed light wave propagates in a straight line and will not spread;
Light waves from ordinary light sources spread out in all directions.
(3) High coherence.
As the light waves within a laser beam propagate, they oscillate with perfectly synchronized peaks and troughs, a property called coherence. When two laser beams overlap each other, the peaks and troughs of each beam only reinforce each other, creating an interference pattern.