A laser is a light that is produced by spontaneous transition from atoms (molecules or ions)and is similar to the light emitted by nature. Although the laser is light, but it is obviously different with ordinary light. Laser light only in a very short time depends on the initial spontaneous emission, then the process is completely determined by the laser radiation. So the laser has a very pure color, direction, almost no divergence of the engraving machine, high luminous intensity. The laser also has high coherence, high strength.