The laser is characterized by high directivity, monochromaticity, high coherence and high brightness. Through the focus and Q-switching of the lens, energy can be concentrated into a small spatial range and time range. In the laser cleaning process, the following characteristics of the laser are mainly utilized:
1. Laser can achieve high concentration of energy in time and space. The focused laser beam can generate several thousand degrees or even tens of thousands of degrees of high temperature near the focus, so that the dirt instantly evaporates, vaporizes or decomposes.
2. The divergence angle of the laser beam is small and the directivity is good. The laser beam can be integrated into the spot of different diameters by the concentrating system. Control laser beam spots of different diameters under the same conditions of laser energy.
3. The energy density of the laser can be adjusted to cause the dirt to expand by heat. When the expansion force of the dirt is greater than the adsorption force of the dirt on the substrate, the dirt will leave the surface of the object.
Therefore, the laser cleaning can not only damage the surface of the substrate, but also the composition inside the substrate does not change, which is true without damaging the substrate.