"Thermal processing" A laser beam with a higher energy density (it is a concentrated energy flow) is irradiated on the surface of the material to be processed, the material surface absorbs the laser energy, and a thermal excitation process occurs in the irradiated area, so that the material surface (or coating) temperature rise, resulting in metamorphosis, melting, ablation, evaporation and other phenomena.
"Cold working" photons with very high loading energy (ultraviolet) can break chemical bonds in materials (especially organic materials) or in the surrounding medium, so that the material is destroyed by non-thermal processes. This cold working is of special significance in laser marking processing, because it is not thermal ablation, but cold peeling that breaks chemical bonds without the side effect of "thermal damage", so it does not affect the inner layer and adjacent areas of the machined surface. Produce heating or thermal deformation and other effects. For example, excimer lasers are used in the electronics industry to deposit thin films of chemical species on substrate materials, creating narrow trenches in semiconductor substrates.
