Working principle of laser marking machine and its typical models

Holmium laser marking is the permanent marking of the surface of various materials with a laser beam. The effect of marking is to expose deep substances through evaporation of surface substances, or to "etch" traces through the chemical and physical changes of surface substances caused by light energy, or to burn away some substances by light energy, showing the required etching.

At present, there are two recognized principles:

"Hot processing" A laser beam with a higher energy density (which is a concentrated energy flow) is irradiated on the surface of the material being processed. The surface of the material absorbs the laser energy and generates a thermal excitation process in the illuminated area, so that the surface of the material (or Coating) temperature rise, resulting in metamorphism, melting, ablation, evaporation and other phenomena.

"Cold processing" (ultraviolet) photons with high load energy can break chemical bonds in materials (especially organic materials) or surrounding media, causing non-thermal process destruction of materials. This cold processing 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 "heat damage", so it does not affect the inner layer and nearby areas of the processed surface. Generates heating or thermal deformation. For example, in the electronics industry, excimer lasers are used to deposit a thin film of a chemical substance on a substrate material to create narrow grooves in a semiconductor substrate.

Aohua Laser marking machine can be divided into: laser pumped YAG laser marking machine, semiconductor pumped laser marking machine, fiber laser marking machine, CO2 laser marking machine.

Krypton lamp pumped YAG laser marking machine is a solid-state laser with a wavelength of 1064nm in the infrared light band. Nd: YAG lasers are generally used as a pump source. Nd (neodymium) is a rare earth element. YAG stands for yttrium aluminum garnet. As a medium for generating laser light, the pump source emits incident light of a specific wavelength, which causes the number of particles in the working substance to be reversed. The laser is released by energy level transition , Amplify and shape the laser energy to focus and form a usable laser beam.

Semiconductor pumped YAG laser marking machine generally uses a semiconductor laser diode (side or end face) to pump Nd: YAG medium, which causes a large number of reversed particles in the medium to form a giant pulse laser output under the action of a Q switch. Compared with the lamp pumped YAG laser marking machine, the semiconductor pumped laser marking machine has the advantages of high stability, power saving, low thermal effect, high electro-optical conversion efficiency and long life, and it is easier to adopt frequency conversion technology. Laser marking machines that generate green light and ultraviolet light are the mainstream models in the current market.

Fiber laser marking machines generally use fiber lasers as laser light sources. The life of the whole machine is about 100,000 hours. Compared with other types of laser marking machines, they have a longer life and better beam quality. The electro-optical conversion efficiency is more than 28%. Other types of laser marking machines have a great conversion efficiency advantage of 2% -10%, and have outstanding performance in energy saving and environmental protection. However, because China's fiber laser technology is not yet mature, its price is relatively high.

CO2 laser marking machine. The CO2 laser is a gas laser with a wavelength of 10.6 μm in the far-infrared light band. CO2 gas is used to fill the discharge tube as the medium for generating laser. When a high voltage is applied to the electrode, a glow discharge is generated in the discharge tube. The gas molecules can emit laser light, and the laser energy is amplified to form a laser beam for material processing, which is suitable for marking non-metal materials such as leather and plastic.