Detailed explanation of laser tube of CO2 laser marking machine

For the CO2 laser marking machine, the quality and performance of the laser tube directly affect the working efficiency of the CO2 laser marking machine, which is also one of the most important parts of the CO2 laser marking machine.

Generally, the laser of CO2 laser marking machine is usually made of hard glass, and generally adopts a layered sleeve structure. The innermost layer is the discharge tube, the second layer is the water-cooled casing, and the outermost layer is the gas storage tube. The diameter of the discharge tube of the carbon dioxide laser is larger than that of the He-Ne laser tube. Generally speaking, the thickness of the discharge tube has no effect on the output power, mainly considering the diffraction effect caused by the size of the spot, which should be determined according to the tube length. The longer tube is thicker, and the shorter tube is thinner. The length of the discharge tube is proportional to the output power. Within a certain length range, the output power per meter of discharge tube length increases with the total length. The purpose of adding a water cooling jacket is to cool the working gas and stabilize the output power.

1. Hard glass: This part is composed of GG17 material fired into discharge tube, water cooling jacket, air storage jacket and return air pipe. The sealed-off CO2 laser is usually a three-layer sleeve structure. The innermost is the discharge tube, the middle is the water purifier, the outermost layer is the gas storage sleeve, and the return gas pipe is used to connect the discharge tube and the gas storage tube.

2. Resonant cavity: This part is composed of a total mirror and an output mirror. The total reflection mirror of the resonant cavity is generally based on optical glass, and the surface is gold-coated. The reflectivity of the gold-film mirror near 10.6um is above 98%; the output mirror of the resonant cavity is generally made of infrared materials that can transmit 10.6um radiation. Germanium (Ge) is the substrate, and a multilayer dielectric film is formed on it.

3. Electrode: CO2 lasers generally use cold cathodes, which are cylindrical in shape. The choice of cathode material has a great impact on the life of the laser. The basic requirements for cathode materials are: low sputtering rate and low gas absorption rate.

The discharge tube is connected to the gas storage tube at both ends, that is, one end of the gas storage tube is connected with the discharge tube with a small hole, and the other end is connected with the discharge tube through the spiral return tube, so that the gas can circulate in the discharge tube and the gas storage tube Flow, the gas in the discharge tube is exchanged at any time. It is widely used for marking and engraving non-metallic materials such as acrylic and plastic products; and has developed the ability to mark electroplated mild steel. CO2 lasers are also used in automated systems for flexible circuit boards and diaphragms of polyimide and polyester sheets of electronic instruments.