As a mid-infrared laser with large magnification and high beam quality, carbon dioxide lasers are often used as intermediate amplifiers in picosecond terawatt laser systems. With the combination of gas discharge and optical pump, the gain spectrum in 10μm can be greatly improved. In this paper, a numerical model is set up to describe the laser amplification and kinetic processes, based on six-temperature level structure, in hybrid pump CO2 laser amplifier system. The influences of the pump power and its amplification results compared with conventional CO2 laser are simulated and discussed. Such a hybrid pump CO2 laser amplifier is very promising in improving output pulse quality by reducing the pulse split.
The Galvanized steel sheet is used as the automotive body material, and the evaporation of zinc into the weld seam will cause welding defects during the laser welding process. The multi-point laser beam has great development potential in automobile industry, because it can effectively reduce the integration of the galvanized layer into the weld seam during welding. In this paper, a panda-shaped three-point beam (panda beam) is proposed to replace the original single beam used in welding and three methods to realize the panda beam have been discussed. The beam splitting of the diffraction grating is performed, and the three, five and four beam-splitting ratio Daman gratings are obtained but with relatively high energy loss. Additionally, based on the theory of grating diffraction, a panda beam has been obtained by splitting the 4kW incident laser through the Bragg grating. The single front beam radius is 0.6mm with a power of 1.1261kW, and the distance between the two front beams is 3.8mm. The radius of the main beam is 1mm with a power of 1.7168kW, and the distance from the front beam to the main beam is 9.7mm. Lastly, based on the beam splitting theory of geometric optics, the multi-point beam and the panda beam are realized by the ridge reflector with an energy loss of 14.09%, which shows the great advantage of laser beam splitter compared with multi-light source structure in practical application. When welding with the panda beam, two functions of zinc coating and solder melting are carried out respectively, which can avoid zinc vapor entering the molten pool and improve the welding quality