Inside the optical system of the handheld laser welding gun, four key lenses work together in sequence according to the optical path to ensure the efficient and stable output of laser energy. Their functions are based on optical principles and form the foundation for the welding process.
First: collimating mirror
The collimating mirror is usually located at the beginning of the optical path and is connected to the optical fiber that transmits the laser. Its main function is to process the laser output from the optical fiber. Since the laser will spread out at the end of the optical fiber, the role of the collimating mirror is to convert this divergent beam into a nearly parallel beam. This prepares the conditions for the subsequent transmission and focusing of the beam, ensuring the regularity of the optical path.
Second: Reflector
In optical systems where the optical path needs to be redirected, reflectors are installed. The surface of the reflector is coated with a high reflectivity film layer. When the laser beam is incident at a specific angle, the mirror surface will reflect it in the predetermined direction. Its function is to guide the light beam, enabling it to bypass mechanical structure obstacles and accurately enter the next stage of the optical path, ultimately reaching the focusing mirror. Not all welding gun designs must include reflectors; their use depends on the internal structure layout.
Third: Focus Lens
The focusing lens is the core component of the optical system and is located inside the welding gun. Its function is to converge the parallel laser beam that has been collimated by the collimating lens through its specific curved surface curvature to a very small point, which is called the focal point. This convergence process significantly increases the energy density of the laser, enabling it to reach the melting threshold of the metal material, thus completing the welding. The focal length parameter of the focusing lens determines the position of the focal point and the size of the light spot, and directly affects the penetration depth and width of the weld seam.
Fourth: Protective Mirror
The protective mirror is installed at the very end of the welding gun, closest to the welding processing area. Its main function is to prevent the splatter, smoke, and metal vapor generated during the welding process from polluting or damaging the internal focusing mirror. The protective mirror itself does not participate in the shaping or focusing of the beam; it is a transparent flat mirror that requires a high transmittance for laser light. Due to direct exposure to harsh environments, the protective mirror is a consumable that needs to be replaced regularly. Keeping the protective mirror clean is a necessary maintenance step for maintaining stable laser power output and the normal operation of the equipment.
These four lenses together form the complete optical path of the handheld laser welding gun. The collimating lens is responsible for beam shaping, the reflecting mirror for guidance, the focusing lens for energy concentration, and the protective lens for pollution prevention. Each of them performs its specific task, working collaboratively based on optical principles to ensure the feasibility and stability of the laser welding process. For the operator, understanding their functions, especially conducting regular inspections and replacements of the protective lenses, is a basic requirement for the daily maintenance of the equipment.