These high-power fiber lasers are standard tools for metal laser cutting and welding in the macro application branch. The standard cutting system is usually equipped with a compact fiber laser pointer. Depending on the power of the cutting system and the thickness of the sheet, it is equipped with a direct processing fiber with a core diameter of 50μm or 100μm. “Welding of automotive parts is frequently implemented in several workstations, which are connected to the laser through different optical cables up to 100m. Explained, “Such a setting helps reduce cycle time and optimize laser utilization. For example, when the laser welds a second workpiece at Workstation B, the parts can be assembled and clamped in Workstation A.
Since the fiber laser can be matched to the application by selecting the fiber size, the same laser can be used for different operations. For example, the manufacture of a car part uses three different laser processing methods to perform sequentially in three work cells: removing the coating (achieved by high beam quality and integrated scanning head processing), cutting the aperture for perfect matching, and welding. .
Kilowatt-level industrial fiber lasers that operate on highly reflective materials face the problem of back reflection. The light reflected from the focus area of the laser optical element on the workpiece is transmitted backwards through the laser system. “Due to the irregularity of the workpiece surface, the lack of precise alignment with the surface normal, and the limited collection angle of the processing elements, the typical back reflection is only a small part of the laser power; in addition, in many cases, the back reflection The duration is short (such as perforation).” Jake Bell, general manager of nLIGHT in the United States, said, “However, some fiber laser designs make it difficult or impossible to process reflective materials.”
The company produces a series of material processing fiber lasers with output power ranging from 500W to 4kW. Among other features, nLIGHT’s alta series has a unique configuration to minimize back reflection. “The damage caused by back reflection is usually the result of optical power being deposited into the polymer material and burned out due to overheating. nLIGHT’s alta strips the back reflection light coupled into the transmission fiber and directs it to the water-cooled beam Collector, where the green laser pointer is converted into heat without any interaction with the polymer, thereby eliminating the main damage mechanism. The polymer-free isolator is designed to continuously collect more than 500W of light.
We evaluated the performance of the isolation system during perforation and produced the highest back reflection signal under this laser cutting. The test successfully processed 4000 consecutive perforations of copper without interruptions or failures. In contrast to the reliable, hardware-based protection provided by our back-reflective isolators, some other fiber lasers use software protection to prohibit the laser in the event of back-reflection; this method may protect the laser, but it hinders successful and continuous Material handling.