High Power Semiconductor Lasers Application

With the development of semiconductor chip technology and optical technology, the output power of semiconductor lasers has been continuously improved, the beam quality has been significantly improved, and more applications have been obtained in the industrial field. At present, the output power and beam quality of industrial high-power semiconductor lasers have surpassed that of lamp-pumped YAG lasers and are close to semiconductor-pumped YAG lasers. Semiconductor lasers have been gradually applied to plastic welding, cladding and alloying, surface heat treatment, metal welding, etc., and have made some application progress in marking and cutting.

Laser plastic welding. The beam of the semiconductor laser is a flat-top beam, and the spatial distribution of the cross-sectional intensity is relatively uniform. Compared to the beam of a YAG laser, the beam of a semiconductor laser can achieve better weld uniformity and weld quality in plastic welding applications, and can be used for wide seam welding. Plastic welding applications do not require high power requirements for semiconductor lasers, typically 50 to 700 W, beam quality less than 100 mm/mrad, and spot size of 0.5 to 5 mm. Welding with this technique does not damage the surface of the workpiece. Local heating reduces thermal stress on the plastic part, avoids damage to the embedded electronic components, and better avoids plastic melting. By optimizing the raw materials and pigments, laser plastic welding can achieve different synthetic colors. At present, semiconductor lasers have been widely used for soldering sealed containers, electronic component housings, automotive parts, and dissimilar plastics.

Laser cladding and surface heat treatment. Surface heat treatment or partial cladding of metal parts with high requirements on wear resistance and corrosion resistance is an important application of semiconductor lasers in processing. Internationally, semiconductor lasers for laser cladding and surface heat treatment have a power of 1 to 6 kW, a beam quality of 100 to 400 mm/mrad, and a spot size of 2 x 2 mm 2 to 3 x 3 mm 2 or 1 x 5 mm 2 . Compared with other lasers, the advantages of cladding and surface heat treatment with a semiconductor laser beam are high electro-optic efficiency, high material absorption rate, low maintenance cost, rectangular shape of the spot, and uniform light intensity distribution. At present, semiconductor laser cladding and surface heat treatment have been widely used in electric power, petrochemical, metallurgy, steel, machinery and other industrial fields, and become one of the important means of new material preparation, rapid direct manufacturing of metal parts, and green remanufacturing of failed metal parts.

Laser metal welding. High-power semiconductor lasers have many applications in metal welding. Applications range from precision spot welding in the automotive industry to thermal conduction welding of production materials and axial welding of pipes. The weld quality is good and no post-processing is required. The semiconductor laser used for sheet metal welding requires a power of 300 to 3000 W, a beam quality of 40 to 150 mm/mrad, a spot size of 0.4 to 1.5 mm, and a thickness of the bonding material of 0.1 to 2.5 mm. Due to the low heat input, the distortion of the part is kept to a minimum. High-power semiconductor lasers can be welded at high speeds, and the welds are smooth and beautiful. They have special advantages in saving labor during and after welding and are very suitable for different needs of industrial welding. It will gradually replace traditional welding methods.

Laser Marking. Laser marking technology is one of the largest applications for laser processing. Currently used lasers are YAG lasers, CO2 lasers, and semiconductor pump lasers. However, with the improvement of the quality of semiconductor laser beams, semiconductor laser marking machines have begun to be used in the marking field. LIMO has introduced a 50W direct output semiconductor laser with a beam mass of 5mm mrad and a 25W semiconductor laser with a 50μm fiber-coupled output, which has met the laser's output power and beam quality requirements for marking applications.

Laser Cutting. The application of high-power semiconductor lasers in the field of cutting started late. Supported by the German Ministry of Education and Research's "Modular Semiconductor Laser System" (MDS) program, the German Fraunhofer Institute developed a semiconductor laser cutting machine with a power of 800W in 2001, which can cut 10mm thick steel plates and cut speed. It is 0.4m/min.

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