Views: 6 Author: Site Editor Publish Time: 2024-10-29 Origin: Site
What are "single mode" and "multi-mode" in cleaning lasers?
In industrial production, cleaning is a vital link. Although traditional cleaning methods, such as mechanical cleaning and chemical cleaning, can meet production needs to a certain extent, they often have problems such as low flexibility and environmental pollution. With the advancement of science and technology, laser cleaning technology has emerged, and with its high efficiency, environmental protection, and non-contact characteristics, it has gradually become a new favorite in the cleaning field. Among them, single-mode and multi-mode in fiber pulse lasers are the two most commonly used laser types. So, what are the differences between them? What are their respective advantages and disadvantages? What application scenarios are they suitable for? This article will reveal them to you one by one.
What is single mode and multi-mode?
The mode of laser usually refers to the energy distribution state in a plane perpendicular to the propagation direction of the laser, and is divided into single-mode and multi-mode. Single-mode means that when the laser is working, it only produces one mode of laser output. The energy intensity of a single mode gradually decreases from the center to the outer edge, and the energy distribution is in the form of a Gaussian curve. Its beam is called a fundamental mode Gaussian beam. The laser beam output by a single mode has the characteristics of high beam quality, small beam diameter, small divergence angle, and energy distribution close to the ideal Gaussian curve. In addition, the single mode has better focusing characteristics, a small focusing spot and strong mode stability, which is suitable for cleaning scenarios that require strong removal, such as rust.
Schematic diagram of single-mode energy distribution
The light spot output by a multi-mode laser is often composed of a combination of multiple modes. The energy distribution in the light spot is relatively uniform, and the more modes there are, the more uniform the energy distribution is. The light beam is also called a flat-top beam. Compared with single-mode, the beam quality of multi-mode lasers is poorer, the divergence angle is larger, and it requires an optical system with a larger aperture for transmission. The focused light spot is larger than that of single-mode. However, multi-mode is easier to achieve large single pulse energy, high peak power and high average power output, and the energy distribution is uniform, which is more advantageous for cleaning scenarios that require less damage and high efficiency, such as molds.
Schematic diagram of multi-mode energy distribution
What are the advantages and disadvantages of single-mode and multi-mode laser cleaning?
Single-mode lasers are suitable for removing strongly adherent contaminants such as rust, and for cleaning thin materials and precision parts that are sensitive to heat input, due to their good beam quality, small focused spot, and high energy density. However, since the single-mode energy is too concentrated, it may cause some damage to the base material during cleaning.
For scenes such as molds that require no damage to the substrate after cleaning, multi-mode lasers must be used. Multi-mode beams have uniform energy distribution and high peak power, and can control the peak power density to be higher than the damage threshold of the contaminants but lower than the substrate. Therefore, during cleaning, contaminants can be effectively removed without damaging the surface structure of the material. In addition, the multi-mode focused spot is larger. For scenes where single-mode and multi-mode can achieve the same cleaning effect, the multi-mode cleaning efficiency is usually higher. However, for strongly attached contaminants, multi-mode laser cleaning may not be able to do it.
Application of single-mode and multi-mode lasers
Based on the advantages and disadvantages of single-mode and multi-mode cleaning lasers, the application scenarios for the two are also different.
The main application scenarios of single-mode:
Metal rust removal: The high energy density of single-mode lasers makes them an ideal choice for metal rust removal. They can efficiently remove the rust layer on the metal surface. The higher the laser power, the stronger the rust removal ability and the higher the efficiency.
1000W high power single mode pulse laser, QBH output is easy to integrate, with the advantages of strong cleaning ability and high efficiency.
Weld oxide cleaning: During the welding process, due to the high processing temperature, oxides and material precipitation debris are easily formed in the weld and its surroundings, affecting the welding quality and appearance. 200~500W single-mode laser can accurately remove oxides to ensure the appearance and quality after welding.
Precision parts cleaning: 100~200W single-mode laser, QCS output, strong cleaning ability, low heat output, small deformation and thermal impact of materials after cleaning.
Main application scenarios of multi-mode:
Mold cleaning: During use, the mold may accumulate residues, such as plastic, metal fragments, dust, etc. These residues will affect the surface quality of the product and cause product defects. Regular mold cleaning can prevent corrosion and wear, thereby extending the service life of the mold. Due to the large difference in the characteristics of the mold substrate and contaminants, the use of a flat-top beam can effectively remove contaminants without damaging the mold. 500~1000W square spot multi-mode laser, high efficiency in cleaning molds without damaging the substrate.
Perovskite cell edge cleaning: Refers to cleaning the film layer at the edge of the thin-film solar cell to create an insulating area, which is conducive to the subsequent packaging work. YFPN-1000-GMC-H50-F laser, square spot output, uniform energy distribution, high peak power, can clean the film layer at one time, without damaging the glass, and high efficiency.
Laser texturing: Using laser to roughen the material surface can significantly improve the adhesion of the material surface. According to different roughness requirements of roughening, we can provide multi-mode lasers with different single pulse energies of 5mJ, 15mJ, and 50mJ to ensure the roughening efficiency while achieving different roughness requirements.