In industrial production, cleaning is a critical link. Traditional cleaning methods, such as mechanical cleaning and chemical cleaning, although to a certain extent to meet the production needs, but there are often inflexible, polluting the environment and other issues. With the progress of science and technology, laser cleaning technology came into being, with its high efficiency, environmental protection, non-contact characteristics, and gradually become the new favorite in the field of cleaning. Among them, single mode and multi-mode in fiber pulsed laser are the two most commonly used laser types. So, what exactly is the difference between them? What are the advantages and disadvantages of each? For which application scenarios? In this article, we will reveal all of them for you.
What is single mode and multi-mode
Laser mode usually refers to the laser perpendicular to the propagation direction of the energy distribution in the plane of the state, there are single mode and multi-mode points. Single mode refers to the laser in the work, only one mode of laser output. Single mode energy intensity from the center to the outer edge of the gradual weakening of the energy distribution in the form of Gaussian curve, the beam is called the base mode Gaussian beam. Single mode output laser beam has high beam quality, small beam diameter, small divergence angle, energy distribution close to the ideal Gaussian curve and other characteristics. In addition, single mode has better focusing characteristics, small focused spot and strong mode stability, suitable for cleaning scenes that require strong removal, such as rust.
Multi-mode laser output spot is often combined by a variety of modes, the spot energy distribution is more uniform, and the more modes, the more uniform energy distribution, the beam is also known as the flat top beam. Compared with single mode, multi-mode laser beam quality is poorer, the divergence angle is larger, requiring a larger aperture optical system transmission and focusing spot is larger than single mode. However, multimode makes it easier to achieve large single-pulse energy, high peak power, and high average power output with uniform energy distribution, which is advantageous for cleaning scenarios that require low damage and high efficiency, such as molds and dies.
What are the advantages and disadvantages of single-mode and multi-mode laser cleaning?
Single-mode lasers are suitable for removing strong adhesion pollutants such as green rust due to good beam quality, small focused spot and high energy density, and also suitable for cleaning thin materials and precision parts that are sensitive to heat input. However, due to the single mode energy is too concentrated, in the cleaning may cause some damage to the substrate material.
For the mold and other requirements of the cleaning of the substrate material without damage to the scene, it is necessary to choose a multi-mode laser. Multi-mode beam energy distribution is uniform, high peak power, can control the peak power density is higher than the damage threshold of the pollutants and lower than the substrate, so the cleaning can effectively remove the pollutants without destroying the structure of the material surface. In addition, the focused spot of the multimode is larger, and for scenarios in which single-mode and multimode can achieve the same cleaning effect, the cleaning efficiency of the multimode is usually higher. However, for strongly adhering contaminants, multimode laser cleaning may not be sufficient.
Application Scenarios for Singlemode and Multimode Lasers
Based on their respective advantages and disadvantages, single-mode and multimode cleaning lasers have different application scenarios.
The main application scenarios for single mode:
● Metal descaling: The high energy density of single mode lasers makes them ideal for metal descaling, which can efficiently remove the corrosion layer on the metal surface, and the higher the laser power, the stronger and more efficient the ability to remove rust spots. Optical to launch 1000W high power single mode pulsed laser, QBH output easy to integrate, with strong cleaning ability, efficiency and other advantages.
● Weld Oxide Cleaning: In the welding process, due to the high temperature of the process, oxides and material precipitation debris are easily formed in and around the weld seam, which affects the quality and appearance of the weld. OPTOTECH has launched 200-500W single mode lasers, which can accurately remove oxides and ensure the appearance and quality of the weld.
● Precision parts cleaning: OPTOTECH introduces 100-200W single mode laser with QCS output, strong cleaning ability, low heat output, small deformation of material after cleaning and low heat effect.
Multi-mode main application scenarios:
● Mold cleaning: Molds may accumulate residues during use, such as plastic, metal fragments, dust, etc. These residues will affect the surface quality of the product and cause product defects. Regular cleaning of molds can prevent corrosion and abrasion, thus prolonging the service life of the molds. Due to the large difference in the characteristics of the mold substrate and the contaminants, the use of a flat-top beam can effectively remove the contaminants without harming the mold. OPTOTECH introduces 500~1000W square spot multimode lasers for high efficiency mold cleaning without damaging the substrate.
●Calcium Titanite Cell Edge Cleaning: This refers to the cleaning of the film layer at the edge of thin film solar cell wafers to create an insulated area for subsequent encapsulation. OPTICAL introduces YFPN-1000-GMC-H50-F laser with square spot output, uniform energy distribution, high peak power, capable of removing the film layer in one go, no damage to the glass, and high efficiency.
● Laser burring: Using laser to burr the material surface can significantly improve the adhesion of the material surface. According to the different requirements of burring roughness, OPTOTECH can provide multi-mode lasers with different single pulse energies of 5mJ, 15mJ, and 50mJ to ensure the burring efficiency and realize different roughness requirements at the same time.
When choosing single-mode or multi-mode cleaning lasers, customers can make comprehensive consideration according to their actual needs and application scenarios. For the cleaning of fine parts or strongly adhering contaminants, such as metal oxidized and plated layers, the high beam quality and small spot size of the single mode series lasers will provide more accurate and powerful cleaning results. For larger cleaning areas or where substrate damage is critical, such as molds, rust spots, oil and thin coatings, the high energy and flat top light of the multi-mode series lasers will ensure higher cleaning efficiency and non-destructive cleaning.
