The use of lasers is becoming more and more widely used not only in the laser cutting machine and laser welding machine industries, but also in all walks of life. As a precision laser cutting equipment, I often receive some inquiries after sales. Can the laser be switched between single-mode and multi-mode? As a production end, there are various needs to simplify the operation as much as possible, which is very understandable, but customers who ask such questions may not know enough about lasers. The following professional laser cutting machine manufacturers introduce in detail the difference between single and multi-mode lasers and how to choose lasers.
Single-mode and multi-mode fiber lasers cannot be switched. In fact, single-mode and multi-mode are not only different modes, but also two different laser types. The single-mode laser has a thinner core and a diameter of about 9um. The beam quality is better than that of multi-mode. Its energy is Gaussian distributed, and the energy density in the middle is high. The effect of the three-dimensional image is like a sharp round mountain peak. The core diameter of multi-mode lasers is mostly 50um, which is relatively thick, and the beam quality is relatively poor, but the energy distribution is more uniform than that of single-mode laser spots, and the 3D image is an inverted cup.
In terms of light sources: multimode lasers use LED light-emitting diodes, or vertical cavity surface emitting lasers (VCSEL) as light sources, LED light sources can produce multiple modes of light, and are more dispersed; single-mode lasers use laser diodes as light sources What is more is a single mode of light, which has the advantages of high brightness and high power.
In terms of dispersion: the refractive index of multimode laser fiber is divided into two types: gradual change and step; while the core of single-mode laser fiber is a single material with no refractive index.
In terms of cost: single-mode optical fiber has a wide transmission frequency bandwidth and long transmission distance, but because it requires a laser source, the cost is high; multi-mode optical fiber has low transmission speed and short distance, but its cost is relatively low.
In terms of transmission quantity: single-mode fiber has a small core diameter and dispersion, allowing only one mode of transmission; multi-mode fiber has a large core diameter and dispersion, allowing hundreds of modes of transmission.
In terms of wavelength: the working wavelength of multimode optical modules is generally 850nm; the working wavelength of single-mode optical modules is generally 1310nm and 1550nm; single-mode and multi-mode are like cars and off-road vehicles. It can also run in the mountains, and it can also run on the road in cross-country, so the choice of multi-mode or single-mode fiber laser depends on the processing needs of the actual end customers.
In terms of focal spot size and focal depth length: focal spot size and focal depth also have a great influence on laser cutting effect and efficiency. After the single-mode beam passes through the short focal length focusing mirror, the spot diameter is relatively small, the focal depth is short, and the power density at the focal point is very high. , it is conducive to high-speed cutting of thin materials, and the cutting precision is high, so it is widely used in the precision laser cutting equipment industry. After the multi-mode beam passes through the long focal length lens, the focal point has a longer focal depth, but the focal point diameter is relatively large. As long as it has sufficient power density, it is more suitable for cutting thick workpieces, and it is widely used in the industrial cutting equipment industry.
In terms of power: Generally, lasers below 3000 watts use single-mode mode, which is mainly biased towards thinner materials. For example, the lasers configured for precision laser cutting machine equipment are all single-mode lasers. High-power industrial laser cutting equipment and welding equipment use multi-mode lasers. Specifically, single-mode or multi-mode lasers are selected according to equipment requirements, and the most suitable lasers are configured to achieve the highest work efficiency.
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