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Applications of Ultrafast Lasers in the RF Field - 2
3. Communication Signal Optimization: Solving the Problem of RF Transmission Blockage in Enclosed Environments
In enclosed environments such as rail transit, RF communication signals are easily blocked by thermal insulation materials, leading to severe signal attenuation.
Taking railway carriages as an example, glass with ultra-thin metal coatings can significantly reduce the energy consumption of carriage heating and cooling systems, but the metal coatings strongly reflect electromagnetic waves, interrupting mobile phone 4G/5G communication signals.
Traditional solutions rely on the installation of repeaters, which are not only costly (50,000 euros per unit) and energy-intensive (power 700 watts, equivalent to the electricity consumption of a Swiss family of four), but also require long-term maintenance and wiring upgrades.
Ultrafast laser structuring technology provides an optimal solution to this contradiction.
The metal coating laser processing technology developed by Swiss company Nu Glass carves fine grid patterns with a thickness of ≤25 microns on the surface of the metal coating of carriage glass, controlling the grid gap size to 1/20-1/10 of the communication signal wavelength.
It not only destroys the conductivity of the coating to allow free penetration of RF signals but also completely retains the thermal insulation performance of the metal coating, achieving a balance between communication quality and energy-saving effects.
This technology can increase the signal strength in the carriage by 25dB, reduce the annual electricity consumption of each train by 28 megawatt-hours, and the portable laser system can complete the transformation of a single window in 15 minutes without removing the glass.
It has been applied in the transformation of 5,700 windows of 40 intercity trains of Swiss Federal Railways.
4. High-End RF Acceleration Systems: Supporting the Development of Free-Electron Lasers
Superconducting Radio Frequency (SRF) cavities have become core components of high-efficiency, high continuous wave gradient accelerators due to their advantages of low wall loss and low wakefield.
Such accelerators are key supports for high-performance Free-Electron Lasers (FEL)—FEL needs to generate relativistic electron beams through accelerators, and then radiate coherent electromagnetic waves through undulators, which are used in scenarios such as ultra-short wavelength light generation and high-power continuous wave light extraction. The core role of ultrafast laser technology in this field is reflected in the precise regulation and pulse synchronization of electron beams.
In multi-pulse X-ray free-electron laser devices, dual-pulse laser irradiation of the cathode plate can generate two electron beams, which need to be accelerated in the RF acceleration cavity.
By adjusting the RF cycle and laser pulse phase, precise acceleration of different RF buckets (single RF bucket phase-differentiated injection, multi-RF bucket cross-cycle injection) can be achieved.
Combined with the multi-undulator scheme, multi-energy and multi-pulse X-ray light sources can be generated, providing adaptive light sources for ultrafast dynamic imaging.
In addition, the development of high-power GHz repetition rate femtosecond fiber lasers has further improved the stability and precision of RF acceleration systems.
Its low-noise and high-coherence characteristics provide a guarantee for the low-emittance and high-peak current control of electron beams, helping FEL achieve higher power and shorter wavelength laser output.
5. Application Prospects and Development Trends
With the increasing demands for higher frequency, lower loss, and more miniaturization of RF technology in fields such as 5G/6G communications, low-altitude economy, and deep-space exploration, the application of ultrafast lasers in the RF field will deepen in three directions:
first, breakthroughs in higher-precision processing technologies, such as the manufacturing of sub-micron RF device structures, to further improve device integration;
second, the implementation of multi-scenario remote RF technologies, such as space energy transmission and cross-regional RF communication enhancement;
third, integration with cutting-edge technologies such as superconducting RF and quantum RF, promoting high-end RF systems toward higher efficiency and stability.
In the future, ultrafast lasers will continue to serve as the core driving force for RF technology innovation, realizing more disruptive applications in key fields.
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What are the precautions for operating a laser marking machine?
1. It is strictly prohibited to start the laser power supply and Q-switching power supply when there is no water or the water circulation is abnormal.
2. The Q power supply is not allowed to operate without load (i.e., the output terminal of the Q power supply should be left floating).
3. In case of any abnormal phenomenon, first turn off the galvanometer switch and the key switch, and then conduct a check.
4. It is not allowed to start other components before the krypton lamp is lit to prevent high voltage from entering and damaging the components.
5. Pay attention to leaving the output terminal (anode) of the laser power supply suspended to prevent sparking and breakdown with other electrical appliances.
6. Keep the internal circulating water clean. Regularly clean the water tank and replace it with clean deionized water or pure water.
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What should we do when laser intensity decreases and the marking is not clear enough?
1. Turn off the machine and check if the laser resonant cavity has changed; Fine-tune the resonant cavity lens. Make the output light spot the best;
2. The acousto-optic crystal is offset or the output energy of the acousto-optic power supply is too low;
Adjust the position of the audio-visual crystal or increase the working current of the audio-visual power supply;
3. The laser entering the galvanometer deviates from the center: Adjust the laser;
4. If the current is adjusted to around 20A but the light sensitivity is still insufficient: the krypton lamp is aging. Replace it with a new one.
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How to maintain a UV laser cutting machine?
1. It is required to carry out regular cleaning every day, remove debris from the countertop, limiters and guide rails, and spray lubricating oil on the guide rails
2. The waste materials in the collection box should be cleared regularly to prevent excessive waste from blocking the exhaust port.
3. Clean the chiller once every 15 days, drain all the internal water, and then fill it with fresh pure water.
4. The reflector and focusing lens should be wiped with a special cleaning solution every 6 to 8 hours.
When wiping, use a cotton swab or cotton swab dipped in the cleaning solution to wipe from the center to the edge of the focusing lens in a counterclockwise direction.
At the same time, be careful not to scratch the lens.
5. The indoor environment can affect the lifespan of the machine, especially in damp and dusty conditions.
A damp environment is prone to causing rust on the reflective lenses and also easily leading to short circuits, discharge and sparking of the velvet laser.
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What accidents might be caused by the laser emission when using a laser cutting machine?
(1) A fire was caused by the laser coming into contact with flammable materials.
Everyone knows that the power of laser generators is very high, especially when it comes to high-power laser cutting machines, the temperature of the emitted laser is extremely high. The possibility of a fire being caused when a laser beam comes into contact with flammable objects is very high.
(2) Harmful gases may be produced when the machine is in operation.
For instance, when cutting with oxygen, it undergoes a chemical reaction with the cutting material, generating unknown chemical substances or fine particles and other impurities. After being absorbed by the human body, it may cause allergic reactions or discomfort in the lungs and other respiratory tracts. Protective measures should be taken when conducting work.
(3) Direct laser exposure to the human body can be harmful.
The damage caused by lasers to the human body mainly includes damage to the eyes and skin. Among the harms caused by lasers, the damage to the eyes is the most severe. Moreover, damage to the eyes is permanent. So when doing homework, you must pay attention to protecting your eyes.
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What is the focused spot diameter of nanosecond, picosecond and femtosecond laser?
Nanosecond: The light spot is 0.5-1mm.
Picosecond: The focused spot is around 0.02mm.
Femtosecond: Under the action of a laser beam with a high repetition rate of 100-200KHz and a very short pulse width of 10ps,
the focused spot diameter is as small as 0.003mm.
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What are the main applications of UV laser cutting machine?
The UV laser cutting machine can be used for cutting and depaneling PCB.
It can precisely cut and shape various types of PCB circuit boards with V-CUT and stamp holes, and open Windows and covers.
It can also be used for separating packaged circuit boards and ordinary smooth boards.
It is suitable for cutting various types of PCB substrates, such as ceramic substrates, rigid-flex boards, FR4, PCBs, FPCs, fingerprint recognition modules, cover films, composite materials, copper substrates, aluminum substrates, etc.
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Precautions for laser cutting machines to process various metal materials?
Copper and brass:
Both materials have high reflectivity and excellent thermal conductivity.
Brass with a thickness of less than 1mm can be processed by nitrogen laser cutting.
Copper with a thickness of less than 2mm can be cut. The gas used for laser cutting processing must be oxygen.
Copper and brass can only be cut when a "reflective absorption" device is installed on the system. Otherwise, reflection will damage the optical components.
Synthetic materials:
Processable synthetic materials include: thermoplastics, thermosetting materials and artificial rubber.
Aluminum:
Despite its high reflectivity and thermal conductivity, aluminum materials with a thickness of less than 6mm can be cut, depending on the type of alloy and the capacity of the laser.
When cutting with oxygen, the cutting surface is rough and hard.
When nitrogen is used, the cutting surface is smooth.
Pure aluminum is extremely difficult to cut due to its high purity.
Only when a "reflection and absorption" device is installed on the fiber laser cutting machine system can aluminum materials be cut.
Otherwise, reflection will damage the optical components
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What should be paid attention to when laser cutting stainless steel?
Laser cutting processing of stainless steel requires the use of oxygen, under the condition that edge oxidation is not a concern.
If nitrogen is used to achieve an edge free of oxidation and burrs, no further processing is required.
Coating an oil film on the surface of the sheet will achieve a better perforation effect without reducing the processing quality.