The principle of laser processing diamond

Laser processing of diamond is mainly achieved by irradiating a high-energy density laser beam onto the surface of diamond material, causing local physical changes such as melting and vaporization, in order to achieve the processing purpose. After being focused, the laser beam can release extremely high energy density in a very small spot area, sometimes even reaching several megawatts per square centimeter.

Principle of Thermal Effect

The thermal effect of laser is a key principle in diamond processing. Due to the high concentration of laser energy, the irradiated area will rapidly heat up. When the temperature reaches the melting point of diamond (about 4000-4500K), the material begins to melt. As the laser energy further increases, the temperature continues to rise, and after reaching the boiling point (around 5100K), diamond will vaporize. By carefully controlling parameters such as laser power, pulse width, and frequency, precise control of material melting and vaporization can be achieved, leading to various processing methods such as cutting, drilling, and carving.

Principles of Photochemistry

In certain specific laser processing processes, in addition to thermal effects, photochemical principles may also be involved. For short wavelength lasers such as ultraviolet lasers, their photon energy is relatively high. When the energy of these high-energy photons exceeds the bond energy of covalent bonds between carbon atoms in diamond, it triggers a photochemical reaction. This reaction can directly lead to the breaking of chemical bonds between carbon atoms, thereby achieving material decomposition. It is worth noting that this photochemical reaction has a significant effect on improving machining accuracy, as it can more accurately break chemical bonds at specific locations and reduce the range of the heat affected zone. However, photochemical processing typically requires lasers of specific wavelengths and suitable processing environments, and is more complex compared to thermal processing.

Research progress of laser technology in diamond processing

（1） Further improvement of machining accuracy

With the continuous development of laser technology, its application in diamond processing is becoming increasingly widespread. In order to meet the growing market demand and constantly improving processing quality requirements, researchers are committed to further improving the accuracy of laser processing diamond. This includes further improving machining accuracy and efficiency through optimizing laser parameters, improving focusing systems, and adopting new materials.

With the continuous advancement of laser technology, its application in diamond processing has also made significant progress. Especially with the introduction of ultra short pulse lasers, the machining accuracy has been significantly improved. The pulse width of this laser can reach the picosecond or even femtosecond level, and the extremely short pulse greatly shortens the interaction time between the laser and the material, allowing for processing to be completed before the material undergoes thermal diffusion. Research has shown that when using femtosecond laser to process diamond, the heat affected zone can be controlled at the micrometer or even sub micrometer level, which is crucial for manufacturing high-precision diamond micro nano structures.

In addition, multi beam laser processing technology also provides a new way to improve processing efficiency. By using multiple laser beams simultaneously to process diamond, the processing speed can be significantly improved. For example, when processing large-area diamond substrates, multi beam laser systems can complete complex texture pattern processing in a short period of time. Meanwhile, optimizing laser parameters such as power and pulse frequency has also been proven to effectively improve processing efficiency.

In addition, the research on new processes such as laser assisted chemical mechanical polishing (L-CMP) and laser-induced plasma processing (LIP) has also brought innovation to diamond processing. L-CMP combines laser pretreatment and traditional chemical mechanical polishing techniques to change the microstructure and chemical properties of diamond surfaces through laser pretreatment, thereby improving polishing quality. LIP technology uses laser generated plasma to etch and process diamond, making it particularly suitable for processing high aspect ratio structures.

Next, we will explore the further application progress of laser technology in diamond processing.

Diamond cutting tools play a crucial role in the field of cutting, and their superhard properties make them an ideal choice for processing high hardness materials such as hard alloys. The introduction of laser technology has brought revolutionary changes to the manufacturing and repair of diamond cutting tools. In the manufacturing process, laser cutting technology can accurately carve diamond raw materials into the predetermined shape of the cutting tool, while laser welding firmly connects the cutting head and handle together. When the cutting tool wears out during use, laser cladding technology can quickly deposit new diamond material into the worn area, thereby quickly restoring the cutting efficiency of the tool. Especially in the automotive engine manufacturing industry, the application of diamond cutting tools is particularly critical because key components of the engine, such as the crankshaft, require precise machining. The tools created with the help of laser technology not only ensure the accuracy of processing, but also extend the service life of the tools, thereby improving the overall processing quality.

（2） Application in Diamond Jewelry Processing

Laser technology plays an indispensable role in diamond jewelry processing. In the field of diamond cutting, laser cutting technology, with its high-precision characteristics, can easily meet the cutting needs of various complex shapes and patterns, thus satisfying consumers' personalized customization. For example, diamond jewelry with unique shapes such as hearts and pentagrams are masterpieces of laser cutting technology. In addition, laser engraving technology has also demonstrated excellent performance in diamond engraving. Its high-precision feature enables the engraving of fine and intricate text and patterns on the surface of diamonds without causing mechanical damage, making it particularly suitable for engraving small fonts and complex patterns.

（3） Applications in the field of electronics

Diamond exhibits excellent heat dissipation performance in the field of electronics and is often used as a heat sink for high-power electronic devices. Laser technology is widely used to process microchannel structures of such heat sinks. Through high-precision laser microfabrication, microchannels can be precisely manufactured on diamond heat sinks, thereby increasing the heat dissipation area and improving heat dissipation efficiency. In addition, laser technology also plays a key role in diamond based electronic devices, such as diamond semiconductor devices. It can be used to process key structures such as electrodes and active areas of devices, thereby improving device performance and integration.

Challenges and Prospects Faced by Zero

Challenges faced:

Material damage issue: Although ultra short pulse lasers can reduce the heat affected zone, uneven distribution of laser energy in actual processing may still cause local damage to diamond materials, such as microcracks, which in turn affect the strength and performance of the product.

High processing cost: High precision laser processing equipment is expensive, and energy consumption is high during the laser processing process. Special laser processing techniques such as femtosecond laser processing also require special environments, further increasing costs.

Process compatibility issue: When laser processing is combined with traditional processing techniques, there may be residues or microstructural changes on the surface after laser processing, which can affect the quality of subsequent traditional processing techniques such as electroplating and chemical plating.

Outlook:

With the advancement of laser technology, laser equipment with higher power and shorter pulse width will further improve processing accuracy and efficiency. By improving laser beam shaping technology, the uniformity of laser energy distribution can be achieved, thereby reducing material damage. In terms of cost reduction, large-scale production can lower the price of laser processing equipment, while researching new processes to improve energy efficiency is also crucial. Although laser processing of diamond faces many challenges, it will still be a key technology in the field of diamond processing in the future, and will develop towards high efficiency, high precision, low damage, high integration, and production automation.