The processing mechanism of femtosecond laser is different from that of ordinary long-pulse laser (CO 2 laser, Nd:YAG laser), which can transfer all its energy at a very fast speed (maximum peak power can be on the order of 1 012W or even 1 015W) Injected into a small area of ​​action, the deposition of high energy density (with a peak power density of more than 1 022 W/cm 2 ) generated in an instant will change the absorption and movement of electrons, avoiding linear absorption, energy transfer and diffusion. The influence of processes and the like has fundamentally changed the mechanism of interaction between laser and matter, which has unique advantages and broad application prospects in ultra-fast laser fine cold processing at the forefront of today's technology. This high-precision, ultra-high spatial resolution and ultra-high-wide cold processing process makes femtosecond lasers have great application prospects in high-tech fields such as microelectronics, photonics and MOEMS (laser electromechanical systems). Although the excimer laser can perform surface micromachining like the femtosecond laser, the excimer laser processing has its inherent defects. The processing object is selective to the material according to the wavelength, and the processing material and range are limited (this is due to The processing is based on the material's resonance absorption of photons). In addition, since the excimer laser can be absorbed by the surface of the transparent material due to the laser radiation, only the surface microfabrication can be performed. The femtosecond laser not only performs surface microfabrication, but also processes inside the transparent material. And the femtosecond laser processing is smaller in size and higher in machining accuracy. Superfine cold working of femtosecond lasers has the following characteristics compared to conventional lasers. (1) The processing size is small, and ultra-fine (sub-micron to nano-scale) processing can be realized. Generally, the lateral dimension of the laser processing area is larger than the laser wavelength size due to the limitation of the diffraction limit. Although the focus spot size of a femtosecond laser is not likely to be less than half a wavelength, femtosecond lasers are extremely high in peak power, and interaction with matter is not a single photon process, but mainly a multiphoton process. If the incident energy of the laser is adjusted, the energy absorption and the range of action of the processing process can be limited to a small part of the volume center position, instead of the entire area irradiated by the focused spot, and the processing size can be much smaller than the focus. The spot size breaks through the beam diffraction limit and reaches sub-micron or even nano-scale. (2) The processing heat affected zone is small, and high-precision non-hot melt processing can be realized. Since the femtosecond laser can act on the material with extremely high laser power density in a very short time and a very small space, the electron temperature is extremely high in a very short time without thermal diffusion, and the substance changes from a solid state to a moment. The high-temperature, high-pressure plasma state, the rapid spray form is separated from the processing substrate, and the surrounding material is still in the "cold state". Therefore, compared with the long pulse laser processing, the femtosecond laser has no thermal diffusion, the processing edge is neat and the processing precision is high. The so-called "non-hot melt" processing. (3) It can overcome plasma shielding, has stable processing threshold, and has high processing efficiency. In long-pulse laser processing, plasma shielding is an important problem because the incident laser is absorbed and scattered by the plasma, which causes the laser-material coupling efficiency to be weakened. When using 100fs ultrashort pulse laser processing, the pulse energy has ended before the critical density of the plasma is reached, that is, the radiation of the femtosecond laser has ended before the plasma expands outward, thus avoiding plasma shielding. Appearing, which is beneficial to improve the energy coupling efficiency of the femtosecond laser, thereby improving the processing efficiency of the femtosecond laser. In addition, in long pulse laser processing, the stability of laser processing is often affected by material doping and defects. When femtosecond laser processing materials, due to multiphoton ionization, the doping and defects of the material have little effect on the laser firing threshold, so the processing threshold can be more stable. (4) Precision three-dimensional machining can be realized. A femtosecond laser beam with a focus intensity near the melting value can reach the focus point in the transparent material without attenuation, and can obtain a very high laser power density at the focus point, resulting in multiphoton absorption and ionization, enabling femtosecond laser processing. The process has a strict spatial positioning capability to achieve three-dimensional ultra-fine machining at any position inside the transparent material. (5) A wide range of processing materials. Since multiphoton absorption (non-resonant absorption) and ionization thresholds are only related to atomic features in the material, regardless of the free electron concentration therein, femtosecond lasers can be finely machined to any material regardless of the type and nature of the material. . The femtosecond laser can finely process optical glass, ceramics, various dielectric materials, various semiconductors, polymers, and various biological materials and even biological tissues, especially for fine processing of metal materials with relatively low melting points and easy heat diffusion. The femtosecond laser exhibits its great advantages and broad application prospects with its "non-hot melt" "cold" processing. Bathtub Faucet,Tub Faucet,Tub Diverter,Jacuzzi Tub Faucet Zhejiang minmetals huitong import and export Co., Ltd , https://www.zjminmetals.com