Research on 3D high speed precision machining of sapphire based on femtosecond laser

Sapphire is widely used in industry, national defense, aerospace, space technology and other fields due to its excellent physical and chemical properties such as ultra-high hardness, good thermal and chemical stability, high transmittance and so on. Because of the brittleness of sapphire, edge collapse and fragmentation are occurring easily during the process of traditional mechanical machining. Therefore, development of a rapid and high-quality processing method has great significance. Compared with continuous / long pulse laser processing, femtosecond laser processing with ultra-short duration and extremely high peak power has the advantages of small thermal effect, high processing accuracy, real three-dimensional and wide material adaptability. In this paper, a method of machining sapphire with a center wavelength of 515 nm femtosecond laser and scanning galvanometer is proposed. The effects of laser power, processing speed and scanning pitch on the machining depth and surface roughness are studied. A 3D structure is fabricated by combining a scanning galvanometer and the XYZ platform with high speed. Finally, two types of arrays of 3D structure have been fabricated on sapphire, which has high machined surface quality.