Progress in diamond polishing with light source assistance

As the hardest substance known in nature, diamond has plenty of excellent characteristics of good chemical stability, high thermal conductivity and high transmittance. Due to its unique physicochemical properties, diamond has shown great application value and prospects in the fields of solid-state power electronics, solid wave gyroscope, quantum communication, and high-precision tools, which make a strict request for the surface quality of diamonds. To this end, people have developed ultra-precision machining methods such as mechanical polishing, chemical mechanical polishing, laser polishing, and ultraviolet-irradiated precision polishing. However, owing to the unique lattice structure and ultra-high hardness of diamond, it is difficult to polish its surface roughness less than one nanometer by conventional methods . Therefore, modificating the physical and chemical properties of the diamond surface through the interaction of light and matter is an extremely promising method to reduce the processing difficulty and improve the fabrication accuracy. In recent years, with the continuous development of light source quality, laser polishing and ultraviolet catalytic polishing based on the interaction between light and diamond have received widespread attention. Laser polishing mainly takes advantage of the diamond graphitization under high-power laser irradiation to achieve the removal of diamond surface materials. While ultraviolet-irradiated precision polishing is based on the theory that ultraviolet light sources with the photon energy greater than bandwidth of diamond can induce photochemical reactions on the diamond surface to achieve diamond surface polishing. This paper introduces the main research progress in the field of diamond laser polishing and ultraviolet-irradiated precision polishing and compares the basic principles and processing devices of these two processing methods. Through the discussion of above problems, the characteristics of two processing methods are summarized, and the consideration on the optimization of diamond ultra-precision polishing methods is proposed accordingly, to further improve the processing accuracy of diamond ultra-precision polishing.