Study of spray-mist-assisted laser processing of micro-structures on CVD diamond surface

Micro-structured chemical vapor deposition (CVD) diamonds with different geometric features tend to demonstrate outstanding performance and functionality in certain aspects. In this paper, an ablation model for machining micro-structures on the surface of CVD diamond coatings using spray-mist-assisted laser processing was established. Firstly, the principle of spray-mist-assisted laser processing was described, where the water film formed by spray impingement was taken into account for its influence on the laser beam through reflection and absorption, resulting in energy losses, as well as refraction causing focal plane shift. Next, a single groove ablation model was developed based on Gaussian optics and ablation threshold theory. Subsequently, the model validity was verified through laser ablation experiments. Meanwhile, the influences of laser parameters, including laser power, scanning speed, and defocusing distance on the machining characteristics, were discussed. Finally, utilizing raster scanning and incorporating the matrix convolution method, the laser ablation model was further extended. Micro-structures with parabolic-like profiles were achieved, indicating the applicability of this approach in guiding the fabrication of micro-structures with specific contours.