Surface modeling and component analysis of picosecond laser ablation of CVD diamond

Abstract

Chemical vapor deposition diamond (CVDD) has several advantages as micro mill material. Picosecond laser machining technology is promising method to machine CVDD, but there are multiple uncertainties. This study aims to optimize the irradiation of CVDD surface via controllable prediction of CVDD surface after picosecond laser irradiation. Based on theories of Gaussian pulse beam and picosecond laser ablation material, machined surface morphology model was developed to predict surface roughness Sa and removal depth of CVDD. Then, the effects of picosecond laser parameters on the morphology, roughness Sa, removal depth, and components of CVDD surface were analyzed. Results showed that the trend of changes in roughness and removal depth based on theoretical model was approximately the same as that in experimental machined surface, with average relative errors of roughness and removal depth of 9.6% and 16.6%, respectively. In addition, removal depth of CVDD surface decreased with the increase in scanning speed and filling pitch, and increased with the increase in average laser power. The variation in surface roughness Sa was the same as that of removal depth in terms of average laser power and scanning speed, while had a concave point at a filling pitch of 7.5 μm. A decrease in overlapping area of pulse spot can reduce the aggravation of sp2 hybrid amorphous carbon defects.