Mechanisms of micro-groove formation on single-crystal diamond by a nanosecond pulsed laser

Micro-grooves were machined onto a single-crystal diamond surface by laser irradiation with a nanosecond pulse, and the resulting damage was investigated. The causes of four different forms of damage have been identified and examined; cracking, ripple formation, groove shape deformation and debris deposition. Cracking is caused by a rapid temperature change; ripples by interference of the laser reflected from the groove walls; groove shape deformation by enhanced absorption of the laser-induced plasma; deposited ablation debris by two different ablation regimes. Cracking and shape deformation is reduced at the center of the groove, which is very smooth and ripple-free for line irradiations using a single pass. These results provide useful information for reducing the laser-induced damage in diamond and creating damage-free micro-grooved diamond cutting tools.