Laser precision engineering of glass substrates

The precise laser microfabrication of glass is a very challenging task due to the stress-induced microcracks generated during laser ablation. In this paper, the results of high-quality glass microfabrication by low-energy NANAG laser (355 nm, 30 ns) ablation and pocket scanning are presented. Pocket scanning involves the scanning of a laser beam along parallel overlapped paths with the last path forming structural edge, while conventional direct scanning involves the scanning of a beam just along single path to obtain the structure edge. It is found that cracks that formed around the edges by pocket scanning are significantly reduced in size compared with those formed by laser direct scanning. Minimum crack sizes of less than 10 mum have been obtained at optimized parameters. Ablation depth. is also enhanced greatly by pocket scanning; it increases almost linearly with laser fluence and the number of scanning loops. There is no saturation of ablation depth as observed in laser direct scanning. This technique has high potential applications in glass precision engineering.