Nano-Cracks and Glass Carving from Non-Symmetrically Converging Shocks

A method is presented to carve into a glass submerged in water with laser-induced surface and shock waves. It starts with an elliptic wave source that launches an elliptically converging Rayleigh and shock wave. At the wave focus a single microscopic crack with controlled location and orientation is induced that has a length of a few micrometers and a width of about 100 nm. Through successive surface waves, this crack may be extended along a specific direction which can be controlled by adjusting the distance, shape, and orientation of the laser focus. Here, either point-like or elliptical laser foci are generated using a spatial light modulator. Furthermore, when the crack is guided along a closed circular path using a point like laser focus, a conchoidal hole may be carved through the glass slide demonstrated with a 160 mu m thick cover slip. The shock waves are modeled in the fluid and the elastic waves in the glass in three dimensions with a finite-volume framework that accounts for fluid-structure interaction. The resulting pressures and stresses for both the elliptical and point-like Rayleigh and shock wave sources are reported. A novel method to carve into a glass with laser-induced surface and shock waves is presented. At the wave focus of an elliptical source, a single microscopic crack with controlled location and orientation is induced. This crack may be extended along a specific and controlled direction by adjusting the distance, shape, and orientation of the laser focus. image