Subsurface engraving is the process of engraving an image inside a solid object, usually made of a transparent glass/crystal material. A diode-pumped solid-state (DPSS) laser with high beam quality and pulse power is normally used for subsurface engraving. The laser beam can be focused at any 3D point within a 3D envelope. At the focal point, due to high laser intensity, a small fracture or bubble is generated. The fractures can be as small as tens of microns. Currently, the image from subsurface engraving can only be seen, but not felt or touched. This has limited the applications of subsurface engraving to tourist souvenirs or artistic crafts. The authors propose that through some changes to the subsurface engraving process, it is feasible to separate the 3D image from the raw material block, and directly generate a 3D prototype that could not only be visualized, but also touched, or even used for subsequent design, or manufacturing processes. When generating the 3D point cloud, the points should be dense enough so that continuous cracks could be generated. It is expected that the cracks may form a gap, separating the image from the raw material block. In order to facilitate removal of the engraved image from the material block, the material portion that does not belong to the image is cut into small grids, such grids should be easily removed.
