Methods of using a laser to spall and drill holes in rocks

摘要

Apparatus and methods of using lasers are provided for spalling and drilling holes into rocks. A rock removal process is provided that utilizes a combination of laser-induced thermal stress and laser induced superheated steam explosions just below the surface of the laser/rock interaction to spall the rock into small fragments that can then be easily removed by a purging flow. Single laser beams of given irradiance spall rock and create holes having diameter and depth approximately equal to the beam spot size. A group of the single laser beams are steered in a controllable manner by an electro-optic laser beam switch to locations on the surface of the rock, creating multiple overlapping spalled holes thereby removing a layer of rock of a desired diameter. Drilling of a deep hole is achieved by spalling consecutive layers with an intermittent feed motion of the laser head perpendicular to the rock surface.