Patent ID: 7816623

Claim:
A method for cutting brittle material by irradiating laser light from a laser light source onto a brittle material to generate thermal distortions over a wide range of the brittle material, providing a crack in the interior of the brittle material and moving that irradiating position along a predetermined line of the brittle material to cut the brittle material, the brittle material having a front face surface and an opposite rear face surface, the method comprising: providing a plurality of optical fibers which guide laser lights from a plurality of laser light sources to the brittle material; sequentially irradiating the plurality of laser light sources, with the plurality of optical fibers in a bundled condition such that optical fibers for irradiating spots of the lights irradiating the brittle material are arranged in a matrix arrangement aligning in a straight row over the brittle material and that irradiating spots are sequentially irradiated from one end of the front face surface to the other end thereof resulting in crack formation from the one end to the other end of the brittle material, measuring a light intensity distribution of the composite laser light on the irradiated front face surface of the brittle material; measuring a light intensity of the composite laser light transmitted through the brittle material to the rear face surface of the brittle material; and in response to measuring the light intensity distribution, adjusting the light intensity distribution of the composite laser light by controlling respectively the light intensity of the plurality of the laser light sources and, if the light intensity on the rear face surface of the brittle material is not appropriate, controlling the selected composite laser light intensity, wherein individual ones of the irradiated spots of light arranged in the matrix arrangement occupy separate individual locations on the front face surface of the brittle material and individual ones of the guided laser lights are emitted directly from respective ones of the plurality of optical fibers onto the front face surface of the brittle material.