US Patent 7007512 Method for machining glass substrate

In the present invention, a surface 7 of a glass substrate 1 is irradiated with a laser beam 2 to thereby form a V-shaped groove 6. At that time, the laser beam 2 is condensed outside and above the glass substrate 1. The distance between a beam-condensing point 4 of the laser beam 2 and the surface 7 of the glass substrate 1 is changed to thereby make it possible to change the angle between opposite side surfaces of the V-shaped groove. The angle is in a range of from 30 degrees to 120 degrees. Further, the laser beam used in the present invention is pulsed light, preferably with a pulse width not larger than 10 picoseconds.