A method for laser-based machining of a flat substrate, to separate the substrate into a plurality of sections, in which the laser beam of a laser is directed at the substrate using an optical arrangement, which is positioned in the beam path of the laser. The optical arrangement forms a laser beam focal line that is extended as viewed along the beam direction and the substrate is positioned relative to the laser beam focal line such that an induced absorption is produced in the material of the substrate along a section of the laser beam focal line that is extended as viewed in the beam direction.