The present disclosure provides a device and a method for laser-based separation of a transparent, brittle workpiece, comprising a laser that emits a laser beam having an intensity (IL) along an optical axis (P), and an optical device. The optical device has at least one one-piece double axicon. The double axicon has an entrance surface and the optical device has an exit surface. The entrance surface is such that in the double axicon, a ring beam is formed. The intensity (IL) in the double axicon is lower than the threshold intensity (IS) of the material of the double axicon. The exit surface is such that a line focus having a maximum intensity (Imax) and a length (LT) is generated in the direction of the laser beam behind the exit.