Patent ID: 9035217
Filing Date: 2015-05-19
Classification: B23K

Abstract:
1. A method for machining material using laser radiation, said method comprising the steps of: (a) focusing unfocused laser radiation through a focusing optics to create an optical beam comprising a smaller beam cross-section and forming a beam waist along an optical beam axis, (b) directing the optical beam axis of the focused laser radiation toward a material surface to create an interface of laser radiation and material, (c) holding the beam waist, which results from focusing the laser radiation, in the region of the interface of laser radiation and material to be machined, wherein the laser radiation is partially absorbed at the interface such that, due to induced material removal or displacement, the interface and thus also the laser radiation penetrates into the material, and wherein the spacing of the beam waist from one of the upper and lower side of the interface in the axial direction corresponds at most to triple the value of the penetration depth of the interface into the material, said method further comprising the step of focusing the optical beam such that components of the laser radiation are divergent not only, in the propagation direction, downstream of the beam waist but also within the beam waist itself and upstream of the beam waist, thus being directed away from the beam axis, these divergent laser radiation components and angles by which they diverge being greater than the effects of imaging errors that are produced with standard optics, wherein the divergent laser radiation components form reduced incident angles on the interface and thus increase the absorption of the radiation components on the interface and reduce the changes of the absorption at fluctuations in the incident angles.