Abstract: A device for beam machining of materials comprising a pin-point source (1) of optical radiation and a concentrating reflector (2) whose reflecting surface has the form of a surface of revolution. The generatrix of said surface of the concentrating reflector (2) is made up of arcs of confocal ellipses (3), lengths of rays (4) emitted from the focus concident with the radiation source (1) and connecting the ends of arcs of ellipses, and arcs of circles (5) with the center in said focus. The size of the boundary segments and their relative arrangement are established on the condition of a most complete collection of the radiation from the pin-point source (1) in the region of the focal point which is coincident with the surface of the machined material, affording a vast possibility of changing the shape of the reflector.