TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The central part of the phase shifter causes a phase shift relative to the peripheral part of the phase shifter, which exhibits half width, where the half width lies in the interval of 0.7-1.7 times the 1/e-radius (Re) of the amplitude function of the input beam profile of the laser beam. The peripheral portion of the amplitude function is inverted back to values with opposite sign or vice versa, relative to the central portion of the amplitude function by means of the phase shifter, so that at least one zero crossing of the amplitude function is generated between the central and peripheral portion of the amplitude function by the phase shift and the phase-shifted amplitude function in the central and peripheral portion exhibits opposite signs. The beam profile of the laser beam before the phase shift through the phase shifter is a Gaussian beam profile and a sign reversal of the amplitude function is effected by means of the phase shifter on both sides of the maximum of the Gaussian beam profile, so that a zero crossing is generated on both sides of the maximum of the Gaussian beam profile by the phase shift and the phase-shifted amplitude function has a positive sign in the central portion on both sides of the maximum of the Gaussian beam profile and has a negative sign in the peripheral portion on both sides of the central portion or vice versa. The amplitude function of the beam directly after the phase shift in the central portion around the maximum and in the two adjacent peripheral portions of the amplitude function is approximated to a sinus cardinalis function. The phase shifter is formed in a one-dimensional transverse manner, so that the phase shifter causes a phase shift of the amplitude function entirely in one dimension vertically to the optical axis. The phase shifter is formed in a two-dimensional transverse manner, so that the phase shifter causes a phase shift of the amplitude function in two dimensions perpendicular to the optical axis. The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, is formed in a circular manner, so that the phase shifter in the plane perpendicular to the optical axis causes a phase shift rotationally symmetrical to the maximum of the amplitude function. The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, is formed in a polygonal, preferably rectangular manner, so that the phase shifter in the plane perpendicular to the optical axis causes a phase shift in a rectangular manner, around the maximum of the amplitude function. The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, includes a sloping ramp portion. The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, exhibits half a relative width ( delta s), exhibits either a plateau part with half a relative plateau width ( delta p is equal to delta s), or a sloping ramp portion with a relative ramp width ( delta r is equal to delta s), or a plateau part with a half relative plateau width ( delta p), and a sloping ramp portion with a relative ramp width ( delta r), where delta s is equal to sum of delta p and delta r, the half relative width delta s of the central part, the half relative plateau width delta p and the relative ramp width delta r are respectively normalized to the half 1/e-width (Re) of the amplitude function of the input beam profile of the laser beam and the half relative width of the central part delta s in the interval delta s is epsilon (0, 7; 1,7). The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, exhibits a cylinder with a polygonal base, a truncated pyramid with polygonal base, a pyramid with polygonal base, a cylinder with circular base, a truncated cone or a cone. The central part of the phase shifter, which causes the phase shift relative to the peripheral part of the phase shifter, exhibits a plateau part with a half relative plateau width delta p and/or a sloping ramp portion with a relative ramp width delta r, where the half relative width of the central part delta s is equal to the sum of delta p and delta r, and delta r is represented by a polynomial function f( delta p) ( delta r is equal to f( delta p) equal to A + B1x delta p + B2x delta p2 + B3x delta p3 + B4x delta p4 + B5x delta p5 + B6x delta p6 + B7x pi 7 + B8x delta p8 + B9x delta p9). The coefficients are A is +1.03979, B1 is +2.29624, B2 is -28.682, B3 is +174.0617, B4 is -605.53235 B5 is +1205.41588, B6 is -1392.66748, B7 is +906.36127, B8 is -298.64468 and B9 is +36.41503. The half relative width delta s of the central part, the half relative plateau width delta p and the relative ramp width delta r are normalized to the half 1/e-width (Re) of the amplitude function of the input beam profile of the laser beam and the half relative width delta p, and the relative ramp width delta r in the strip interval is represented by delta r is equal to f( delta p) equal to A + B1x delta p + B2x delta p2 + B3x delta p3 + B4x delta p4 + B5x delta p5 + B6x delta p6 + B7x pi 7 + B8x delta p8 + B9x delta p9 plus minus 0.35. The central part of the phase shifter, which cases the phase shift relative to the peripheral part of the phase shifter, has a cylindrical shape with round or polygonal base area and thus the phase shifter exhibits a level in cross-section on both sides of the maximum of the amplitude function, where the half width delta S of the central cylindrical part lies in the interval 1-1.2 Re, where Re is the half 1/e-width of the amplitude function of the input beam profile of the laser beam and the level exhibits a maximum width of 5% of Re. The phase shift of the plateau part or the tip of the pyramid or the tip of the cone lies in the interval relative to the peripheral part of the phase shifter, which is represented by an equation ((((4n-3) pi )/2; ((4n-1) pi )/2)), where n is an integer. The laser system for generating a shared laser beam, comprises a laser for generating a laser beam, an expansion lens for expanding the laser beam, the device for beam shaping, where in the working plane, a laser beam with a beam profile is produced with at least two maxima separated from one another, and a beam splitter. The peripheral portion of the amplitude function relative to the central portion of the amplitude function is inverted back to values of opposite sign or vice versa via the phase shifter, so that at least one zero crossing of the phase-shifted amplitude function is generated by the phase shift between the central and peripheral portion of the amplitude function and the amplitude function in the central and peripheral portion has opposite signs. The beam profile of the laser beam before the phase shift through the phase shifter is a Gaussian beam profile and a sign reversal of the amplitude function is effected via the phase shifter on both sides of the maximum of the Gaussian beam profile, so that a zero crossing is generated by the phase shift on both sides of the maximum of the Gaussian beam profile and the amplitude function has a positive sign in the central portion on both sides of the maximum of the Gaussian beam profile and has a negative sign in the peripheral portion on both sides of the central portion or vice versa. The amplitude function of the beam profile directly after the phase shift in the area of the maximum and the two adjacent peripheral portions, is approximated to a sinus cardinalis function.