NOVELTY - Device for beamforming of a laser beam (72) to produce a target beam profile (34) of the laser beam, where the radial beam profile of the laser beam is defined by a complex amplitude function, comprises a beamformer, where the beamformer is formed as a phase shifter with a central and a peripheral part and a phase shift of the complex amplitude function of the laser beam is effected between the two parts, so that in the input plane, the phase of the complex amplitude function in the central part of the laser beam profile is shifted relative to the peripheral portion of the laser beam profile.    USE - The pre-defined target beam profile of the laser beam, preferably a cylindrical-beam profile is useful for material processing, e.g. solar cell production.    ADVANTAGE - The device produces cylindrical-beam profile of laser beam with low production cost, and accurate and simple manufacturing method.    DETAILED DESCRIPTION - Device for beamforming of a laser beam (72) to produce a pre-defined target beam profile (34) of the laser beam, preferably a cylindrical-beam profile in a working plane (46), from an input beam profile (32) of the laser beam in an input plane, comprises a beamformer in the input plane, where the radial beam profile of the laser beam is defined by a complex amplitude function and the complex amplitude function in a central and a peripheral portion can be divided. The beamformer is formed as a phase shifter with a central and a peripheral part and a phase shift ( delta psi ) of the complex amplitude function of the laser beam is effected between the central and the peripheral portion, so that in the input plane, the phase ( psi ) of the complex amplitude function in the central portion of the laser beam profile is shifted relative to the peripheral portion of the laser beam profile via the phase shifter and when the laser beam hits on the phase shifter and a focusing lens (42) by which the partially phase-shifted complex amplitude function of the laser beam is Fourier-transformed from the input plane into the working plane, so that the target beam profile of the laser beam in the working plane is formed as Fourier transform of the phase-shifted amplitude function from the input plane. INDEPENDENT CLAIMS are also included for:    (1) a laser system for generating a laser beam with a pre-defined different target-beam profile of the laser beam in the working plane, preferably for materials processing of a substrate in the working plane by a Gaussian function, comprising a laser for generating a laser beam, an expansion lens for expanding the laser beam and the device for beam shaping; and    (2) beam forming of the laser beam to generate a predefined deviant target beam profile of the laser beam, preferably a cylinder beam profile in a working plane by a Gaussian function, where the radial beam profile of the laser beam is defined by a complex amplitude function and the complex amplitude function along the beam axis is Fourier transformed from an input plane into the working plane, which is associated with a change of the radial beam profile along the beam axis and the laser beam profile can be divided radially or transversally into a central and a peripheral portion and a beam former is provided in the form of a phase shifter, by which the phase ( psi ) of the complex amplitude function is suspended in the central portion of the laser beam profile relative to a peripheral portion of the laser beam profile.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the device and the laser beam profile before the beamforming and after the beamforming.    Input beam profile of the laser beam (32)    Pre-defined target beam profile of the laser beam (34)    Focusing lens (42)    Working plane (46)    Laser beam (72)