Abstract: A method for laser welding a multiplicity of foils onto a carrier includes arranging the foils one on top of the other to provide a foil stack, folding the foil stack to provide a folded region of the foil stack that protrudes up from two side regions of the foil stack, pressing the side regions against the carrier, and pressing together the side regions toward the folded region. The method further includes welding the foils to one another and to the carrier by directing a laser beam onto the folded region and moving the laser beam along the folded region.

Abstract: A method for separating an ultrathin glass using ultrashort laser pulses of an ultrashort pulse laser includes focusing the ultrashort laser pulses into the ultrathin glass such that a resulting focal zone is elongated in a beam direction and extends over an entire thickness of the ultrathin glass. The ultrashort laser pulses have a non-radially symmetric beam cross section perpendicular to a beam propagation direction. The method further includes introducing material modifications into the ultrathin glass along a separating line using the ultrashort laser pulses focused into the ultrathin glass, and separating the ultrathin glass along the separating line.

Abstract: A processing optical unit for workpiece processing includes a polarizer arrangement comprising a birefringent polarizer element for splitting at least one input laser beam into at least two partial beams each partial beam having one of two different polarization states, and a focusing optical unit arranged downstream of the polarizer arrangement in the beam path and configured to focus the partial beams onto at least two focus zones. The polarizer arrangement has a further optical element arranged downstream of the birefringent polarizer element in the beam path and configured to change an angle and/or a distance of at least one of the partial beams relative to an optical axis of the processing optical unit.

Abstract: A method for hardening a transparent material includes the steps of introducing a material modification to the transparent material using a laser beam of ultrashort laser pulses of an ultrashort pulse laser so as to harden at least a portion of the transparent material.

Abstract: A method for producing at least one optically usable microstructure, in particular at least one waveguide structure, on an optical crystal is provided. The method includes irradiating a pulsed laser beam onto a surface of the optical crystal, moving the pulsed laser beam and the optical crystal relative to one another along a feed direction in order to remove material of the optical crystal along at least one ablation path in order to form the optically usable microstructure. The pulsed laser beam is irradiated onto the surface of the optical crystal with pulse durations of less than 5 ps, preferably less than 850 fs, more preferably less than 500 fs, in particular less than 300 fs, and with a wavelength of less than 570 nm, preferably less than 380 nm.

Abstract: A method for laser welding a multiplicity of foils onto a carrier includes arranging the foils one on top of the other to provide a foil stack, folding the foil stack to provide a folded region of the foil stack that protrudes up from two side regions of the foil stack, pressing the side regions against the carrier, and pressing together the side regions toward the folded region. The method further includes welding the foils to one another and to the carrier by directing a laser beam onto the folded region and moving the laser beam along the folded region.

Abstract: Methods for determining the quality of a weld of a workpiece welded by laser-beam welding, wherein at least a partial region of a molten pool and/or of a surrounding area of the molten pool is observed by means of a measuring system during the laser-beam welding and the quality of the weld of the welded workpiece is determined on the basis of the observation result. At least one characteristic value that correlates with molten pool oscillation of the molten pool is observed during the laser-beam welding and a measure of an amplitude of the molten pool oscillation and/or a measure of a frequency of the molten pool oscillation is determined from the observed time curve of the characteristic value. A probability and/or a frequency for the occurrence of hot cracks at the weld of the workpiece is inferred.

Abstract: A laser beam directed is moved relative to a workpiece to weld along a weld seam and form a weld pool in the area surrounding the laser beam. The weld pool has a characteristic oscillation frequency fco, and a laser power is modulated with a modulation frequency f and a modulation amplitude ?=1?Pmin/Pmax, where Pmin is minimal and Pmax is maximal laser power during a modulation period. For a normalized characteristic oscillation frequency ?co and a normalized modulation frequency ?, ??2.2*?co, with ?=f·df/?, where ? is the feed rate of the laser beam, and df is diameter of a beam focal spot. Also, ?co=f,cotest·df,cotest/vcotest, where fcotest is a measured characteristic oscillation frequency, df,cotest the diameter of the beam focal spot, and vcotest is the feed rate of laser beam, all during a test measurement without modulation of the laser power.

Abstract: A method and a computer program for recognizing and differentiating a flow rate error and a dynamic error of an exhaust gas recirculation system (EGR) of an internal combustion engine. Measured and modeled EGR mass flow signals are each subjected to bandpass filtering using time constants optimized for determining flow rate errors and bandpass filtering using time constants optimized for determining dynamic errors. The energy is determined for each of the filtered signals and an energy quotient is computed between the energies of the signals filtered for dynamic errors and the signals filtered for flow rate errors. A dynamic error and a flow rate error of the exhaust gas recirculation may be recognized and differentiated from one another on the basis of the energy quotients.

Abstract: A laser beam directed is moved relative to a workpiece to weld along a weld seam and form a weld pool in the area surrounding the laser beam. The weld pool has a characteristic oscillation frequency fco, and a laser power is modulated with a modulation frequency f and a modulation amplitude ?=1?Pmin/Pmax, where Pmin is minimal and Pmax is maximal laser power during a modulation period. For a normalized characteristic oscillation frequency ?co and a normalized modulation frequency ?, ??2.2*?co, with ?=f·df/?, where ? is the feed rate of the laser beam, and df is diameter of a beam focal spot. Also, ?co=f,cotest·df,cotest/vcotest, where fcotest is a measured characteristic oscillation frequency, df,cotest the diameter of the beam focal spot, and vcotest is the feed rate of laser beam, all during a test measurement without modulation of the laser power.

Abstract: Methods for determining the quality of a weld of a workpiece welded by laser-beam welding, wherein at least a partial region of a molten pool and/or of a surrounding area of the molten pool is observed by means of a measuring system during the laser-beam welding and the quality of the weld of the welded workpiece is determined on the basis of the observation result. At least one characteristic value that correlates with molten pool oscillation of the molten pool is observed during the laser-beam welding and a measure of an amplitude of the molten pool oscillation and/or a measure of a frequency of the molten pool oscillation is determined from the observed time curve of the characteristic value. A probability and/or a frequency for the occurrence of hot cracks at the weld of the workpiece is inferred.

Abstract: A method and a computer program for recognizing and differentiating a flow rate error and a dynamic error of an exhaust gas recirculation system (EGR) of an internal combustion engine. Measured and modeled EGR mass flow signals are each subjected to bandpass filtering using time constants optimized for determining flow rate errors and bandpass filtering using time constants optimized for determining dynamic errors. The energy is determined for each of the filtered signals and an energy quotient is computed between the energies of the signals filtered for dynamic errors and the signals filtered for flow rate errors. A dynamic error and a flow rate error of the exhaust gas recirculation may be recognized and differentiated from one another on the basis of the energy quotients.

Abstract: A method for improving the prediction of polymer properties and a system having improved polymer property prediction capabilities is provided. The method for improving the prediction of polymer properties comprises: (1) providing a polymer; (2) providing a prediction model; (3) utilizing said prediction model to define an average polymer property prediction value; (4) determining a feasible range; (5) measuring one or more properties of said polymer; (6) determining whether said one or measured polymer properties are within said feasible range: (7) validating said one or more measured polymer properties if said one or more measured polymer properties fall within the feasible range or invalidating said one or more measured polymer properties if said one or more measured polymer properties fall outside of the feasible range; (8) optionally updating said prediction model; (9) repeating said previous steps at least one or more times; and (10) thereby improving the prediction of polymer properties.

Abstract: The instant invention is a method for improving the prediction of polymer properties and a system having improved polymer property prediction capabilities.