Abstract: The invention relates to a method for machining a transparent workpiece (4) by generating non-linear absorption of laser radiation in a laser beam focus located in a volume of the workpiece (4). The object of the invention is that of providing a method of improved precision and quality, and a corresponding device, for laser machining of workpieces. In particular, it is also intended for it to be possible for workpieces made of composite materials or of other special materials, such as filter glass, to be machined at an improved level of quality. For this purpose, the method according to the invention comprises the following steps: spectroscopic measurement of the linear absorption of the laser radiation in the workpiece (4), selecting a working wavelength at which the linear absorption is low, and machining the workpiece (4) by means of the application laser radiation at the working wavelength. The invention furthermore relates to a corresponding device for machining a transparent workpiece (4).

Abstract: A method and an apparatus for processing an object by generation of laser radiation as a collimated laser beam, influencing the intensity distribution and/or the phase progression over the cross section of the laser beam, splitting the laser beam into two partial beams, and deflection and focusing of the partial beams so that the partial beams are superimposed in a processing zone in the material of the object.

Abstract: The invention relates to a method for producing polyisocyanates having a low monomer content, said method comprising the following steps: (i) modifying at least one monomeric diisocyanate to obtain a mixture containing at least one polyisocyanate and unconverted monomeric diisocyanate, (ii) separating the mixture obtained in step (i) into at least one gaseous stream containing monomeric diisocyanate and a liquid stream depleted of monomeric diisocyanate, (iii) partially condensing the gaseous stream from (ii) in at least one condenser, so that a liquid condensate and an uncondensed vapour stream are obtained, (iv) post-condensing the uncondensed vapour stream obtained in step (iii) in at least one post-condenser, so that a post-condensate and an uncondensed waste gas are obtained, and (v) delivering the uncondensed waste gas from step (iv) to the suction side of a vacuum pump, characterised in that the at least one post-condenser in step (iv) is operated at a post-condenser temperature, and the at least one c

Abstract: The invention relates to an arrangement for producing a Bessel beam (5), comprising a beam-forming element (2), which transforms a beam (1) incident as a plane electromagnetic wave into a Bessel beam (5). According to the invention, the beam-forming element (2) comprises at least one annular lens (3, 3?) and a Fourier optical unit, e.g. in the form of a Fourier lens (4).

Abstract: An exemplary laser microscope can be provided, comprising at least one first laser source which emits at least one (e.g., pulsed) excitation beam, a scanning optical configuration (e.g., configured to scan the excitation beam over the surface of a sample), a focusing optical configuration (e.g., configured to focus the excitation beam onto the sample), and at least one detector configured to detect light emitted by the sample due to an optical effect in response to the excitation beam. A second laser source facilitates a pulsed ablation beam for a local ablation of the material of the sample. The ablation beam can be guided to the sample via the scanning and focusing optical configurations. The first and second laser sources can be fed by a mutual continuous wave pump laser and/or a mutual pulsed pump laser. The first laser source can emit pulses with at least two different wavelengths.

Abstract: The invention relates to a device for generating a sequence of laser pulses consisting of pulse bursts. The object of the invention is to provide a possibility of generating laser pulses for material processing in the burst mode at a high quality based on the principle of beam combination.

Abstract: The invention relates to an arrangement for producing a Bessel beam (5), comprising a beam-forming element (2), which transforms a beam (1) incident as a plane electromagnetic wave into a Bessel beam (5). According to the invention, the beam-forming element (2) comprises at least one annular lens (3, 3?) and a Fourier optical unit, e.g. in the form of a Fourier lens (4).

Abstract: The invention relates to a method for machining a transparent workpiece (4) by generating non-linear absorption of laser radiation in a laser beam focus located in a volume of the workpiece (4). The object of the invention is that of providing a method of improved precision and quality, and a corresponding device, for laser machining of workpieces. In particular, it is also intended for it to be possible for workpieces made of composite materials or of other special materials, such as filter glass, to be machined at an improved level of quality. For this purpose, the method according to the invention comprises the following steps: spectroscopic measurement of the linear absorption of the laser radiation in the workpiece (4), selecting a working wavelength at which the linear absorption is low, and machining the workpiece (4) by means of application of laser radiation at the working wavelength. The invention furthermore relates to a corresponding device for machining a transparent workpiece (4).

Abstract: The invention relates to a mode filter for reducing higher-order modes, with an optical fiber (1), which has a core (2) and a cladding (3) surrounding the latter, wherein the cladding (3) and core (2) have refractive indices that differ from one another. In order to develop an alternative to the prior art, the mode filter according to the invention is designed in such a manner that the fiber (1) has, in a transition region (4) between core (2) and cladding (3), at least one local refractive index modification region (5) which is arranged in the radially outer region of the core (2) and extends into the region of the cladding (3).

Abstract: The invention relates to a mode filter for reducing higher-order modes, with an optical fibre (1), which has a core (2) and a cladding (3) surrounding the latter, wherein the cladding (3) and core (2) have refractive indices that differ from one another. In order to develop an alternative to the prior art, the mode filter according to the invention is designed in such a manner that the fibre (1) has, in a transition region (4) between core (2) and cladding (3), at least one local refractive index modification region (5) which is arranged in the radially outer region of the core (2) and extends into the region of the cladding (3).

Abstract: The invention relates to a transverse mode filter in an optical waveguide (3). The aim of the invention is to produce a transverse mode filter that permits a monolithic construction of a laser in a multi-mode waveguide. To achieve this, according to the invention the filter comprises a Fabry-Perot cavity integrated into the optical waveguide (3) and comprising two reflective elements (5) situated at a distance from one another. In addition, the waveguide (3) is modified in the region of the Fabry-Perot cavity and/or in the region of the reflective elements (5) in relation to the remaining regions of the waveguide with respect to the effective refractive index of at least one mode of the waveguide.

Abstract: The present invention relates to a method for laser-assisted bonding of substrates, in which these are connected together firstly frictionally by pressing together and subsequently strengthening of the connection between the substrates is effected by activation in regions which is induced by laser irradiation. The invention likewise relates to substrates produced accordingly.

Abstract: The invention relates to a transverse mode filter in an optical waveguide (3). The aim of the invention is to produce a transverse mode filter that permits a monolithic construction of a laser in a multi-mode waveguide. To achieve this, according to the invention the filter comprises a Fabry-Perot cavity integrated into the optical waveguide (3) and comprising two reflective elements (5) situated at a distance from one another. In addition, the waveguide (3) is modified in the region of the Fabry-Perot cavity and/or in the region of the reflective elements (5) in relation to the remaining regions of the waveguide with respect to the effective refractive index of at least one mode of the waveguide.

Abstract: The present invention relates to a method for laser-assisted bonding of substrates, in which these are connected together firstly frictionally by pressing together and subsequently strengthening of the connection between the substrates is effected by activation in regions which is induced by laser irradiation. The invention likewise relates to substrates produced accordingly.