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: In a method for incorporating temperature-regulating hollow structures into a substrate, in particular into a substrate for an optical element, such as a mirror for an EUV projection exposure apparatus, there are the following steps: (A) providing a substrate; (B) progressively focusing a processing light beam on ablation locations at which temperature-regulating hollow structures are intended to arise; (C) a scanning process is carried out in which the processing light beam is guided with a focus in such a way that an ablation focus is moved along a scanning trajectory; (D) the scanning trajectory comprises a plurality of scanning patterns; (E) the scanning positions are spaced apart from one another in a longitudinal direction of the temperature-regulating hollow structure to be produced; and (F) the scanning trajectory additionally comprises pattern jump paths.

Abstract: A hollow structure (28) is produced in a workpiece (25) to form a substrate for a mirror through material-removing processing with pulsed laser radiation (35). The pulsed laser radiation is focused into a focal region (39), forming a removal front (46) for the areal removal of material of the workpiece (25) by moving the focal region (39) along a movement pattern (41), and producing the hollow structure (28) by moving the removal front (46) within the workpiece (25). The removal front is not aligned perpendicular to an incoming radiation direction (Z) of the pulsed laser radiation (35) at the radiation entrance side (27) of the workpiece at least intermittently during the production. The hollow structure is produced in the form of a channel through which a fluid is able to flow.

Abstract: The invention relates to a method for dividing a transparent workpiece (1) by means of pulsed laser radiation (2) by way of creating a beam convergence zone (3) in the volume of the workpiece, in which the intensity of the laser radiation (2) exceeds a threshold value for non-linear absorption, wherein the beam convergence zone (3) and the workpiece (1) are moved relative to each other, thereby creating a two-dimensional weakening in the workpiece (1) extending along a predetermined separating line (4), and wherein the workpiece (1) is subsequently divided along the separating line (4). The invention proposes that by selecting the duration of the energy input generated by the non-linear absorption of the pulsed laser radiation and by spatial beam shaping, non-linear propagation of the laser radiation (2) in the volume (1) of the workpiece outside the beam convergence zone (3) is suppressed.

Abstract: The invention relates to a method for welding a first workpiece (11) to a second workpiece (12) by means of a laser. It is an object of the invention to provide a reliable, repeatable and reproducible approach for laser welding of two workpieces one of which consists of a semiconductor material.

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 method for producing an optical component (1) by means of laser radiation. The object of the invention is that of providing a method that is improved compared with the prior art, which method allows for the correction of deviations of the optical functionality of the component from specified target parameters. For this purpose, the method according to the invention comprises the following method steps: generating a structure in the material of the component (1) which gives the component (1) an optical functionality, and modifying the refractive index in the material of the component (1) by means of laser beams in a pre- and/or post-processing step, i.e. before or after the generation of the structure, in order to correct deviations of the optical functionality of the component (1) from specified target parameters.

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 concerns a method and an apparatus for processing an object (1) by means of interfering laser beams. It is the task of the invention to provide for an improved compensation of the aberrations accumulated over the beam path in such processes/apparatuses, since these are a substantial disturbing factor with respect to the precision in structuring the material. Furthermore, the influence of the period course, i.e. the spatial modulation of the period of the modification produced in the material of the object (1), shall be improved. The invention proposes that laser radiation is generated as a collimated laser beam (3). The intensity distribution and/or the phase progression is influenced over the cross-section of the laser beam (3) to correct aberrations. The laser beam (3) is divided into two partial beams (6, 7). Finally, the partial beams (6, 7) are deflected and focused so that the partial beams (6, 7) overlap in a processing zone (10) in the material of the object (1).

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.