Method for laser-machining a workpiece

Abstract

The present invention relates to a method for laser-machining a workpiece (1) by means of a laser-machining device (100), wherein the laser-machining device (100) has a laser-beam-generation source (2), a process head (4) and a spectrometer (5). The spectrometer (5) makes it possible to monitor plasma radiation (6) produced during laser-machining, which offers advantages in process control.

Description

[0001] Methods for laser processing of a workpiece

[0002] The present invention relates to a method for laser processing of a workpiece. The invention further relates to a laser processing device for carrying out the method.

[0003] When laser processing workpieces, especially high-value (high-priced) and / or large-area workpieces, reducing or eliminating processing errors is a crucial objective. One quality requirement for laser processing can be the production of first-time-right workpieces, thus eliminating the need for rework.

[0004] Reliable detection of processing errors in laser processing is often technically complex and / or involves considerable effort. Error detection is frequently only possible after the actual laser processing has taken place, making reliable error correction virtually impossible. Particularly in time-consuming laser processing operations, some of which run continuously, process-related fluctuations can occur. Furthermore, the likelihood of workpiece-related inhomogeneities increases with large-area workpieces, which can also lead to processing errors.

[0005] During laser processing of a workpiece, local vaporization of the workpiece material can occur, which is thereby ionized into a plasma. As the plasma decays, it emits radiation that is characteristic of the workpiece composition. It is known to analyze such plasma radiation spectroscopically, for example, to determine the composition of a sample. The corresponding analytical method is called laser-induced plasma spectroscopy (LIBS).

[0006] It is therefore known to obtain spectroscopic information about the workpiece from the plasma that is generated during laser processing anyway.

[0007] The present invention therefore aims to provide a method and a laser processing device with which spectroscopic information from the plasma generated during laser processing can be used to monitor the processing quality.

[0008] This problem is solved by a method and a laser processing device according to the independent claims. Further advantageous embodiments are specified in the dependent claims. Some features are explained with regard to the proposed method, others with regard to the proposed laser processing device. However, the corresponding aspects can be transferred interchangeably.

[0009] The invention relates to a method for laser processing of a workpiece using a laser processing device, wherein the laser processing device comprises a laser beam generation source, a processing head and a spectrometer.

[0010] The process comprises the following steps: a. Generating a laser beam, in particular an ultrashort pulse laser beam, using the laser beam generation source, b. Directing the generated laser beam to the processing head, c. Applying the laser beam to the workpiece using the processing head, d. Monitoring the laser processing of the workpiece with the spectrometer, whereby a spectroscopic measurement of plasma generated during the laser processing of the workpiece, in particular of plasma radiation emitted by the plasma, is carried out with the spectrometer.

[0011] A workpiece can be understood as a three-dimensional body or object that is processed using laser technology. A workpiece can have different shapes and be made of different materials. For example, a workpiece can be a planar flat product (such as a foil or sheet), a shaped (e.g., bent) flat product, or an object that deviates from a flat shape.

[0012] The aforementioned laser processing device initially comprises a laser beam generation source. This source preferably generates a pulsed laser beam, which is preferably an ultrashort pulse (USP) laser beam. Its pulse length can be in the femtosecond or picosecond range. Following the generation of the laser beam, it can be guided along an optical path to the processing head. Optical components of known type can be arranged in the optical path to, for example, shape (so-called beam shapers) or split (so-called beam splitters) the laser beam. A laser beam split into partial beams is also to be understood as a "laser beam" in the context of the present invention. Preferably, a wavelength is used for the laser beam at which the workpiece is transparent or at least partially transparent.In this context, transparency means that the laser radiation is not diffusely scattered by the workpiece material, so that a laser beam largely retains its propagation direction in the medium.

[0013] Using the process head, the laser beam is applied to the workpiece, i.e., directed onto it or projected onto the workpiece. The laser beam is focused on a specific processing area of ​​the workpiece.

[0014] The laser beam, or a laser spot focused on / within the workpiece, can be moved relative to the workpiece using a scanning unit to create laser structuring along a movement path. Alternatively, the workpiece (e.g., using a movable workpiece table) can be moved relative to a stationary laser beam. It is also possible for both the workpiece and the laser beam to move during processing. In this case, the movements must be coordinated.

[0015] A laser beam can be used to create a "structure" within the workpiece. A "structure" can be understood as a desired or achievable feature within the workpiece. This structure can be a surface feature or one formed within the workpiece (i.e., within the solid material of the workpiece). The latter is made possible by in-volume laser processing. Typical structures formed within the workpiece include hollow structures such as channels or cavities. These structures can consist of substructures that are either separate or interconnected. An example of an interconnected structure is a channel system formed from several linked channels. One and the same workpiece can exhibit both a surface feature and a hollow structure.Surface features can include, for example, bores, holes, grooves, slots, or the like.

[0016] Laser processing can involve laser ablation or laser drilling (e.g., single-pulse drilling, percussion drilling, trepanation or rotary drilling).

[0017] As mentioned, a spectrometer is used to perform a spectroscopic measurement of the plasma (i.e., a spectroscopic measurement signal is recorded). A spectroscopic measurement makes it possible, for example, to determine or extract wavelength- or frequency-dependent information from the underlying measurement signal. Thus, a wavelength- or frequency-dependent spectrum can be recorded using a spectroscopic measurement. Such a spectrum can represent a wavelength- or frequency-resolved signal amplitude or signal intensity.

[0018] The plasma mentioned above is generated directly during laser processing, meaning that spectroscopic measurement can provide spectroscopic spatial information regarding the plasma generated at a processing point on the workpiece. Thus, spectroscopic measurement of the plasma allows spectroscopically determined information to be correlated with the laser-processed area (or the processing quality present there) of the workpiece.

[0019] The resulting "plasma" emits electromagnetic radiation. This can be referred to as plasma radiation. The plasma radiation can also contain radiation from hot particles, sparks, processing residues, ionized impurities, etc., generated during laser processing. The plasma radiation preferably has a wavelength in the UV or visible range, which is detectable by the spectrometer.

[0020] For example, if a spectroscopically observed anomaly or deviation in the spectroscopic measurement signal is detected, it can be checked whether a processing error has occurred at a corresponding processing point. Processing errors can be reflected, for example, by a redshift with respect to the wavelength of the plasma radiation. In this case, the laser processing can be interrupted or terminated if necessary. The processing error can then be corrected (e.g., by reprocessing or intermediate processing). Processing parameters of the laser processing can also be adjusted as a result of the detected error. A spectroscopically observable anomaly or deviation in the spectroscopic measurement signal can be detected by performing a time-resolved spectroscopic measurement. In the case of error-free laser processing, it can be assumed that the spectroscopic measurement signal...Certain characteristics of the spectroscopic measurement signal remain constant over time. If the spectroscopic measurement signal changes, or if a spectroscopic measurement signal recorded at a current time deviates from a previously recorded spectroscopic measurement signal (under the same or similar process conditions), this can indicate a processing error. Processing errors can directly affect plasma generation, which can then be monitored spectroscopically.

[0021] Correlation patterns can be obtained by correlating spectroscopically observed anomalies or spectroscopic measurement signals with actual processing errors (but also by correlating spectroscopically observed anomalies or spectroscopic measurement signals with error-free processing areas). These patterns can then be used to train the monitoring system. Such training can also be performed using a neural network or based on artificial intelligence.

[0022] Further embodiments of the invention are specified in the dependent claims.

[0023] According to a first embodiment of the invention, laser processing can be either surface processing (surface structuring) or in-volume processing (structuring) of the workpiece. If it is surface processing, processing can be performed on a side of the workpiece facing the processing head and / or on a side of the workpiece facing away from the processing head. Surface processing of a side of the workpiece facing away from the processing head can also be referred to as back-side processing.

[0024] In in-volume machining, structures (e.g., channels) can be formed within the solid material of the workpiece. The machining area in the depth direction of the workpiece is primarily adjustable by the z-focus position of the laser beam or laser spot. In the lateral direction, the focus position of the laser beam can be adjusted by a scanning unit (e.g., a galvanometer scanner), but also by moving the processing head relative to the workpiece and / or by moving the workpiece relative to the processing head.

[0025] In a further embodiment, a transparent substrate, particularly a glass substrate, can be used as the workpiece. The workpiece material can also include at least one of the following: a glass-ceramic (e.g., Zerodur), a quartz glass, a borosilicate glass, a metallic glass such as titanium silicate glass (SiC-TiC glass), or sapphire. The workpiece can also be a metal-doped glass, for example, titanium-doped quartz glass. The workpiece can also be made of plastic, for example, a plastic glass such as acrylic glass, Plexiglas, etc.

[0026] The workpiece can also be made of a composite material. Furthermore, the workpiece can comprise a multi-layered structure of different materials. It should be emphasized that the workpiece can include materials other than those already mentioned.

[0027] The aforementioned materials, such as glass, glass-ceramics, quartz glass, borosilicate glass, metallic glass, metal-doped glass (e.g., titanium-doped quartz glass), sapphire, plastic, plastic glass, etc., may only refer to a specific workpiece processing area that is to be processed using laser machining. This can mean that the workpiece is made of one or more of the aforementioned materials in one processing area, but may be made of a different material in other areas (which are not to be processed).

[0028] According to a further embodiment of the invention, the process head can comprise an F-theta lens and a scanning unit, in particular a galvanometer scanner. The aforementioned F-theta lens can provide a focusing optic (objective). F-theta lenses can also be referred to as plane-field lenses. An F-sin(theta) corrected lens can also be used as the focusing optic. Galvanometer scanners are known from the prior art. Galvanometer scanners are mirror scanners whose mirrors can be rotated by a defined angle via a rotary drive. In this way, a laser beam incident on such a mirror can be directed to different processing points on the workpiece.According to a further embodiment of the invention, the plasma radiation is directed to the spectrometer for spectroscopic measurement along an optical path. The plasma radiation first passes through the F-theta lens and is then guided by the scanning unit, in particular by the galvanometer scanner, towards a first mirror. This first mirror reflects the plasma radiation and directs it towards a second mirror, which then transmits the plasma radiation towards the spectrometer. This means that the first mirror reflects the plasma radiation, and the second mirror transmits the plasma radiation. Furthermore, the first and second mirrors are arranged in the optical path of the laser beam generated by the laser beam source and directed to the processing head.This means that the first and second mirrors are positioned between the processing head and the laser beam source. Starting from the laser beam source, the laser beam is first reflected by the second mirror (the plasma radiation is transmitted through this second mirror), while the laser beam is also reflected by the first mirror (the plasma radiation is also reflected by the first mirror).

[0029] In a further embodiment, it is possible that instead of the aforementioned first and second mirrors, only one mirror is provided, through which the plasma radiation passes and reaches the spectrometer. Simultaneously, the laser beam is reflected by this mirror as it propagates towards the workpiece. In this case, the plasma radiation is directed to the spectrometer for spectroscopic measurement along an optical path, whereby the plasma radiation first passes through the F-theta lens, then is guided by the scanning unit, in particular by the galvanometer scanner, towards a mirror that transmits the plasma radiation towards the spectrometer.

[0030] In principle, a setup would also be conceivable in which the laser beam is transmitted through the second mirror and reflected by the first mirror towards the process head, with the plasma radiation being reflected at the first and second mirrors at the same time.

[0031] According to a further embodiment of the invention, the spectroscopic measurement can be performed during laser processing, i.e., online, or during processing breaks in the laser processing. Performing the spectroscopic measurement during laser processing is advantageous because it allows for a direct local correlation of spectroscopic measurements of currently laser-processed (local) processing points on the workpiece. This spatial information can be used to monitor processing quality. For example, if processing defects occur, a locally affected area of ​​the workpiece can be correlated with the corresponding spectroscopic measurement signal. The spectroscopic measurement can, for example, be performed at a measurement rate of 100 Hz.In principle, spectroscopic measurements during pauses in laser processing are also conceivable, provided that plasma is spectroscopically measurable during these pauses. For example, it is conceivable that plasma "afterburns" following the application of a laser pulse. Furthermore, it is conceivable to monitor the decay of the plasma radiation after laser processing. This allows processing steps (e.g., further laser processing, intermediate or post-processing) to be linked to the complete decay or a specific decay value of the plasma radiation.

[0032] According to a further embodiment of the invention, the spectroscopic measurement can be performed with time resolution. This means, in particular, that the laser processing is tracked or monitored at a metrologically accessible measurement rate (e.g., 100 Hz) by means of a spectroscopic measurement of the generated plasma. A time-resolved measurement can therefore mean that spectroscopic measurement signals or spectra were recorded sequentially over time, thus making the laser processing observable with respect to the plasma over time. The time-resolved execution of the spectroscopic measurement can enable the spectroscopic measurement signal to be monitored with respect to temporal changes (of certain features). For example, if laser processing is carried out with constant parameters (e.g., processing speed or...), the measurement signal can be monitored with respect to the time-dependent changes of the plasma.If the process parameters are changed, a change in the spectroscopic measurement signal of the plasma over time can indicate a change in the processing conditions or even a processing error. For example, a decrease in amplitude can indicate a shift in the laser focus. According to a further embodiment of the invention, a wavelength- or frequency-dependent spectrum of the plasma radiation can be recorded during the spectroscopic measurement, wherein the wavelength- or frequency-dependent spectrum or a feature thereof (e.g., an amplitude at a specific wavelength) provides the spectroscopic measurement signal. The spectrum can be an amplitude or intensity spectrum, with the amplitude or intensity plotted against the wavelength or frequency.

[0033] The feature of the spectrum can, for example, relate to a signal peak or signal band of the spectrum or a portion thereof, whereby the feature can be, in particular, the presence, shape, amplitude, integral, wavelength, wavelength range, frequency, frequency range, and / or bandwidth of the signal peak or signal band. Multiple features of a spectrum can also be monitored. For example, the amplitude of one or more signal peaks can be tracked over time. If an observed feature remains constant over an observation period, this may indicate flawless laser processing, whereas a feature that changes over an observation period may indicate flawless laser processing, a change in a processing condition, or a change in a laser processing parameter.

[0034] According to a further embodiment of the invention, the spectroscopic measurement signal can be compared with a stored measurement signal or a previously acquired spectroscopic measurement signal using an evaluation unit to determine a deviation. A stored measurement signal can be a typical signal for a specific laser processing operation, a signal characterizing error-free processing, or a target measurement signal. A comparison of a metrologically acquired spectroscopic measurement signal with such a stored signal can be used to determine deviations of the laser processing from error-free laser processing.Furthermore, assuming that a flawless laser processing process generates a constant spectroscopic measurement signal with respect to the plasma, a temporal change in the spectroscopic measurement signal can be an indication of an anomaly in the processing process, e.g., indicating a laser processing error.

[0035] According to a further embodiment of the invention, in the event of a deviation, the evaluation unit can perform an assessment to determine whether a processing defect from the laser processing is present in a processing area of ​​the workpiece from which the plasma radiation associated with the spectroscopic measurement signal was emitted during laser processing. The evaluation unit can execute an evaluation algorithm for this purpose. The evaluation unit can, for example, include or be connected to a testing unit (e.g., a camera), particularly an optical one. The aforementioned evaluation by the evaluation unit can be preceded by a measurement (e.g., an optical measurement) of the processing area using the testing unit. The evaluation by the evaluation unit can be initiated automatically in the event of a deviation.In principle, it is also conceivable that the evaluation is not carried out with an evaluation unit, but manually, for example by optical inspection.

[0036] According to a further embodiment of the invention, the evaluation unit can be used to check whether the machining error exhibits a previously known error characteristic, for example, concerning the type or pattern of the machining error. Previously known error characteristics can be stored in a data memory. These characteristics can represent process-specific machining errors or workpiece-specific (e.g., material-specific) machining errors.

[0037] According to a further embodiment of the invention, it can be provided that, in the event of one or more processing errors in the laser processing and / or one or more known error characteristics, the laser processing is interrupted or terminated. The evaluation unit can transmit a corresponding signal to the control unit.

[0038] The occurrence of a processing error or error characteristic, or even the mere detection of a deviation between the spectroscopic measurement signal and the stored measurement signal or the previously determined spectroscopic measurement signal, can be referred to as an error event. It may be designed so that the evaluation unit or the evaluation algorithm running on it initiates an interruption or termination of the laser processing upon a single error event. Alternatively, it may be designed so that the evaluation unit or the evaluation algorithm running on it only initiates an interruption or termination of the laser processing (by transmitting a corresponding command to the control unit) after a certain number (threshold) of error events (e.g., of a specific category, which may be defined by a specific error characteristic) have occurred.

[0039] Interrupting or terminating laser processing is essential to ensure first-time-right machining of the workpiece. This is the only way to adjust processing parameters, such as machining parameters or process parameters, to correct any machining errors. Early detection of machining errors during laser processing, and the ability to interrupt or terminate the process accordingly, is crucial for meeting the high demands on the machining quality of expensive or large workpieces.

[0040] According to a further embodiment of the invention, it can be provided that, after the laser processing has been interrupted, an operating parameter of the laser processing device is adjusted or another laser processing-related adjustment is made. Operating parameters of the laser processing device can be any parameters that may underlie the components of the laser processing device during laser processing. Examples include the laser power, the pulse length, the type of laser beam generation source, a setting of the scanning unit, parameters relating to beam shaping or beam splitting. Another laser processing-related adjustment can be understood as any adjustment that is in a specific way related to the laser processing, for example, an adjustment of the positioning / movement of the workpiece or of environmental conditions (e.g.,This can be understood as an ambient temperature. The movement path of the laser beam or its focus can also be adjusted.

[0041] According to a further embodiment of the invention, it can be provided that after the operating parameter of the laser processing device has been adjusted or another laser processing-related adjustment has been made, the laser processing is resumed. This can be understood as a resume function of the laser processing device.

[0042] According to a further embodiment of the invention, it can be provided that, in the event of one or more processing errors and / or one or more error characteristics, a processing parameter of the laser processing is adjusted online, i.e., during the laser processing. This embodiment is in contrast to an interruption or termination of the laser processing, but rather focuses on the correction or adjustment of a processing parameter, e.g., laser power, during the laser processing.

[0043] According to a further embodiment of the invention, the laser beam can be moved across the workpiece by means of the scanning unit, in particular the galvanometer scanner, and the movement or path of the laser beam is adjusted as a processing parameter of the laser processing by controlling the scanning unit with the control unit. For example, a processing area that was initially insufficiently or incorrectly processed can thus be reprocessed (correctively) by means of a repeated processing step. It can be provided, for example, that the laser beam is moved again across the edge region of a previously formed structure, for example to create a more contrasting edge contour.

[0044] According to a further embodiment of the invention, the evaluation unit or the evaluation algorithm executed by the evaluation unit can be trained using a training routine, wherein the training routine in particular utilizes a neural network and / or artificial intelligence. Training data (as input parameters) can be used as the basis for the training routine, wherein the training data is in particular spectroscopic measurement signals and / or data on processing errors and / or correlations between spectroscopic measurement signals and data on processing errors. This enables a self-learning process to be carried out by means of the training routine, which continuously improves the processing with increasing processing time. Furthermore, training data from previous laser processing operations of comparable or similar processing tasks or workpieces can also be provided to the training routine.

[0045] The training routine can be based on positive mappings as training data, i.e., spectroscopic measurement signals that correspond to actual processing errors and / or error characteristics. Positive mappings are valuable because they allow for the correct past assignment of spectroscopic measurement signals (or temporal deviations thereof) to actual processing errors and / or error characteristics.

[0046] Alternatively or additionally, the training routine can be based on misattributions, i.e., spectroscopic measurement signals that were incorrectly assigned to processing errors.

[0047] The optical path of the plasma radiation was described previously. Now, the optical path of the laser radiation generated by the laser beam source towards the workpiece will be briefly described. The laser beam source generates a laser beam. The laser beam, applied to or into the workpiece, is focused or positioned relative to a processing height relative to the workpiece by means of a focus shifter (also called a z-shifter). The laser beam is thus not only movable in an xy-processing plane relative to the workpiece (mediated by the scanning unit), but also perpendicular to it, i.e., in the z-direction. A processing height is therefore shifted or positioned in the z-direction, which runs along a z-axis perpendicular to a horizontal xy-processing plane. The z-shifter works in conjunction with a focusing unit to achieve this.A z-shifter allows for flexible adjustment of the machining position within the workpiece. For example, the z-shifter can be used to select a specific machining point within the workpiece's volume. It is also possible to adjust the z-position during laser machining. In conjunction with the scanning unit, this enables the creation and machining of three-dimensional structures within the workpiece.

[0048] Further embodiments of the invention are shown in the accompanying Figure 1. This figure shows the schematic structure of a laser processing device used in a method according to the invention. The method serves for the laser processing of a workpiece 1 with said laser processing device 100, wherein the laser processing device 100 comprises a laser beam generation source 2, a processing head 4, and a spectrometer 5. The method comprises the steps: a. Generating a laser beam 3, in particular an ultrashort pulse laser beam, by means of the laser beam generation source 2, b. Directing the generated laser beam 3 to the processing head 4, c. Applying the laser beam 3 to the workpiece 1 using the processing head 4, d.Monitoring the laser processing of the workpiece 1 with the spectrometer 5, wherein a spectroscopic measurement of the plasma generated during the laser processing of the workpiece 1, in particular of the plasma radiation 6 emitted by the plasma, is carried out with the spectrometer 5.

[0049] The processing can involve surface machining or in-volume machining of workpiece 1. The illustration shows, by way of example, the focusing of the laser beam 3 onto a surface of workpiece 1.

[0050] The process head 4 comprises an F-theta lens 7 and a scanning unit 8, in particular a galvanometer scanner.

[0051] The plasma radiation 6 is directed to the spectrometer 5 for spectroscopic measurement along an optical path. The plasma radiation 6 first passes through the F-theta lens 7 and is then guided by the scanning unit 8, specifically the galvanometer scanner, towards a first mirror 11. This mirror reflects the plasma radiation 6 towards a second mirror 12, which then transmits the plasma radiation 6 towards the spectrometer 5. This means that the first mirror 11 reflects the plasma radiation 6, and the second mirror 12 transmits the plasma radiation 6. The first mirror 11 and the second mirror 12 are also located in the optical path of the laser beam 3 generated by the laser beam source 2 and directed to the processing head 4.This means that the first mirror 11 and the second mirror 12 are arranged between the processing head 4 and the laser beam generation source 2. Originating from the laser beam generation source 2, the laser beam 3 is first reflected at the second mirror 12 (the plasma radiation 6 is transmitted through this second mirror 12), while the laser beam 3 is also reflected at the first mirror 11 (the plasma radiation 6 is also reflected at the first mirror 11).

[0052] The spectroscopic measurement can be performed during laser processing, i.e., online, or during processing breaks. The spectroscopic measurement is preferably performed with time resolution. During the spectroscopic measurement, a wavelength- or frequency-dependent spectrum of the plasma radiation 6 can be recorded, wherein the wavelength- or frequency-dependent spectrum, or a feature thereof, provides a spectroscopic measurement signal. To detect deviations, the spectroscopic measurement signal can be compared with a stored measurement signal or a previously acquired spectroscopic measurement signal using an evaluation unit 13. For this purpose, an evaluation algorithm can be executed on the evaluation unit 13.

[0053] In the event of a deviation, a test unit 9, belonging to or connected to the evaluation unit 13 via data transmission, can be used to check whether a processing defect from the laser processing is present in a processing area of ​​the workpiece 1 from which the plasma radiation 6 associated with the spectroscopic measurement signal was emitted during laser processing. A data transmission connection 10, which can be wired or wireless, can exist between the test unit 9, the spectrometer 5, and the evaluation unit 13. In this example, the test unit 9 is arranged in the area of ​​the process head 4 so that the processing area of ​​the workpiece 1 can be observed from above. The test unit 9 can, for example, be a camera. The test unit 9 does not have to be part of the laser processing device 100, but can also be arranged externally.

[0054] The evaluation unit 13 can be used to determine whether a processing error exhibits a known error characteristic, for example, regarding the type or pattern of the processing error. If one or more processing errors during laser processing and / or one or more known error characteristics are present, the laser processing can be interrupted or terminated. For this purpose, the evaluation unit 13 can be connected to a control unit 101, which is linked to the evaluation unit via data transmission and controls the laser processing device 100. After the laser processing has been interrupted, an operating parameter of the laser processing device 100 can be adjusted, or another laser processing-related adjustment can be made. This can be mediated by the control unit 101.It may be provided that after the operating parameter of the laser processing device 100 has been adjusted or another laser processing-related adjustment has been made, the laser processing is resumed. This can be referred to as a resume function and mediated by the control unit 101.

[0055] It can also be provided that, in the event of one or more processing errors and / or one or more error characteristics, a processing parameter of the laser processing is adjusted online, i.e., during the laser processing. This can also be mediated by the control unit 101.

[0056] Advantageously, the laser beam 3 can be moved over the workpiece 1 by means of the scanning unit 8, in particular the galvanometer scanner, whereby a movement or a movement path of the laser beam 3 is adapted as a processing parameter of the laser processing by controlling the scanning unit 8 with the control unit 101.

[0057] Evaluation unit 13, or an evaluation program executed by evaluation unit 13, or the aforementioned evaluation algorithm, can be trained using a training routine, which in particular utilizes a neural network and / or artificial intelligence. The training routine can be based on training data, which in particular includes spectroscopic measurement signals and / or data from processing errors and / or correlations between spectroscopic measurement signals and data from processing errors.

[0058] The training routine can be based on positive mappings as training data, i.e., spectroscopic measurement signals that correspond to actual processing errors and / or error characteristics. Alternatively or additionally, the training routine can be based on incorrect mappings, i.e., spectroscopic measurement signals that were incorrectly assigned to processing errors.

[0059] The optical path of the plasma radiation 6 has been described in detail above. Now, the optical path of the laser radiation generated by the laser beam source 2 in the direction of the workpiece 1 will be briefly described. The laser beam source 2 generates a laser beam 3. The laser beam 3, applied to or into the workpiece 1, is adjusted with respect to its focus or processing point by means of a z-shifter 20 in relation to a processing height relative to the workpiece 1. Thus, a processing height is shifted or vertically positioned in the z-direction, which runs along a z-axis perpendicular to a horizontally extending processing plane. The z-shifter 20 works in conjunction with a focusing unit for this purpose. A processing position in the workpiece 1 can therefore be flexibly adjusted using a z-shifter 20.The z-shifter 20, for example, serves to select a specific processing point within the volume of workpiece 1. It is also possible to adjust the z-position during laser processing. In conjunction with the scan unit 8, three-dimensional structures can thus be formed or processed within workpiece 1.

[0060] Reference symbol list

[0061] 1 workpiece

[0062] 2 Laser beam generation source

[0063] 3 Laser beam 4 Process head

[0064] 5 spectrometers

[0065] 6 Plasma radiation

[0066] 7 F-Theta lens

[0067] 8 Scan unit 9 Test unit

[0068] 10 Data transmission connection

[0069] 11 first mirror

[0070] 12 second mirror

[0071] 13 evaluation units 20 z-shifters

[0072] 100 laser processing devices

[0073] 101 Control unit

Claims

Patent claims 1. A method for laser processing of a workpiece (1) with a laser processing device (100), wherein the laser processing device (100) comprises a laser beam generating source (2), a processing head (4) and a spectrometer (5), the method comprising the steps: a. generating a laser beam (3), in particular an ultrashort pulse laser beam, by means of the laser beam generating source (2), b. directing the generated laser beam (3) to the processing head (4), c. applying the laser beam (3) to the workpiece (1) using the processing head (4), d. monitoring the laser processing of the workpiece (1) with the spectrometer (5), wherein a spectroscopic measurement of plasma generated during the laser processing of the workpiece (1), in particular of plasma radiation (6) emitted by the plasma, is carried out with the spectrometer (5).

2. Method according to claim 1, wherein the laser processing is a surface processing or an in-volume processing of the workpiece (1).

3. Method according to claim 2, wherein the surface treatment involves the treatment of a side of the workpiece (1) facing the process head and / or a side of the workpiece (1) facing away from the process head.

4. Method according to one of claims 1 to 3, wherein a transparent substrate, in particular a glass substrate, is used as the workpiece (1).

5. Method according to one of the preceding claims, wherein the process head (4) comprises an F-theta lens (7) and a scanning unit (8), in particular a galvanometer scanner.

6. Method according to one of the preceding claims, wherein the plasma radiation (6) is directed to the spectrometer (5) for spectroscopic measurement along an optical path, and wherein the plasma radiation (6) first passes through the F-theta lens (7), then is directed by the scanning unit (8), in particular by the galvanometer scanner, towards a first mirror (11), which reflects the plasma radiation (6) towards a second mirror (12), wherein the second mirror (12) transmits the plasma radiation (6) towards the spectrometer (5).

7. Method according to one of the preceding claims, wherein the spectroscopic measurement is carried out during laser processing, i.e. online, or wherein the spectroscopic measurement is carried out during processing breaks of the laser processing.

8. Method according to one of the preceding claims, wherein the spectroscopic measurement is performed with time resolution.

9. Method according to one of the preceding claims, wherein a wavelength- or frequency-dependent spectrum of the plasma radiation (6) is recorded during the spectroscopic measurement, wherein the wavelength- or frequency-dependent spectrum or a feature thereof provides a spectroscopic measurement signal.

10. Method according to claim 9, wherein the spectroscopic measurement signal is compared with a stored measurement signal or a previously determined spectroscopic measurement signal using an evaluation unit (13) to determine a deviation.

11. Method according to claim 10, wherein, in the event of a deviation, a test is performed with the evaluation unit (13) to determine whether a processing area of ​​the workpiece (1), from which the laser processing is carried out, is affected. plasma radiation (6) associated with the spectroscopic measurement signal was emitted, indicating a processing error in the laser processing.

12. Method according to claim 11, wherein the evaluation unit checks whether the processing error has a previously known error characteristic, for example concerning the type or error pattern of the processing error.

13. Method according to one of the preceding claims, wherein in the event of one or more processing errors in the laser processing and / or one or more previously known error characteristics, the laser processing is interrupted or terminated.

14. The method of claim 13, wherein, after the laser processing has been interrupted, an operating parameter of the laser processing device is adjusted or some other laser processing-related adjustment is made.

15. The method of claim 14, wherein after the operating parameter of the laser processing device has been adjusted or any other laser processing-related adjustment has been made, the laser processing is resumed.

16. Method according to one of claims 1 to 12, wherein in the event of one or more processing errors and / or one or more error characteristics, a processing parameter of the laser processing is adjusted online, i.e. during the laser processing.

17. Method according to one of the preceding claims, wherein the laser beam (3) is movable over the workpiece (1) by means of the scanning unit, in particular the galvanometer scanner, and wherein a movement or a motion path the laser beam (3) is adjusted as a processing parameter for laser processing by controlling the scanning unit with a control unit (101).

18. Method according to one of the preceding claims, wherein the evaluation unit (13) or the evaluation algorithm executed by the evaluation unit (13) is trainable with a training routine, wherein the training routine in particular uses a neural network and / or artificial intelligence.

19. Method according to claim 18, wherein the training routine is based on training data, wherein the training data are in particular spectroscopic measurement signals and / or data of processing errors and / or correlations of spectroscopic measurement signals and data of processing errors.

20. Method according to claim 18 or 19, wherein the training routine is based on positive assignments as training data, i.e., spectroscopic measurement signals that correspond to actual processing errors and / or error characteristics, and / or wherein the training routine is based on incorrect assignments, i.e., spectroscopic measurement signals that were incorrectly assigned to processing errors.

21. Laser processing device (100) for carrying out a method according to one of claims 1 to 20, wherein the laser processing device comprises a laser beam generating source (2), a processing head (4) and a spectrometer (5).

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