Method and device for forming a structure on a workpiece using machining radiation

Abstract

Device for forming a structure on a workpiece (6) by means of processing radiation, comprising a transport device (3) for moving the workpiece (6) along a path of movement, a radiation source (1) for generating processing radiation, a main deflection unit (2a) for the processing radiation which is arranged in the beam path of the processing radiation, and a position measuring unit (5) for measuring a position of the workpiece (6) on the transport device (3) before and / or during processing by means of the processing radiation, characterized in that the device comprises a velocity measuring unit (4a) for measuring the speed of movement of the workpiece (6) during processing by means of the processing radiation and a reference velocity measuring unit (4a) for measuring a reference velocity of the workpiece (6),that the device, in addition to the main deflection unit (2a), has a correction deflection unit (7b) for the processing radiation, which is arranged in the beam path of the processing radiation, and the device has a control unit which is connected to and configured with the main deflection unit (2a) and the correction deflection unit (7b) to control the main deflection unit (2a) in order to deflect the processing radiation to a processing point of the workpiece (6) during the transport of the workpiece (6) by means of the transport device (3), and to control the correction deflection unit (7b) in order to correct the deflection of the processing radiation by means of the correction deflection unit (7b) depending on the measurement data of the speed measuring unit (4a).

Description

[0001] When machining workpieces, it is known to form a structure on a workpiece using electromagnetic machining radiation. Forming the structure can include modifying the workpiece using the machining radiation and / or removing material, in particular ablating it, using the machining radiation.

[0002] Laser radiation is typically used as the processing radiation. This type of structure formation on a workpiece using laser radiation is particularly used in the manufacture of photovoltaic solar cells and in printed circuit board production.

[0003] To achieve high throughput in production, it is known to process the workpiece using processing radiation while the workpiece is moved by the transport device. This makes inline processing particularly possible.

[0004] The transport of the workpiece by means of a transport device during the machining of the workpiece has the disadvantage that fluctuations in the transport speed and / or movements of the workpiece on the transport device, in particular vibrations and rotations of the workpiece, lead to inaccuracies in the machining.

[0005] It is therefore known to detect an incoming edge of the workpiece using an optical sensor before machining with the processing radiation. Such a device is described in EP 2940740 A1.

[0006] The present invention is based on the object of providing a device and a method for forming a structure on a workpiece by means of processing radiation, which enables higher precision in the case of irregular transport of the workpiece by means of the transport device.

[0007] This object is achieved by a device for forming a structure on a workpiece by means of processing radiation according to claim 1 and a method for forming a structure on a workpiece by means of processing radiation according to claim 11. Advantageous embodiments of the device can be found in dependent claims 2-9 and of the method in dependent claims 12-15.

[0008] The device according to the invention is preferably designed to carry out the method according to the invention, in particular a preferred embodiment thereof. The method according to the invention is preferably designed to be carried out using the device according to the invention, in particular a preferred embodiment thereof.

[0009] The invention is based on the finding that a high accuracy of the machining location in typical transport devices is impaired by fast, typically movements and in particular speed changes due to vibrations of the workpiece during machining by means of machining radiation.

[0010] The invention therefore provides two deflection units for the processing beam: a main deflection unit, in particular in a conventional manner, deflects the processing beam to the desired processing point on the workpiece. Furthermore, a second deflection unit, the corrective deflection unit, is provided, which can compensate for fluctuations, in particular wow and flutter, in the movement of the workpiece during processing. By providing a separate main deflection unit on the one hand and a corrective deflection unit on the other, the deflection units can each be controlled with different control signals and, in particular, can be technically optimized for the respective functionality.

[0011] The device according to the invention for forming a structure on a workpiece by means of processing radiation has a transport device for moving the workpiece along a preferably rectilinear movement path, a radiation source for generating processing radiation, a main deflection unit for the processing radiation, which is arranged in the beam path of the processing radiation, and a position measuring unit for measuring a position of the workpiece on the transport device before and / or during processing by means of the processing radiation.

[0012] Such devices are known per se, for example, to detect the position of the workpiece for the start of processing using the position measuring unit and to deflect the processing radiation to one or more desired processing points on the workpiece using the main deflection unit.

[0013] It is essential that the device has a speed measuring unit for measuring the movement speed of the workpiece during processing by means of the processing radiation, that the device has, in addition to the main deflection unit, a corrective deflection unit for the processing radiation, which is arranged in the beam path of the processing radiation, and that the device has a control unit which is connected to the main deflection unit and the corrective deflection unit and is designed to control the main deflection unit in order to deflect the processing radiation onto a processing point of the workpiece during the transport of the workpiece by means of the transport device and to control the corrective deflection unit in order to correct the deflection of the processing radiation by means of the corrective deflection unit depending on the measurement data of the speed measuring unit.

[0014] The device according to the invention thus has the previously explained advantage that a basic deflection of the processing radiation takes place by means of the main deflection unit, but a separate correction deflection unit is additionally provided in order to correct the deflection of the processing radiation based on speed changes which are determined by means of the speed measuring unit.

[0015] This enables greater precision in processing.

[0016] The object mentioned above is further achieved by a method for forming a structure in a workpiece by means of processing radiation according to claim 11.

[0017] The method according to the invention comprises the following process steps: A. Providing a workpiece on a transport device B. Moving the workpiece along a preferably straight path of movement by means of the transport device C. Processing the workpiece by means of the processing radiation while moving the workpiece by means of the transport device, wherein the processing radiation is generated by means of a radiation source and deflected to a processing point on the workpiece by means of a main deflection unit arranged in the beam path of the processing radiation.

[0018] It is essential that in step C. the movement speed of the workpiece is measured by means of a speed measuring unit and that in step C. during the processing of the workpiece, the deflection of the processing radiation is corrected depending on measurement data of the speed measuring unit by means of a correction deflection unit arranged in the beam path of the processing radiation in addition to the main deflection unit.

[0019] This results in the advantages mentioned in the explanation of the device according to the invention.

[0020] In the present invention, the main deflection unit enables deflection over larger solid angles in order to cover the desired processing field on the workpiece. The corrective deflection unit, on the other hand, is preferably used to correct smaller and in particular higher-frequency position changes of the workpiece due to external influences and / or disturbances and vibrations of the transport device. Therefore, the corrective deflection unit preferably achieves a faster, in particular higher-frequency change in the deflection, but preferably over smaller solid angles, compared to the deflection of the processing radiation by means of the main deflection unit. It is within the scope of the invention that the main deflection unit is arranged in the beam path of the processing radiation between the radiation source and the corrective deflection unit.However, due to the advantageous embodiment explained above, it is advantageous that the correction deflection unit is arranged in the beam path of the processing radiation between the radiation source and the main deflection unit.

[0021] It is therefore advantageous that a signal is used for controlling the main deflection unit which has a spectrum with lower frequencies on average and the spectrum of the signal used for controlling the correction deflection unit has higher frequencies on average.

[0022] Based on a measured speed measurement signal from the speed measurement unit, it is therefore advantageous to split the speed measurement signal into a higher-frequency part and a lower-frequency part, and to control the main deflection unit depending on the low-frequency part and the correction deflection unit depending on the higher-frequency part in order to perform the correction. Advantageously, a crossover frequency is used for this purpose, preferably in the range of 0.1 Hz to 10 kHz, preferably 1 Hz to 500 Hz, in particular 1 Hz to 100 Hz.

[0023] The speed measuring unit preferably has a plurality of optical detectors, particularly preferably a plurality of separate optical detectors. The speed measuring unit preferably has at least 3, particularly preferably at least 5, preferably at least 10 optical detectors. In particular, it is advantageous for the optical detectors of the speed measuring unit to be arranged in an array, particularly preferably in a grid arrangement, wherein in a grid with rectangular, preferably square, cells, the detectors are arranged at the grid intersection points. The plurality of optical detectors allows, in particular, smaller, high-frequency position changes of the workpiece to be detected with greater accuracy.In addition, the use of several optical detectors, in particular the use of optical detectors arranged in an array, also enables the determination of a displacement of the workpiece which does not occur along the transport direction, in particular perpendicular to the transport direction, as well as the determination of a rotation of the workpiece, in particular about a rotation axis perpendicular to the transport direction.

[0024] The array preferably has at least 2, in particular at least 3, preferably at least 30, and in particular at least 50 detectors. The array preferably has rows aligned transversely to the transport direction, with at least 2, preferably 4, and preferably at least 3 sensors arranged in each row. The array preferably has at least 2, preferably at least 4, and in particular at least 8 rows.

[0025] The optical detectors are preferably designed as motion sensors. Such motion sensors, also known as tracking sensors, are commercially available and are used, for example, in computer mice for motion detection. Such tracking sensors are inexpensive and enable precise detection, especially of short-term changes in speed. It is particularly advantageous to use optical tracking sensors as described in US Pat. No. 7,057,148 B2.

[0026] In an advantageous embodiment, each of the optical detectors of the speed measuring unit has its own data processing unit for processing the raw signals measured by the detector. This enables fast, decentralized processing of the measurement data from the optical detectors. It is particularly advantageous for the data processing units of the optical detectors to be designed to output digital measurement signals, preferably speed measurement signals. Therefore, each detector preferably has a processor unit, in particular a signal processing processor (DSP), preferably with at least one microprocessor and / or a field programmable gate array (FPGA), and preferably a program and data memory.

[0027] Advantageously, the device for the detectors of the speed measuring unit has at least one data line to the control unit, so that a plurality of the detectors of the array, preferably all detectors of the array, are connected in parallel to the control unit. This allows data from the detectors to be read out in parallel, resulting in a higher processing speed when calculating the workpiece's movement data.

[0028] In an advantageous embodiment, the speed measuring unit comprises at least one, preferably several, laser Doppler velocimeters. Laser Doppler velocimeters allow a speed, and in particular a change in speed, of the workpiece to be determined with high accuracy and high temporal resolution.

[0029] The control unit preferably has at least one processor unit, preferably with one or more microprocessors, in particular with an FPGA (Field Programmable Gate Array). Furthermore, the control unit preferably has at least one program and data memory connected to the processor unit.

[0030] The present invention has the advantage that by providing two separate deflection units, the respective deflection units can be technically optimized for different requirements.

[0031] As previously described, the main deflection unit preferably serves to deflect the processing radiation over a desired processing space, which preferably covers the entire width of the workpiece in a single-axis configuration, and preferably the entire surface of the workpiece in a multi-axis configuration. The main deflection unit therefore preferably has one or more single-axis rotatable mirrors. In particular, it is advantageous for the main deflection unit to have at least one single-axis rotatable polygon mirror. Such deflection units are known per se and commercially available. In particular, it is advantageous to design the radiation source as a laser and the main deflection unit as a laser scanner. In a further advantageous embodiment, the main deflection unit has at least one, preferably at least two, galvanometric mirrors.

[0032] Advantageously, the main deflection unit is therefore designed as one of the following units or a combination of the following units: - galvanometer scanner, in particular a multi-axis galvanometer scanner, - Polygon scanner.

[0033] The corrective deflection unit, on the other hand, is preferably used to correct low-amplitude, high-frequency position and / or speed changes of the workpiece. It is therefore advantageous that the corrective deflection unit enables rapid changes in the deflection angle. Conversely, a deflection at smaller solid angles is tolerable compared to the deflection by the main deflection unit. It is therefore advantageous that the corrective deflection unit has at least one micromirror actuator. Micromirror actuators are microelectromechanical components for dynamic light modulation. In particular, it is advantageous that the corrective deflection unit has a micromirror actuator designed as a microscanner.

[0034] Advantageously, the correction deflection unit is therefore designed as one of the following units or a combination of the following units: - Microscanner, especially micromirror actuator, - Piezo-operated mirror unit, in particular piezo tilting mirror, - Voice-coil tilting mirror

[0035] It is also within the scope of the invention to design the correction deflection unit as a spatial light modulator.

[0036] It is therefore advantageous that the main deflection unit is based on a different physical deflection principle, in particular a different actuator principle, than the corrective deflection unit. It is advantageous that the main deflection unit and the corrective deflection unit each have at least one optical mirror for deflecting the processing radiation. In particular, it is advantageous that the movement of the mirror for deflecting the processing radiation in the main deflection unit is based on a different physical deflection principle, in particular a different actuator principle, than the corrective deflection unit.

[0037] In an advantageous embodiment, both the main deflection unit and the corrective deflection unit are designed as galvanometer scanners. In this advantageous embodiment, the corrective deflection unit preferably has a smaller free aperture than the main deflection unit.

[0038] In order to enable a faster deflection of the corrective deflection unit compared to the main deflection unit, the elements of the corrective deflection unit used to deflect the processing radiation, in particular the moving elements, preferably have a lower mass than the elements of the main deflection unit used to deflect the processing radiation, in particular the moving elements of the main deflection unit.

[0039] It is within the scope of the invention to detect changes in the workpiece's speed in all three spatial directions and to correct them using the corrective deflection unit. Investigations by the applicants show that, in particular, changes in speed in the transport direction are corrected using the corrective deflection unit. In a preferred embodiment, therefore, the corrective deflection unit is used exclusively to correct changes in the workpiece's speed in the transport direction.

[0040] To increase the accuracy of the speed measurement using the speed measuring device, it is advantageous for the device to have a reference speed measuring unit for measuring a reference speed of the workpiece, in particular an average movement speed of the workpiece as a reference speed. The reference speed can be used to calibrate and thus increase the precision of the speed measuring unit.

[0041] It is within the scope of the invention that the reference speed measuring unit has optical detectors for speed measurement. It is also within the scope of the invention that the reference speed measuring unit is designed to measure the transport speed of a transport means of the transport device. It is within the scope of the invention that the transport device has a conveyor belt or a conveyor belt-like transport means for the workpiece. In an advantageous embodiment, the reference speed measuring unit is connected to a drive of the conveyor means in order to determine the movement speed of the transport means and thus of the workpiece via the drive speed. In particular, it is within the scope of the invention to use a motor encoder of a drive of the transport device and / or an encoder on a rotational axis of the transport device to measure the reference speed.

[0042] In particular, it is advantageous that the reference speed measuring unit comprises one or more of the following reference measuring units a) a reference measuring unit for determining the transport speed of a transport element of the transport device, wherein the transport element is designed to hold and / or place the workpiece, b) a reference measuring unit which measures the duration of the movement of the workpiece over a specific measuring distance along the movement path of the workpiece between at least two optical sensors of the reference measuring unit in order to determine an average movement speed from the duration and the measuring distance, in particular it is advantageous that the position measuring unit is part of the reference measuring unit.

[0043] In the method according to the invention, it is accordingly advantageous that a separate measurement of a reference speed of the workpiece is carried out by means of a reference speed measuring unit, preferably during processing by means of the processing radiation, wherein the reference speed is preferably measured by means of a) Determination of the transport speed of a transport element of the transport device, wherein the workpiece is arranged on the transport element and / or rests on the transport element, b) measuring the time duration of the movement of the workpiece over a specific measuring distance along the movement path of the workpiece between at least two optical sensors of the reference speed measuring unit in order to determine an average movement speed from the time duration and the measuring distance.

[0044] The control unit of the device according to the invention is preferably designed to carry out a calibration of the speed measuring unit depending on the reference speed determined by means of the reference speed measuring unit, in particular such that an average movement speed of the speed measuring unit corresponds to the reference speed.

[0045] Accordingly, the method is preferably designed such that a calibration of the speed measuring unit is carried out depending on the reference speed, in particular such that an average movement speed of the speed measuring unit corresponds to the reference speed.

[0046] The correction of the deflection of the processing radiation by means of the correction deflection unit is preferably carried out by determining an average movement speed of the workpiece and, depending on the measurement data of the speed measuring unit, determining deviations of the movement speed of the workpiece from the average speed, wherein the correction of the deflection of the processing radiation is determined by means of the correction deflection unit depending on these deviations.

[0047] In particular, it is advantageous that a time-resolved movement speed of the workpiece is determined depending on the measurement data of the speed measuring unit and the deflection of the processing radiation by means of the main deflection unit is carried out depending on a low-frequency component of the movement speed and the deflection of the processing radiation by means of the main deflection unit is carried out depending on a higher-frequency component of the movement speed.

[0048] Advantageously, the speed of movement of the workpiece is measured using the speed measuring unit on a side of the workpiece opposite the side on which the workpiece is being processed using the processing radiation. This allows movement measurement even during the processing of the workpiece, and the arrangement of the motion sensors is not spatially restricted by the beam path of the processing radiation or optical components for the processing radiation.

[0049] Preferably, the workpiece for processing rests on the transport device, and processing by means of the processing radiation takes place from above. Therefore, the movement data of the workpiece is advantageously recorded from below using the speed measuring unit. In particular, it is advantageous that at least some of the movement sensors of the speed measuring unit, preferably the array of movement sensors, and particularly preferably all of the movement sensors of the speed measuring unit, are arranged on the side of the transport device opposite the deflection unit, in particular below the transport device.

[0050] To improve measurement quality, additional illumination is advantageous, particularly infrared illumination, directed onto the workpiece from above. Therefore, when recording the correction data, the workpiece is advantageously illuminated using infrared radiation, particularly from the side of the workpiece opposite the sensor. The device therefore preferably has a radiation source for infrared radiation, which is preferably arranged and configured to illuminate the workpiece from the side on which the machining is taking place.

[0051] The position measuring unit is preferably designed as a light barrier. In an advantageous embodiment, greater precision in position detection is achieved by embodying the position measuring unit as a camera or optical micrometer.

[0052] It is within the scope of the invention to use different types of processing radiation for processing, in particular ion beams. The use of electromagnetic radiation, in particular laser radiation, is particularly preferred. It is therefore particularly advantageous that the workpiece is processed using laser radiation in process step C. Laser radiation has a high energy density and low divergence and is therefore particularly suitable for creating structures on a workpiece.

[0053] Another source of error when machining a workpiece using machining radiation occurs when workpieces are uneven or have different height profiles. The method and device according to the invention are particularly suitable for machining flat, particularly plate-like workpieces, in particular for machining semiconductor substrates for the production of components, in particular for the production of photovoltaic solar cells.

[0054] Advantageously, therefore, in the method according to the invention, a workpiece is provided on the transport device, which is a dimensionally stable workpiece, in particular a flat, in particular plate-like workpiece, preferably a semiconductor substrate, particularly preferably a photovoltaic solar cell or a precursor in the production of a photovoltaic solar cell.

[0055] Advantageously, a focusing device is used during processing to focus the processing radiation onto a processing point on the workpiece. This allows higher energy densities to be achieved and smaller structures to be formed. With knowledge of the workpiece's height profile, the focusing device is preferably controlled such that the processing radiation is always focused onto the workpiece's surface.

[0056] Advantageously, the focusing device comprises a passive component, in particular an optical lens with a fixed focal length, and an active component, in particular a liquid lens or a mirror system. The device comprises a height profile measuring unit, wherein the active component shifts the focus depending on the height data of the height profile measuring unit, e.g., a liquid lens or a mirror system. Advantageously, the focusing unit is designed and controlled as described in Jahn, Axel, 3-dimensional beam shaping for dynamic adjustment of focus position and intensity distribution for laser welding and cutting, http: / / publica.fraunhofer.de / documents / N-645639.html.

[0057] As described above, the method and device according to the invention enable the workpiece to be exposed to the processing radiation with very high spatial precision at the desired location on the workpiece's surface. This can be combined particularly advantageously with optics that produce smaller structures due to a large numerical aperture but only have small image fields, in particular microlens arrays or cylindrical lenses. By transporting the workpiece, it is possible to produce the small structures with precise location even over a large area. It is generally known that cylindrical lenses can be used advantageously to form structures on a workpiece using processing radiation, as described, for example, in Khan et al. Formation of thin laser ablated contacts using cylindrical lens, https: / / doi.org / 10.1063 / 5.0056740.

[0058] Advantageously, an optical element for focusing the processing radiation, in particular an optical lens, preferably a cylindrical lens, is arranged in the beam path of the processing radiation between the main deflection unit and the workpiece. The optical element, preferably the cylindrical lens, is preferably arranged close to the workpiece, in particular at a distance of less than 20 cm, more preferably less than 10 cm, in particular less than 5 cm from the workpiece. This allows particularly narrow structures to be formed.

[0059] It is within the scope of the invention that the transport device is designed to transport the workpiece along a non-rectilinear path of movement. In particular, the transport of the workpiece on a curved, in particular circular, path of movement is within the scope of the invention. Likewise, the formation of a structure on a workpiece using the roll-to-roll process (R2R process), in particular on a strip-shaped workpiece, is within the scope of the invention. For integration into an inline process, it is advantageous that the transport device is designed to transport the workpiece on a rectilinear path of movement.

[0060] Further advantageous features and embodiments are explained below with reference to a figure and an embodiment.

[0061] Preferably, the speed measuring unit measures the speed of the workpiece with a sample rate of at least 10 Hz, preferably at least 100 Hz, in particular at least 500 Hz.

[0062] This shows Fig. 1 shows a schematic, not to scale, embodiment of a device according to the invention for forming a structure on a workpiece by means of processing radiation.

[0063] The device comprises a radiation source 1 for generating processing radiation. The radiation source 1 is in the present case a laser for generating laser radiation (dashed lines in Fig. 1) is designed as a processing beam. Furthermore, the device has a transport device 3. The transport device 3 has a motor-driven conveyor belt as a transport means. The workpieces to be processed are placed on the conveyor belt. In the schematic representation according to Fig. 1 shows three workpieces 6 lying on the conveyor belt. The workpieces are shown in the illustration according to Fig. 1 moved horizontally to the right.

[0064] The device further comprises a main deflection unit 2a, which in this case has two uniaxially rotatable deflection mirrors, allowing deflection of the processing beam in two mutually perpendicular spatial directions. By means of the main deflection unit 2a, the processing beam can be directed during transport of the workpiece to any point on the entire upper side of the workpiece facing the main deflection unit 2a in order to perform processing. The main deflection unit 2a is thus designed as a laser scanner in this case.

[0065] In this case, the device has four position measuring units 5 designed as light barriers. The position measuring units 5 can be used to detect the retraction and extension of a workpiece at the position of the respective position measuring unit.

[0066] It is essential that the device comprises a speed measuring unit 4a for measuring the movement speed of the workpiece during processing using the processing radiation. In this case, the speed measuring unit 4a comprises an array of optical tracking sensors arranged in a rectangular grid of 8 rows and 4 columns. The speed measuring unit thus comprises a total of 32 separate optical detectors.

[0067] Furthermore, in addition to the main deflection unit 2a, the device comprises a corrective deflection unit 7b. The corrective deflection unit 7b is arranged in the beam path of the processing radiation between the radiation source 1 and the main deflection unit 2a. A stationary deflection mirror 7c is also arranged between the corrective deflection unit 7b and the radiation source 1.

[0068] The device has a control unit, which in this case has a data processing unit 4b, a main deflection unit control unit 2c and a correction deflection unit control unit 7a.

[0069] In order to focus the processing radiation, a focusing unit 2b with a focusing lens is arranged in the beam path of the processing radiation between the main deflection unit 2a and the workpiece 6.

[0070] In one embodiment of a method according to the invention, the workpiece 6 is transported by means of the transport device 3 to a processing area below the main deflection unit 2a in order to carry out processing by means of processing radiation at a plurality of processing points to which the processing radiation is directed by means of the main deflection unit 2a during the transport of the workpiece 6.

[0071] The speed measuring unit 4a covers a measuring area that encompasses the conveyor path of the workpiece during processing. The speed measuring unit 4a thus records speed data using the tracking sensors throughout the entire processing of the workpiece by means of processing radiation. The position measuring units 5 can also detect the time at which the workpiece enters and leaves the processing area.

[0072] For the speed measurement, the measured values ​​from the optical detectors of the speed measuring unit are combined. For this purpose, the sectors in whose field of view the workpiece is located are taken into account. By averaging the speed measurement data, the data processing unit 4b determines an average movement speed of the workpiece 6. Using the position data acquired by the position measuring units 5 and the average movement speed, the main deflection unit control unit 2c controls the main steering unit 2a such that the processing beam is successively directed to the desired processing points on the workpiece 6.

[0073] The tracking sensors of the speed measuring unit 4a also enable a high-resolution measurement of the speed of the workpiece 6. The data processing unit 4b additionally determines the deviation of the current movement speed of the workpiece from the average movement speed with high temporal resolution (in this case, with a sample rate of 3 kHz). This deviation is sent to the corrective deflection unit control unit 7a in order to correct the position deviations of the workpiece due to the speed deviations from the average speed using the corrective deflection unit 7b.

[0074] The speed of the workpiece was thus divided into an average speed and an oscillatory component, whereby the control of the main deflection unit 2a takes place depending on the average speed and the control of the correction deflection unit 7b takes place depending on the oscillatory component.

[0075] In an advantageous further development, the average speed is determined from the speed measurement signal of the speed measurement unit 4a using a low-pass filter, in particular an Infinite Impulse Response (IIR) or Finite Impulse Response (FIR) low-pass filter.

[0076] In a further advantageous development of the exemplary embodiment, a reference speed of the workpieces is measured. This can be done by measuring the rotational speed of the drives of the conveyor belt of the transport device 3. In a development described here, the position measuring units 5 are used to determine the reference speed: The distance between the two left and between the two right position measuring units 5 is known, so that the movement speed can be determined as a reference speed with high accuracy from the time span during the movement of an edge of the workpiece between the position measuring units.

[0077] The reference speed is also calculated by the data processing unit 4b and used to calibrate the speed measurement of the speed measuring unit 4a. For this purpose, the speed measurement of the speed measuring unit 4a is scaled so that the average speed of the speeds transmitted by the speed measuring unit 4a corresponds to the reference speed. List of reference symbols 1 radiation source 2a Main deflection unit 2c Main deflection unit control unit 2b Focusing unit 3 Transport device 4a Speed ​​measuring unit 4b Data processing unit 5 Position measuring unit 6 Workpiece 7a Correction deflection unit control unit 7b Correction deflection unit 7c Deflecting mirror QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2940740 A1

[0005] US 7,057,148 B2

[0025] Cited non-patent literature

[0000] Jahn, Axel, 3-dimensional beam shaping for dynamic adjustment of focus position and intensity distribution for laser welding and cutting, http: / / publica.fraunhofer.de / documents / N-645639.html

[0056] Khan et al. Formation of thin laser ablated contacts using cylindrical lens, https: / / doi.org / 10.1063 / 5.0056740

[0057]

Claims

[1] Device for forming a structure on a workpiece by means of processing radiation, with a transport device for moving the workpiece along a preferably straight path, a radiation source for generating processing radiation, a main deflection unit for the processing radiation, which is arranged in the beam path of the processing radiation, and with a position measuring unit for measuring a position of the workpiece on the transport device before and / or during processing by means of the processing radiation, characterized by , that the device has a speed measuring unit for measuring the movement speed of the workpiece during processing by means of the processing radiation, that the device has, in addition to the main deflection unit, a corrective deflection unit for the processing radiation, which is arranged in the beam path of the processing radiation, and the device has a control unit which is connected to and formed with the main deflection unit and the corrective deflection unit, to control the main deflection unit to deflect the processing radiation onto a processing point of the workpiece during the transport of the workpiece by means of the transport device and to control the correction deflection unit in order to correct the deflection of the processing radiation by means of the correction deflection unit depending on the measurement data of the speed measuring unit. [2] Device according to claim 1, characterized by that the correction deflection unit is arranged in the beam path of the processing radiation between the radiation source and the main deflection unit. [3] Device according to one of the preceding claims, characterized by that the speed measuring unit has a plurality of optical detectors, in particular a plurality of separate optical detectors, preferably at least 3, in particular at least 10, in particular at least 50 optical detectors, preferably optical detectors arranged in an array. [4] Device according to claim 3, characterized by that the optical detectors are designed as motion sensors. [5] Device according to one of claims 3 to 4, characterized by that each of the optical detectors of the speed measuring unit has its own data processing unit for processing the raw signals measured by the detector, in particular for outputting digital measuring signals, preferably speed measuring signals. [6] Device according to one of the preceding claims, characterized bythat the speed measuring unit has at least one, preferably several laser Doppler velocimeters. [7] Device according to one of the preceding claims, characterized by that the correction deflection unit is designed as one of the following units or a combination of the following units: - Microscanner, especially micromirror actuator, - Piezo-operated mirror unit, especially piezo tilting mirror - Voice coil tilting mirror and that the main deflection unit is designed as one of the following units or a combination of the following units: - galvanometer scanner, in particular a multi-axis galvanometer scanner, - Polygon scanner. [8] Device according to one of the preceding claims, characterized bythat the device has a reference speed measuring unit for measuring a reference speed of the workpiece, in particular an average movement speed of the workpiece as a reference speed. [9] Device according to claim 8, characterized by that the reference speed measuring unit comprises one or more of the following reference measuring units: A. a reference measuring unit for determining the transport speed of a transport element of the transport device, wherein the transport element is designed to hold and / or place the workpiece, B. a reference measuring unit which measures the time duration of the movement of the workpiece over a specific measuring distance along the movement path of the workpiece between at least two optical sensors of the reference measuring unit in order to determine an average movement speed from the time duration and the measuring distance, in particular that the position measuring unit is part of the reference measuring unit. [10] Device according to one of the preceding claims 8 to 9, characterized by that the control unit is designed to carry out a calibration of the speed measuring unit depending on the reference speed determined by means of the reference speed measuring unit, in particular in such a way that an average movement speed of the speed measuring unit corresponds to the reference speed. [11] Method for forming a structure on a workpiece by means of processing radiation, with the method steps A. Providing a workpiece on a transport device B. Moving the workpiece along a preferably straight path of movement by means of the transport device C. Processing the workpiece by means of the processing radiation while moving the workpiece by means of the transport device, wherein the processing radiation is generated by means of a radiation source and deflected to a processing point on the workpiece by means of a main deflection unit arranged in the beam path of the processing radiation, characterized by that in step c. the movement speed of the workpiece is measured by means of a speed measuring unit, that in step c. during the machining of the workpiece the deflection of the machining radiation is corrected depending on measurement data of the speed measuring unit by means of a correction deflection unit arranged in the beam path of the machining radiation in addition to the main deflection unit. [12] Method according to claim 11, characterized by that an average movement speed of the workpiece is determined and, depending on the measurement data of the speed measuring unit, deviations of the movement speed of the workpiece from the average speed are determined, whereby the correction of the deflection of the processing radiation is determined by means of the correction deflection unit depending on these deviations. [13] Method according to one of claims 11 to 12, characterized by that a time-resolved movement speed of the workpiece is determined depending on the measurement data of the speed measuring unit and the deflection of the processing radiation by means of the main deflection unit is dependent on a low-frequency component of the movement speed and the deflection of the processing radiation by means of the main deflection unit is dependent on a higher-frequency component of the movement speed. [14] Method according to one of claims 11 to 13, characterized by that a separate measurement of a reference speed of the workpiece is carried out by means of a reference speed measuring unit, preferably during processing by means of the processing radiation, wherein the reference speed is preferably measured by means of at least one of the steps A. Determination of the transport speed of a transport element of the transport device, wherein the workpiece is arranged on the transport element and / or rests on the transport element, B. Measuring the time duration of the movement of the workpiece over a specific measuring distance along the movement path of the workpiece between at least two optical sensors of the reference speed measuring unit in order to determine an average movement speed from the time duration and the measuring distance. [15] Method according to claim 14, characterized bythat the speed measuring unit is calibrated depending on the reference speed, in particular in such a way that an average movement speed of the speed measuring unit corresponds to the reference speed.

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