Apparatus for processing a workpiece with a laser beam

Abstract

The present invention relates to an apparatus (100, 200, 300, 700) and a method (400) for processing a workpiece (101) using a laser beam (10a). The apparatus (100, 200, 300, 700) includes a processing unit (103) configured to provide a pressurized fluid jet (104) onto the workpiece (101) and couple a laser beam (102) toward the workpiece (101) into the fluid jet (104) via at least one optical element (105). Furthermore, the apparatus includes a sensing unit (107) arranged to receive electromagnetic radiation (106) induced by the laser propagating away from the workpiece (101) through the fluid jet (104) and through the at least one optical element, and configured to convert the received electromagnetic radiation (106) into a signal (108). The devices (100, 200, 300, 700) also include a signal processing unit (109) configured to determine the state of processing the workpiece (101) based on the signal (108).

Description

[0001] This application is a divisional application of the invention patent application filed on October 4, 2018, with application number "201880064929.7" and invention title "Apparatus for Processing Workpieces Using a Laser Beam". Technical Field

[0002] This invention relates to an apparatus and a corresponding processing method for machining workpieces using a laser beam. Specifically, the apparatus and method are used to machine workpieces using a laser beam coupled to a fluid jet. More specifically, this invention relates to controlling the machining process of the apparatus and method based on process emission. Background Technology

[0003] Traditional equipment for machining workpieces using laser beams is known. Similarly, traditional equipment for machining workpieces using laser beams coupled to a fluid jet (where the fluid jet impacts the workpiece) is also generally known.

[0004] A common problem encountered in laser beam processing using conventional equipment is the difficulty in determining the characteristic states of the workpiece during processing due to the lack of mechanical interaction between the equipment and the workpiece. This difficulty often leads to a significant increase in processing time. For example, when using conventional equipment to cut a workpiece with a laser beam, accurately determining whether and when the laser beam has penetrated the workpiece material is problematic. Therefore, the cutting process cannot be completed in a time-optimized manner. Furthermore, the ability to accurately determine other states of the workpiece during processing (such as states indicating instability in the processing) would also be beneficial.

[0005] Determining the process status by visually inspecting the workpiece is difficult or even dangerous because the laser beam can splash back from it uncontrollably. Furthermore, if conventional equipment uses a laser beam guided in a fluid jet, additional difficulties arise due to the humid workpiece environment. For example, fluid can accumulate on the workpiece's surface due to the uncontrolled splashing, making it even more difficult to determine the processing status.

[0006] Traditional solutions primarily rely on visual inspection using cameras (e.g., placed next to the equipment and / or workpiece). However, due to the aforementioned environmental challenges, especially in humid environments, conventional visual inspection is not very accurate. Furthermore, the inspection equipment (e.g., the camera) is at high risk of being damaged by splashed fluids. Additionally, the equipment based on this traditional solution is relatively large and inconveniently distributed across multiple individual components.

[0007] In view of these problems and drawbacks, the present invention aims to improve upon conventional equipment and solutions. Therefore, the object of the present invention is to provide an apparatus and method for machining workpieces using a laser beam coupled to a fluid jet, which allows for a reduction in machining time. In particular, the present invention should allow for more precise determination of the state of the machining process. The higher the accuracy of determining the state of the machined workpiece, the better the time optimization of the machining process can be achieved. Specifically, the present invention aims to reliably determine whether the laser beam has penetrated the workpiece material. Therefore, the objective of the present invention is particularly a compact apparatus and solution unaffected by the humid environment caused by the fluid jet. This avoids damage to the equipment and apparatus. Summary of the Invention

[0008] The object of this invention is achieved by the solution provided in the appended independent claims. Advantageous implementations of the invention are defined in the dependent claims.

[0009] In particular, the present invention proposes a process emission-based method, which uses electromagnetic radiation induced by laser generated when processing a workpiece with a laser beam to detect the state of the workpiece.

[0010] A first aspect of the present invention provides an apparatus for processing a workpiece using a laser beam, the apparatus comprising: a processing unit configured to provide a pressurized fluid jet onto the workpiece and couple the laser beam toward the workpiece into the fluid jet via at least one optical element; a sensing unit arranged to receive electromagnetic radiation sensed by the laser propagating away from the workpiece through the fluid jet and through the at least one optical element and configured to convert the received electromagnetic radiation into a signal; and a signal processing unit configured to determine a state of processing the workpiece based on the signal.

[0011] In the processing unit, a laser beam is coupled into a pressurized fluid jet, which acts as a waveguide for the laser beam and guides it toward the workpiece via total internal reflection. The pressurized fluid jet is preferably provided by a fluid nozzle, and the laser beam can be guided through the nozzle into the fluid jet and toward the workpiece via the at least one optical element. The fluid nozzle and the at least one optical element can be separated, for example, by an optical window to prevent contact between the optical element and the fluid.

[0012] The sensing unit can be a photodetector or a photosensor, and is preferably configured such that it can detect the laser-induced electromagnetic radiation traveling along the fluid jet in the opposite direction to the main laser beam (i.e., propagating away from the workpiece). It is noteworthy that some of the electromagnetic radiation induced by the laser beam processing the workpiece may not propagate back through the fluid jet, but may travel to other locations.

[0013] The electromagnetic radiation sensed by the laser, received by the sensing unit, provides a highly accurate fingerprint of the different states of the workpiece being processed. Specifically, the signal output by the sensing unit accordingly reveals characteristic behaviors depending on the different states of the workpiece. Therefore, the signal processing unit can accurately and efficiently determine the state of the workpiece based on this signal. Consequently, the signal processing unit can trigger corresponding actions of the equipment based on the determined state, thereby significantly improving the processing time.

[0014] The fact that the sensing unit can receive laser-induced electromagnetic radiation via a fluid jet allows the sensing unit to be safely located away from the humid environment of the processing. Advantageously, the fluid jet also serves as a waveguide for the back-propagating laser-induced radiation, thus allowing for more accurate detection of the radiation and subsequent analysis or post-processing of the signal supplied by the sensing unit when it senses the radiation. Preferably, the sensing unit is housed within the device; more preferably, the sensing unit is separated from any fluid circuitry and fluid nozzles to protect it from fluid contact, thereby extending its lifespan. The device of the first aspect can be constructed in a very compact manner, and all components of the device can be advantageously integrated together.

[0015] In a preferred embodiment of the device, the signal processing unit is configured to determine, for the state of the workpiece being processed, whether the laser beam has penetrated the workpiece.

[0016] The device of this invention can determine, with particular accuracy and speed, whether a laser beam has penetrated a workpiece. Therefore, processing time can be significantly reduced, especially when the device is used to cut workpieces using a laser beam. This is because once it is determined that the laser beam has penetrated the workpiece, the processing can be stopped immediately. The signal processing unit can be configured to automatically provide such instructions.

[0017] In another preferred embodiment of the device, the sensing unit is arranged to receive electromagnetic radiation propagating through the fluid jet and through the laser-induced light transmitted through the at least one optical element, the at least one optical element being configured to couple the laser beam into the fluid jet.

[0018] In this particular manner, the device can be constructed in a very compact manner. Furthermore, the amount of optical components required is minimal.

[0019] The device may include an optical head comprising the processing unit and a sensing unit. Therefore, within the optical head, the processing unit can couple a laser beam into a fluid jet, and the sensing unit can sense electromagnetic radiation induced by the laser propagating back from the workpiece. In this case, the signal processing unit may be arranged within the device, for example, within the device housing, but external to the optical head. The laser unit, including the laser source and / or laser controller, may or may not be part of the device, but it must be at least separate from the optical head.

[0020] In another preferred embodiment of the device, the device includes an optical head having the processing unit and a laser unit having the sensing unit.

[0021] The laser unit may include a laser source and / or a laser controller. In this implementation, a laser beam may be provided by the laser unit to an optical head, where a processing unit couples the laser beam into a fluid jet. Laser-sensed radiation propagating back from the workpiece can be guided by the optical head to the laser unit, where it is received by a sensing unit. The optical head may be optically connected to the laser unit, for example, via an optical fiber.

[0022] Surprisingly, it was found that even when the sensing unit is located within the laser unit (i.e., away from the optical head), the signal processing unit can accurately determine the state of the workpiece based on a signal provided by the sensing unit based on the radiation received from the laser. The advantage of placing the sensing unit and optionally associated optical elements (such as beam splitters, optical separation units, and / or focusing optics) within the laser unit is that handling these elements (e.g., maintenance or replacement) becomes much easier. Another advantage is that the optical head can be replaced without replacing the sensing unit and associated optical elements. Because there is more available space within the laser unit, the optical head can also be built smaller, while the sensing unit and associated optical elements can be built larger.

[0023] In another preferred embodiment of the device, the device further includes an optical connection element, particularly an optical fiber, for optically connecting the optical head and the laser unit, wherein the processing unit in the optical head is configured to receive the laser beam via the optical connection element, and the sensing unit in the laser unit is configured to receive laser-induced electromagnetic radiation via the optical connection element.

[0024] Therefore, the same optical connection element (e.g., optical fiber) is used to transmit the laser beam for the laser beam and the radiation for laser sensing separately within the device (i.e., between the optical head and the laser unit). Nevertheless, the state of the workpiece being processed can still be accurately determined by the processing unit based on the signals correspondingly generated by the sensing unit.

[0025] In another preferred embodiment of the device, the at least one optical element includes a lens for coupling the laser beam into the fluid jet, and the sensing unit is arranged to receive electromagnetic radiation sensed by the laser propagating in the back through the lens.

[0026] This particular implementation therefore allows for the use of the lens in a dual manner and allows the positioning sensing unit to be kept free from contact with the fluid. Furthermore, the device can be constructed in a compact manner.

[0027] In another preferred embodiment of the device, the device further includes a spectral separation unit (preferably an optical filter unit) configured to separate only at least a portion of the electromagnetic radiation of interest, including the laser-sensed electromagnetic radiation, onto the sensing unit and / or configured to prevent the initial laser from reaching the sensing unit.

[0028] Specifically, a spectral separation unit is arranged and configured to receive radiation, which is either laser-induced electromagnetic radiation propagating away from the workpiece or includes laser-induced electromagnetic radiation propagating away from the workpiece. The spectral separation unit can separate the electromagnetic radiation of interest from the received radiation, and can provide the radiation of interest, including at least a portion of the laser-induced electromagnetic radiation, to the sensing unit. The function of the spectral separation unit is to more accurately and reliably determine the state of the processed workpiece. The spectral separation unit prevents unwanted radiation from reaching the sensing unit. The sensing unit can therefore detect the radiation of interest more sensitively and accurately. The radiation of interest can be laser-induced electromagnetic radiation with other unwanted radiation removed, or it can be a portion of laser-induced electromagnetic radiation. It is possible, for example, that the laser beam senses different kinds of electromagnetic radiation caused by different mechanisms. In this case, the electromagnetic radiation of interest can be laser-induced electromagnetic radiation caused only by one specific mechanism.

[0029] In another preferred embodiment of the device, the laser-induced electromagnetic radiation includes secondary radiation emitted from the portion of the workpiece processed by the laser beam.

[0030] Secondary radiation in this case is caused by processing the workpiece with a laser beam, for example, because the processed surface area of ​​the workpiece is converted into plasma. This plasma emits characteristic radiation, which can be easily separated onto or by the sensing unit, for example, by means of the aforementioned spectral separation unit, in order to allow for particularly accurate determination of the state of the processed workpiece, especially whether the laser beam has penetrated the workpiece.

[0031] In another preferred embodiment of the device, the laser-sensed electromagnetic radiation includes primary laser radiation reflected from the workpiece.

[0032] This provides a simple method for implementing the invention. The laser reflected from the workpiece includes at least a portion of the light from a primary laser beam and propagates in the opposite direction through the fluid toward the sensing unit. The corresponding signal converted by the sensing unit provides the status of the processed workpiece, and in particular, an accurate fingerprint of whether the laser beam has penetrated the workpiece.

[0033] In another preferred embodiment of the device, the laser-induced electromagnetic radiation includes secondary radiation generated by the scattering of the laser beam in the fluid jet, preferably by Raman scattering.

[0034] The advantage of laser-induced scattering within a fluid jet is that the scattering does not form directly on the workpiece surface where environmental conditions are difficult to control, but rather within a laminar and / or more controlled fluid jet. Nevertheless, this scattering-induced radiation provides an accurate fingerprint of the state of the workpiece being processed, particularly whether the laser beam has penetrated it.

[0035] The possible scenarios are: secondary radiation emitted from the laser-processed portion of the workpiece, primary laser radiation reflected from the workpiece, and / or secondary radiation generated by the scattering of the laser beam in the fluid jet, propagating away from the workpiece through the fluid jet and through at least one optical element. In this case, the aforementioned spectral separation unit can be used to filter out any unwanted laser-induced electromagnetic radiation and focus only the laser-induced electromagnetic radiation of interest (e.g., secondary radiation emitted from the laser-processed portion of the workpiece) onto the sensing unit.

[0036] In another preferred embodiment of the device, the signal processing unit is configured to process the signal with a time resolution of less than 0.5 s, preferably less than 0.1 s.

[0037] For example, the time resolution of the signal processing unit can be 0.2s-0.5s, or 0.1s-0.5s, or 0.1s-0.2s, or even 0.01s-0.1s. These preferred time resolutions provided by the signal processing unit allow for accurate detection of the workpiece's state and thus allow for particularly stable control of the machining process. In particular, using such a signal processing unit can further reduce the machining time.

[0038] In another preferred embodiment of the device, the laser beam is a pulsed laser beam, the sensing unit is configured to convert the received radiation into a signal for each laser pulse, and the signal processing unit is configured to aggregate multiple signals over time to generate an aggregated signal, and determine the state of processing the workpiece based on the pattern or pattern change in the aggregated signal.

[0039] The aggregation of signals over time further improves the reliability of determining the state of the workpiece. In particular, patterns appearing in a single (non-aggregated) signal can be enhanced in the aggregated signal. Furthermore, additional patterns appearing only in the aggregated signal can allow for the determination of other states, or more precise state determinations. Moreover, the sensitivity of the determination is generally improved due to the reduction of signal noise.

[0040] In another preferred embodiment of the device, the device further includes at least one peripheral device, which is preferably a laser controller, a fluid supply controller, a gas supply controller, and / or a moving axis controller, wherein the signal processing unit is configured to provide instruction signals to the at least one peripheral device based on the determined state of processing the workpiece, so as to start, interrupt, stop, and / or restart the operation of the peripheral device.

[0041] Therefore, the processing time can be optimized. In particular, based on the determined state of the workpiece, the equipment can react quickly to take necessary actions. For example, if the laser beam penetrates the workpiece, the equipment can stop the processing. As another advantage, the quality of the processing can be improved.

[0042] A second aspect of the invention provides a method for machining a workpiece using a laser beam, the method comprising: providing a pressurized fluid jet to the workpiece and coupling the laser beam toward the workpiece into the fluid jet via at least one optical element; receiving laser-induced electromagnetic radiation propagating away from the workpiece through the fluid jet and through the at least one optical element, and converting the received electromagnetic radiation into a signal; and determining a state of machining the workpiece based on the signal.

[0043] Using the second method, the same advantages and effects as the first method can be achieved.

[0044] In a preferred implementation of the method, the method further includes: recording a plurality of signals to determine the state of processing the workpiece, comparing the recorded plurality of signals with a predetermined reference signal, and determining the state of processing the workpiece based on a similar or matching reference signal.

[0045] A simple implementation with very accurate results can be provided by providing reference signals and comparing them.

[0046] In another preferred embodiment of the method, the method further includes: in order to determine the state of processing the workpiece, aggregating multiple signals over time to generate an aggregated signal, evaluating a pattern or pattern change in the aggregated signal, and determining the state of processing the workpiece based on the pattern or pattern change.

[0047] Thus, the same advantages and effects as the corresponding implementation of the device described above are achieved.

[0048] In another preferred implementation of the method, the laser-sensed electromagnetic radiation is secondary radiation emitted from a portion of the workpiece processed by the laser beam, and the method includes determining that the laser beam has penetrated the workpiece when, for a state of processing the workpiece, the value of a single signal or the aggregated signal increases after processing the workpiece is initiated and then decreases again to below a predetermined threshold.

[0049] In another preferred implementation of the method, the electromagnetic radiation sensed by the laser is a single laser radiation reflected from the workpiece, and the method includes: for the state of processing the workpiece, determining that the laser beam has penetrated the workpiece when the value of a single signal or the aggregated signal decreases after processing of the workpiece is started, and then increases again to above a predetermined threshold.

[0050] It has been found that the aforementioned characteristic fingerprints in single or aggregated signals, i.e., the patterns followed by the signals or aggregated signals, provide very accurate identification results. Furthermore, the low processing load allows this method to be executed very quickly. Attached Figure Description

[0051] The above-described aspects and preferred embodiments of the present invention are illustrated in the following detailed description with reference to the accompanying drawings, wherein: Figure 1 An apparatus according to an embodiment of the present invention is shown.

[0052] Figure 2 An apparatus according to an embodiment of the present invention is shown.

[0053] Figure 3 An apparatus according to an embodiment of the present invention is shown.

[0054] Figure 4 A method according to an embodiment of the present invention is shown.

[0055] Figure 5 The schematic diagram illustrates the characteristic signal pattern used in a method according to an embodiment of the present invention.

[0056] Figure 6 An apparatus according to an embodiment of the present invention is shown.

[0057] Figure 7 An apparatus according to an embodiment of the present invention is shown. Detailed Implementation

[0058] Figure 1 An apparatus 100 according to an embodiment of the present invention is shown. Specifically, the apparatus 100 is configured to process a workpiece 101 using a laser beam 102. The workpiece 101 may be made of a material including, for example, metals, ceramics, diamond, semiconductors, carbides, alloys, superalloys, or superhard materials. The workpiece 101 is not, in particular, part of the apparatus 100. However, the workpiece 101 may be placed on a processing surface, which may or may not be part of the apparatus 100. In either case, the apparatus 100 may be arranged such that it can process the workpiece 101 disposed on the processing surface. The apparatus 100 can also control the movement of the processing surface in up to three dimensions.

[0059] The device 100 includes a processing unit 103, a sensing unit 107, and a signal processing unit 109. These units 103, 107, and 109 are preferably all integrated into the device 100; that is, these units 103, 107, and 109 are preferably disposed within the housing or enclosure of the device 100. The device 100 may also include additional units also disposed within the same housing or enclosure.

[0060] Processing unit 103 is configured to provide a pressurized fluid jet 104 to workpiece 101 and couple a laser beam 102 into the fluid jet 104. Specifically, the laser beam 102 is coupled into the fluid jet 104 by means of at least one optical element 105. This at least one optical element 105 may include, for example, one or more lenses, lens assemblies, light-guiding optics, beam splitters, mirrors, filters, or polarizers. The laser beam 102 is guided by the preferably fine (i.e., having a diameter in the micrometer (μm) range) fluid jet 104, in principle as if the laser beam were guided in an optical fiber. The laser beam 102 is, for example, a pulsed laser beam 102, and is directed toward and onto workpiece 101, thus allowing the laser beam 102 to be used for precise processing of workpiece 101 while the fluid jet 104 continuously cools workpiece 101 and potentially removes debris. For example, device 100 may be specifically configured to accurately cut or shape workpiece 101.

[0061] The laser beam 102 is provided by a laser, which may be part of the device or may be external but couples the laser beam 102 to the laser supply port of the device 100. The laser beam 102 may be visible and preferably originates from the green spectrum. For example, the laser beam 102 may have a wavelength of 532 nanometers (nm).

[0062] Sensing unit 107 is arranged to receive laser-induced electromagnetic radiation 106, i.e., electromagnetic emission generated when workpiece 101 is processed using laser beam 102. Therefore, laser-induced electromagnetic radiation 106 can also be referred to as "process emission". Sensing unit 107 is arranged such that it can receive and thus sense laser-induced electromagnetic radiation 106 propagating away from workpiece 101 through fluid jet 104 and through at least one optical element. Therefore, the reverse-propagating process emission 106 can be guided in and by fluid jet 104 to sensing unit 107. The at least one optical element by which sensing unit 107 receives process emission 106 can be at least one optical element 105 for coupling laser beam 102 into fluid jet 104. This is in... Figure 1 As exemplarily shown in the figure.

[0063] The sensing unit 107 is also configured to convert the received laser-sensed electromagnetic radiation 106 into a signal 108, for example, the sensing unit 107 provides a photocurrent as an output signal. The sensing unit 107 can therefore be, for example, a photodetector, but it can also be any other device or optical sensor capable of converting at least the electromagnetic radiation of interest into an electrical signal. The signal 108 is provided to the signal processing unit 109 for further analysis and / or processing.

[0064] The signal processing unit 109 is implemented, for example, by a microprocessor or computer, and is specifically configured to determine the state of the workpiece 101 being processed based on the signal 108 it receives from the sensing unit 107. Specifically, the signal processing unit 109 is configured to determine, for the processing state of the workpiece 101, whether the laser beam 102 has penetrated the workpiece 101. In other words, the signal processing unit 109 can determine whether the laser beam 102 has penetrated the workpiece 101 and when the laser beam 102 has penetrated the workpiece 101. To this end, the signal processing unit 109 can perform signal processing on the signal 108. Signal processing may include, for example, scaling, averaging, recording over time, aggregating over time, or transforming the signal 108, and may include comparing the signal 108 or the aggregated signal with one or more reference signals. For example, the signal processing unit 109 may be configured to record multiple signals 108 and compare the recorded signals 108 with pre-stored reference signals. The signal processing unit 109 may alternatively or additionally be configured to aggregate multiple signals 108 over time to generate an aggregated signal and evaluate the pattern or pattern changes in the aggregated signal. If the laser beam 102 is a pulsed laser beam, then in each case, multiple signals 108 can be generated by the electromagnetic radiation 106 sensed by the laser pulse and sensed by the sensing unit 107.

[0065] The signal processing unit 109 can then be configured to determine the state of the workpiece 101 based (in the first case) on a similar or matching reference signal or (in the second case) on a pattern or a change in pattern. Preferably, the signal processing unit 109 provides a time resolution of less than 0.5 seconds (s), preferably less than 0.2 seconds, and more preferably less than 0.1 seconds, because preferably, the sensing unit 107 operates at at least 10 Hz, and more preferably at at least 15 Hz.

[0066] Figure 2 A device 200 according to an embodiment of the present invention is shown, the device 200 being built on Figure 1 Based on the device 100 shown in the figure. Figure 2 and Figure 1 The same elements in the drawing are labeled with the same reference numerals and have the same function. Therefore, Figure 2The device 200 includes a processing unit 103 configured to provide a pressurized fluid jet 104 to a workpiece 101 and couple a laser beam 102 into the fluid jet 104. The device 200 also includes a sensing unit 107 configured to receive laser-induced electromagnetic radiation 106 propagating back through the fluid jet 104 and through the processing unit 103, preferably through at least one optical element 105, and configured to convert the laser-induced electromagnetic radiation 106 into a signal 108. A signal processing unit 109 (referred to herein as a "digital signal processing unit + IPC," i.e., the signal processing unit 109 may also provide inter-process communication (IPC)) is again configured to determine the processing state of the workpiece 101 based on the signal 108. Figure 2 Further details regarding the preferred overall layout of device 200 are also shown. Figure 2 The equipment 200 specifically includes multiple peripheral devices.

[0067] Device 200 may include a laser source 221 and a laser controller 207 for controlling the laser source 221. The laser source 221 is configured to supply laser 204 to the laser beam 102. The laser source 221 may also be an external device not included in device 200 but used to supply laser 204 to the laser supply port of device 200. In device 200, the laser beam 102 is preferably guided towards processing unit 103 by an optical unit 201 of device 200, which is preferably a beam splitter and preferably arranged in the optical path between processing unit 103 and sensing unit 107. In processing unit 103, the laser beam 102 is coupled into a fluid jet 104. Notably, the back-propagating laser-induced electromagnetic radiation 106 preferably passes through the optical unit 201 but is guided towards sensing unit 107.

[0068] The apparatus 200 preferably further includes a spectral separation unit 202 configured to separate only the electromagnetic radiation 203 of interest, including the laser-induced electromagnetic radiation 106, onto the sensing unit 107. The spectral separation unit 202 is preferably arranged in the optical path between the processing unit 103 and the sensing unit 107, so that it can receive the laser-induced electromagnetic radiation 106 traveling away from the workpiece 101 via the fluid jet 104 and via at least one optical element 105, and can output the radiation of interest 203, including at least a portion of the received laser-induced electromagnetic radiation 106, to the sensing unit 107. The spectral separation unit 202 may be an optical filter unit, which may consist of one or more optical filters and is configured to filter out unwanted electromagnetic radiation, i.e., to prevent electromagnetic radiation of certain (unwanted) wavelengths from reaching the sensing unit 107. The electromagnetic radiation of interest 203 can specifically be only the laser-induced electromagnetic radiation 106, wherein other electromagnetic radiation that accidentally reaches the spectral separation unit 202 (and would reach the sensing unit 107 without the spectral separation unit 202) is filtered out. The electromagnetic radiation of interest 203 can also be a portion of the laser-induced electromagnetic radiation 106 that reaches the spectral separation unit 202 (and would reach the sensing unit 107 without the spectral separation unit 202), wherein uninteresting laser-induced electromagnetic radiation is filtered out. If the laser-induced electromagnetic radiation is secondary radiation or includes secondary radiation, the spectral separation unit 202 can be configured to prevent the laser from reaching the sensing unit 107. That is, the spectral separation unit 202 can be configured to filter out light with the same wavelength as that provided by the laser source 221. Specifically, the present invention envisions three mechanisms for generating the laser-induced electromagnetic radiation of interest 106 that can provide an accurate fingerprint of the state of the processed workpiece 101.

[0069] First, the laser-induced electromagnetic radiation 106 can be secondary radiation 206a emitted by the portion of the workpiece 101 processed by the laser beam 102, or the laser-induced electromagnetic radiation 106 may include secondary radiation 206a emitted by the portion of the workpiece 101 processed by the laser beam 102. For example, the processed surface portion of the workpiece 101 can be converted into plasma by the laser beam 102, and this plasma is the source of the secondary radiation 206a. Typically, this secondary radiation 206a comes from the yellow and / or orange spectrum. Therefore, in this case, the spectral separation unit 202 can be configured to allow light from the yellow and / or orange spectrum to reach the sensing unit 107, while blocking light from other spectral portions, particularly blocking laser light from, for example, the green spectrum. Therefore, the radiation of interest 203 may consist only of secondary radiation 206a. In this case, the sensing unit 107 can be configured to be particularly sensitive to the yellow and / or orange spectrum.

[0070] Second, the laser-sensing electromagnetic radiation 106 can be primary laser radiation 206b reflected from the workpiece 101, particularly from the workpiece surface, or the laser-sensing electromagnetic radiation 106 can include primary laser radiation 206b reflected from the workpiece 101, particularly from the workpiece surface. Since the laser preferably originates from the green spectrum, in this case, the spectral separation unit 202 can be configured to allow light from the green spectrum to reach the sensing unit 107, while blocking light from other spectral portions. Therefore, the radiation of interest 203 can consist only of secondary radiation 206b. In this case, the sensing unit 107 can be configured to be particularly sensitive to the green spectrum.

[0071] Third, the laser-sensing electromagnetic radiation 106 can be secondary radiation 206c generated by the scattering of the laser beam 102 in the fluid jet 104, or the laser-sensing electromagnetic radiation 106 can include secondary radiation 206c generated by the scattering of the laser beam 102 in the fluid jet 104. Specifically, this secondary radiation 206c can be caused by Raman scattering of the laser beam 102. Typically, this secondary radiation 206c originates from the red spectrum. Therefore, in this case, the spectral separation unit 202 can be configured to allow light from the red spectrum to reach the sensing unit 107, while blocking light from other spectral portions, particularly blocking laser light from, for example, the green spectrum. Therefore, the radiation of interest 203 can consist only of secondary radiation 206c. In this case, the sensing unit 107 can be configured to be particularly sensitive to the red spectrum.

[0072] It is worth noting that both the secondary radiation 206a and the laser reflection 206b originate from the workpiece 101, particularly from the machined surface portion of the workpiece, while the secondary radiation 206c originates from the fluid jet 104, particularly from one or more different locations along the fluid jet 104.

[0073] The device 200 may also include a plurality of peripheral devices, and the signal processing unit 109 is preferably configured to provide instruction signals to one or more of the plurality of peripheral devices based on the determined state of the workpiece 101 being processed. In this way, the signal processing unit 109 can control the peripheral devices according to the determined state, and can, for example, instruct these peripheral devices to start, interrupt, stop, and / or restart their respective operations.

[0074] For example, Figure 2 The illustrated device 200 includes a laser controller 207 as a peripheral device, a fluid supply controller (optionally integrated with a fluid pump) 205, a gas supply controller 223 (here referred to as a "protective gas controller" because the gas is preferably used to protectively surround the fluid jet 104), and a motion axis controller 208 (here referred to as a "computer numerical control"). The motion axis controller 208 can be configured to move the machining surface perpendicular to the X, Y, and Z directions and / or rotate the machining surface along the a, b, and c directions (where the workpiece 101 is placed on the machining surface), or alternatively, to move the workpiece 101 itself perpendicular to the X, Y, and Z directions and / or rotate the workpiece 101 itself along the a, b, and c directions.

[0075] The signal processing unit 109 is configured to provide corresponding command signals to different peripheral devices. Preferably, the signal processing unit 109 can control the laser controller 207 via signal 217, the fluid supply controller 205 via signal 214, the gas supply controller 223 via signal 216, and the motion axis controller 208 via signal 213. The signal processing unit 109 preferably controls the peripheral devices independently of each other and without any external input, based solely on signal 108 and the determined state of the workpiece 101. Nevertheless, the device 200 may also include a human-machine interface 210 that can receive human input / script input 204 to provide additional commands to the signal processing unit 109 via signal 212.

[0076] Based on instructions provided by the signal processing unit 109 based on the determined state of the workpiece 101, peripheral devices can take indicated actions. For example, the laser controller 207 can start, pause, or stop the supply of laser light for the laser beam 102. The fluid supply controller 205 can control the fluid pressure control valve 215 to start, interrupt, or stop the supply of fluid 222 (preferably water) to the processing unit 103. The gas supply controller 223 can control the protective gas control valve 211 to start, interrupt, or stop the supply of gas 219 (preferably helium) to the processing unit 103. The motion axis controller 208 can provide specific movement of the workpiece 101, that is, the motion axis controller 208 can control the processing surface on which the workpiece 101 is arranged.

[0077] Figure 3 A device 300 according to an embodiment of the present invention is shown, the device 300 being built on Figure 1 The device 100 shown in the figure and Figure 2 Based on the device 200 shown in the figure. Figure 3 and Figure 1 and / or Figure 2 The same elements in the figures are labeled with the same reference numerals and have the same function. In particular, Figure 3 Further details are shown regarding the optical devices of the apparatus 300 and, in particular, the fluid circuitry provided in the processing unit 103. The processing unit 103 may specifically include a lens 305 for coupling the laser beam 102 into the fluid jet 104. Furthermore, the back-propagating laser-induced electromagnetic radiation 106 preferably travels through the fluid jet 104 and past the lens 305, and then further toward the sensing unit 107. Thus, the radiation 106 preferably travels from the lens 305 through the optical unit 201 to the spectral separation unit 202, and further reaches the sensing unit 107 as radiation 203 of interest, comprising at least a portion of the radiation 106.

[0078] The processing unit 103 may also include an optically transparent protective window 301 to separate the optical device (exemplarily a lens 305 here) from the fluid circuitry and the area in the processing unit 103 where the fluid jet 104 is generated. To generate the fluid jet 104, the processing unit 103 preferably includes a fluid nozzle 302. This fluid nozzle 302 is supplied with fluid via a fluid supply section 222, which may be implemented as a channel passing through the housing or enclosure of the device 300. For this purpose, the fluid nozzle 302 includes a fluid orifice that defines the width of the fluid jet 104. The diameter of the fluid orifice is preferably 10 μm to 200 μm, and the diameter of the fluid jet 104 is preferably about 0.6 to 1 times the diameter of the fluid orifice. A pressure for pressurizing the fluid jet 104 is provided via the fluid supply section 222. Preferably, the pressure is 50 bar to 800 bar.

[0079] from Figure 3 It can also be seen that a protective gas (preferably helium) can be supplied to the processing unit 103 through the gas supply unit 219, and in particular to the space provided within the processing unit 103, through which the generated fluid jet 104 passes after leaving the fluid nozzle 302. Here, the protective gas can protectively surround the fluid jet 104 before it leaves the processing unit 103 through the lower outlet hole and then travels further toward and onto the workpiece 101.

[0080] Figure 3 The device 300 shown also includes a focusing optics 300, which is preferably arranged in the optical path between the spectral separation unit 202 and the sensing unit 107, and is used to guide light onto the sensing unit 107. Specifically, the back-propagating electromagnetic radiation 106, which is laser-sensed by the lens 305 and passes through the fluid jet 104, preferably passes through the optical unit 201, then through the optical separation unit 202, and the remaining filtered electromagnetic radiation of interest 203 is focused onto the sensing unit 107 by the focusing optics 300, particularly onto the photosensitive area of ​​the sensing unit 107. The focusing optics 300 preferably includes at least one lens, but may also include another optical element, such as a parabolic mirror. The sensing unit 107 is configured to convert the received filtered radiation of interest 203 into a signal 108 for further analysis and / or processing by a signal processing unit 109 (not shown).

[0081] Figure 3It is also shown that the aforementioned components of the device 300 can be disposed within a housing, particularly within the optical head 303. That is, the device 300 may further include an optical head 303, which may include a processing unit 103 and a sensing unit 107. The optical head 303 may also include an optical unit 201, a spectral separation unit 202, and / or a focusing optics 300.

[0082] Figure 4 A method 400 according to an embodiment of the present invention is illustrated. The method 400 includes step 401: providing a pressurized fluid jet 104 to a workpiece 101 and coupling a laser beam 102 toward the workpiece 101 into the fluid jet 104 via at least one optical element 105. The method 400 further includes step 402: receiving laser-induced electromagnetic radiation 106 propagating away from the workpiece 101 through the fluid jet 104 and through at least one optical element (preferably at least one optical element 105 for coupling the laser beam 102 to the fluid jet 104). The method 400 further includes step 403: converting the received radiation into a signal 108. Finally, the method 400 includes step 404: determining the state of the workpiece being processed based on the signal 108.

[0083] The method 400 can be derived from... Figure 1 The device 100 shown Figure 2 The device 200 shown and Figure 3 Each of the devices 300 shown performs its own operation. Specifically, step 401 can be performed by the processing unit 103, steps 402 and 403 can be performed by the sensing unit 107, and step 404 can be performed by the signal processing unit 109.

[0084] The method 400 may specifically include automatic time recording of a plurality of signals 108, wherein each signal 108 may be caused by one of a plurality of laser pulses. That is, the laser beam 102 is a pulsed laser beam. Laser pulses may be provided periodically and may be on the order of nanoseconds (ns). Each signal 108 may be represented by a single value or by a series of values ​​over time. A plurality of acquired signals 108 may also be aggregated over time to produce an aggregated signal. The method 400 may further include automatically comparing the acquired signals 108 with a reference signal read from a reference memory, for example, from the memory of the signal processing unit 109. The method 400 may then include evaluating a pattern or pattern change in the acquired signals 108 or the aggregated signal, and may determine the state of the workpiece 101 based on the pattern or pattern change. Optionally, the method 400 may include automatically generating a command signal or command code, and subsequently transmitting the command signal or command code to one or more peripheral devices, thereby causing these peripheral devices to start, interrupt, stop, or restart their respective operations.

[0085] Figure 5 Two specific signal patterns 500a and 500b are schematically shown. These two signal patterns are preferably used in the method 400 (or by the signal processing unit 109 of the devices 100, 200, and 300) to determine the state of the workpiece 101.

[0086] Specifically, if the laser-induced electromagnetic radiation 106 is the secondary radiation 206a emitted from the portion of workpiece 101 processed by laser beam 102 as described above, or if the laser-induced electromagnetic radiation 106 includes the secondary radiation 206a emitted from the portion of workpiece 101 processed by laser beam 102 as described above, then the signal pattern 500a on the left is preferably used. Signal pattern 500a indicates that when signal 108 or the aggregated signal first increases towards the "In-Process" time period after "starting" the processing of workpiece 101, and then decreases again after the "In-Process" time period, the laser beam has penetrated workpiece 101. When signal 108 or the aggregated signal drops below a predetermined threshold, the process is considered "completed," and it can be determined that the laser beam has penetrated workpiece 101.

[0087] Similarly, if the laser-induced electromagnetic radiation 106 is the primary laser radiation 206b reflected by the workpiece 101, or if the laser-induced electromagnetic radiation 106 includes the primary laser radiation 206b reflected by the workpiece 101, then the signal pattern 500b on the right is preferably used. Signal pattern 500b indicates that when the signal 108 or the aggregated signal decreases first towards the "processing" time period after "starting" the processing of the workpiece 101, and then increases again from the "processing" time period, the laser beam has penetrated the workpiece 101. When the signal 108 or the aggregated signal rises above a predetermined threshold, "completion" is reached, meaning the laser beam has penetrated the workpiece 101.

[0088] Figure 6 A device 200 according to an embodiment of the present invention is shown, the device 200 being built on Figure 2 Based on the device 200 shown in the figure. Figure 2 and Figure 6 The same elements in the figure are labeled with the same reference numerals and have the same function.

[0089] Figure 6 Specifically, the device 200 may also include a housing, particularly an optical head 600, which may include a processing unit 103 and a sensing unit 107. The optical head 600 may further include an optical unit 201 and a spectral separation unit 202. See reference... Figure 2 As already described, the laser for the laser beam 102 may be provided by the laser unit 601 (including the laser source 201 and / or the laser controller 207) via, for example, optical fiber 204, and provided to the laser supply port of the device 200 (if the laser unit 601 is not part of the device 200) or to the optical head 600, for example, to the laser supply port of the optical head 600 (if the laser unit 601 is part of the device 200).

[0090] Figure 7 A device 700 according to an embodiment of the present invention is shown. The device 700 is built on Figure 1 Based on the device 100 shown and having the same Figure 2 and Figure 6 Common equipment 200. Figure 7 and Figure 1 , Figure 2 and / or Figure 6 The same elements in the figure are labeled with the same reference numerals and have the same function.

[0091] Figure 7 The device 700 has the same Figure 6The device 200 shown has different configurations. In particular, the device 700 includes an optical head 701, which includes a processing unit 103. However, the optical head 701 does not include a sensing unit 107. The sensing unit 107 is disposed in the laser unit 703 (including a laser source 221 and / or a laser controller 207). It is worth noting that the laser unit 703 can be formed by disposing of the laser controller 207 in the laser source 221, and vice versa. The laser unit 703 is part of the device 700. The processing unit 103 in the optical head 701 is configured to couple a laser beam 102 into a fluid jet 104. The sensing unit 107 in the laser unit 703 is configured to receive laser-induced electromagnetic radiation 106 (e.g., secondary radiation 206a emitted from a portion of the workpiece 101 processed by the laser beam 102, or primary laser radiation 206b reflected from the workpiece 101, or secondary radiation 206c generated by scattering of the laser beam 102 in the fluid jet 104).

[0092] The device 700 also includes an optical connection element 702, particularly an optical fiber 702, which optically connects the optical head 701 and the laser unit 703. The laser unit 703 is configured to provide laser light for the laser beam 102, which is transmitted via the optical connection element 702 to the optical head 701, for example, to a supply port of the optical head 701, where the laser beam 102 is further provided to a processing unit 103, which couples the laser beam 102 into a fluid jet 104. Laser-induced electromagnetic radiation 106 is received by the processing unit 103 via the fluid jet 104 and further provided to the laser unit 703 via the optical head 701 and the optical connection element 702, for example, to a supply port of the laser unit 703, where it is further provided to a sensing unit 107, which converts the laser-induced electromagnetic radiation 106 into a signal 108.

[0093] The laser unit 703 may also include an optical unit 201, which is preferably a beam splitter and preferably arranged in the optical path between the laser source 222 and the optical connection element 702, so as to provide the laser beam 102 from the laser source 221 to the optical connection element 702. Furthermore, the back-propagating laser-induced electromagnetic radiation 106 can pass through the optical unit 201 but is subsequently directed toward the sensing unit 107. The laser unit 703 may also include a spectral separation unit 202, which is configured to separate only the electromagnetic radiation 203 of interest, including the laser-induced electromagnetic radiation 106, onto the sensing unit 107. The spectral separation unit 202 is preferably arranged in the optical path between the optical unit 201 and the sensing unit 107, such that the spectral separation unit 202 receives the laser-induced electromagnetic radiation 106 from the optical unit 201 and provides the electromagnetic radiation 203 of interest onto the sensing unit 107.

[0094] In summary, the present invention provides devices 100, 200, 300, and 700, as well as a method 400, which enable the processing of workpiece 101 using a laser beam 102 coupled to a fluid jet 104, wherein the processing time can be significantly reduced due to the accurate determination of the processing state.

[0095] The invention has been described in conjunction with various embodiments and implementations as examples. However, those skilled in the art can understand and implement other variations and practice the claimed invention by studying the drawings, specification, and independent claims. In the claims and specification, the use of the word "comprising" does not exclude other elements or steps, and the indefinite article "a" ("a" or "an") does not exclude multiple. A single element or other unit can perform the function of multiple entities or items recited in the claims. The mere fact that specific measures are recited in mutually different dependent claims does not imply that combinations of these measures cannot be used in advantageous embodiments.

Claims

1. An apparatus (100, 200, 300, 700) for processing a workpiece (101) using a laser beam (102), said apparatus (100, 200, 300, 700) comprising: A processing unit (103) is configured to provide a pressurized fluid jet (104) to the workpiece (101) and couple the laser beam (102) toward the workpiece (101) into the fluid jet (104) via at least one optical element (105); A sensing unit (107) is arranged to receive electromagnetic radiation (106) that propagates away from the workpiece (101) through the fluid jet (104) and through the laser-sensed laser of the at least one optical element, and is configured to convert the received electromagnetic radiation (106) into a signal (108). A signal processing unit (109) is configured to determine the state of processing the workpiece (101) based on the signal (108).

2. The device (100, 200, 300, 700) according to claim 1, wherein, The signal processing unit (109) is configured to determine, in relation to the state of processing the workpiece (101), whether the laser beam (102) has penetrated the workpiece (101).

3. The device (100, 200, 300, 700) according to claim 1 or 2, wherein, The sensing unit (107) is arranged to receive electromagnetic radiation (106) induced by the laser propagating through the fluid jet (104) and through the at least one optical element (105), the at least one optical element (105) being configured to couple the laser beam (102) into the fluid jet (104).

4. The device (700) according to any one of claims 1 to 3, comprising: An optical head (701) includes the processing unit (103). as well as The laser unit (703) includes the sensing unit (107).

5. The device (700) according to claim 4, further comprising: An optical connector (702), specifically an optical fiber, is used to optically connect the optical head (701) and the laser unit (703), wherein... The processing unit (103) in the optical head (701) is configured to receive the laser beam (102) via the optical connection element (702); and The sensing unit (107) in the laser unit (703) is configured to receive the electromagnetic radiation (106) sensed by the laser through the optical connection element (702).

6. The device (300) according to any one of claims 1 to 5, wherein, The at least one optical element (105) includes a lens (305) for coupling the laser beam (102) into the fluid jet (104); and The sensing unit (107) is arranged to receive the electromagnetic radiation (106) sensed by the laser propagating in the reverse direction through the lens (305).

7. The device (200, 300, 700) according to any one of claims 1 to 6, comprising: A spectral separation unit (202), preferably an optical filter unit, is configured to separate only the electromagnetic radiation of interest (203) including at least a portion of the electromagnetic radiation (106) sensed by the laser onto the sensing unit (107) and / or is configured to prevent the initial laser (102) from reaching the sensing unit (107).

8. The device (100, 200, 300, 700) according to any one of claims 1 to 7, wherein, The laser-induced electromagnetic radiation (106) includes secondary radiation (206a) emitted from the portion of the workpiece (101) processed by the laser beam (102).

9. The device (100, 200, 300, 700) according to any one of claims 1 to 7, wherein, The laser-induced electromagnetic radiation (106) includes primary laser radiation (206b) reflected from the workpiece (101).

10. The device (100, 200, 300, 700) according to any one of claims 1 to 7, wherein, The laser-induced electromagnetic radiation (106) includes secondary radiation (206c) generated by the scattering of the laser beam (102) in the fluid jet (104), preferably by Raman scattering.

11. The device (100, 200, 300, 700) according to any one of claims 1 to 10, wherein, The signal processing unit (109) is configured to process the signal (108) with a time resolution of less than 0.5s, preferably less than 0.1s.

12. The device (100, 200, 300, 700) according to any one of claims 1 to 11, wherein, The laser beam (102) is a pulsed laser beam; The sensing unit (107) is configured to convert the received radiation into a signal (108) for each laser pulse; and The signal processing unit (109) is configured to aggregate multiple signals (108) over time to generate an aggregated signal, and to determine the state of processing the workpiece (101) based on the changes in the pattern (500a, 500b) or pattern (500a, 500b) in the aggregated signal.

13. The device (200, 300, 700) according to any one of claims 1 to 12, further comprising: At least one peripheral device (207, 205, 223, 208), wherein the at least one peripheral device (207, 205, 223, 208) is preferably a laser controller (207), a fluid supply controller (205), a gas supply controller (223), and / or a moving axis controller (208). The signal processing unit (109) is configured to provide instruction signals (217, 214, 216, 213) to the at least one peripheral device (207, 205, 223, 208) based on the determined state of processing the workpiece (101) in order to start, interrupt, stop and / or restart the operation of the peripheral device (207, 205, 223, 208).

14. A method (400) for processing a workpiece (101) using a laser beam (102), the method comprising: A pressurized fluid jet (104) is provided (401) to the workpiece (101), and the laser beam (102) is coupled into the fluid jet (104) toward the workpiece (101) through at least one optical element (105); Receive (402) electromagnetic radiation (106) propagating away from the workpiece (101) through the fluid jet (104) and through laser-induced radiation by at least one optical element, and convert the received electromagnetic radiation (106) into a signal (108); and The state of processing the workpiece (101) is determined (404) based on the signal (108).

15. The method (400) according to claim 14, further comprising: In order to determine the state of processing the workpiece (101) (404), Record multiple signals (108); The recorded signal (108) is compared with a predetermined reference signal; and The state of machining the workpiece (101) is determined based on similar or matching reference signals.

16. The method (400) according to claim 14 or 15, further comprising: In order to determine the state of processing the workpiece (101) (404), Multiple signals (108) are aggregated over time to generate an aggregated signal; Evaluate the changes in the pattern (500a, 500b) or pattern (500a, 500b) in the aggregated signal; as well as The state of processing the workpiece (101) is determined based on the pattern (500a, 500b) or the change in the pattern (500a, 500b).

17. The method (400) according to claim 16, wherein, The laser-induced electromagnetic radiation (106) includes secondary radiation (206a) emitted from a portion of the workpiece (101) processed by the laser beam (102), and the method (400) includes: When processing the workpiece (101), if the value of a single signal (108) or the aggregated signal increases after processing the workpiece (101) is started and then decreases again to below a predetermined threshold, it is determined that the laser beam (102) has penetrated the workpiece (101).

18. The method (400) according to claim 17, wherein, The laser-induced electromagnetic radiation (106) includes primary laser radiation (206b) reflected from the workpiece (101), and the method (400) includes: When processing the workpiece (101), if the value of a single signal (108) or the aggregated signal decreases after processing the workpiece (101) is started, and then increases again to above a predetermined threshold, it is determined that the laser beam (102) has penetrated the workpiece (101).

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