Vibration detection in machining workpieces using a liquid jet-guided laser beam

Abstract

The present invention relates to an apparatus for machining a workpiece with a laser beam guided by a liquid jet. The apparatus comprises a nozzle that generates a liquid jet, at least one lens that couples a laser beam to the liquid jet, and a housing having an opening that surrounds at least the nozzle and provides the liquid jet onto the workpiece. A vibration sensor of the apparatus is mounted on the housing and configured to measure at least a first vibration of the housing and / or a second vibration of the housing, the first vibration being caused by machining the workpiece and the second vibration being caused by the liquid jet. Furthermore, a processor of the apparatus is configured to determine a first set of parameters related to machining the workpiece and / or a second set of parameters related to the liquid jet based on the first and / or second vibrations.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for machining a workpiece using a laser beam guided, i.e., induced, within a liquid jet and by the liquid jet. The present disclosure provides an apparatus and method having the ability to detect vibrations of the housing of the apparatus in order to derive parameters related to the apparatus in general, the liquid jet, and / or the machining process of the workpiece.

Background Art

[0002] Liquid jet-guided laser machining apparatuses are widely used in various industries for material removal applications such as cutting, ablation, drilling, or marking. They provide high precision and speed and are a common choice for many machining and manufacturing processes. The accuracy and quality of the workpiece machined with a liquid jet-guided laser beam depend on the proper functioning of the apparatus.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Malfunctions or deviations from the expected performance of the apparatus can result in lower quality or damaged workpieces, or may even cause damage to the apparatus itself.

[0004] Therefore, it is beneficial to analyze the apparatus parameters or the machining state of the workpiece in order to timely detect such malfunctions or deviations.

Means for Solving the Problems

[0005] The present disclosure and its solution are further based on the following considerations.

[0006] In the first method, an exemplary apparatus for liquid jet-guided laser machining includes an acoustic sensor used to detect ambient noise while the apparatus is in use. Based on the output signal of the acoustic sensor, the apparatus can analyze, for example, the machining status of the workpiece, the machining depth, or whether the liquid jet is in contact with the object to detect abnormalities in a timely manner.

[0007] For example, an acoustic sensor can be specifically designed to detect the frequency of sound associated with material removal, and the detected sound can indicate that the device is functioning correctly. However, if no sound is detected in the expected frequency range, the device will stop processing and warn the operator to investigate any problems. The exemplary device can also determine and optimize the processing parameters of the device based on the detected sound, thereby increasing the efficiency and precision of the device.

[0008] However, it became clear that this method is susceptible to ambient noise interference, making it difficult to distinguish between sounds generated by machining using a liquid jet-guided laser beam and other ambient noise. Ambient noise detection can also be affected by factors such as distance, sound attenuation within the workpiece itself, atmospheric conditions, liquid splashing, and signal reflection, which can lead to a degradation of signal quality. Furthermore, ambient noise detection is not suitable for all forms of workpieces or laser processing applications.

[0009] In view of the above, an object of the present invention is to provide an improved apparatus for machining a workpiece with a liquid jet-guided laser beam that does not have the aforementioned drawbacks. For example, an object is to accurately and reliably determine one or more machining parameters of the apparatus, in particular parameters related to the machining process of the workpiece and / or the liquid jet. Based on this, an object is to improve the machining efficiency and reliability of the apparatus. Another object is to enable various machining support applications such as penetration detection, backstrike protection, liquid jet quality monitoring, depth detection during machining of the workpiece, monitoring of machining efficiency, and / or optimization of the machining parameters of the apparatus.

[0010] These and other objectives are achieved by the solutions described in the independent claims. Advantageous embodiments are described in the dependent claims.

[0011] A first aspect of the present disclosure provides an apparatus for machining a workpiece with a laser beam guided by a liquid jet, the apparatus comprising: a nozzle configured to generate a liquid jet; at least one lens configured to couple a laser beam to the liquid jet; a housing enclosing at least the nozzle and having an opening for providing the liquid jet onto a workpiece; a vibration sensor mounted on the housing; and a processor, the vibration sensor configured to measure at least a first vibration of the housing and / or a second vibration of the housing, the first vibration being caused by machining the workpiece with the laser beam and the second vibration being caused by the liquid jet; and the processor configured to determine, based on the measurement of the first vibration and / or the second vibration, a first set of parameters related to machining the workpiece and / or a second set of parameters related to the liquid jet.

[0012] The laser beam has, for example, a laser output in the range of 1 to 2000 W. The nozzle opening defines the diameter of the liquid jet and may have a diameter of, for example, 10 to 200 μm. The liquid jet may have a diameter of, for example, about 0.6 to 1 times the diameter of the opening. The liquid jet may be a water jet, i.e., the liquid used by the device may be water or a mixture of water and a chemical. The pressure of the liquid jet is 50 to 800 bar (50 to 800 × 10⁻⁶). 5 The range may be Pa). The liquid jet may be laminar. The housing may be a coupling unit in which the nozzle is located and the laser beam is optically coupled to the liquid jet, or may include such a unit. For this reason, the lens does not need to be located within the coupling unit.

[0013] The liquid jet is configured to guide the laser beam. This means that the laser light of the laser beam is completely guided within the liquid jet by total internal reflection. As a result, the laser light is constantly reflected within the liquid by the walls of the liquid jet (i.e., the interface between the liquid and the surrounding atmosphere). Such a laser beam guided by a liquid jet uses both the laser beam and the liquid jet, but differs from a laser beam in a system where the liquid jet does not guide the laser light by total internal reflection. In such a system, the laser beam is focused directly onto the workpiece as it passes through the liquid. In such a system, the liquid does not guide the laser light to the workpiece, but it rarely happens that the laser light of the laser beam propagates through a relatively large liquid jet.

[0014] Since the vibration sensor is mounted on the housing, it can accurately and reliably measure the vibration of the housing. The measured values ​​are not affected by environmental noise and are not constrained by distance, atmospheric conditions, or signal reflection. The vibration measured by the vibration sensor is caused by the sound generated by machining the workpiece using a liquid jet-guided laser beam and / or by the liquid jet itself. This sound is transmitted to the housing via the liquid jet. For example, if an acoustic sensor is used for detecting ambient noise and is placed near the apparatus, at least some portion of the sound is difficult to measure through the air. In contrast to detecting ambient noise, the vibration sensor of the apparatus in the first embodiment is configured to perform directional acoustics of the machining of the workpiece and / or the liquid jet sound.

[0015] The device's processor is configured to determine a different set of parameters related to the machining of a workpiece and / or the fluid jet based on one or more detected vibrations. Each parameter set may include one or more parameters. These parameters may be used by the processor to monitor the performance of the device, particularly the machining process and / or the fluid jet. The processor may also adapt the processing parameters and / or fluid jet parameters accordingly to improve the efficiency of the device. The determined parameters may also enable the processor to perform various processing support applications, such as detecting penetration of a laser beam through a workpiece, stopping machining in case of penetration to reduce machining time or to protect items or components located behind the workpiece, monitoring fluid jet quality indicating the machining quality of the workpiece (e.g., laminar flow or laminar flow length of fluid jets, sprays, photoacoustic effects, etc.), determining the material removal depth in the workpiece, determining the material removal rate of the material in the workpiece, or aligning the fluid jet with an object, or performing similar applications.

[0016] In particular, the housing on which the vibration sensor is installed is a housing that directly surrounds the nozzle (e.g., a coupling unit), and this does not necessarily have to be the mechanical housing of the liquid jet-guided laser machine on which the device is installed.

[0017] In short, the present disclosure provides an improved apparatus through a vibration sensor mounted on the housing of the apparatus, and through a specific configuration of the vibration sensor and processor.

[0018] In one embodiment of the apparatus, a vibration sensor is further configured to measure a third vibration and / or a fourth vibration, the third vibration being caused by photoacoustics induced by a laser beam inside the housing, and the fourth vibration being caused by the movement and / or rotation of the housing, and a processor is configured to determine a set of third parameters related to the apparatus based on the measurement of the third vibration and / or the fourth vibration.

[0019] Photoacoustics may involve the interaction of the laser beam with components or liquids located within the housing, or with the housing itself, which can cause a third vibration. The movement and / or rotation of the housing may be controlled by the device's processor and / or computer numerical control (CNC) device when machining a workpiece. A third parameter set may provide the processor with additional information, which it can use to improve the efficiency of the device and / or perform machining assistance applications.

[0020] In one embodiment of the apparatus, a first vibration is based on a first sound generated in the workpiece by machining the workpiece with a laser beam and transmitted to the housing via a liquid jet and the liquid in the housing, and / or a second vibration is based on a second sound (33) generated by the liquid jet and transmitted to the housing via a liquid jet and the liquid in the housing.

[0021] Therefore, the vibration sensor can detect sound transmitted by a liquid jet (propagating within the liquid jet), for example, by the liquid chamber of the housing, causing the housing to vibrate. This enables very accurate detection of sound generated by the machining of the workpiece and / or the liquid jet, and is therefore useful for deriving the parameter set.

[0022] The first sound, which causes the first vibration, is generated by the laser cutting process of the workpiece material and is transmitted through the liquid jet and then through the housing as the first vibration to the vibration sensor. The second sound (33), which causes the second vibration, is generated by the liquid jet contacting (colliding with) the workpiece and is also transmitted through the liquid jet and then through the housing as the second vibration to the vibration sensor. Both the first and second vibrations are useful vibrations that the vibration sensor may measure and be configured to distinguish from other vibrations and any other vibrations. For example, the first vibration may be used to determine information related to laser cutting (as an example of parameters related to machining the workpiece), and the second vibration may be used to determine information related to the liquid jet in contact with the workpiece (as an example of parameters related to the liquid jet). Surprisingly, it was found that the laser cutting of the workpiece material and the liquid jet in contact with the workpiece generate sounds of different frequencies.

[0023] According to the solution of the present invention, both the laser light from the laser beam and the sound, which is ultimately measured as vibration by a vibration sensor, are completely guided from the workpiece to the housing by a liquid jet.

[0024] In one embodiment of the apparatus, the first sound traveling through the liquid jet has a higher velocity than the first sound has in a gaseous atmosphere. Similarly, the second sound traveling through the liquid jet has a higher velocity than the second sound has in a gaseous atmosphere, such as air.

[0025] Sound moving through a liquid has a higher speed than the same sound has in, for example, air. Thus, the vibration sensor can be configured to measure within a shorter time frame than is required to measure sound through air, e.g., a shorter time frame than that used by an ambient sound sensor. The speed difference is due to the different media through which the sound propagates, e.g., water and air. The speed of sound is generally higher in a liquid such as water than in a gas such as air. This increase in speed is due to the higher density nature of the liquid where the molecules are closer to each other, facilitating a more rapid transmission of sound waves.

[0026] In one embodiment, the apparatus further comprises a frequency filter arranged and configured to separate a first sound and / or a second sound traveling within the liquid jet from other sounds.

[0027] Both the first vibration and the second vibration are useful vibrations and can be separated by using a frequency filter to filter other acoustic signals. Thus, more accurate detection of the first vibration and / or the second vibration can be achieved, especially with less noise interference. Filtering by the frequency filter may enable the vibration sensor to better distinguish the above-mentioned information related to the contact of the liquid jet with the workpiece and the information related to the laser ablation of the workpiece.

[0028] Furthermore, the frequency filter can also filter out (remove) all vibrations based on sounds that did not propagate through the liquid jet. For example, the frequency filter may be configured to remove vibration noise collected from the ambient atmosphere. In this way, only the vibrations resulting from the sound arriving through the liquid jet can be measured by the vibration sensor to accurately collect the desired information. In short, the frequency filter can have two functions: (1) the function of distinguishing the first vibration and the second vibration, and (2) the function of removing vibrations coming from other sound sources or transmission methods.

[0029] In one embodiment of the apparatus, the laser beam is pulsed, and the vibration sensor is configured to measure the occurrence of a first vibration within a time frame shorter than the time delay between two consecutive laser pulses of the pulsed laser beam.

[0030] Therefore, vibrations can be caused by individual laser pulses or by a certain number of laser pulses. The correlation between vibrations and laser pulses allows for the determination of certain parameters, such as the length of the liquid jet and therefore the processing depth.

[0031] In one embodiment of the apparatus, the laser beam is pulsed, and the processor is configured to determine a time difference between a first time when a specific laser pulse of the laser beam is generated and a second time when the correlation of a first vibration occurs and is measured by a vibration sensor.

[0032] In one embodiment of the apparatus, the processor is configured to calculate, based on a time difference, the distance between the nozzle and the point of incidence of the laser beam on the workpiece, and / or the distance between the aperture and the point of incidence.

[0033] Therefore, the processor can calculate the laser pulse duration and the arrival time of the sound generated by that laser pulse that causes vibration, and then use the flight time (time difference) to determine the distance to the point of contact of the liquid jet.

[0034] In one embodiment of the device, the vibration sensor is either mounted on the outer surface of the housing and in direct contact with it, or mounted on an adapter attached to the outer surface of the housing.

[0035] Therefore, the vibration sensor can accurately measure the vibration of the housing and / or can be easily removed and reinstalled.

[0036] In one embodiment of the device, the housing comprises a first part and a second part, the first part being detachably attached to the second part, the second part of the housing comprising at least one lens, the first part of the housing comprising a nozzle and a liquid chamber located above the nozzle, and a vibration sensor being positioned in the first part of the housing above the liquid chamber above the nozzle.

[0037] The first part may be the coupling unit of the apparatus, in which the laser beam and the liquid jet are coupled, that is, the laser beam is inserted into the liquid jet, and as a result the laser beam is guided in the liquid jet by total internal reflection. The vibration sensor may be a contact sensor that contacts the outer or inner wall of the coupling or the liquid chamber (e.g., water chamber) within the coupling. Since the vibration sensor is very close to the liquid, and the sound that causes the housing vibration is transmitted mainly through the liquid (jet), accurate and virtually noiseless detection is achieved.

[0038] In one embodiment of the apparatus, at least one of the first set of parameters indicates one or more of the following: the material type of the workpiece; the material removal rate or material removal rate of the workpiece material removed by machining the workpiece with a laser beam; and whether the laser beam has penetrated the workpiece.

[0039] In one embodiment of the apparatus, the processor is configured to determine whether or not the liquid jet has come into contact with the workpiece based on whether or not a first vibration has been measured by a vibration sensor.

[0040] In one embodiment of the apparatus, at least one of the second set of parameters indicates one or more of the following: the jet quality and / or laminar flow length of the liquid jet, the flow characteristics of the liquid jet, whether the laser beam strikes the nozzle, and whether the liquid jet contacts the edge of an impactor positioned near the workpiece or the workpiece itself.

[0041] The concept of detecting (also known as auditory detection) whether a liquid jet is in contact with the workpiece, whether the liquid jet is free, or whether the liquid jet has penetrated the workpiece is extremely useful for controlling the workpiece machining process and achieving precise machining results. Using the impacting object, the processor may be configured to detect the liquid jet position and / or liquid jet angle.

[0042] In one embodiment, the apparatus further comprises an acoustic transducer positioned and configured to deliver sound waves onto a workpiece through a liquid jet, and a vibration sensor further configured to measure a third vibration resulting from the sound waves reflecting back from the workpiece through the liquid jet to the housing.

[0043] Therefore, the device can also actively transmit sound waves, detect their reflections, measure the flight time of the sound waves, and determine the corresponding distance.

[0044] In one embodiment, the apparatus further comprises one or more optical sensors configured to detect a first synchrotron radiation or a second synchrotron radiation, wherein the first synchrotron radiation is caused by machining a workpiece with a laser beam, and the second synchrotron radiation is caused by a laser beam induced in a liquid jet or by machining a workpiece with a laser beam, wherein the first synchrotron radiation includes at least one of the laser light of the laser beam reflected from the workpiece and secondary synchrotron radiation emitted by a portion of the workpiece machined with the laser beam, and the processor is further configured to determine a first set of parameters and / or a second set of parameters based on measuring the first synchrotron radiation and / or the second synchrotron radiation.

[0045] Additional radiated signals may allow the processor to determine parameters for various parameter sets with even greater accuracy and reliability.

[0046] In one embodiment of the apparatus, the second synchrotron radiation includes at least one of the following: secondary radiation generated by scattering of a laser beam in a liquid jet, such as Raman scattering; laser light from the laser beam scattered in the liquid jet; fluorescence of the liquid in the liquid jet induced by the laser beam; and secondary processing light of a wavelength other than laser light, such as thermal radiation or infrared radiation.

[0047] In one embodiment of the device, the processor is further configured to fuse the output signals of a vibration sensor and one or more optical sensors, the output signals being generated based on measured first and / or second vibrations and measured first and / or second radiant light, and to determine a first set and / or second set based on the fused output signals.

[0048] In one embodiment of the device, the processor includes a trained model or a rule-based algorithm and is configured to input output signals to the trained model or rule-based algorithm, the trained model is configured to fuse the output signals and determine a first set and / or a second set based on the fused output signals.

[0049] The rule-based algorithm may be installed on the processor or executed by the processor. The trained model may be a trained neural network, such as a convolutional neural network (CNN). The neural network may be a deep neural network (DNN). The use of the trained model can improve the accuracy of detected parameters and automatically optimize various machining parameters of the apparatus to achieve improved machining results.

[0050] In one embodiment of the apparatus, the processor is further configured to adapt at least one processing parameter of the laser beam and / or liquid jet based on a determined first set of parameters and / or a second set of parameters.

[0051] A second aspect of the present disclosure provides a method for machining a workpiece with a laser beam guided by a liquid jet, the method comprising: generating a liquid jet in a nozzle; coupling a laser beam to the liquid jet with at least one lens; measuring at least a first vibration and / or a second vibration of a housing surrounding the nozzle, wherein the first vibration is caused by machining the workpiece with the laser beam and the second vibration is caused by the liquid jet; and determining a first set of parameters related to machining the workpiece and / or a second set of parameters related to the liquid jet based on measuring the first and / or second vibrations.

[0052] In one embodiment, the method further includes modifying at least one processing parameter of the laser beam and / or liquid jet based on a determined first set of parameters and / or a second set of parameters.

[0053] The method of the second embodiment achieves the same advantages as the apparatus of the first embodiment and can be extended by respective embodiments corresponding to the embodiments described above for the apparatus of the first embodiment.

[0054] A third aspect of this disclosure provides a computer program that includes instructions for controlling a device according to the first aspect when the instructions are executed by a processor, or for causing a device to perform a method according to the second aspect when the instructions are executed by a computer.

[0055] The above-described aspects and embodiments will be explained in the following description of embodiments with reference to the attached drawings. [Brief explanation of the drawing]

[0056] [Figure 1] An exemplary apparatus as described herein is shown. [Figure 2] An example of the apparatus according to the present invention having a housing consisting of two parts is shown. [Figure 3]The operating principle of the apparatus according to the present invention is shown below. [Figure 4] An exemplary apparatus according to the present disclosure is shown, having additional components for vibration detection and optical detection. [Figure 5] An exemplary processor of the apparatus according to this disclosure, capable of signal fusion, is shown. [Figure 6] An exemplary apparatus according to the present invention, having an acoustic transducer, is shown. [Figure 7] The method according to the present invention is shown. [Figure 8] This shows the device according to the present invention inside a liquid jet-guided laser machine. [Figure 9] This disclosure provides an exemplary algorithm for signal fusion using a rule-based algorithm, which may be executed by the processor of the device according to this disclosure. [Modes for carrying out the invention]

[0057] Figure 1 shows a basic embodiment of the apparatus 10 according to the present disclosure. The apparatus 10 is configured to machine a workpiece 11 with a laser beam 12, the laser beam 12 being guided into and by a liquid jet 13, for example, in and by a water jet. The workpiece 11 may be made from one or more materials, including, for example, metals, ceramics, diamonds, semiconductors, carbides, alloys, superalloys, or superhard materials. The workpiece 11 is not part of the apparatus 10, but the workpiece 11 may be placed on a machining surface which may or may not be part of the apparatus 10. In either case, the apparatus 10 can be configured to machine a workpiece 11 placed on a machining surface. The apparatus 10 may also control the movement of the machining surface up to three dimensions, or it may control the movement of the liquid jet-guided laser beam relative to the workpiece 11 by moving and / or rotating a nozzle or housing which generates the liquid jet 13, for example.

[0058] The apparatus 10 comprises a nozzle 14, at least one lens 15, and a housing 16. The housing 16 encloses at least the nozzle 14 and optionally also encloses at least one lens 15. The housing 16 has an opening 19 for discharging a liquid jet 13 and providing it onto a workpiece 11. The nozzle 14 can be supplied with liquid to form the liquid jet 13 through a liquid supply unit which includes a channel through the housing 16. A gas supply source may also be provided which may include another channel through the housing 16, and this gas supply source can supply a protective gas, such as helium, into the housing 16, particularly to the area through which the fluid jet 13, generated after exiting the nozzle 14, passes. Here, the protective gas can encapsulate the fluid jet 13 to protect it before it is discharged from the housing 16.

[0059] At least one lens 15 is configured to couple the laser beam 12 to the liquid jet 13, for example, to focus the laser beam 12 to a nozzle 14. The at least one lens 15 may be a single lens or a group of lenses. The at least one lens 15 may be located inside or outside the housing 16. Preferably, the at least one lens 15 is separated from the liquid inside the housing 16, which can be achieved by an optical window that prevents contact between the lens 15 and the liquid, and / or by a multi-chamber housing.

[0060] The device 10 further includes a vibration sensor 17 and a processor 18. The vibration sensor 17 is mounted to the housing 16 from the outside or the inside, for example, as shown in the figure. The vibration sensor 17 may be directly mounted to the housing, or it may be mounted indirectly, for example, using an adapter. The processor 18 may be located outside the housing 16.

[0061] The vibration sensor 17 measures vibrations of the housing 16. The vibration sensor 17 is configured in particular to measure at least a first vibration and / or a second vibration of the housing 16. The first vibration is caused by the processing of the workpiece 11 by the laser beam 12, and the second vibration is caused by the liquid jet 13. The vibration sensor 17 may be configured to measure further vibrations, for example, a third vibration and / or a fourth vibration of the housing 16. For example, the third vibration may be caused by photoacoustics induced by the laser beam 12 inside the housing 16. For example, the fourth vibration may be caused by the movement and / or rotation of the housing 16. Each vibration is associated with a specific frequency in a frequency band, and the frequency or frequency band is different for different vibrations. The vibration sensor 17 may be adapted in particular to detect vibrations of these frequencies or these frequency bands. The vibration sensor 17 may output a signal 17s that can reflect or indicate the detected vibrations.

[0062] The processor 18 is configured to determine a first set of parameters p1 related to the machining of the workpiece 11 and / or a second set of parameters p2 related to the liquid jet 13, based on the measurement of a first vibration and / or a second vibration. The processor 18 may also receive an output signal 17s from the vibration sensor 17, which may indicate the result of vibration measurement by the vibration sensor 17. The signal 17s may indicate that a first vibration was measured, or that a first vibration was measured or not. The processor 18 may be configured to determine a first set of parameters p1 based on the occurrence of a first vibration and / or the absence of a first vibration. Furthermore, the processor 18 may be configured to determine a second set of parameters p2 based on the occurrence of a second vibration and / or the absence of a second vibration. The processor 18 may be further configured to determine an additional set of parameters, for example, a third set of parameters related to the apparatus 10, based on the occurrence of a third vibration and / or a fourth vibration, or the absence of either or both of these vibrations.

[0063] By detecting each vibration, the device 10 can determine specific machining conditions for machining the workpiece 11, and these can be used for different optimizations of machining support applications (e.g., efficiency optimization, penetration detection, or other applications as described above). The device 10 can perform depth detection, i.e., it can determine the coordinates of the contact point between the liquid jet 13 and the workpiece 11, which may be within a hole or crevice in the workpiece 11. For example, the device 10 can determine the time of vibration occurrence for this purpose. For example, if the laser beam 12 is pulsed, the processor 18 can determine the time difference between a first time when a specific laser pulse of the laser beam 12 is generated and a second time when the correlation of vibration occurrence is measured by the vibration sensor 17. However, the device 10 can also detect vibration over time and correlate it with pulse parameters such as pulse width, pulse duration, pulse power, etc., over this time.

[0064] In particular, vibrations of the housing 16 can be caused, for example, by various types of sounds generated in the workpiece 11 when the workpiece 11 is machined using a laser beam 12, or by the liquid jet 13 itself. These sounds can be transmitted to the housing 16 via the liquid jet 13 or via the liquid located inside the housing 16 to cause the housing 16 to vibrate. Some sound components of these sounds may be transmitted to the vibration sensor 17 via an air path, for example, if the vibration sensor 17 is mounted on the outside of the housing. However, the liquid path that carries sound to the housing 16 is usually of better quality.

[0065] The processor 18 may include processing circuits (not shown) configured to perform, carry out, or initiate various operations of the processor 18 as described herein. The processing circuits may include hardware and / or the circuits may be controlled by software. The hardware may include analog circuits, digital circuits, or both analog and digital circuits. The digital circuits may include components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multipurpose processors. The processor 18 may further include memory circuits that store one or more instructions that can be executed by the processing circuits, particularly under software control. For example, the memory circuits may include non-temporary storage media that, when executed by the processing circuits, store executable software code that causes the processor 18 to perform various operations.

[0066] Figure 2 shows an embodiment of the apparatus 10 according to this disclosure, based on the apparatus 10 shown in Figure 1. The same elements in Figures 1 and 2 are labeled with the same reference numerals and function similarly, so there is no need for redundant explanation.

[0067] As shown in Figure 2, the housing 16 of the device 10 comprises a first portion 16a and a second portion 16b. The first portion 16a is detachably attached to the second portion 16b, for example, by mechanical or magnetic connection. The second portion 16b of the housing 16 comprises at least one lens 15, and the first portion 16a of the housing 16 comprises a nozzle 14 and a liquid chamber 21 formed above the nozzle 14. The first portion 16a may be the coupling unit of the device 10, where the laser beam 12 is coupled to the liquid jet 13. When the first portion 16a and the second portion 16b are attached to each other, they may be separated from each other by their housing walls 22, each including an optical window, or the walls 22 may be transparent. The liquid chamber 21 may be defined within the first portion 16a by an inner wall 23, the inner wall 23 may include a window 25 for coupling the laser beam 12 into the liquid chamber 21 and the nozzle 14. In particular, the housing 16 may have more than two parts 16a, 16b.

[0068] In the embodiment of the apparatus 10 shown in Figure 2, the vibration sensor 17 is exemplary positioned on the outer surface of the housing 16, specifically outside the first portion 16a of the housing 16. However, the vibration sensor 17 may also be positioned on the outer wall of the liquid chamber 21 above the nozzle 14, i.e., inside the first portion 16a of the housing 16. The vibration sensor 17 may also be positioned on the inner surface of the housing 16, specifically inside the first portion 16a of the housing 16. The vibration sensor 17 may also be an acoustic microphone. The sound causing the vibration of the housing 16 that the vibration sensor 17 measures can arrive at the housing 16 and the sensor 17 from its original sound source via the liquid jet 13 and the liquid chamber 21.

[0069] Figure 3 shows the operating principle of the apparatus 10 of this disclosure, as well as exemplary sounds and vibrations that can be generated and detected by the vibration sensor 17 of the apparatus 10.

[0070] For example, the first sound 32 may be generated in the workpiece 11 by machining the workpiece 11 with the laser beam 12. The first sound 32 may also be generated by the laser beam 12 when the laser beam 12 cuts or drills through the workpiece 11, thereby generating plasma 34 in a depression 35 formed in the workpiece 11. The first sound 21 may be an acoustic (shock) wave generated by the laser pulse of the laser beam 12 on the workpiece 11. The acoustic wave can travel at least partially through the liquid jet 13 and the liquid in the housing 16 and be transmitted to the housing 16, and the vibration sensor 17 is configured to measure it as a first vibration of the housing 16. In another example, the second sound 33 may be generated by the liquid jet 13 itself, and the second sound may similarly be transmitted to the housing 16 at least partially through the liquid jet 13 and the liquid in the housing 16, and the vibration sensor 17 is configured to measure it as a second vibration of the housing 16.

[0071] The processor 18 can, for example, determine the time of flight, and in particular, determine the time difference between the laser pulse of the laser beam 12 and the arrival of the correlated sound (i.e., the occurrence of vibration) measured by the vibration sensor 17. In other words, the processor 18 may be configured to determine the time difference between a first time when a particular laser pulse of the laser beam 12 is generated and a second time when the occurrence of the correlated vibration of each vibration is measured by the vibration sensor 17. In this way, for example, the depth of a depression 35 in the workpiece 11 can be estimated.

[0072] Figure 3 also shows a moving axis controller 31 (e.g., a CNC device) that can move the machined surface holding the workpiece 11 or workpiece 31, for example, under the control of the processor 18.

[0073] Figure 4 shows an embodiment of apparatus 10 based on the embodiment of apparatus 10 shown in Figure 1. The same elements in Figures 1 and 4 are labeled with the same reference numerals and function similarly, so there is no need for redundant explanation.

[0074] Figure 4 shows that the apparatus 10 may further include a frequency filter 41 configured to isolate a first sound 32 and / or a second sound 33 moving within the liquid jet 13 (for example, as shown in Figure 3) from other sounds, or to isolate a first vibration and / or a second vibration from other vibrations of the housing 16. The frequency filter 41 can remove specific sound or vibration frequencies and allow specific other sound or vibration frequencies of interest to pass through. The frequency filter 41 may be located, for example, in the signal path of signal 17s, for example, on a signal cable, and can filter and remove specific frequencies from the electronic signal 17s by an electronic filter. In this case, the clean signal 17c is generated based on signal 17s (as shown). Alternatively, the frequency filter 41 may be integrated into the processor 18 for software filtering of signal 17s.

[0075] Furthermore, as also shown in Figure 4, the device 10 may include an adapter 42 that allows the vibration sensor 17 to be easily attached to and removed from the housing 16. In this case, the adapter 42 may be attached in direct contact with the outer surface of the housing 16, and the vibration sensor 17 is attached to the adapter 42. This is different from, for example, the situation shown in Figure 1 where the vibration sensor 17 is directly attached to the outer surface of the housing 16, or the situation shown in Figure 2 where the vibration sensor 17 is shown to be directly attached to the outer surface of the first portion 16a of the housing 16. Also, attachment to the inner surface of the vibration sensor 17 can be done via the adapter 42. Furthermore, a frequency filter 41 may be incorporated into the adapter 42 to filter the signal (vibration) before detection by the vibration sensor 17.

[0076] As further shown in Figure 4, in addition to the frequency filter 41, the device 10 may also include an amplifier 45 included in the signal path of the signal 17s on the signal cable, for example. This amplifier 45 increases the signal amplitude to a voltage that can be more easily measured by the processor 18.

[0077] Figure 4 also shows that the apparatus 10 may include one or more optical sensors or detectors, for example, one or both of optical sensors 43 and / or 44, where the first optical sensor 43 is configured to detect first synchrotron radiation, and the second optical sensor 44 is configured to detect second synchrotron radiation. The first optical sensor may be a sensor chip contained within the housing (or casing 16) of the apparatus 10. The second optical sensor 44 may be a camera 44 located outside the housing 16, for example, near the workpiece 11. The first synchrotron radiation may be caused, for example, by machining the workpiece 11 using a laser beam 12. The first synchrotron radiation may be secondary synchrotron radiation (i.e., not laser light) emitted by, for example, the plasma 34 shown in Figure 3, which is generated by machining the workpiece 11. Alternatively, the first synchrotron radiation may be reflected laser light. The second synchrotron radiation may be caused, for example, by a laser beam 12 induced in a liquid jet 13. The second synchrotron radiation may be, for example, secondary synchrotron radiation (not the laser beam 13) generated by (e.g., Raman) scattering of the laser beam 12 in the liquid jet 13. Alternatively, the second synchrotron radiation may be the laser light of the laser beam 12 scattered in the liquid jet 13.

[0078] At least one of the optical sensors 43, 44, for example, the first optical sensor 43 in Figure 4, may be positioned to receive the first synchrotron radiation through the liquid. That is, the first synchrotron radiation propagates away from the workpiece 11 through the liquid jet 13 and within the liquid jet 13, optionally through at least one lens 15. In other words, the first synchrotron radiation can be induced within the liquid jet 13, similar to the laser beam 12. The apparatus 10 may include one or more spectral separation units, each spectral separation unit (e.g., an optical filter) may be configured to separate only the electromagnetic synchrotron radiation of the target, including the first or second synchrotron radiation on the first or second optical sensor 43 or 44.

[0079] The processor 18 of the apparatus 10 in Figure 4 may be further configured to take into account output signals 43s and / or 44s provided by the optical sensors 43 and / or 44 when determining a first set of parameters p1 and / or a second set of parameters p2. These signals 43s and 44s can indicate the generation of first and / or second synchrotron radiation, respectively.

[0080] Figure 5 shows an exemplary processor 18 of the apparatus 10. The processor 18 in Figure 5 is configured to perform signal fusion. That is, the processor 18 can, for example, fuse the output signal 17s (or signal 17c if signal 17s is frequency filtered) of the vibration sensor 17 with the output signals 43s and 44s of the first and second optical sensors 43 and 44, respectively (see Figure 4). Fusion may mean, for example, calculating a fused signal from the output signals 17s, 43s, and 44s by combining them and arbitrarily weighting them. As described above, the output signals 17s (or 17c), 43s, and 44s may be generated based on the first vibration and / or the second vibration, and based on the first synchrotron radiation and / or the second synchrotron radiation, respectively. The processor 18 may, for example, determine a first set of parameters p1 and / or a second set of parameters p2 based on the signal obtained by fusing the output signals 17s, 43s, and 44s.

[0081] For this purpose, the processor 18 may include and / or be adapted to perform a rule-based algorithm that uses different types of signal characteristics or thresholding to merge decisions based on the output signals 17s (or 17c), 43s, 44s. An example is shown in Figure 9 and described below.

[0082] Alternatively, the processor 18 may be equipped with and use a pre-trained model 51, such as a neural network (as shown in the figure). This pre-trained model 51 may be configured to receive output signals 17s (or signal 17c if signal 17s is frequency-filtered), 43s, and 44s. The pre-trained model 51 may be trained to fuse the output signals 17s (or 17c), 43s, and 44s, and to determine a first set of parameters p1 and / or a second set of parameters p2 based on the result of the fusion. The pre-trained model 51 may be trained in a supervised manner, for example, by determining a known set of parameters based on the output signals and then correcting them. Alternatively, the pre-trained model 51 may be trained unsupervised. The pre-trained model may be further trained during use of the device 10.

[0083] Figure 6 shows an embodiment of apparatus 10 based on the embodiment of apparatus 10 shown in Figure 1. The same elements in Figures 1 and 6 are labeled with the same reference numerals and function similarly, so there is no need for redundant explanation.

[0084] Figure 6 also shows an embodiment in which the vibration sensor 17 is located inside the liquid chamber 21 of the housing 16 (for example, inside the first portion 16a as shown in Figure 2). The vibration sensor 17 may be configured to measure vibrations of the liquid transmitted to the housing 16. In this embodiment, since the vibration sensor 17 is located inside the housing 16, it can be shielded from external ambient noise.

[0085] As also shown in Figure 6, in one embodiment, the apparatus 10 may further include an acoustic transducer 61 positioned and configured to transmit sound waves 62 onto the workpiece 11 through the liquid jet 13 (so that the sound waves are guided within the liquid jet 13). The sound waves 62 may travel along a similar path to the laser beam 12 when machining the workpiece (not shown in Figure 6). The sound waves 62 and the laser beam 12 may be provided alternately or simultaneously. A vibration sensor 17 may further be configured to measure a third vibration caused by the sound waves 62 reflecting back from the workpiece 11 and being guided through the liquid jet 13 into the housing 16. Using the acoustic transducer 61, the processor 18 can determine the flight time of the sound waves 62, and from this flight time or similar geometric parameters, the length of the fluid jet 12 or the distance between the housing 16 and the workpiece 11 can be derived.

[0086] In particular, additional features of various (optional) embodiments of the apparatus 10 shown in Figures 2 to 5 can be added individually and in any combination to the features of the basic embodiment of the apparatus 10 shown in Figure 1.

[0087] Each of the shown embodiments of the apparatus 10 (Figures 1 to 6) may include a laser source and a laser controller for controlling the laser source. In this case, the laser source is configured to supply laser light for a laser beam 12. The laser source may be an external device not included in the apparatus 10, but may be, for example, an optical fiber, for supplying laser light to the laser supply port of the apparatus 10. In the apparatus 10, the laser beam 12 may be directed toward a lens 15 used to couple the laser beam 12 to a fluid jet 13, for example, by a beam splitter.

[0088] Each illustrated embodiment of the apparatus 10 (Figures 1 to 6) may optionally or additionally include one or more peripheral devices such as a fluid supply controller (which may optionally be integrated with a fluid pump), a gas supply controller (for example, for a gas used to surround and protect the fluid jet 12), and a moving axis controller 31 (see Figure 3 or Figure 8, for example, a CNC device), the moving axis controller 31 may be configured to move the machined surface on which the workpiece 11 is placed, or alternatively the workpiece 11 itself, in mutually perpendicular x, y, and z directions and / or rotational a, b, c directions.

[0089] The processor 18 may be configured to provide command signals to different peripheral devices of the apparatus 10. For example, the processor 18 may be a controller capable of controlling a laser controller, a fluid supply controller, a gas supply controller, and / or a moving axis controller via its respective signals. The processor 18 may be configured to control these devices based on a first set of parameters p1 related to machining the workpiece 11, and / or a second set of parameters p2 related to the liquid jet 13, and / or a third set of parameters related to the apparatus 10. The processor 18 may be further configured to adapt at least one machining parameter of the laser beam 12 and / or the liquid jet 13 by controlling one or more of the devices accordingly based on the first, second, and / or third set of parameters.

[0090] Figure 7 shows a method 70 of the present disclosure for machining a workpiece 11 using a laser beam 12 guided by a liquid jet 13. The method 70 includes a step 71 of generating a liquid jet using a nozzle and a step 72 of coupling the laser beam 12 to the liquid jet 13 using at least one lens 15. Furthermore, the method 70 includes a step 73 of measuring at least a first vibration and / or a second vibration of a housing 16 surrounding at least a nozzle 14. The first vibration is caused by machining the workpiece 11 with the laser beam 12, and the second vibration is caused by the liquid jet 13. The method 70 may then include a step 74 of determining a first set of parameters related to machining the workpiece 11 with the laser beam 12 and / or a second set of parameters related to the liquid jet 13, based on the measurement of the first vibration and / or the second vibration.

[0091] Figure 8 shows an embodiment of apparatus 10 based on the embodiment of apparatus 10 shown in Figure 1. The same elements in Figures 1 and 8 are labeled with the same reference numerals and function similarly, so there is no need for redundant explanation.

[0092] As shown in Figure 8, the apparatus 10 may be located inside a liquid jet-guided laser machine, which comprises a machine housing 82 (also called an outer housing). The machine housing 82 is not particularly identical to the housing 16 in which the vibration sensor 16 is located. The housing 16 is sometimes called the inner housing 16 of the machine (because it is inside the machine housing 82), and is, for example, a coupling unit in which the laser beam 12 is coupled to the liquid jet 13. In particular, the housing 16 is an enclosure that directly surrounds the nozzle 14 and optionally the lens 15 (for example, in the case of the first part 16a and the second part 16b of the housing 16, as shown in Figure 8). In other words, inside the housing 16 or the first part 16a of the housing 16, the nozzle 14 is not surrounded by any further enclosure or housing. As also shown in Figure 8, the liquid chamber 21 may be located inside the housing 16 or the first part 16a of the housing 16.

[0093] Figure 8 also shows that the apparatus 10 may include an impact object 81, which may be positioned adjacent to and / or near the workpiece 11. At least one parameter of a second set p2 that the processor 18 can determine can indicate whether or not the liquid jet 13 contacts the edge of the impact object 81. For example, by determining one or more positions (e.g., coordinates set by the CNC 31) where the liquid jet 13 contacts the impact object 81, and optionally further determining one or more positions where the liquid jet 13 does not contact the impact object 81, the processor 18 can determine the liquid jet position and / or liquid jet angle (with respect to a given axis), and can be further configured to perform, for example, correction or alignment of the liquid jet 13 with respect to a given axis.

[0094] Figure 9 shows an example of signal fusion using a rule-based algorithm 90. In the initial step 91 of the algorithm 90, the apparatus 10 is machining the workpiece 11 using a liquid jet-guided laser beam.

[0095] In step 92, algorithm 90 checks whether the signal 44s from the light sensor 44 is greater than a first threshold (T1). If the signal 44s is greater than the first threshold, algorithm 90 proceeds to step 94; otherwise, there is a problem and machining can be automatically stopped in step 93.

[0096] In step 94, algorithm 90 checks whether the signal 17s from the vibration sensor 17 (or the frequency-filtered signal 17c from the vibration sensor 17 after the frequency filter 41) is greater than the second threshold (T2) and less than the third threshold (T3). If this is true, algorithm 90 proceeds to step 95. Otherwise, machining continues and algorithm 90 returns to step 91.

[0097] In step 95, algorithm 90 checks whether the signal 17s (or 17c) remains between the second and third thresholds (T2, T3) for at least X seconds. X may be selected by the user. X may be measured using a timer. If this is at least X seconds, algorithm 90 proceeds to step 96. If this is not the case for at least X seconds, machining continues and algorithm 90 returns to step 91.

[0098] In step 96, algorithm 90 checks whether the average of the signals 43s from the light sensor 43 falls below a third threshold (T3) for at least Z seconds. Z may be selected by the user or may be equal to X. Z may be measured using a timer. If this is true for at least Z seconds, algorithm 90 proceeds to step 97. If this is not true for at least Z seconds, machining continues and algorithm 90 returns to step 91.

[0099] In step 97, the processor 18 may determine that the processing is complete and proceed to the next step.

[0100] In particular, steps 91-95 can be performed simultaneously to analyze the machining process and make decisions regarding the machining process. As detailed above, such an algorithm 90 can also be used, for example, to optimize machining efficiency or to achieve machining depth control.

[0101] This disclosure is described in conjunction with various embodiments and implementations as examples. However, other modifications can be understood, achieved, and carried out by those skilled in the art from the drawings, this disclosure, and the implementation of the independent claims. In the claims and specification, the word “including” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude plurals. A single element or other unit can satisfy the function of several entities or items described in the claims. The mere fact that certain means are described in different dependent claims does not imply that combinations of these means cannot be used in advantageous embodiments.

Claims

1. A device (10) for machining a workpiece (11) with a laser beam (12) guided by a liquid jet (13), wherein the device (10) A nozzle (14) configured to generate the liquid jet (13), At least one lens (15) configured to couple the laser beam (12) to the liquid jet (13), A housing (16) having at least the nozzle (14) and an opening (19) for providing the liquid jet (13) onto the workpiece (11), A vibration sensor (17) attached to the housing (16), and A processor (18) and, The vibration sensor (17) is configured to measure at least a first vibration and / or a second vibration of the housing (16), The first vibration is caused by machining the workpiece (11) using the laser beam (12), and the second vibration is caused by the liquid jet (13). The processor (18) is configured to determine a first set of parameters (p1) related to machining the workpiece (11) and / or a second set of parameters (p2) related to the liquid jet (13) based on measuring the first vibration and / or the second vibration.

2. The vibration sensor (17) is further configured to measure a third vibration and / or a fourth vibration of the housing (16), The third vibration is caused by photoacoustics induced by the laser beam (12) inside the housing (16), and the fourth vibration is caused by the movement and / or rotation of the housing (16). The apparatus (10) according to claim 1, wherein the processor (18) is configured to determine a third set of parameters related to the apparatus (10) based on measuring the third vibration and / or the fourth vibration.

3. The first vibration is a first sound (32) generated in the workpiece (11) by machining the workpiece (11) using the laser beam (12), and is based on the first sound (32) transmitted to the housing (16) via the liquid jet (13) and the liquid in the housing (16), and / or The apparatus (10) according to claim 1 or claim 2, wherein the second vibration is a second sound (33) generated by the liquid jet (13) and is based on the second sound (33) transmitted to the housing (16) via the liquid jet (13) and the liquid in the housing (16).

4. The apparatus (10) according to claim 3, further comprising a frequency filter arranged and configured to separate the first sound (32) and / or the second sound (33) traveling within the liquid jet (13) from other sounds.

5. The laser beam (12) is pulsed, The apparatus (10) according to any one of claims 1 to 4, wherein the vibration sensor (17) is configured to measure the occurrence of the first vibration within a time frame shorter than the time delay between two consecutive laser pulses of the pulsed laser beam (12).

6. The laser beam (12) is pulsed, The apparatus (10) according to any one of claims 1 to 5, wherein the processor (18) is configured to determine a time difference between a first time when a specific laser pulse of the laser beam (12) is generated and a second time when the correlated occurrence of the first vibration is measured by the vibration sensor (17).

7. The apparatus (10) according to claim 6, wherein the processor (18) is configured to calculate the distance between the nozzle (14) and the incident point of the laser beam (12) on the workpiece (11), and / or the distance between the aperture (19) and the incident point, based on the time difference.

8. The apparatus (10) according to any one of claims 1 to 7, wherein the vibration sensor (17) is attached to and in direct contact with the outer surface of the housing (16), or is attached to an adapter (42) attached to the outer surface of the housing (16).

9. The housing (16) comprises a first portion (16a) and a second portion (16b), the first portion (16a) being detachably attached to the second portion (16b), The second portion (16b) of the housing (16) comprises at least one of the lenses (15), The first portion (16a) of the housing (16) comprises the nozzle (14) and a liquid chamber (21) positioned above the nozzle (14), The apparatus (10) according to any one of claims 1 to 8, wherein the vibration sensor (17) is positioned in the first portion (16a) of the housing (16) above the liquid chamber (21) above the nozzle (14).

10. At least one parameter of the first parameter set (p1) is, The type of material of the workpiece (11), The material removal rate or material removal rate is determined by using the laser beam (12) to process the workpiece (11) and remove material from the workpiece. The apparatus (10) according to any one of claims 1 to 9, which indicates at least one of whether or not the laser beam (12) has penetrated the workpiece (11).

11. At least one parameter of the second parameter set (p2) is, The jet quality of the liquid jet (13) and / or the laminar flow length of the liquid jet (13), The flow characteristics of the liquid jet (13) and Whether or not the laser beam (12) collides with the nozzle (14), The apparatus (10) according to any one of claims 1 to 10, wherein the liquid jet (13) contacts the edge of an impact object (81) placed near the workpiece (11), or contacts the workpiece (11) itself.

12. The system further comprises an acoustic transducer (61) arranged and configured to send sound waves (62) onto the workpiece (11) through the liquid jet (13), The apparatus (10) according to any one of claims 1 to 11, wherein the vibration sensor (17) is further configured to measure a third vibration caused by the sound wave (62) reflecting back from the workpiece (11) through the liquid jet (13) into the housing (16).

13. The system further comprises one or more optical sensors (43, 44) configured to detect a first synchrotron radiation or a second synchrotron radiation, The first synchrotron radiation is generated by processing the workpiece (11) using the laser beam (12), and the second synchrotron radiation is generated by the laser beam (12) guided in the liquid jet (13), or by processing the workpiece (11) using the laser beam (12). The first synchrotron radiation includes at least one of the laser light of the laser beam (12) reflected from the workpiece (11) and the secondary synchrotron radiation emitted by a portion of the workpiece (11) processed by the laser beam (12). The apparatus according to any one of claims 1 to 12, wherein the processor (18) is configured to determine the first parameter set (p1) and / or the second parameter set (p2) based on measuring the first synchrotron radiation and / or the second synchrotron radiation.

14. The aforementioned processor (18) The output signals (17s, 43s, 44s) of the vibration sensor (17) and one or more of the light sensors (43, 44) are merged, wherein the output signals (17s, 43s, 44s) are generated based on the measured first vibration and / or second vibration and the measured first synchrotron radiation and / or second synchrotron radiation. The apparatus (10) according to claim 13, wherein the first parameter set (p1) and / or the second parameter set (p2) are determined based on the fused output signals (17s, 43s, 44s).

15. The processor (18) includes a trained model or a rule-based algorithm and is configured to input the output signals (17s, 43s, 44s) to the trained model or the rule-based algorithm. The apparatus (10) according to claim 14, wherein the trained model is configured to fuse the output signals (17s, 43s, 44s) and determine the first parameter set (p1) and / or the second parameter set (p2) based on the fused output signals (17s, 43s, 44s).

16. The apparatus (10) according to any one of claims 1 to 15, wherein the processor (18) is further configured to adapt at least one processing parameter of the laser beam (12) and / or the liquid jet (13) based on the determined first parameter set (p1) and / or second parameter set (p2).

17. A method (70) for machining a workpiece (11) using a laser beam (12) guided by a liquid jet (13), The liquid jet (13) is generated using the nozzle (14) (71), The laser beam (12) is coupled to the liquid jet (13) using at least one lens (15) (72), The first and / or second vibrations of the housing (16) surrounding the nozzle (14) are measured (73), The first vibration is caused by machining the workpiece (11) using the laser beam (12), and the second vibration is caused by the liquid jet (13). A method (70) comprising determining a first set of parameters (p1) related to machining the workpiece (11) and / or a second set of parameters (p2) related to the liquid jet (13) based on measuring the first and / or second vibrations (74).

18. The method according to claim 17 (70), further comprising modifying at least one processing parameter of the laser beam (12) and / or the liquid jet (13) based on the determined first parameter set (p1) and / or the second parameter set (p2).

19. A computer program for controlling the apparatus (10) according to any one of claims 1 to 16 when the instruction is executed by the processor (18), or a computer program including an instruction for causing the apparatus (10) to execute the method (70) according to claim 17 or claim 18 when the instruction is executed by a computer.

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