Measuring module with adjustable path length difference for laser processing device

Abstract

The application relates to a measuring module (10) for a laser processing device (1) in which a first optical path (P1) and a second optical path (P2) for laser light are defined within a housing (11). The first optical path (P1) has a fixed predetermined optical path length. A second optical path (P2) is defined between the connection port (12) and the coupling port (14) of the housing and has a variable optical path length adjustable by an optical path length adjuster system (20). The present application also relates to an interferometer system comprising a measurement module having a first optical path (P1) corresponding to a reference arm of the interferometer system and a second optical path (P2) corresponding to an object arm of the interferometer system wherein an optical path length adjuster system (20) is configured to adjust an optical path length of the second optical path (P2), the optical path length is the optical path length of the object arm of the interferometer system. The invention further relates to a laser machining device (1) comprising a laser machining module (30) for laser machining a workpiece (P) on a working field (37) using a working beam (W), and a measuring module (10) according to the invention.

Description

Technical Field

[0001] The present application relates to the fields of applied optics and laser processing. In particular, the present application relates to an interferometer system and a measuring module that can be used with a laser processing module as an adjustable optical subsystem for directing a measuring beam to a detection device configured to measure distances within a wide range of measurable distances, in particular the distance between the laser processing module or its deflection unit and the surface of a workpiece being laser processed. The present application also relates to a laser processing module comprising such a measuring module. Background Art

[0002] The use of lasers is now ubiquitous in the materials processing industry. Examples are additive manufacturing (AM), 3D printing, welding, cutting, marking, or engraving of different materials such as metals or polymers.

[0003] In laser processing technology, a deflection system, such as an XY pair of rotatable mirrors operated by corresponding galvanometer motors, is used to scan a working laser beam over the surface of the material to be laser processed. The rotatable mirrors can be used to direct the working laser beam to a desired target position of the surface to be laser processed so as to laser process the material in a controlled manner.

[0004] In this technique, it is generally desirable to keep the focus of the working laser beam on the surface to be laser processed in order to ensure high material quality of the final product. Uncontrolled variations in the focus position may be associated with uncontrolled variations in the amount of laser energy transmitted to the material in a given target position, which may lead to undesirable irregularities in the final product, for example when welding, 3D-printing or cutting a piece of material.

[0005] Known solutions for keeping the focus of a laser processing module on the target surface, i.e. on the corresponding working field, are, for example, the use of f-theta lenses as in KR 20120114651A, and the use of focusing systems with variable focal length, for example by means of a movable lens integrated in the system and configured to shift the position of the focus of the working laser beam, as, for example, in US 2014 / 0263221 A1.

[0006] The use of f-theta lenses allows focusing a collimated working beam on a working field (target surface) without the use of movable optical components. However, this brings with it a very limited range of possible working distances between the deflection system and the working field, and thus a correspondingly limited range of possible working field sizes. In addition, f-theta lenses are expensive optical components.

[0007] The use of an adjustable focus system to continuously set the position of the focal point of the working beam overcomes some of the disadvantages of f-theta lenses. Compared to f-theta lenses, an adjustable focus system can achieve a wider range of usable working distances, and therefore possible working field sizes.

[0008] However, the use of an adjustable focus system also presents technical challenges. When the deflection system is operated to scan the working laser beam over the surface to be laser processed, the real optical distance between the deflection system and the surface may vary. For example, depending on the setting of the deflection system, in particular depending on the deflection angle, the real optical distance may vary in the case of a planar surface to be laser processed. Therefore, preset settings of the adjustable focus system may be pre-stored for the corresponding settings of the deflection system, for example in a lookup table format, in order to dynamically adjust the focus of the focus system when the deflection system scans the planar working surface.

[0009] As another example, even for a given working distance between the deflection system and the working surface and for a given deflection angle, the actual distance between the deflection system and a point on the working surface may undergo uncontrollable variations, e.g. due to irregularities in the working surface itself, such as improper orientation of the working surface or uncontrollable variations in its height profile.

[0010] Therefore, in order to track such irregularities and react accordingly by controlling the adjustable focus system to compensate for them, it may be important to implement continuous distance detection. Thus, some optical path length adjuster systems include a detection system configured to measure the distance in real time, for example based on triangulation, time-of-flight distance measurement or chromatic confocal distance measurement. However, such distance measurement techniques are generally not suitable for integration in on-axis (coaxial) structures, especially for large working distances.

[0011] However, the detection system may be subject to the same variability and error sources to which the working laser beam itself is subject, which may lead to inaccurate and unreliable distance determinations and thus to inaccurate correction of the focal position of the working laser and thus to poor laser quality.

[0012] One known possibility for implementing an adaptive distance measurement system is based on the use of optical coherence tomography (OCT). DE 102013008269A and US2016 / 059347A1 describe examples of distance detection using OCT in an optical path length adjuster system with an adjustable focusing system. The optical coherence tomography machine is integrated in a laser processing device and is configured to perform distance measurement based on interference between a laser forming a measuring beam and a reference beam, the measuring beam propagating along an object arm path and reflecting at a working surface, the reference beam being obtained from the same laser and propagating along a reference arm path. The adjustable focusing system sets the focal position for both the working beam and the measuring beam. The system includes an optical path length adjuster system configured to adapt the variable optical path length of the reference arm path according to a change in the position of the focus under the control of a control unit, so that after each change in the position of the focus, the optical path length difference between the object arm path and the adjustable reference arm path depending on the position of the focus is maintained within the coherence length of the optical coherence tomography machine. However, the control unit is not configured to control the optical path length of the object arm path in real time.

[0013] However, OCT devices are very expensive optical devices and their integration in existing optical path length adjuster systems can be very complex. In particular, the OCT device described in DE 102013008269A places some requirements on the laser processing system in which it should be combined, for example regarding the settings and characteristics of the focusing system, which should also be usable by the OCT device based on the measurement light it measures. Typically, this system has the technical limitation that any optical elements that interact with both the measurement beam and the laser processing beam must be configured accordingly, for example regarding their coatings, in order to be compatible with two different wavelength ranges, which generally leads to non-optimal operating conditions. In addition, the OCT device described in DE 102013008269A has a limited optical path length adaptability range. According to this document, only optical path length changes from about 20 mm to about 200 mm can be compensated.

[0014] DE 102019001858 B3 describes an interferometric optical measuring device having an optical path length variable device for adjusting the optical path lengths of a reference arm and an object arm. The deflection head of the device only deflects the measuring beam, but not the working beam.

[0015] US 2020 / 0038954 A1 also discloses the use of an interferometer as a distance detector for a laser processing device in a non-adaptive manner.

[0016] US 2015 / 0230705 A1 describes an interferometric ophthalmic device having an adjustable object arm and a fixed reference arm.

[0017] Other optical devices are disclosed in US 2006 / 165350 A1 and US 2015 / 230705 A1.

[0018] Thus, there is room for technical improvements in the area of ​​distance measurement in laser processing systems. Summary of the invention

[0019] The object of the present application is to overcome the above-mentioned disadvantages of the prior art, in particular by providing a measurement module which allows a detection system of a laser processing device to achieve an accurate and reliable continuous distance determination, capable of resolving and compensating for different sources of distance variability. This problem is solved by a measurement module according to claim 1, an interferometer system according to claim 13, and a laser processing device according to claim 14, the laser processing device comprising such a measurement module. Preferred embodiments of the present application are defined in the attached dependent claims.

[0020] A first aspect of the present application relates to a measuring module for a laser processing device. The laser processing device may include a laser processing module and a measuring module, the laser processing module being used to laser process a workpiece on a work site, such as an AM module. The measuring module may be optically and mechanically coupled to the laser processing module, although the two modules may be structurally independent. The laser processing module may correspond to a portion of the laser processing device in which a laser is generated / input and optically configured to laser process a workpiece on a work site, while the measuring module may correspond to a portion of the laser processing device in which a laser is generated / input and output and optically configured to perform laser-based distance measurement, which may be used by the laser processing device, for example, for correctly focusing the working beam on the work site and / or the workpiece. This modular structure may allow the measurement module according to the present application to be integrated in different laser processing modules, and different laser processing modules to be integrated in the measurement module according to the present application.

[0021] The measuring module comprises a housing. The housing comprises a connection port, which may be a single connection port. The connection port is configured to optically couple the measuring module to a distance detection device. In particular, the connection port may be configured to receive laser light from and output laser light to the distance detection device, which may comprise an interferometric sensor or be optically coupled to an interferometric sensor, such that the measuring module and the distance detection device may implement an interferometer, in particular for performing interferometric distance detection.

[0022] The laser light inputted from and / or outputted to the distance detection device may be a laser light suitable for performing interferometric measurements, in particular a coherent laser light, preferably a broadband low coherence light. The laser light inputted from and / or outputted to the distance detection device may be separable, or may be separated in two parallel optical paths or arms for performing interferometric measurements. The separation of the laser light into two separate optical paths may be performed outside the measurement module or inside the measurement module.

[0023] For example, if the separation of the laser light into two separate optical paths is performed outside the measurement module, the connection port can be configured to input and output the laser light via the two corresponding optical paths, for example in the form of two separate beams. If the separation of the laser light into two separate optical paths is performed in the measurement module, the connection port can be configured to input the laser light via a single optical path, for example in the form of a single beam, and the measurement module can include a beam splitter for splitting the laser light into separate optical paths (interferometer arms). In the latter case, the connection port can be configured to output the laser light via the two corresponding optical paths, for example in the form of two separate beams.

[0024] The housing of the measuring module also includes a coupling port for optically coupling the measuring module to the laser processing module of the laser processing device. When the measuring module is optically coupled to the laser processing module via the coupling port, laser light can be transmitted from the measuring module to the laser processing module and from the laser processing module to the measuring module through the coupling port and through a corresponding further coupling port of the laser processing module. The measuring module can be mechanically attached to the laser processing module for optically coupling the measuring module to the laser processing module.

[0025] In the measurement module of the present application, a first optical path and a second optical path are defined at least partially within the housing for the laser light received and output through the connection port. The first optical path and the second optical path may be completely contained within the housing. The first optical path and the second optical path may be independent and separate from each other, and may not overlap in particular, or may overlap partially in the portion between the connection port and the beam splitter, where the laser light received through the connection port may be split into the first optical path and the second optical path.

[0026] A reference optical reflector from the connection port to the measurement module defines a first optical path. The reference optical reflector reflects the laser back to the connection port. The reference optical reflector may include any reflective optical component, in particular a reflector or a retroreflector, preferably a fixed (immovable) reflector or retroreflector. The laser received through the connection port may be guided to the reference optical reflector through the first optical path, and reflected back to the connection port by the reference optical reflector through the first optical path. The reference optical reflector may be arranged at a predetermined optical distance from the connection port to act as a reference for interferometric measurement, wherein the laser received and output through the connection port and reflected by the reference optical reflector covers a predetermined optical distance from the connection port to the reference optical reflector and returns within a corresponding predetermined time, possibly through one or more correspondingly configured optical fibers. Then, the aforementioned predetermined optical distance may be determined by one or more optical fibers, for example, by the length and / or refractive index of one or more optical fibers, through which the laser may propagate between the connection port and the reference optical reflector.

[0027] Thus, the first optical path may correspond to a so-called reference arm of the interferometer optical arrangement, in particular a reference arm of the interferometer arrangement which may be formed by the measuring module and the previously mentioned distance detection device which may be optically coupled thereto.

[0028] The second optical path is defined as from the connection port to the coupling port and back to the connection port. The laser received through the connection port can be guided to the coupling port through the second optical path, the laser can be fed from the coupling port to the laser processing module, and the measurement module can be optically and possibly mechanically coupled to the laser processing module. The laser received from the measurement module via the coupling port in the laser processing module can be guided by the laser processing module to the work field and / or the workpiece processed by the laser, where the laser can be reflected back. The laser processing module can then guide the reflected light back to the measurement module through the coupling port. The reflected light is then guided back to the connection port along the second optical path so as to be transmitted to a distance detection device that can be optically coupled to the connection port. The distance detection device can then perform interferometry to determine the distance based on the lasers received from the first optical path and from the second optical path.

[0029] The second optical path may correspond to a so-called object arm of the interferometer optical arrangement, in particular the object arm of the interferometer arrangement which may be formed by the measuring module and the previously mentioned distance detection device which may be optically coupled thereto.

[0030] The measuring module can be considered as an intermediate optical path length adjuster system optically arranged between the distance detection device and the laser processing module, wherein the distance detection device can be optically connected to the laser processing system via the measuring module. The laser received from the distance detection device and / or from the corresponding laser source can enter the measuring module and be transmitted to the laser processing module through the second optical path and the connection port, where the laser can be guided to its working field and / or the workpiece processed by the laser. Then, the laser reflected by the working field and / or by the workpiece can be guided back to the distance detection device by the laser processing module and the measuring module through the connection port and the second optical path for the distance detection device to perform distance measurement based on its interference with the laser reflected by the reference optical reflector.

[0031] The measurement module of the present application further includes an optical path length adjuster system configured to adjust an optical path length difference between an optical path length of the first optical path and an optical path length of the second optical path.

[0032] The first optical path has a first optical path length, and the second optical path has a second optical path length, which may be different from the first optical path length. The optical path length difference corresponds to the difference between the first optical path length and the second optical path length. Monitoring changes in the optical path length difference may allow for determining a distance based on interferometry using interference between laser light received from the first optical path and laser light received from the second optical path, which laser light received from the second optical path may initially be coherently generated with the laser light received from the first optical path. The manner in which such interferometric distance determination may be performed is well known to those skilled in the art and is therefore not explained in detail herein.

[0033] "Optical path length" is understood herein to mean the product of the local refractive index integrated over a given optical path multiplied by the unit length. In mathematical terms, for a path with geometric length s, for a medium with a constant refractive index n, the optical path length OPL can be expressed as:

[0034] OPL = n·s.

[0035] For a medium with a variable refractive index over the path length, the OPL can be expressed mathematically as the path integral:

[0036] OPL = ∫n(s)·ds.

[0037] The optical path length adjuster system is configured to controllably set the optical path length difference, in particular by controllably modifying the optical path length of the second optical path, corresponding to the so-called "object arm". This may mean controllably setting and / or modifying the geometric path length of the second optical path (see s and ds in the above equation) and / or the refractive index of at least part of the second optical path (see n and n(s) in the above equation). For this purpose, the optical path length adjuster system is integrated in the second optical path, which can act as an object arm of the interferometer device formed by the measuring module and by the aforementioned distance detection device, which can be optically connected to the connection port. In other words, the second optical path can extend partially along / in the optical path length adjuster system. For example, the optical path length adjuster system can include a plurality of reflective and / or refracting optical elements, such as mirrors, lenses and / or prisms, at which the laser light transmitted through the second optical path can be reflected and / or refracted.

[0038] The optical path length adjuster system may comprise a motion control unit which is specifically configured to controllably set the optical path length difference by operating one or more optical elements of the optical path length adjuster system, such as a reflector, a lens and / or a prism, in particular by manually or automatically moving any one or a combination of these elements. For example, the motion control unit of the optical path length adjuster system may be programmed to associate each specified value of the optical path length difference with a corresponding setting of one or more optical elements of the optical path length adjuster system. By way of example, in order to achieve an adjustment of an optical path length difference of 400 mm, the control unit of the optical path length adjuster system may move one or more optical elements thereof so as to correspondingly modify the optical path length of the second optical path by 400 mm. This may in particular comprise transferring one or more optical elements, in particular along a corresponding predetermined movement path, for example manually or automatically.

[0039] The aforementioned change in the optical path length difference may be expected or unexpected, and this change in the optical path length difference may in particular be due to a change in the optical path length change of the measuring beam transmitted along the second optical path for performing the distance detection. An example of an expected change in the optical path length difference may correspond to a change in the setting of a deflection unit of a laser processing module for scanning the measuring beam, in particular when laser processing a workpiece on a planar working field, a change in the setting of the deflection unit, in particular a change in the deflection angle. If the optical center of the deflection unit for scanning the measuring beam on the working field, in particular the optical center of its movable mirror closest to the working field (e.g. X or Y mirror), is the shortest distance from the working field, the change ΔD of the distance D for a change in the deflection angle α corresponds, according to a simple trigonometric relationship, to:

[0040]

[0041] As a result, if the deflection angle changes by an angle α, the optical path of the measurement beam changes by 2ΔD. An optical path length adjuster system can be used to compensate for this change accordingly by correspondingly changing the second optical path length 2ΔD.

[0042] Examples of unintended variations in the optical path length difference may correspond to surface irregularities of the workpiece being processed, such as the uppermost layer of the workpiece being laser processed, or to a work field that is unexpectedly tilted relative to an initially intended horizontal plane.

[0043] An additional example of an expected change in the optical path length difference may correspond to an expected change in the "working distance", i.e., an expected change in the minimum (e.g., vertical) distance between the laser processing module, in particular the laser processing module of its housing, and the corresponding working field. Such a change may occur, for example, when the distance between the laser processing module and the underlying working field is intentionally modified, for example to change the size of the working field. In particular, for operation at a larger working field, the working distance may be increased, while for operation at a smaller working field, the working distance may be reduced.

[0044] According to the present application, the first optical path has a fixed predetermined optical path length, which can be determined by the position of the reference optical reflector and / or the characteristics of one or more optical fibers through which the laser light can propagate between the connection port and the reference optical reflector, in particular by its length and / or refractive index. The second optical path has a variable optical path length, which can be adjusted by the optical path length adjuster system. Therefore, the optical path length adjuster system is configured to adjust the optical path length of the second optical path. Thus, the optical path length adjuster system can adjust the optical path length difference by correspondingly adjusting the optical path length of the second optical path, while the optical path length of the first optical path remains constant.

[0045] Thus, the measuring module according to the present application, by means of its optical path length adjuster system, allows the use of a second optical path for transmitting a laser beam (measurement beam) for performing an interferometric distance measurement with a corresponding distance detection device, as well as allowing a reaction to changes in the optical path length of the second optical path (corresponding to the object arm of the interferometric device) by correspondingly re-adjusting the optical path length of the second optical path to compensate for such changes. As a result, the total optical path length difference initially predetermined for the optical path length adjuster system can be kept substantially constant even after such changes have occurred.

[0046] The aforementioned distance detection device may have a measurement range (also referred to as a "measurement depth") within which the distance detection device can determine the distance with a predetermined accuracy. For example, the distance detection device may be configured to detect an optical path length difference equal to zero when the object is arranged at position P, and may be able to accurately determine a change in the position of the object within a detection range P±Δ, where Δ may be, for example, 4 mm to 15 mm. The ability to compensate for changes in the optical path length difference, in particular the ability to compensate for the previously described "expected changes", may allow the use of the previously mentioned distance detection device, when optically coupled to the measurement module of the present application via a connection port, to perform interferometric distance measurements with a predetermined accuracy, regardless of changes in the optical path length of the measurement beam. In the absence of an optical path length adjuster, such changes may cause the position of the object to leave the detection range, so that the predetermined accuracy is no longer guaranteed. According to the present application, the measurement module allows such changes to be compensated by a corresponding change in the second optical path, so that if, for example, the object moves from position P1 to position P2, where P2-P1>ΔP, the second optical path may correspondingly change the distance P2-P1, and as a result, the position of the object is within the detection range P2±Δ and can be accurately detected within this range. In other words, when the optical path length difference is modified due to the previously described changes, it is particularly contemplated that the optical path length adjuster system can be used to restore the previous value of the optical path length difference and distance measurements can continue to be made accurately and reliably.

[0047] Advantageously, the measuring module according to the present application allows compensation for variations in the difference in the total optical path length of the measuring light beam used to determine the distance, possibly automatically, preferably continuously (i.e. not necessarily in a step-by-step manner), without having to manipulate the interior of the measuring module and possibly without having to adjust the setting of the focus of the measuring light beam transmitted through the measuring module, in particular through its second optical path.

[0048] Compared to previous solutions known from the prior art, e.g. DE 102013008269 A, which were based on adjusting the optical path length of a reference arm of an interferometric device, the present application allows combining two functions when the optical path length difference varies: 1) ensuring that the interference-based distance detection remains fully operational and does not lose accuracy, and 2) ensuring that the measuring beam remains focused in the optical path length adjuster system. When the second optical path undergoes a change, e.g. due to any of the reasons discussed above, a corresponding adjustment effected by the optical path length adjuster system can simultaneously ensure that the initial optical path length difference on which the interferometric distance detection device can be based remains substantially constant, while also ensuring that the position of the focus of the measuring beam also remains substantially unchanged, without having to modify any settings of the focusing system.

[0049] For example, in the case where the working distance of a laser processing module optically coupled to the measuring module of the present application has to be modified, for example increased by 700 mm, the measuring module of the present application allows this to be solved by correspondingly operating the optical path length adjuster system, for example by reducing the second optical path used by the measuring beam by 700 mm. As a result, the interferometric distance detection device connected to the measuring module can continue to operate without having to be reconfigured, and there is no need to reconfigure the focus setting for the measuring beam. In contrast, in a system such as the system known from DE 102013008269A, it is necessary to reconfigure the focus setting of the corresponding focusing system and to separately implement the adjustment of the optical path length of the reference arm.

[0050] The housing of the measuring module may surround at least some of the remaining components of the measuring module. The first optical path and the second optical path may be at least partially defined within the housing, possibly completely included within the housing. The optical path length adjuster system may be completely surrounded by the housing. The connection port and / or the coupling port may be formed by the housing. The housing may be fluid-tight and / or dust-proof. Preferably, the housing may provide a sealing to a degree according to IP64. The housing may include attachment means for mechanically attaching the measuring module to the laser processing module, in particular so that the laser processing module and the measuring module are optically coupled via the coupling port, as explained in further detail below.

[0051] According to a preferred embodiment, the optical path length adjuster system can be configured to change the optical path length of the second optical path by changing the optical path length in a range from 3 μm to 1200 mm, in particular from 10 μm or from 20 μm to 1200 mm, preferably from 40 μm to 750 mm. This can be achieved by the optical path length adjuster system, in particular the corresponding adjustment range of its optical elements, such as the reflective element pair and / or the refractive element pair described above. The optical path length difference adjustable within the above range allows compensation for changes in the optical path length of the measurement beam propagated through the second optical path of the measurement module of the present application, as long as such changes are within these ranges. In particular, the optical path length adjuster system can compensate for changes in the optical path length of 200 mm or more, or 250 mm or more, 500 mm or more, or even 700 mm or more.

[0052] The aforementioned optical path length variation range includes: relatively small optical path length variation values, such as from 20 μm to 25 mm, preferably from 50 μm to 15 mm; medium optical path length variation values, such as from 25 mm to 200 mm; and relatively large optical path length variation values, such as from 200 mm to 1200 mm, preferably from 250 mm to 700 mm. The above relatively small values ​​may, for example, correspond to an adjustment of the optical path length of the second optical path, which reflects an (expected) distance variation caused by a relatively small change in the deflection angle of the laser processing module to which the measurement module can be attached and / or an (unexpected) irregularity in the working surface, wherein the (expected) distance variation is, for example, up to 25°, and the (unexpected) irregularity is such as a ridge or tilt. The above relatively medium values ​​may, for example, correspond to an adjustment of the optical path length of the second optical path, the adjustment of the optical path length of the second optical path reflecting an (expected) distance change caused by a relatively large change of the deflection angle of the laser processing module to which the measuring module can be attached, for example greater than 25°. The above relatively large values ​​may, for example, correspond to an adjustment of the optical path length of the second optical path, the adjustment of the optical path length of the second optical path reflecting an (expected) distance change caused by a change of the working distance of the laser processing module to which the measuring module can be attached.

[0053] According to a preferred embodiment, the measuring module may further include a focusing device arranged in the second optical path, in particular between the connection port and the optical path length adjuster system. The focusing device may be configured to focus the laser transmitted through the second optical path, thereby corresponding to, for example, a measuring beam for performing distance measurement. The focusing device may preferably have a fixed focal length. For example, the focusing device may include one or more static lenses and no movable lenses. However, in other embodiments, the focusing device may have a variable focal length. For example, the focusing device may include one or more static lenses and one or more movable lenses, a corresponding galvanometer motor for setting the position of the movable lens, and a corresponding control unit for adjusting the focal length of the focusing device. Then, the focusing device may be or include a focusing device as described by the applicant in WO 2018 / 078137A1. The focusing device of the measuring module may be used to focus the measuring beam transmitted through the second optical path on the work field and / or on the workpiece laser-processed by the laser processing module of the laser processing device when the measuring module is optically coupled thereto and possibly mechanically attached. As previously described, this can ensure the best signal-to-noise ratio of the measuring beam, and therefore ensure the best measurement accuracy, even for large values ​​of the deflection angle. Furthermore, the focusing device may allow the spot size of the measuring beam to be kept constant for all values ​​of the deflection angle even on a planar working field.

[0054] According to a preferred embodiment, the optical path length adjuster system may include a plurality of reflective elements for reflecting the laser light along the second optical path. In particular, the plurality of reflective elements may include an even number of reflective elements. The reflective element may be a reflector or include a reflector. The plurality of reflective elements may include at least two movable reflective elements, wherein the optical path length of the second optical path, in particular its extension or geometric path length, may be adjusted, in particular continuously adjustable, by setting the positions of the at least two movable reflective elements. In this context, "continuously" may refer to the possibility of setting the aforementioned geometric path length of the second optical path to any desired arbitrary value within a continuous value range. The at least two movable reflective elements may be configured to move simultaneously and / or in the same direction, i.e., to be movable together.

[0055] Preferably, the optical path length adjuster system may include at least one pair of reflective elements for reflecting the laser light along the second optical path. By setting the relative position, in particular the spacing distance, between the reflective elements of each of the at least one pair of reflective elements, the extension of the second optical path between the reflective elements of each of the at least one pair of reflective elements (i.e. the geometric path length) can be adjusted, in particular continuously adjustable. Therefore, the optical path length adjuster system may be configured to adjust the optical path length difference by correspondingly setting the relative position, in particular the spacing distance, between the reflective elements of each of the at least one pair of reflective elements, thereby modifying the optical path length difference by modifying the geometric path length of the second optical path.

[0056] It is worth noting that the total number of reflective elements of the measurement module according to the present application can be an even number or an odd number, although the number of optical reflective elements of the optical path length adjuster system can be an odd number or an even number, respectively. In other words, the measurement module can include an additional reflective element, such as a reflector, at which the laser beam propagating through the second optical path can be reflected, and the additional reflective element can be fixed (immovable) and / or may not be part of any of the at least one pair of reflective elements mentioned above. The measurement module can also include an additional optical element as part of the first optical path and / or the second optical path, instead of the above-mentioned additional reflective element, such as an optical fiber, through which the laser can be propagated along the first optical path and / or the second optical path, respectively.

[0057] Preferably, each pair of reflective elements may comprise a movable reflective element which may be movable in a direction corresponding to the second optical path. The other reflective element in each pair of reflective elements may be static. Thus, the optical path length difference may be adjusted by simply setting the position of the movable reflective element of each pair of reflective elements. Preferably, all movable reflective elements may be moved together at the same time and / or in the same direction, corresponding to the direction of the second optical path. The movable reflective elements may be moved parallel to each other, but not necessarily in the same plane. Different pairs of reflective elements may define different segments of the second optical path, which different segments may in particular be parallel to each other and may have the same length.

[0058] For the previously discussed embodiments, the reflective elements of each pair of reflective elements may have reflective surfaces that are parallel to each other.

[0059] In a preferred embodiment, the optical path length adjuster system can be configured to simultaneously and / or equally displace two or more of the movable reflective elements, preferably all of the movable reflective elements. For example, the optical path length adjuster system can include two or more pairs of reflective elements, wherein the extension of the second optical path between the reflective elements of each of the two or more pairs of reflective elements can be adjusted simultaneously by setting the spacing distance between the reflective elements equally. For example, the optical path length adjuster system can include multiple pairs of reflective elements, which are arranged relative to each other so as to define corresponding multiple parallel segments of the second optical path. Each of the two or more pairs of reflective elements can include a movable reflective element, which can be moved together with the movable reflective elements of the remaining pairs of reflective elements. Therefore, an overall change in the optical path length difference can be achieved by modifying the spacing distance between the reflective elements of each of the two or more pairs of reflective elements by X / N, in particular in the optical path length of the second optical path, the value of the overall change is 2X, where N is the number of reflective element pairs. For the factor of 2, it must be remembered that each path segment is covered twice by the corresponding beam (once on the way towards the working field and once on the way back from the working field). For example, in the case of three pairs of reflective elements, by reducing the separation distance between the reflective elements of each of the three pairs of reflective elements by 150 mm, for example by shifting one reflective element of each of the three pairs together by 150 mm, the optical path length difference can be reduced by 900 mm, for example reflecting an increase in the working distance of 450 mm.

[0060] In this arrangement of reflective elements, the reflective elements of a first pair of reflective elements of a first segment of the second optical path formed therebetween can be arranged to be rotated 90° with respect to the reflective elements of an adjacent pair of reflective elements of a second segment of the second optical path formed therebetween, the second segment being parallel to the first segment. Similarly, the reflective elements of a third pair of reflective elements of a third segment of the second optical path formed therebetween, parallel to the first segment and the second segment, can be arranged to be rotated 90° with respect to the reflective elements of the second pair of reflective elements, and so on.

[0061] In a preferred embodiment, the optical path length adjuster system may include at least one pair of tilted reflective elements, in particular one or two pairs of such reflective elements, each pair being configured to reflect the laser light multiple times along the second optical path at its reflective surface, wherein the reflective surfaces of each of the reflective elements of each of the at least one pair of tilted reflective elements may face each other and may be angled relative to each other, for example 5° to 20°, preferably 10° to 15°. By setting the relative position between the tilted reflective elements, preferably by moving one or two of the tilted reflective elements, the extension of the second optical path (geometric path length) between the tilted reflective elements of each of the at least one pair of mutually tilted reflective elements may be adjusted. Moving one or two of the tilted reflective elements may in particular include tilting or shifting the one or two of the tilted reflective elements. In this context, a pair of tilted reflective elements may refer to two reflective elements, such as mirrors, which may be arranged in front of each other so as to form an angle between them, i.e., not parallel.

[0062] The two tilted reflective elements can in particular be arranged symmetrically with respect to a symmetry axis arranged between the two reflective elements. In other words, the two tilted reflective elements can be angled so that the light beam can be reflected back and forth several times between the reflective surfaces of the two reflective elements, from the first reflection when the light beam is first incident on one of the tilted reflective elements to the last reflection of the light beam by one of the tilted reflective elements.

[0063] Since the two reflective elements in a pair of tilted reflective elements are angled relative to each other, the laser can be reflected back and forth multiple times from one of the reflective elements to the other between the two reflective elements, and reflected back between the first reflection and the last reflection of the laser at the pair of tilted reflective elements. In particular, the two reflective elements of each pair of tilted reflective elements can be configured to reflect the light beam of the laser incident on the pair at each reflective surface 2 times, 4 times, 6 times, 8 times, 10 times or more. Therefore, each single pair of tilted reflective elements can be functionally operated as a plurality of the aforementioned reflective element pairs with paired parallel reflective surfaces. By moving one or two tilted reflective elements in the pair of tilted reflective elements relative to another tilted reflective element, the distance through which the light beam multiplied by the pair of tilted reflective elements propagates can be adjusted. The distance can be increased, for example, by increasing the spacing distance between the two tilted reflective elements or by increasing the relative angle between the two tilted reflective elements. On the contrary, the distance can be reduced by reducing the spacing distance between the two tilted reflective elements or by reducing the angle between the two tilted reflective elements.

[0064] Due to the multiple reflections of the laser light between each two reflective elements of each pair of tilted reflective elements, a small movement of one of the reflective elements in a pair of tilted reflective elements may be sufficient to achieve a relatively large adjustment of the optical path length of the second optical path. For example, if the two reflective elements of a pair of tilted reflective elements are configured to reflect a laser beam incident on the pair 4 times at each reflective surface, an increase in the distance D between the two reflective elements of the pair may result in an increase in the optical path length of the second optical path by the order of k D, where k may be an integer having a value from 4 to 12 or more, depending on the arrangement and / or the direction of movement.

[0065] In some preferred embodiments, the optical path length adjuster system may include at least one pair of refractive elements configured to transmit the laser light along the second optical path therethrough. By setting the relative positions of the refractive elements, in particular by shifting one or both of the refractive elements relative to each other, preferably by shifting both of the refractive elements relative to each other, the extension of the second optical path (i.e., the geometric path length) through the refractive element of each of the at least one pair of refractive elements may be adjusted. By shifting the two refractive elements relative to each other, an uncontrolled shift in the direction of the measuring beam due to refraction at one of the refractive elements may be compensated and avoided.

[0066] By means of such a refractive element, the optical path length of the second optical path can be modified by modifying the refractive index (see n in the above equation for OPL) of the medium through which the light propagates along the second optical path. The refractive element may comprise a refractive optical element, such as a lens, a prism and / or a wedge. For example, each pair of refractive elements may comprise two polygonal prisms, which are arranged adjacent to each other via one of their outer surfaces, which surfaces may in particular be arranged obliquely relative to the second optical path, so that the extension of the second optical path through the two refractive elements may be modified by shifting the refractive elements relative to each other, thereby modifying the portion of the corresponding face where the two refractive elements overlap. The refractive index of the refractive elements of the at least one pair of refractive elements may in particular be greater than the refractive index of air (i.e., n>1) or higher than the refractive index of other parts of the second optical path.

[0067] In a preferred embodiment of the present application, the measuring module may further include a distance detection device, which is optically coupled to the connection port and configured to perform distance detection based on interference of laser light received by the distance detection device from the first optical path and laser light received by the distance detection device from the second optical path. The distance detection device may specifically include an interference sensor or may be connected to an interference sensor, which is configured to detect and analyze interference of laser light received from the first optical path and the second optical path.

[0068] The distance detection device and the measurement module may be independent of each other in structure. For example, each of the distance detection device and the measurement module may be surrounded by a corresponding housing.

[0069] In a preferred embodiment of the present application, the measurement module may further include a monitoring port and an optical element, wherein the optical element may be configured to reflect a first portion of the laser light propagating along the second optical path, and to transmit a second portion of the laser light propagating along the second optical path, so that the first portion or the second portion is extracted from the second optical path and directed toward the monitoring port. The laser light may correspond to a monitoring laser beam for monitoring the laser processing performed by the laser processing module, to which the measurement module may be connected. The monitoring port may then be used to connect an optical monitoring device to obtain information about the laser processing performed using the laser processing module, to which the measurement module of the present application may be connected, as further explained below. The monitoring laser beam may be generated by the optical monitoring device and may co-propagate with the measurement beam at least on a portion of the second optical path. The optical element, which may in particular be a dichroic element or include a dichroic element, such as a dichroic filter, may correspond to one of the reflective elements of the measurement module, in particular to one of the reflective elements of the optical path length adjuster system. The monitoring port and the optical element may be configured to extract the first portion or the second portion from the second optical path at a position of the second optical path between the optical path length adjuster system and the connection port. For example, in an embodiment comprising a focusing device arranged in the second optical path between the connection port and the optical path length adjuster system, the monitoring port and the optical element may be configured to extract the first portion or the second portion from the second optical path at a location in the second optical path between the focusing device and the connection port. This allows extracting light for monitoring purposes in a manner that is insensitive to variations in the length of the second optical path, in particular in a manner that is insensitive to the expected variations and the unexpected variations mentioned previously.

[0070] As mentioned above, the measuring module and the distance detection device can be combined to realize an interferometer, wherein the first optical path and the second optical path correspond to the reference arm and the object arm of the interferometer, respectively. The distance detection device, in particular its interference sensor, can be configured to detect the interference of the laser beam corresponding to the reference arm with the laser beam corresponding to the object arm, so as to perform distance detection based thereon in a manner known to those skilled in the art according to conventional interferometric measurement techniques.

[0071] Therefore, the second aspect of the present application relates to an interferometer system, which includes a measurement module, a distance detection device and a connection port. The measurement module can correspond to the measurement module of any one of the aforementioned embodiments according to the first aspect of the present application, and the distance detection device can correspond to the distance detection device according to the aforementioned embodiments.

[0072] In any case, the measurement module of the interferometer system according to the second aspect of the present application defines a first optical path corresponding to the reference arm of the interferometer system and a second optical path corresponding to the object arm of the interferometer system. The measurement module includes an optical reflector arranged in the first optical path for reflecting back the laser light received along the first optical path. In addition, the measurement module includes an optical path length adjuster system configured to adjust the optical path length of the second optical path, i.e., the optical path length of the object arm of the interferometer system.

[0073] The coupling port of the interferometer system according to the second aspect of the application is configured to optically couple the second optical path with the laser processing module, in particular with its measurement beam path, as explained in more detail above and below.

[0074] The distance detection device is configured to perform distance measurement based on interference of laser light transmitted along the first optical path and laser light transmitted along the second optical path.

[0075] According to a preferred embodiment, the measurement module may further comprise a beam rotation element arranged along the second optical path, preferably between the optical path length adjuster system and the coupling port. The beam rotation element may be capable of rotating around an axis corresponding to the optical axis of the second optical path. The beam rotation element may be or include one or more rotatable wedge prisms. The beam rotation element may be configured to modify the effective optical path length of the second optical path differently at different positions around the optical axis and / or around the periphery of the beam rotation element. Thus, the beam rotation element may allow a laser beam propagating along the second optical path, in particular a measuring beam of a laser system including a laser module, to be rotated around a center point corresponding to the optical axis, thereby implementing a seam tracking function on the work site. The beam rotation element may be operated, for example, to analyze the vicinity of the point using the measuring beam before and / or after laser processing of a point on the work site using the working beam, for example during a laser welding process.

[0076] The third aspect of the present application relates to a laser processing device, which includes a laser processing module and a measuring module according to any embodiment of the first aspect of the present application. The laser processing module is configured to use a working beam to laser process a workpiece on a work field. The working beam can be a laser beam that is independent of the laser transmitted in the measuring module, in particular, through the second optical path of the measuring module. The measuring module is optically connected to the laser processing module through its connection port, and is used to receive laser light from the laser processing module in the form of a measuring beam and output laser light to the laser processing module.

[0077] The laser processing module includes an optical element for reflecting one of the working beam and the measuring beam, and for transmitting the other of the working beam and the measuring beam through the optical element. For example, the optical element can be configured to reflect light in a wavelength range corresponding to the working beam, and for transmitting light in a wavelength range corresponding to the measuring beam. Alternatively, the optical element can be configured to transmit light in a wavelength range corresponding to the working beam, and for reflecting light in a wavelength range corresponding to the measuring beam. The optical element can, for example, include a dichroic element, such as a dichroic filter.

[0078] The measuring beam may correspond to light in the infrared part of the spectrum, in particular with a wavelength in the range of 700 nm to 1400 nm, preferably from 800 nm to 1000 nm, more preferably from 815 nm to 850 nm, for example 830 nm. The working beam may correspond to light in a wavelength range different from - possibly greater or less than - the wavelength range corresponding to the measuring beam. Thus, the optical element of the laser processing module is transmissive for part of the spectrum, in particular part of the infrared spectrum, and reflective for the rest of the spectrum or at least for part thereof. As a result, the measuring beam and the working beam may propagate separately on one side of the optical element before being reflected at the optical element or transmitted through the optical element, while they may propagate along the same optical path on the other side of the optical element after being reflected at the optical element or transmitted through the optical element.

[0079] The laser processing module further comprises a deflection unit configured to deflect the working beam and the measuring beam to and from the workpiece and / or the working field. The deflection unit may, for example, comprise a pair of rotatable mirrors tiltable about mutually orthogonal axes, i.e. a so-called XY scanning unit, possibly comprising corresponding galvanometers. The deflection unit may be configured to controllably scan the measuring beam and the working beam over the working field, where the workpiece to be laser processed by the laser processing module may be arranged.

[0080] The deflection unit can be arranged after the optical element along the optical path of the measuring beam and the working beam. Thus, the working beam and the measuring beam can be deflected by the deflection unit towards corresponding target points of the working field after being transmitted through the optical element or reflected at the optical element.

[0081] In the laser processing module, a working beam path and a measuring beam path are defined for the working beam and the measuring beam, respectively. The working beam path is defined so that the working beam can be reflected / transmitted by the optical element toward the deflection unit and deflected by the deflection unit to the workpiece and / or the working field.

[0082] The measuring beam propagates in the measuring module along a second optical path of the measuring module. In addition, the measuring beam path is defined such that the measuring beam propagates from the connection port of the measuring module to the optical element and the deflection unit and returns to the connection port, is transmitted / reflected by the optical element to and from the deflection unit, is deflected by the deflection unit to and from the workpiece and / or the working field, and is reflected back at the workpiece and / or the working field. Thus, the measuring beam path and the second beam path can be considered as different parts of the entire optical path of the measuring beam propagating in the laser processing module and the measuring module, respectively.

[0083] Thus, the working beam first propagates from an input (or from a corresponding light source), where the working beam can be fed to a laser processing module, to an optical element, where the working beam is reflected or transmitted toward a deflection unit, which then deflects the working beam toward a corresponding target point on the workpiece and / or on the work field to laser process the working material by transmitting thermal energy to the working material.

[0084] The measuring beam corresponds to the laser light fed into the measuring module through the connection port and propagating along its second optical path, including through the optical path length regulator system, and then entering the laser processing module through the connection port towards the optical element, where the measuring beam is respectively transmitted or reflected (if the working beam is reflected, the measuring beam can be transmitted, and if the measuring beam is reflected, the working beam can be transmitted) towards the deflection unit, which deflects the measuring beam in the same direction as the working beam used to perform measurement, such as distance measurement.

[0085] Therefore, the working beam and the measuring beam have a common path between the optical element and the workpiece. At the point of the workpiece on which the measuring beam is incident, the measuring beam is at least partially reflected back toward the deflection unit, then deflected back toward the optical element, and transmitted or reflected toward the connection port as the case may be, through which the measuring beam re-enters the measurement module, propagates back along the second optical path, and reaches the connection port to be transmitted to the detection device, where the interference of the measuring beam with the laser propagating along the first optical path of the measurement module can be analyzed to perform distance detection.

[0086] Advantageously, the measuring module allows adjusting the optical path length of the measuring beam in order to keep the optical path length substantially constant, e.g. at a predetermined value, regardless of variations in the total optical path length over which the measuring beam propagates, e.g. due to variations in the working distance of the laser processing module, wherein the working distance may be understood in this context as the minimum / shortest distance between the housing of the laser processing module and its working field. Thus, the technical advantages of the measuring module according to the first aspect of the application are exploited for use in a laser processing device.

[0087] In a preferred embodiment, the laser processing device may further include the above-mentioned distance detection device for the measurement module according to the first aspect of the present application. The distance detection device may be optically connected to the connection port of the measurement module, and may be configured to determine the change in the distance between the working field and / or the workpiece and the deflection unit based on the interference of the measurement beam with the laser propagating along the first optical path in the measurement module, in particular the change in the distance between the optical center of the reflector of the deflection unit closest to the working field and the position of the working field on which the measurement beam is incident. Additionally or alternatively, the distance detection device may be configured to determine the distance (expressed in absolute or relative terms) based on the interference of the measurement beam with the laser propagating along the first optical path in the measurement module.

[0088] Determining the working distance may include determining an absolute value of the working distance, such as 700 mm. Determining a change in the working distance may include determining a change in the working distance, such as a change of 300 mm in the working distance when the working distance increases from 700 mm to 1000 mm; a change of 2.6 mm to 7 mm in the working distance due to a change in the deflection angle of 5° (e.g., relative to a deflection angle of 0° when the working distance is 700 mm); or a change in the distance of 50 μm to 10 mm due to surface irregularities of the outermost surface of the working material of the workpiece being laser processed. The distance detection device may be a component of the laser processing apparatus that allows distance measurements to be performed using a measuring beam transmitted through a measuring module, which distance measurements may then be used to control the laser processing module and / or the measuring module accordingly.

[0089] As used herein, a "control unit" may refer to a hardware-based unit or a software-based unit, possibly including a processing unit, specifically configured to control another entity or device described herein. The control unit may, for example, be a control card or module or be included in a control card or module, such as a SP-ICE control card.

[0090] The information obtained by the distance detection device, in particular information related to the distance or the change in distance, can be used to control the laser processing device based on this information, for example, to correctly focus the working beam on the work field and / or the workpiece taking into account real-time information about the actual distance between the deflection unit of the laser processing device and the work field and / or the workpiece.

[0091] According to a preferred embodiment, the laser processing device may further include a control unit configured to control the optical path length adjuster system of the measuring module based on a change in the working distance of the laser processing module. The working distance may refer in this context to the minimum distance (possibly vertical) between the working field, in particular its center, and the laser processing module, such as its housing. This distance change may be detected by the aforementioned distance detection device. However, this is not necessary, as the change in the working distance may also be detected in other ways, such as via direct communication with an adjustable table that can be configured at different heights for achieving different working distances or via user input.

[0092] The control unit or another control unit may also be configured to compensate for the change in the optical path length of the measuring optical path caused by the change in the working distance by controlling the optical path length adjuster system to correspondingly adjust the optical path length of the second optical path, for example by correspondingly moving one or more reflective elements and / or refractive elements in the optical path length adjuster system. As a result of the change in the working distance of the laser processing module, for example, when the laser processing module is to be used for a different use than previously, a different size of the working field may be required, the working field may be closer to or further away from the laser processing module, which means that the optical path length of the measuring beam path may be correspondingly shorter or longer than before the change in the working distance. The control unit or another control unit may be configured to control the optical path length adjuster system to adjust the optical path length of the second optical path so as to compensate for the change caused by the change in the working distance. For example, if the working distance has increased by an amount D, the control unit may control the optical path length adjuster system to shorten the optical path length of the second optical path by an amount D. As a result, the optical path length of the measuring beam path may be substantially the same as the optical path length before the change in the working distance.

[0093] The control unit or another control unit (different from the aforementioned control unit) can also be configured to control the optical path length adjustment system of the measuring module based on a change in the deflection setting of the deflection unit of the laser processing module, for example based on a change in the deflection angle. This distance change can be detected by the aforementioned distance detection device. However, this is not necessary, because the change in the deflection setting of the deflection unit of the laser processing module can also be detected in other ways, for example via direct communication with the deflection unit or via user input.

[0094] The control unit or another control unit may also be configured to compensate for the change in the optical path length of the measuring beam path caused by the change in the deflection setting of the deflection unit by correspondingly adjusting the optical path length of the second optical path by controlling the optical path length adjuster system, for example by correspondingly moving one or more reflective elements and / or refractive elements in the optical path length adjuster system. For example, as previously described, if the deflection angle is increased to deflect the measuring beam and / or the working beam to a position on the working field away from the center of the working field (corresponding to a deflection angle of 0°), the optical path length of the measuring beam path is effectively increased (see the formula provided above for ΔD). The control unit or another control unit may then be configured to control the optical path length adjuster system of the measuring module to modify the optical path length of the second optical path so that, in the present exemplary case, this change is compensated by correspondingly shortening the optical path length of the second optical path. As a result, the optical path length of the measuring beam path before the change in the deflection setting of the deflection unit can be restored.

[0095] According to a preferred embodiment, the control unit or another control unit (different from the aforementioned control unit) can be configured to control the optical path length adjuster system of the measuring module based on the distance determined by the distance detection device and / or the change of the distance determined by the distance detection device. The control unit can allow the optical path length of the second optical path of the measuring module to be adjusted according to such distance and / or such change of the distance determined by the detection device. For example, the optical path length adjuster system can be controlled based on the detection of a 1 mm irregularity / protrusion of the surface of the workpiece being laser processed by the distance detection device, so as to correspondingly adjust the optical path length of the second optical path by 1 mm.

[0096] According to a preferred embodiment, the laser processing device, in particular the laser processing module, may further include a working beam focusing device configured to focus the working beam. Preferably, the working beam focusing device may be configured to focus only the working beam, i.e., not the measuring beam, which may be focused by a dedicated focusing device included in the measuring module according to the present application. Preferably, the measuring beam may not propagate through the working beam focusing device.

[0097] The working beam focusing device may have a variable focal length and may preferably be arranged in the working beam path between the optical element and a source or input of the working beam, from which the working beam may be generated. This means that the laser processing module may correspond to a pre-focusing laser processing module, for example a pre-focusing laser processing module similar to that described in WO2018 / 078137A1. The above-mentioned control unit (or another control unit) may be configured to control the pre-focusing device, possibly based on a distance and / or a change in distance determined by a distance detection device. Additionally or alternatively, the laser processing device, in particular the laser processing module, may include an f-θ lens configured to focus the working beam.

[0098] In a preferred embodiment of the present application, the measuring module may comprise the above-mentioned focusing device for the measuring module of the first aspect of the present application, the focusing device being configured to focus the measuring beam on the working field and / or on the workpiece, in particular at a position corresponding to the focal point of the working beam. By keeping the focus on the working field and / or on the workpiece, the measuring beam allows to perform distance measurements with an optimized signal-to-noise ratio and improved accuracy, even for large deflection angle values, due to the compensation allowed by the focusing device and the optical path length adjuster system.

[0099] According to a preferred embodiment, the measuring beam may be formed by light having a wavelength range from 700 nm to 1400 nm, preferably from 800 nm to 1000 nm, more preferably from 815 nm to 850 nm, for example 830 nm. In addition, the working beam may be formed by light having a wavelength range different from the wavelength range of the measuring beam, for example from 1000 nm to 1100 nm, possibly using a YAG laser. However, the working beam may be formed by light in other wavelength ranges, such as from 500 nm to 550 nm.

[0100] In a preferred embodiment, the minimum distance between the working field and the laser processing module, in particular the housing of the laser processing module, i.e. the working distance, can vary within a range from 200 mm to 1200 mm, preferably from 250 mm to 750 mm, more preferably from 300 mm to 700 mm. As previously mentioned, the optical path length adjuster system of the measuring module can be configured to achieve compensation of the optical path length of the measuring beam, which is transmitted along the second optical path, corresponding to these ranges.

[0101] The size of the working field associated with the laser processing module can be from 200×200 mm 2 Up to 1400×1400mm 2 The size of the working field can vary within a range, especially as a function of the working distance. The size of the working field can be proportional to the working distance. For example, 250×250mm 2The working field size can be associated with a working distance of 250 mm, while a working distance of 1000 mm can be associated with 850×850 mm 2 The working field size is associated with the working field size. It is worth noting that the working field can be square, but this is not necessary. According to other related embodiments, the working field can be rectangular, polygonal or circular.

[0102] In a preferred embodiment of the present application, the measuring module may include the above-mentioned housing for the first aspect of the present application, and the laser processing module may include another housing that surrounds at least some of the remaining components of the laser processing module. The working beam path and the measuring beam path may be at least partially defined within the housing of the laser processing module. In particular, the working beam path may be completely included in the housing of the laser processing module. The measuring beam may be partially included in the housing of the laser processing module and partially included in the housing of the measuring module, wherein the portion of the measuring beam included in the housing of the measuring module corresponds to the second optical path of the measuring module.

[0103] A further connection port connectable to the connection port of the measuring module may be formed by the housing of the laser processing module.Preferably, the housing of the laser processing module may be fluid-tight and / or dust-proof, in particular according to IP64.

[0104] Preferably, the measuring module and the laser processing module can be attached to each other, in particular mechanically. The housing of the measuring module can be attached to the housing of the laser processing module, in particular such that the measuring module can be arranged adjacent to the laser processing module. When the laser processing module and the measuring module are attached to each other, the measuring module, in particular the second optical path, can be optically coupled to the laser processing module via a coupling port of the measuring module and a (further) coupling port of the laser processing module. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Figure 1 A schematic diagram of a measurement module including a movable reflective element according to some embodiments of the present application is shown.

[0106] Figure 2 Shown in the modification Figure 1 After the reflective element of the measurement module is positioned to modify the optical path length of the second optical path Figure 1 Measurement module.

[0107] Figure 3 A schematic diagram of a measurement module including a movable refractive element according to some embodiments of the present application is shown.

[0108] Figure 4 Shown in the modification Figure 3After the position of the refractive element of the measurement module is modified to the optical path length of the second optical path Figure 3 Measurement module.

[0109] Figure 5 A schematic diagram of a measurement module including a pair of tilted reflective elements according to some embodiments of the present application is shown.

[0110] Figure 6 A schematic diagram of a measurement module including a movable reflective element and two pairs of tilted reflective elements according to some embodiments of the present application is shown.

[0111] Figure 7 The embodiment according to the present application includes Figure 3 and Figure 4 Schematic diagram of the laser processing device showing the measurement module.

[0112] Figure 8 The embodiment according to the present application includes Figure 3 and Figure 4 Another schematic diagram of the laser processing device of the measurement module shown.

[0113] Fig. 9 A schematic diagram of a laser processing device according to an embodiment of the present application is shown.

[0114] Fig.10 shows a beam rotation element Figure 3 An embodiment of the measurement module is shown.

[0115] Fig.11 shows a beam rotation element Fig. 9 An embodiment of the laser processing device is shown. DETAILED DESCRIPTION

[0116] In order to promote the understanding of the principles of the present application, reference will now be made to the specified preferred embodiments shown in the drawings, and the embodiments will be described using the specified language. However, it should be understood that the scope of the present application is not intended to be limited thereby, and within the scope defined by the claims, such changes and further modifications in the illustrated devices and further applications of the principles of the present application are conceivable to those skilled in the art to which the present application relates, and such changes and further modifications are within the scope defined by the claims.

[0117] Figure 1A schematic diagram of a measuring module 10 according to an embodiment of the present application is shown. The measuring module 10 comprises a housing 11 in which a connection port 12 and a coupling port 14 are formed. The connection port 12 allows the measuring module 10 to be optically coupled to a distance detection device. The coupling port 14 allows the measuring module 10 to be optically coupled to a laser processing module of a laser processing device, wherein the measuring module 10 can be integrated in the laser processing device.

[0118] The measurement module 10 defines a first optical path PI and a second optical path P2 for laser light received and output through the connection port 12. The first optical path PI and the second optical path P2 may be considered as a reference arm and an object arm, respectively, of an interferometric setup.

[0119] The first optical path P1 is defined between the connection port 12 and the reference optical reflector 16. The reference optical reflector 16 may be, for example, a fixed mirror configured to determine the optical path length of the first optical path according to a predetermined value. Figure 1 In the illustrated embodiment, the first optical path P1 includes an optional optical fiber F1, through which the laser light input and output through the connection port 12 propagates to and from the reference optical reflector 16, where the laser light is reflected back. Therefore, the first optical path P1 has a fixed optical path length.

[0120] The second optical path P2 is defined between the connection port 12 and the coupling port 14. The laser light received through the connection port 12 propagates from the connection port 12 to the coupling port 14, and returns to the connection port 12 through the second optical path P2.

[0121] The measuring module 10 further comprises an optical path length adjuster system 20. A portion of the second optical path P2 extends through the optical path length adjuster system 20, which is configured to adjust the optical path length of the second optical path P2. Thus, the second optical path P2 has a variable optical path length that can be adjusted by the optical path length adjuster system 20. By adjusting the optical path length of the second optical path P2, the optical path length adjuster system 20 can adjust the optical path length difference between the fixed optical path length of the first optical path P1 and the variable optical path length of the second optical path P2, thereby affecting the interferometric measurement performed using the first optical path P1 and the second optical path P2 as the reference arm and the object arm of the interferometric setup, respectively, in particular so that the difference can remain constant despite the presence of other sources of geometric or optical distance variability relative to the outside of the measuring module 10 and / or so that the object to be detected for distance measurement remains within a measurement range, wherein within this range the distance detection device used guarantees a predefined measurement accuracy.

[0122] exist Figure 1 In the illustrated embodiment, the second optical path P2 includes an optional optical fiber F2, through which the laser light input and output through the connection port 12 propagates between the connection port 12 and the optical path length adjuster system 20. In addition, in this exemplary embodiment, the measurement module 10 includes a focusing device 18, which is arranged between the connection port 12 and the optical path length adjuster system 20 in the second optical path P2 and is configured to set the focal position of the laser beam propagating through the second optical path P2. The focusing device 18 preferably has a fixed focal length.

[0123] exist Figure 1 In the illustrated embodiment, the optical path length adjuster system 20 includes three pairs of mirrors for reflecting laser light along the second optical path P2. The first pair of mirrors 22a, 22b, the second pair of mirrors 22c, 22d and the third pair of mirrors 22e, 22f respectively define three mutually parallel portions of the second optical path P2. The first portion of the second optical path P2 extending between the mirrors 22a and 22b is parallel to the second portion of the second optical path P2 extending between the mirrors 22c and 22d and the third portion of the second optical path P2 extending between the mirrors 22e and 22f.

[0124] The reflectors 22a to 22f are arranged so that the reflective surfaces of each pair of reflectors are parallel to and opposite to each other, that is, the reflective surfaces of the reflectors 22a and 22b are parallel to and opposite to each other, and the reflective surfaces of the reflectors 22c and 22d and the reflective surfaces of the reflectors 22e and 22f are also parallel to and opposite to each other, wherein the reflective surfaces of the reflectors 22c and 22d are rotated 90° clockwise relative to the reflective surfaces of the reflectors 22a and 22b, respectively, and wherein the reflective surfaces of the reflectors 22e and 22f are oriented as the reflective surfaces of the reflectors 22a and 22b, respectively.

[0125] The measuring module 10 further comprises an additional reflector 23 configured to direct the second optical path P2 from the optical path length adjuster system 20, in particular the second optical path P2 from the reflector 22F, towards the coupling port 14. Figure 1 In the embodiment, the reflective surface of the reflector 23 is oriented as the reflective surface of the reflector 22d, so that the laser light propagating through the second optical path P2 continues to be guided to and from the connection port 14 regardless of the position of the movable reflectors 22b, 22d, 22f and 23.

[0126] Figure 1Each of the three pairs of reflectors of the measurement module 10 of the illustrated embodiment includes a fixed reflector and a movable reflector. The positions of the reflectors 22a, 22c and 22e are fixed, while the reflectors 22b, 22d and 22f are movable relative to the fixed reflectors 22a, 22c and 22e so as to adjust the respective distances between the corresponding fixed reflectors 22a, 22c and 22e and the corresponding movable reflectors 22b, 22d and 22f. The mirror 23 is also movable. Figure 1 In the illustrated embodiment, the movable mirrors 22b, 22d, 22f and 23 can be moved simultaneously and together by the same distance, so that the mirrors of each of the three mirror pairs mentioned above are arranged at the same mutual distance, wherein the distance can be selectively reduced or increased by correspondingly setting the positions of the movable mirrors 22b, 22d, 22f and 23 in the horizontal direction.

[0127] If the movable mirrors 22b, 22d, 22f and 23 are moved away from the fixed mirrors 22a, 22c and 22e (for example, Figure 1 ), the optical path length of the second optical path P2 increases. In contrast, if the movable reflectors 22b, 22d, 22f, and 23 move toward the fixed reflectors 22a, 22c, and 22e (for example, in Figure 1 ), the optical path length of the second optical path P2 decreases. More specifically, Figure 1 In the exemplary embodiment of FIG. 1 , if the movable reflectors 22 b, 22 d, 22 f and 23 are away from the fixed reflectors 22 a, 22 c and 22 e (for example, Figure 1 The optical path length of the second optical path P2 increases by a distance 8D because the segment corresponding to the second optical path P2 and the bidirectional transmission of light from and to the connection port 12 along the second optical path P2 are taken into consideration, and thus the distance increment D is calculated twice for each of the movable reflectors 22b, 22d, 22f and 23.

[0128] Figure 2 The diagram shows a state of the measuring module 10, wherein the state is when the movable mirrors 22b, 22d, 22f and 23 have been moved relative to each other. Figure 1 After the situation in FIG. 1 is moved away from the fixed reflecting mirrors 22a, 22c and 22e so as to increase the optical path length of the second optical path P2.

[0129] For any embodiment of the measurement module 10 of the present application, the movement (e.g., translation and / or tilting) of the optical element of the optical path length adjuster system 20 can be achieved by a set of corresponding motor units (not shown in the figure), which may include a galvanometer configured to move the optical element of the optical path length adjuster system 20, for example, Figure 1 and Figure 2 The movable mirrors 22b, 22d, 22f and 23 are in the case of the embodiment shown.

[0130] exist Figure 1 and Figure 2 In the exemplary embodiment shown, the optical path length adjuster system 20 is configured to adjust the geometric optical path length of the second optical path P2 by correspondingly moving the movable mirrors 22b, 22d, 22f and 23, thereby adjusting the optical path length of the second optical path P2. This allows, for example, the optical path length of the second optical path P2 to be continuously adjusted within a range of optical path length variations from 40 μm to 750 mm. In some examples, the optical path length adjuster system 20 can allow the optical path length variation to be adjusted manually or using a stepper motor with an accuracy of ±5 mm. A finer adjustment can be achieved using a pressure gauge or a galvanometer.

[0131] Figure 3 1 shows a schematic diagram of a related embodiment of the measurement module 10 according to the present application, wherein the optical path length adjuster system 20 includes a pair of refractive elements 26a and 26b, and the second optical path P2 propagates through the refractive elements 26a and 26b. The refractive elements 26a and 26b can move relative to each other, such as Figure 3 . The optical path length adjuster system 20 can adjust the optical path length of the second optical path P2 by adjusting the length of the portion of the second optical path P2 extending through the refractive elements 26a, 26b, which have a refractive index higher than the refractive index of air, i.e., n>1 (or higher than the refractive index of other portions of the second optical path). In other related embodiments, only one of the refractive elements 26a, 26b can be moved relative to the other of the refractive elements 26a, 26b. However, as Figure 3 In the embodiment shown, the fact that both refractive elements 26a, 26b are movable can advantageously compensate and prevent uncontrolled deviations of the laser beam transmitted through the second optical path P2 caused by refraction.

[0132] Figure 4 The diagram shows the status of the measurement module 10, and Figure 3Compared with the case in FIG. 1 , this state is a state after the refractive elements 26a and 26b have been moved relative to each other so as to increase the optical path length of the second optical path P2. Figure 4 By moving the movable refractive elements 26a and 26b relative to each other as shown, the extension of the portion of the second optical path P2 extending through the refractive elements 26a and 26b, which portion has a refractive index higher than 1 (or higher than the refractive index of other portions of the second optical path), increases, thereby correspondingly increasing the optical path length of the second optical path P2. Similarly, by moving the movable refractive elements 26a and 26b relative to each other, the optical path length of the second optical path P2 can be reduced, thereby reducing the extension of the portion of the second optical path P2 extending through the refractive elements 26a and 26b.

[0133] exist Figure 3 and Figure 4 In the illustrated exemplary embodiment, the refractive elements 26a and 26b are triangular prisms that are arranged adjacent to each other through one of their outer surfaces, and they are arranged obliquely relative to the direction of the second optical path P2. By correspondingly adjusting the relative positions of the refractive elements 26a and 26b, the portion of the second optical path P2 extending through the refractive elements 26a and 26b can be adjusted, thereby modifying the portion of the adjacent surface where the refractive elements 26a and 26b overlap.

[0134] exist Figure 3 and Figure 4 In the illustrated exemplary embodiment, all components except the optical path length adjuster system 20 may be connected with respect to Figure 1 and Figure 2 The remaining elements described in the exemplary embodiment discussed are the same as or correspond to the same, and the same reference numerals are used for these elements. For the sake of brevity, these elements will not be explained again. It should also be noted that for ease of representation, the remaining figures are not explicitly indicated in the Figure 1 The positions of the first optical path P1 and the second optical path P2 are clearly indicated in FIG.

[0135] Figure 5A schematic diagram of yet another related embodiment of the measurement module 10 of the present application is shown, in which the optical path length adjuster system 20 is configured differently from the optical path length adjuster system 20 of the previously discussed embodiment. In this case, the measurement module 10 includes a plurality of fixed mirrors 21a, 21b, 21c, 21d and 23, at which the laser light is reflected along the second optical path P2. In addition, the optical path length adjuster system 20 includes a pair of tilted mirrors 24a, 24b, which are configured to multiply reflect the laser beam propagating through the second optical path P2 at their reflective surfaces.

[0136] The mirrors 24a and 24b are arranged so that their reflective surfaces face each other and are angled with each other, for example, forming an angle of about 8°, so that the laser beam propagating through the second optical path P2, in particular between the mirrors 20, 21c and 21d, is reflected back and forth multiple times between the mirrors 24a and 24b, such as Figure 5 For illustration purposes, Figure 5 The angle between the reflectors 24a and 24b is magnified in FIG.

[0137] In this case, the optical path length adjuster system 20 can adjust the optical path length of the second optical path P2 by setting the relative position between the two tilted reflective elements 24a and 24b, for example by moving the reflector 24a relative to the reflector 24b, such as Figure 5 As shown by the arrows in FIG. 24 . The reflector 24 b may also be movable or may be fixed. When the reflectors 24 a and 24 b are moved relative to each other, the length of each of the multiple segments of the second optical path P2 extending between the reflectors 24 a and 24 b is modified accordingly. Since the beam of laser light transmitted along the second optical path P2 is reflected multiple times between the inclined reflectors 24 a and 24 b, it can be transmitted through the inclined reflectors 24 a and 24 b. Figure 5 In an embodiment comprising a plurality of movable mirrors, for example Figure 1 and Figure 2 In the embodiment illustrated in FIG. 2 , overall adjustment of the optical path length of the second optical path P2 is achieved.

[0138] Front relative to Figures 1 to 5 The use of different reflective elements and refractive elements discussed in the illustrated embodiments is not mutually exclusive, and a person skilled in the art will appreciate that different types of reflective elements and / or refractive elements disclosed herein may be arbitrarily combined in a measurement module according to the present application. In particular, this means that the above relative Figures 1 to 5The different configurations of the optical path length adjuster system 20 discussed in the illustrated exemplary embodiments may be combined with one another. Figure 6 FIG. 1 shows a schematic diagram of a measurement module 10 according to another embodiment of the present application, wherein an optical path length adjuster system 20 integrates a set of movable mirrors and two pairs of tilted mirrors. Figure 1 and Figure 2 In the embodiment of the present invention, a system of reflectors is used, wherein the tilted reflectors are similar to Figure 5 An embodiment of a pair of tilted mirrors.

[0139] exist Figure 6 In the measurement module 10 shown, the optical path length adjuster system 20 includes a plurality of movable mirrors 22b, 22d, 22f and 22h, a plurality of static mirrors 21a, 21c, 21e and 23 and two pairs of tilted mirrors 24-1 and 24-2. Therefore, the optical path length adjuster system 20 of the present embodiment can adjust the optical path length of the second optical path P2 in different ways.

[0140] exist Figure 6 In the embodiment of the present invention, a first way to adjust the optical path length of the second optical path P2 is by modifying the position of the movable mirrors 22b, 22d, 22f and 22h, which results in a corresponding modification of the optical path length of the second optical path P2. The movable mirrors 22b, 22d, 22f and 22h can be moved together in the same direction at the same time. If the block including the movable mirrors 22b, 22d, 22f and 22h is shifted in the horizontal direction by a distance D, as shown in FIG. Figure 6 As shown by the arrow in the middle, the optical path length of the second optical path P2 is correspondingly modified by a distance 8D (4D in the forward direction and 4D in the backward direction).

[0141] exist Figure 6 In the illustrated embodiment, a second way to adjust the optical path length of the second optical path P2 is by using two pairs of tilted mirrors 24-1 and 24-2. The first pair of tilted mirrors 24-1 includes a fixed mirror 24-1b and a movable mirror 24-1a. The second pair of tilted mirrors 24-2 includes a fixed mirror 24-2b and a movable mirror 24-2a. The movable mirrors 24-1a and 24-2a can move together, simultaneously and / or in the same direction as appropriate.

[0142] In relation to Figure 1-Figure 6 In any of the exemplary embodiments of the measuring module 10 described, the housing 11 is preferably fluid-tight and / or dust-proof, in particular according to IP64.

[0143] Figure 7 A schematic diagram of a laser processing device 1 according to the present application is shown, which includes a laser processing module 30, a measuring module 10 and a distance detection device 40. The laser processing module 30 is configured to laser process a workpiece P, which is arranged on a working field 37 associated with the laser processing module 30. The working field 37 may be defined on a movable table, which is configured to hold the workpiece P and / or a working material layer for forming the workpiece P, possibly at different configurable heights relative to the laser processing module 30.

[0144] The workpiece may be, for example, an object additively manufactured by the laser processing module 30 , or an electronic device or device component, such as a battery or a battery component, wherein the laser processing module 30 may implement a laser welding process.

[0145] The laser processing module 30 is configured to laser process a workpiece on the work field 37 by scanning a laser working beam W on the work field 37, thereby thermally interacting with a working material for manufacturing the workpiece. The working beam W is input into the laser processing module 30 via an input 38. In other related embodiments, the input 38 may include or may be replaced by a laser source for generating the working beam W.

[0146] The laser processing module 30 includes an optical element 32, such as a dichroic mirror, which is reflective for the working beam W and is configured to reflect the working beam W toward a deflection unit 34, which is configured to scan the working beam W on a working field 37 through a laser transparent window 33 formed in a housing 31 of the laser processing module 30. The deflection unit 34 includes a pair of XY-movable mirrors 34a and 34b. The housing 31 surrounds the remaining components of the laser processing module 30.

[0147] The measuring module 10 of the device 1 may correspond to the measuring module 10 according to any embodiment of the present application, in particular according to the above with respect to Figure 1-Figure 6 The measurement module 10 of any of the exemplary embodiments discussed. Figure 7 In the specified exemplary embodiment shown, the measurement module 10 corresponds to Figure 3 and Figure 4 , but this should be understood as a non-limiting example.

[0148] The measuring module 10 is optically coupled to the laser processing module 30 via the coupling port 14 and via a corresponding coupling port 39 of the laser processing module 30, wherein the coupling port 39 is formed by the housing 31 of the laser processing module 30. The housing 31 may be fluid-tight and / or dust-proof, in particular according to IP64.

[0149] The measuring module 10 is mechanically coupled to the laser processing module 30 by a mechanical coupling between the housing 11 of the measuring module 10 and the housing 31 of the laser processing module 30 , so that the measuring module 10 is arranged adjacent to the laser processing module 30 .

[0150] like Figure 7 As shown, the laser beam propagating through the second optical path P2 of the measuring module 10 is optically coupled to the laser processing module 30 through the coupling port 14 and the coupling port 39 in the form of the measuring beam M, and the measuring beam M is transmitted toward the deflection unit 34 of the laser processing module 30 through the optical element 32. Therefore, the deflection unit can scan both the working beam W and the measuring beam M on the working field 32. The dichroic mirror 32 is transmissive to the measuring beam M.

[0151] According to some examples, the working beam may be formed by a laser having a wavelength of 1000 nm to 1100 nm, and the measuring beam may be formed by a laser having a wavelength of 810 nm to 850 nm. Figure 7 In the embodiment shown, the dichroic mirror is reflective for wavelengths from 1030 nm to 1090 nm and transmissive for wavelengths from 400 nm to 950 nm.

[0152] The distance detection device 40 is optically coupled to the connection port 12 of the measurement module 10. In the exemplary embodiment shown, the distance detection device 40 includes a laser light source for generating coherent laser light for generating a laser beam propagating along the first optical path P1 and the second optical path P2 of the measurement module 10. In addition, the distance detection device 40 includes an interferometric sensor configured to perform distance detection measurement based on interference of the laser light propagating through the first optical path P1 of the measurement module 10 and the laser light propagating through the second optical path P2 of the measurement module 10 (corresponding to the measurement beam M).

[0153] Thus, the distance detection device 40 and the measuring module 10 in combination realize an interferometer system, wherein the first optical path P1 forms a reference arm of the interferometer system, and the second optical path P2 forms an object arm of the interferometer system. Due to the configuration of the measuring module 10, the reference arm of the interferometer system has a fixed optical path length, while the optical path length of the object arm can be adjusted by the optical path length adjuster system 20 of the measuring module 10, wherein the measuring beam M follows the optical path length of the object arm.

[0154] The laser light transmitted through the connection port 14 between the measuring module 10 and the laser processing module 30 forms a measuring beam M which is used in the laser processing apparatus 1 , in particular, by the distance detection device 40 , to perform distance measurement.

[0155] After reaching the workpiece P and / or the working field 37, the measuring beam M is reflected back through the deflection unit 34 and through the optical element 32 into the measuring module 10, where the measuring beam M propagates again along the second optical path P2 (backwards) into the distance detection device 40. Based on an interference comparison between the measuring beam M received through the second optical path P2 and the corresponding beam of laser light propagating along the first optical path P1, the distance detection device 40 can perform a distance measurement, for example to determine a change in the distance between the workpiece P and / or the working field 37 and the deflection unit 34. Additionally or alternatively, the distance detection device 40 can be configured to determine an absolute value of such a distance.

[0156] Different distances related to the laser processing of the workpiece P by the laser processing module 30 can change during the laser processing process. For example, the working distance WD corresponding to the minimum distance between the working field 37 or the workpiece P and the laser processing module 30 can change. For example, the laser processing device 1 can be used for a working distance WD=200mm for a first purpose, and a working distance WD=1000mm for a second purpose different from the first purpose. As a result, the working field 37 and / or the workpiece P may no longer be within the optical distance range of the distance detection device 40, where the distance detection device 40 guarantees distance detection with a given accuracy. The measurement module 10 of the present application allows compensation for such changes in the working distance WD by correspondingly adjusting the optical path length of the second optical path P2 to ensure that the distance detection device 40 can continue to operate with optimal detection conditions regardless of the concurrence of such sources of distance variability, that is, the working field 37 and / or the workpiece P remain within the optimal detection range of the distance detection device even after the working distance is modified.

[0157] For example, if the working distance WD is modified, for example from a value WD=300 mm to a value WD=1000 mm or conversely from a value WD=1000 mm to a value WD=300 mm, this causes a corresponding modification of 700 mm in the optical path length of the measuring beam M. Therefore, if the distance detection device 40 is initially configured to perform accurate distance detection at an optical distance from the distance detection device 40 corresponding to a working distance WD=300 within a detection range of ±10 mm, then when the working distance takes the value WD=1000 mm, the distance detection performed by the distance detection device 40 will no longer be possible or at least not be as accurate, since the working field 37 and / or the workpiece P will be outside the detection range of the distance detection device 40. In addition, if for the initial value of the working distance WD=300 mm the measuring beam M was focused on the working field 37 and / or the workpiece P, the modification of the working distance WD may cause the measuring beam M to be defocused, and this results in a deterioration of the signal-to-noise ratio of the distance detection device 40, which can no longer operate under optimal detection conditions. In order to compensate for this, the optical path length adjuster system 20 of the measuring module 10 of the present application can operate to compensate for the modification of the optical path length of the measuring beam M caused by the modification of the working distance WD by correspondingly adjusting the optical path length of the second optical path P2 within the measuring module 10, so that the difference between the fixed optical path length of the first optical path P1 and the optical path length of the second optical path P2 re-takes the initial value. Once this compensation is achieved by the optical path length compensation system 20, the distance detection performed by the distance detection device 40 will continue to be as accurate as the initial value of the working distance, because the working field 37 and / or the workpiece P will be within the detection range of the distance detection device 40 again. In addition, for the new working distance WD, the measuring beam M will be automatically focused on the working beam 37 and / or the workpiece P again, and the distance detection device 40 will continue to operate with the optimal signal-to-noise ratio and therefore with the optimal accuracy. It is worth noting that this does not require the operation of the focusing device 18 and / or the distance detection device 40 or the modification of its settings.

[0158] Operating in the same manner, the measuring module 10 of the present application can compensate for the accidental deviation / tilt of the working field 37 (see Figure 7 The change in the optical path length of the measuring beam caused by the deviation from the horizontal plane X shown in FIG.

[0159] The distance detection device 40 can be configured to perform distance measurements, for example to determine the distance between the workpiece P and / or the working field 37 and the deflection unit 34 and / or due to an unexpected deviation / tilt of the working field 37 (see Figure 7) and / or variations of this distance due to the presence of surface irregularities 35 in the working field 37 and / or the workpiece P. The distance detection device 40 may also perform distance measurements to detect an absolute value of the working distance WD or a variation of the working distance WD.

[0160] The laser processing module 30 comprises a focusing device 36 arranged between the input end 38 and the optical element 32, the focusing device being configured to focus the working beam W on the working field 37 and / or the workpiece P. The focusing device 36 is comprised in a housing 31 of the laser processing module 30. The focusing device 36 may in particular correspond to a focusing unit (see “Fokussierungsvolurichtung”), as disclosed in WO 2018 / 078137A1. It is worth noting that the measuring module 10 comprises a focusing device 18, which may be configured (in combination with the optical path length adjuster system 20) to focus the measuring beam M on the working field 37 and / or the workpiece P, in particular such that the position of the focus of the measuring beam M corresponds to the position of the focus of the working beam W. Thus, the working beam W and the measuring beam M may be focused by respective dedicated focusing devices 36 and 18, respectively. This allows adjusting the focus setting of the focusing device 36 of the working beam W without affecting the focus setting of the measuring beam M. Furthermore, the focusing device 36 does not need to be adapted to the distance detection device 40 , and the distance detection device 40 does not need to be adapted to the focusing device 36 .

[0161] Figure 8 Shows Figure 7 The embodiment of the laser processing device 1 shown in FIG. 1 includes a laser processing module 30, a measuring module 10 and a distance detection device 40. Figure 8 In the illustrated embodiment, the laser processing apparatus 1 further comprises a control unit 56, which is operably connected to the deflection unit 34, in particular to each of the reflectors 34a and 34b, to the focusing unit 36, to the distance detection device 40, to the focusing device 18, and to the optical path length adjuster system 20. The control unit 56 may be, for example, a SP-ICE control card.

[0162] Figure 8Another source of distance variability that can be compensated by the optical path length adjuster system 20 of the measuring module 10 is schematically illustrated. When the deflection unit 34 of the laser processing module 30 is operated at different deflection angles α to scan the measuring beam M on the planar working field 37, the focus of the measuring beam M defines a circular trajectory S. Therefore, if no compensation is implemented, the optical path length of the measuring beam M may vary uncontrollably with increasing deflection angle, i.e. at peripheral positions on the working field 37 away from the center of the working field 37. For example, with increasing deflection angle α, the optical path length of the measuring beam M may increase by a factor of Thus, in particular for large values ​​of the deflection angle α, the working field 37 and / or the workpiece P may leave the detection range of the distance detection device 40, wherein the distance detection device 40 may be configured to perform an accurate distance detection. As a result, the distance detection performed by the distance detection device 40 may lose accuracy or may even cease. In addition, the measuring beam M may become increasingly out of focus.

[0163] In order to compensate for this, so that even for large values ​​of the deflection angle α (i.e. even in the peripheral region of the working field 37), the distance detection by the distance detection device 40 is still possible to be as accurate as for smaller values ​​of the deflection angle α (i.e. in the central region of the working field 37), and so that the measuring beam M remains focused on the planar working field 37 independently of the setting of the deflection unit 34, i.e. independently of the deflection angle α, the control unit 56 is configured to correspondingly control the optical path length adjuster system 20 of the measuring module 10 as a function of the deflection angle α achieved by the deflection unit 34. For example, for each setting of the deflection unit 34, the control unit 56 may be configured to compensate for corresponding changes in the optical path length of the measuring beam M by correspondingly controlling the optical path length adjuster system 20 to adjust the optical path length of the second optical path P2, such that the difference between the fixed optical path length of the first optical path P1 and the variable optical path length of the second optical path P2 remains constant for all values ​​of the deflection angle α.

[0164] Additionally or alternatively, the control unit 56 may be configured to control the optical path length adjuster system 20 based on the distance and / or distance change determined by the distance detection device 40, and / or to compensate for the above ... Figure 7 Any possible sources of distance variability discussed in the embodiments.

[0165] For example, if the working distance WD is modified, the control unit 56 can detect this change, for example via user input, via direct communication with the movable stage on which the working field 37 can be defined (in this case, the working distance WD corresponds to the distance between the movable stage and the laser processing module 30), and the control unit 56 can then control the optical path length adjuster system 20 accordingly to adjust the optical path length of the second optical path P2 to compensate for the change in the working distance WD, as described above.

[0166] Refer to Figure 7 , the work field 37 is aligned relative to its intended target, for example relative to Figure 7 Misalignment of the horizontal alignment of the horizontal plane X shown may result in an unintended change in the distance between the deflection unit 34 and the working field 37. As another example, the presence of surface irregularities 35 on the upper surface of the working field 37 or the workpiece P may also result in an unintended change in the distance between the deflection unit 34 and the working field 37. Any of these sources of distance variation is associated with a corresponding (unintended) change in the total optical path length of the measuring beam M, which, however, does not substantially affect the detection of the distance by the distance detection device 40, as long as the unintended change in the total optical path length of the measuring beam M does not result in the working field 37 and / or the workpiece P leaving the detection range of the distance detection device 40. In the event that such an unintended change in the total optical path length of the measuring beam M may result in the working field 37 and / or the workpiece P leaving the detection range of the distance detection device 40, the optical path length adjuster system 20 may be used to compensate for the unintended distance variation, possibly in real time.

[0167] The control unit 56 can be configured to operate the optical path length adjuster system 20 to correspondingly adjust the optical path length of the second optical path P2, the optical path length of the second optical path P2 being subject to the condition that a change in the total optical path length of the measuring beam M is detected to be greater than a predetermined threshold corresponding to the detection range of the distance detection device 40, in particular detected by the distance detection device 40.

[0168] For example, when the distance between the deflection unit 34 and the working field 37 is changed due to irregularities 35 on the surface of the working field 37 or the workpiece P or due to misalignment of the working field 37 itself (see Figure 7), this can be detected by the distance detection device 40, and if necessary, the control unit 56 can control the optical path length adjuster system 20 to correspondingly adjust the optical path length of the second optical path P2 to keep the working field 37 and / or the workpiece P within the detection range of the distance detection device 40. Otherwise, if no compensation is needed to keep the working field 37 and / or the workpiece P within the detection range of the distance detection device 40, the control unit 56 does not need to operate the optical path length adjuster system 20.

[0169] Fig. 9 Shown with Figure 8 The illustrated laser processing device is a schematic diagram of a related embodiment of the laser processing device 1 similar to the laser processing device 1, but in which the measuring module 10 corresponds to Figure 6 The measurement modules shown are not Figure 3 and Figure 4 In this embodiment, the movable reflectors 22b, 22d, 22f and 22h (see Figure 6 ) or by moving the movable and tiltable mirrors 24-1a and 24-2a, the optical path length adjuster system 20 is operated to adjust the optical path length of the second optical path P2.

[0170] Fig. 9 The control unit 56 of the embodiment shown may be configured to control the optical path length adjuster system 20 to adjust the optical path length of the second optical path P2 by moving the movable mirrors 22b, 22d, 22f and 22h when the distance change to be compensated is caused, for example, by a change in the working distance WD, for example in the range from 200 mm to 750 mm, since such compensation may not require a high compensation speed and / or real-time fine adjustment. When the distance change to be compensated corresponds to a change in the setting of the deflection unit 34 (see Figure 8 ), for example, corresponding to a change in the deflection angle α, corresponding to a misalignment of the working field 37 and / or corresponding to the presence of surface irregularities 35 on the working field 37 or on the outer surface of the workpiece P, the distance variation may be, for example, in the range of 20 mm to 50 mm, and the control unit 56 may be configured to operate the optical path length adjuster system 20 to quickly compensate for such distance variation in real time, possibly during a scanning operation of the deflection unit 34, by a corresponding adjustment of the optical path length of the second optical path P2 by moving the movable tiltable mirrors 24-1a and 24-2a. In this case, by moving a reduced number of mirrors, in particular two mirrors with a reduced total mass, a fast fine adjustment of the optical path length of the second optical path P2 may be achieved in real time, for example within a reaction time of from 2 ms to 5 ms.

[0171] like Fig. 9As shown, the measurement module 10 may include a dichroic element 64 configured to extract a portion (a wavelength sub-range) of the laser light propagating along the second optical path P2 via a monitoring port 62 formed in the housing 11 of the measurement module. Then, an optical monitoring device 60 may be connected to the monitoring port 62 and used to obtain information about laser processing performed with the laser processing module 30 using the light extracted through the monitoring port 62. The optical monitoring device 60 generates a monitoring laser beam, which propagates along a portion of the measurement beam path together with the measurement beam M to the working field 37 and back to monitor the laser processing performed by the working beam W of the laser processing module 38. The monitoring laser beam may have a wavelength different from the wavelength of the measurement beam M and / or the working beam W, for example a wavelength of 633 nm. The optical monitoring device 60 may be a camera or include a camera. The monitoring laser beam corresponds to the portion of the laser beam propagating along the second optical path P2 extracted by the dichroic element 64.

[0172] exist Fig. 9 In the exemplary embodiment shown, the dichroic element 64 replaces Figure 3 The dichroic element 64 is configured to reflect the measuring light beam M from the connection port 14 toward the optical path length adjuster system 20 and to transmit the monitoring laser beam from the connection port 14 toward the monitoring port 62 .

[0173] In other related embodiments, instead of replacing Figure 3 The reflector 23 and the dichroic element 64 can be arranged at Fig. 9 1 and 12. An alternative position indicated by a black arrow between the connection port 12 and the focusing device 18 is shown in FIG. 1 to extract the light of the measuring beam between the focusing device 18 and the connection port 12. In a similar embodiment, the dichroic element 64 can be arranged between the focusing device 18 and the optical path length adjuster system 20 to extract the light of the monitoring beam there. These configurations have the advantage that the extracted light can be kept within the detection range of the optical monitoring device 60 and can be focused regardless of possible changes in the optical path length of the measuring beam M, because such changes can be compensated by the optical path length adjuster system 20.

[0174] Fig.10 Shows Figure 3-Figure 4 The embodiment of the measuring module of the present invention is characterized in that the beam rotation element 27 is arranged between the optical path length adjuster system 20 and the connection port 14 along the second optical path P2 of the measuring module 10. The beam rotation element 27 is rotatable around a central axis corresponding to the optical axis of the second optical path P2. The beam rotation element 27 is configured as a rotatable wedge prism 27.

[0175] Fig.11 Shows Fig. 9 The embodiment of the laser processing device includes a beam rotating element 27, which corresponds in function and structure to Fig.10 The beam rotation element 27. The rotation of the wedge prism 27 causes the measuring beam M (see Figure 8 ) rotates or precesses around a center point on the working field 37. This allows a so-called seam tracking function to be implemented. The beam rotation element 27 can be rotated so that the measuring beam M is used to analyze the surroundings of a point on the working field 37 before and / or after laser processing of the point with the working beam W, for example during a laser welding process.

[0176] Although preferred exemplary embodiments are shown and specified in detail in the drawings and the foregoing description, these embodiments should be regarded as purely exemplary and not limiting to the present application. It is noted at this point that only preferred exemplary embodiments are shown and specified, and all changes and modifications that are currently or in the future within the scope of protection of the present application as defined by the claims should be protected.

Claims

1. A measurement module (10) for a laser processing device (1), comprising: A housing (11) comprising a connection port (12) and a coupling port (14), wherein the connection port (12) is used to optically couple the measuring module (10) to a distance detection device, and the coupling port (14) is used to optically couple the measuring module (10) to a laser processing module (30) of the laser processing device (1); wherein a first optical path (P1) and a second optical path (P2) for laser light are defined within the housing (11) for laser light received and output through the connection port (12), wherein the first optical path (P1) is defined from the connection port (12) to a reference optical reflector (16), wherein the reference optical reflector (16) reflects the laser light back to the connection port (12), wherein the second optical path (P2) is defined from the connection port (12) to the coupling port (14) and back to the connection port (12); and wherein the measurement module (10) further comprises an optical path length adjuster system (20), the optical path length adjuster system being configured to adjust an optical path length difference between an optical path length of the first optical path (P1) and an optical path length of the second optical path (P2); wherein the first optical path (P1) has a fixed predetermined optical path length; and The second optical path (P2) has a variable optical path length that can be adjusted by the optical path length adjuster system (20).

2. The measurement module according to claim 1, wherein: The optical path length adjuster system (20) is configured to: The optical path length of the second optical path (P2) is varied by varying the optical path length within a range from 20 μm to 1200 mm, preferably from 40 μm to 750 mm.

3. The measurement module according to claim 1 or 2, further comprising a focusing device (18), which is arranged in the second optical path (P2), in particular between the connection port (12) and the optical path length adjuster system (20), and the focusing device (18) is configured to focus the laser light transmitted through the second optical path (P2), wherein: The focusing device (18) preferably has a fixed focal length.

4. A measuring module according to any one of the preceding claims, wherein: The optical path length adjuster system (20) comprises a plurality of reflective elements (22a, 22b, 22c, 22d, 22e, 22f) for reflecting the laser light along the second optical path (P2), wherein the plurality of reflective elements (22a, 22b, 22c, 22d, 22e, 22f) comprises at least two movable reflective elements (22b, 22d, 22f), wherein the optical path length of the second optical path (P2) can be adjusted, in particular continuously adjusted, by setting the positions of the at least two movable reflective elements (22b, 22d, 22f).

5. The measurement module according to claim 4, wherein: The optical path length adjuster system (20) comprises at least one pair of reflective elements (22a, 22b, 22c, 22d, 22e, 22f) for reflecting the laser light along the second optical path (P2), wherein an extension portion of the second optical path (P2) between the reflective elements (22a, 22b, 22c, 22d, 22e, 22f) of each of the at least one pair of reflective elements is adjustable by setting the relative positions of the reflective elements (22a, 22b, 22c, 22d, 22e, 22f) of each of the at least one pair of reflective elements, in particular by setting the spacing distance of the reflective elements (22a, 22b, 22c, 22d, 22e, 22f) of each of the at least one pair of reflective elements, and in particular is continuously adjustable.

6. The measurement module according to claim 5, wherein: Each pair of reflective elements (22a, 22b, 22c, 22d, 22e, 22f) includes a movable reflective element (22b, 22d, 22f) that is movable in a direction corresponding to the second optical path (P2).

7. The measurement module according to claim 4 or 5, wherein: The optical path length adjuster system (20) is configured to: Two or more of the movable reflective elements (22b, 22d, 22f), preferably all of the movable reflective elements are displaced simultaneously and / or equally.

8. The measurement module according to claim 6 or 7, wherein: All movable reflective elements (22b, 22d, 22f) are capable of moving together in the same direction.

9. A measuring module according to any one of the preceding claims, wherein: The optical path length adjuster system (20) comprises at least one pair of tilted reflective elements (24a, 24b) for multiply reflecting the laser light at their reflective surfaces along the second optical path (P2), wherein the reflective surfaces of each of the reflective elements of each of the at least one pair of tilted reflective elements face each other and are angled relative to each other, wherein the extension of the second optical path (P2) between the tilted reflective elements (24a, 24b) of each of the at least one pair of mutually tilted reflective elements is adjustable by setting the relative position between the tilted reflective elements (24a, 24b), preferably by moving the two tilted reflective elements (24a, 24b).

10. A measuring module according to any one of the preceding claims, wherein: The optical path length adjuster system (20) comprises at least one pair of refractive elements (26a, 26b) for transmitting the laser light along the second optical path (P2) through the at least one pair of refractive elements (26a, 26b), wherein the extension of the second optical path (P2) through the refractive elements (26a, 26b) of each of the at least one pair of refractive elements (26a, 26b) is adjustable by setting the relative position of the refractive elements (26a, 26b), preferably by moving the two refractive elements (26a, 26b) relative to each other.

11. The measuring module according to any one of the preceding claims, further comprising a distance detection device (40), in particular comprising an interference sensor or a detection device connectable to an interference sensor, the distance detection device (40) being optically connected to the connection port (12) and configured to detect the distance based on interference between the laser received by the distance detection device (40) from the first optical path (P1) and the laser received by the distance detection device (40) from the second optical path (P2).

12. The measurement module according to any of the preceding claims, further comprising a monitoring port (62) and an optical element (64), the optical element (64) being configured to: A first portion of the laser light propagating along the second optical path (P2) is reflected, and a second portion of the laser light propagating along the second optical path (P2) is transmitted, so that the first portion or the second portion is extracted from the second optical path (P2) and directed toward the monitoring port (62).

13. An interferometer system comprising a distance detection device (40), a connection port (14) and a measuring module (10), in particular a measuring module (10) according to any one of the preceding claims; in, The measurement module (10) defines a first optical path (P1) corresponding to a reference arm of the interferometer system and a second optical path (P2) corresponding to an object arm of the interferometer system, wherein the measurement module (10) includes an optical reflector (16) arranged in the first optical path (P1) for reflecting back laser light received along the first optical path (P1); Wherein, the measuring module (10) further comprises an optical path length adjuster system (20), wherein the optical path length adjuster system (20) is configured to adjust the optical path length of the second optical path (P2); wherein the connection port (14) is configured to optically connect the second optical path (P2) to a laser processing module; and The distance detection device (40) is configured to perform distance measurement based on interference between laser light transmitted along the first optical path (P1) and laser light transmitted along the second optical path (P2).

14. A laser processing device (1), comprising: A laser processing module (30) performs laser processing on a workpiece (P) on a working field (37) using a working beam (W); as well as The measuring module (10) according to any one of claims 1 to 12, wherein the measuring module (10) is optically connected to the laser processing module (30) through the connecting port (14) thereof, so as to receive laser light in the form of a measuring beam (M) from the laser processing module (30) and output laser light in the form of a measuring beam (M) to the laser processing module (30); Wherein, the laser processing module (30) comprises: an optical element (32) for reflecting one of the working light beam (W) and the measuring light beam (M) and for transmitting the other of the working light beam (W) and the measuring light beam (M) therethrough; and a deflection unit (34) for deflecting the working light beam (W) and the measuring light beam (M) toward the workpiece (P) and / or the work field (37), and deflecting them away from the workpiece (P) and / or the work field (37); wherein a working beam path and a measuring beam path are defined for the working beam (W) and the measuring beam (M) respectively in the laser processing module (30), wherein the working beam path is defined such that the working beam (W) is reflected / transmitted by the optical element (32) toward the deflection unit (34) and is deflected by the deflection unit (34) to the workpiece (P) and / or the working field (37), The measuring light beam (M) propagates in the measuring module (10) along the second optical path (P2) of the measuring module (10), wherein the measuring light beam path is defined such that the measuring light beam (M) propagates from the connection port (14) of the measuring module (10) to the optical element (32), and to the deflection unit (34), and propagates back to the connection port (14), is transmitted / reflected by the optical element (32) to the deflection unit (34) and is transmitted / reflected from the deflection unit (34), is deflected by the deflection unit (34) to the workpiece (P) and / or the working field (37) and is reflected back at the workpiece (P) and / or the working field (37).

15. The laser processing device (1) according to claim 14, further comprising the distance detection device (40) according to claim 11, wherein: The distance detection device (40) is configured to determine a change in the distance between the workpiece (P) and / or the working field (37) and the deflection unit (34), and / or to determine the distance (D) based on interference of the measuring light beam with laser light propagating in the measuring module (10) along the first optical path (P1) of the measuring module (10).

16. The laser processing device (1) according to claim 14 or 15, further comprising a control unit (56), wherein the control unit (56) is configured to: Based on the distance determined by the distance detection device and / or a change in the distance determined by the distance detection device (40), the optical path length regulator system (20) of the measuring module (10) is controlled.

17. The laser processing device (1) according to any one of claims 14 to 16, wherein: The control unit (56) or another control unit is configured to: controlling the optical path length regulator system (20) of the measuring module (10) based on a change in a working distance (WD) of the laser processing module (30), wherein the working distance (WD) corresponds to a minimum distance between the working field (37) and the laser processing module (30), Wherein, the control unit (52) or the other control unit is configured to: By controlling the optical path length adjuster system (20) to correspondingly adjust the optical path length of the second optical path (P2), changes in the optical path length of the measuring beam path due to changes in the working distance (WD) are compensated.

18. The laser processing device (1) according to any one of claims 14 to 17, wherein: The control unit (56) or another control unit is configured to: control the optical path length adjuster system (20) of the measuring module (10) based on a change in the deflection setting of the deflection unit (34) of the laser processing module (30), The control unit (56) or the other control unit is configured to compensate for a change in the optical path length of the measuring beam path caused by the change in the deflection setting of the deflection unit (34) by controlling the optical path length adjuster system (20) to correspondingly adjust the optical path length of the second optical path (P2).

19. The laser processing device (1) according to any one of claims 14 to 18, wherein: The laser processing module (30) comprises a working beam focusing device (36) for focusing the working beam (W), wherein the working beam focusing device (36) has a variable focal length and is preferably arranged in the working beam path between the optical element (32) and a source or input (38) of the working beam (W).

20. The laser processing device (1) according to any one of claims 14 to 19, wherein: The measuring module (10) comprises a focusing device (18) according to claim 3, wherein the focusing device (18) is configured to focus the measuring beam (M) on the working field (37) and / or on the workpiece (P), in particular on a position corresponding to the focus of the working beam (W).

21. The laser processing device (1) according to any one of claims 14 to 20, wherein: The measuring beam (M) is formed by light in a wavelength range from 700 nm to 1400 nm, wherein the working beam (W) is preferably formed by light in a wavelength range different from the wavelength range of the measuring beam.

22. The laser processing device (1) according to any one of claims 14 to 21, wherein: The laser processing module (30) includes a housing (31) which surrounds at least some of the remaining components of the laser processing module (30), wherein the working beam path and the measuring beam path are at least partially defined within the housing (31) of the laser processing module (30), wherein a further connection port (39) is formed through the housing (31) of the laser processing module (30) and can be connected to the connection port (14), wherein the housing (31) of the laser processing module (30) is preferably fluid-tight and / or dust-proof.

23. The laser processing device (1) according to claim 22, wherein: The measuring module (10) and the laser processing module (30) can be attached to each other, wherein the housing (11) of the measuring module (10) can be attached to the housing (31) of the laser processing module (30), in particular so that the measuring module (20) can be arranged adjacent to the laser processing module (30).

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