Laser machining process monitoring sensor device and laser machining system with sensor device

Abstract

To more precisely monitor a laser beam machining process.SOLUTION: A beam splitter arrangement for separating a plurality of visible partial beams having individual visible wavelength ranges from a process beam, and a first photosensor arrangement comprising a plurality of photosensors for sensing the intensity of one of the visible partial beams, wherein the beam splitter arrangement is configured to separate and couple the first to fourth visible partial beams having the first to fourth visible wavelength ranges to the first photosensor arrangement, and wherein the first photosensor arrangement comprises first to fourth photosensors arranged to sense the intensities of the first to fourth visible partial beams.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sensor device for monitoring a laser processing process and to a laser processing system equipped with the sensor device. [Background technology]

[0002] In a laser processing system, also known as a laser processing plant, a laser beam emitted by a laser beam source or by the end of a laser guide fiber is directed and focused by beam guiding and focusing optics onto a workpiece to be processed. Possible processes include laser welding and laser cutting. A laser processing system may include a laser processing head, such as a laser welding head or a laser cutting head, in which the optics are arranged. Possible laser processing processes include laser welding and laser cutting.

[0003] Continuous monitoring of the laser processing process is important to ensure the quality of the process. Monitoring is typically performed by sensing and evaluating optical process radiation produced during the laser processing process. This includes laser radiation back-reflected or scattered from the workpiece, radiation produced in the infrared wavelength range of light (the so-called "infrared wavelength range"), such as temperature radiation (thermal radiation) from the melt pool, and radiation produced in the visible wavelength range of light, such as radiation from the plasma produced during processing. The optical process radiation can be referred to as process radiation or process beam.

[0004] The process beam is typically sensed by a photosensor, e.g., a photodiode. These photosensors may be part of a sensor device arranged on the laser processing head. The process beam is coupled into the sensor device via the laser processing head. Each photosensor senses the intensity of the process beam in a specific wavelength range and generates a corresponding sensor signal. The sensor signal corresponds to the average intensity of the individual wavelength range. For evaluation and monitoring, the profile of the sensor signal is compared, for example, with a predetermined envelope and / or threshold value, and an error is output if the sensor signal is outside the envelope or above or below the threshold value.

[0005] Due to the broadband spectral sensitivity of photodiodes, the total intensity of the process beam is currently measured over a wide wavelength range (the so-called integrated sensor signal or integrated sensor signal value) and used for process monitoring. Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors have recognized that such integrated intensity sensing can be a disadvantage for precise monitoring of laser processing processes, particularly laser welding processes, in certain applications: because the sensor signal corresponds to the average intensity of the process beam over the sensing wavelength range, variations in intensity at individual wavelengths within that wavelength range cannot detect changes in the sensor signal to the extent of process error.

[0007] This is illustrated in FIG. 4, which shows a graph depicting the process beam intensity during laser welding in a broad wavelength range (λ1-λ3). The solid line shows the process beam intensity as a function of wavelength λ when a process error occurs, and the dashed line shows the laser welding intensity without the process error. On the left side of the graph (wavelength range λ1-λ2), the intensity is lower than when there is no process error due to the process error, while on the right side (wavelength range λ2-λ3), the intensity is higher than when there is no process error. However, if only one intensity-related sensor signal is sensed within the broad, i.e., broadband, wavelength range λ1-λ3, changes within the individual wavelength ranges λ1-λ2 and λ2-λ3 cannot be detected. Therefore, the process error and the resulting poorly welded workpiece cannot be detected.

[0008] Furthermore, the inventors have found that optical imaging of the processing area around the processing point onto a separate photosensor, e.g., a photodiode, is another crucial aspect of precise monitoring of laser processing processes. For specific laser processing processes, an optimal imaging or an optimal imaging area may exist for each monitored wavelength range. In particular, it would be advantageous if the image section or imaging area from the processing area could be individually selected or set for each monitored wavelength range or for each partial beam separated from the process beam.

[0009] For example, there is an optimal imaging wavelength range for detecting back reflections of a laser beam; in this case, it would be advantageous to make the imaging approximately the same size as the laser beam's point of incidence (i.e., the processing point) on the workpiece. For example, it may be advantageous to limit the aperture size or sensor area size to an image of the laser beam's point of incidence on the workpiece or to the size of the laser beam focus. In other words, it would be advantageous to design the aperture size or sensor area size to correspond to the imaging of the processing point. This ensures that, for example, only process radiation from a specific region of the workpiece (e.g., from the keyhole and / or melt pool) is reliably evaluated in that wavelength range. For other wavelengths or wavelength ranges, such as the infrared wavelength range, it is more advantageous to make the imaging or imaging area significantly larger than the size of the processing point. This allows for the detection of effects that affect heat dissipation away from the point of incidence. However, different imaging ranges or optimal imaging configurations require different aperture sizes or sensor area sizes for individual wavelength ranges.

[0010] The inventors have also recognized that for precision monitoring of laser processing processes, especially laser welding processes, in other wavelength ranges, it is advantageous to amplify the sensor signal differently: for example, the sensor signal of the laser back reflection is usually very intense, whereas the intensity of the process beam in the infrared wavelength range is several orders of magnitude lower.

[0011] Such optimization is impossible or difficult to achieve with optical spectrometers. Here, the process beam is typically split onto a CMOS or CCD chip or a diode array using a dispersive element. Individual adjustment of the imaging is no longer possible after the dispersive element. While the pixel size can be used to adjust the spectral sensitivity range after the dispersive element, the imaging is not. The imaging is generally kept the same for every pixel and is defined by the imaging before the dispersive element. Individual signal amplification could, in principle, be achieved with a diode array instead of an array with individual diodes, for example. However, this would introduce the problem of crosstalk between neighboring diodes within the diode array.

[0012] Monitoring of a laser processing process is also unsuccessful if only the sensed intensity of the process beam over a wide, broadband wavelength range is used for that purpose. This means that certain effects or errors in the laser processing process cannot be recognized because the sensed intensity represents only the average intensity over the broadband wavelength range. Furthermore, precise configuration and adjustment of the monitor becomes more difficult or impossible when a broadband wavelength range is used.

[0013] It is therefore an object of the present invention to provide a sensor device for improved laser machining process monitoring, in particular one that can be more precise and allows for improved detection of process errors.

[0014] It is an object of the present invention to provide a sensor device capable of monitoring a laser machining process based on process beam intensities sensed independently or separately at multiple distinct wavelength bands.

[0015] It is an object of the present invention to provide a sensor device for laser processing process monitoring that can be configured and / or adjusted independently for each monitored wavelength range of the process beam.

[0016] It is an object of the present invention to provide a sensor device that allows independently configurable and / or adjustable imaging of the process beam for each monitored wavelength range.

[0017] It is an object of the present invention to provide a sensor device in which the sensor signal gain for each monitored wavelength range of the process beam can be independently configured and / or adjusted.

[0018] It is also an object of the present invention to provide a laser processing system having such a sensor device. [Means for solving the problem]

[0019] At least one of these objects is achieved by the subject matter of the independent claims. Advantageous embodiments and further improvements are the subject matter of the dependent claims.

[0020] According to one aspect of the present disclosure, a sensor device is provided for monitoring a laser processing process, such as a laser welding process, by sensing the intensity of a process beam produced during the laser processing process, the laser processing process being performed with a laser beam to process a workpiece, particularly a metallic workpiece.

[0021] The sensor device includes a beam splitter array configured to separate at least two visible partial beams, each having one of at least two distinct visible wavelength ranges, and at least one infrared partial beam, also having an infrared wavelength range, from the process beam; a first photosensor array that senses the intensity of the process beam in the visible wavelength range with at least two photosensors positioned to sense the intensity of one of the visible partial beams; and a second photosensor array that senses the intensity of the process beam in the infrared wavelength range with at least one photosensor positioned to sense the intensity of the infrared partial beam.

[0022] According to a further aspect of the present invention, there is provided a laser processing system for performing a laser processing process, the laser processing system comprising a laser processing head configured to emit a laser beam onto a workpiece to perform the laser processing process, and a sensor device according to aspects and embodiments of the present disclosure.

[0023] The laser processing head can include at least one beam splitter positioned to separate a process beam generated during the laser processing process from the beam path of the laser beam and / or to couple the process beam into the sensor device.

[0024] According to a further aspect of the present disclosure, a sensor device is provided for monitoring a laser processing process by sensing the intensity of a process beam produced during the laser processing process. The sensor device comprises a beam splitter array configured to separate a plurality of visible partial beams having distinct visible wavelength ranges from the process beam, and a first photosensor array configured to sense the intensity of the process beam in the visible wavelength range with a plurality of photosensors arranged to sense the intensity from one of the visible partial beams, wherein the beam splitter array is configured to separate a first visible partial beam having a first visible wavelength range, a second visible partial beam having a second visible wavelength range, a third visible partial beam having a third visible wavelength range, and a fourth visible partial beam having a fourth visible wavelength range, and each of the separated beams is coupled to one of the photosensors of the first photosensor array, and the first photosensor array comprises a first photosensor arranged to sense the intensity of the first visible partial beam, a second photosensor arranged to sense the intensity of the second visible partial beam, a third photosensor arranged to sense the intensity of the third visible partial beam, and a fourth photosensor arranged to sense the intensity of the fourth visible partial beam.

[0025] Within the scope of the present disclosure, a "monitoring wavelength range" refers to a wavelength range of the process beam that is sensed by a photosensor in a laser processing process monitoring device. Specifically, the intensity of the process beam in that wavelength range is sensed, and a corresponding sensor signal is generated. The sensor signal may then be evaluated and / or recorded. The term "visible wavelength range" refers to a wavelength range that primarily includes wavelengths within the visible spectrum of light. Specifically, the visible wavelength range may be or include wavelengths from 350 nm to 850 nm, 390 nm to 850 nm, or 380 nm to 800 nm. The term "infrared wavelength range" refers to a wavelength range that primarily includes wavelengths within the infrared spectral range. However, this wavelength range is not limited to wavelengths within the infrared spectral range, because thermal radiation, i.e., light thermal radiation, can also occur in other spectral ranges, such as the ultraviolet and visible ranges. Specifically, the infrared wavelength range may be or include wavelengths from 1200 nm to 2100 nm. Furthermore, a "visible partial beam" refers to a partial beam within the visible wavelength range, an "infrared partial beam" refers to a partial beam within the infrared wavelength range, and a "back-reflected partial beam" refers to a partial beam within the back-reflected wavelength range. "Non-overlapping" wavelength ranges imply that the wavelengths of one wavelength range are not contained within the other wavelength range. "Non-overlapping" is synonymous with "completely different from each other." "Separating partial beams" by a beam splitter array implies that the beam splitter array splits the process beam into two partial beams, i.e., the partial beam and another partial beam, at least once. The separated partial beams will have undergone at least one reflection and / or at least one transmission by the beam splitter array. For this purpose, the beam splitter array can have at least one beam splitter. The splitting into two partial beams is not limited to when the beam splitter and the incident beam (process beam or a partial beam of the process beam) form an angle of 45°, but rather can be at any angle.The splitting into two partial beams may be achieved by a neutral and / or non-selective beam splitter (e.g., in a 50:50 or 90:10 ratio), or may be selective based on optical properties (e.g., based on wavelength and / or polarization). A partial beam "passed" by a beam splitter means that a portion of the beam (the process beam or a partial beam of the process beam) is reflected by the beam splitter as the partial beam or transmitted by the beam splitter as the partial beam.

[0026] A beam splitter array can comprise multiple beam splitters, with which the light of the process beam interacts after entering the sensor device and on its way to the photosensor. A primary beam splitter can be defined as the first beam splitter encountered in the beam path of the process beam after entering the sensor device. The process beam is split into (exactly) two partial beams: a reflected partial beam and a transmitted partial beam. Beam splitters in the beam paths of the partial beams are called secondary beam splitters, etc. The order of the individual beam splitters (beam splitter order) increases with further interactions (reflection / transmission) of the individual partial beams with other beam splitters in the beam splitter array: tertiary, quaternary, fifth, sixth, seventh, etc. Thus, in a beamsplitter array, there can be (at most) one primary beamsplitter, two secondary beamsplitters, four tertiary beamsplitters, eight quaternary beamsplitters, sixteen fifth-order beamsplitters, etc. Conversely, "primary beamsplitter order" refers to a primary beamsplitter in the beamsplitter array, "secondary beamsplitter order" refers to a secondary beamsplitter in the beamsplitter array, etc. A primary beamsplitter is also a beamsplitter in the first beamsplitter order. A secondary beamsplitter is also a beamsplitter in the second beamsplitter order. A third-order beamsplitter is also a beamsplitter in the third beamsplitter order. A fourth-order beamsplitter is also a beamsplitter in the fourth beamsplitter order. A fifth-order beamsplitter is also a beamsplitter in the fifth beamsplitter order. A sixth order beam splitter is also a beam splitter of the sixth beam splitter order.

[0027] In other words, the beam splitter order specifies the maximum number of optical interactions (series) that a partial beam can have with its corresponding beam splitter in the beam splitter array. Optical interactions can include transmission of light from the process beam through an individual beam splitter and / or reflection of light from the process beam at an individual beam splitter. The terms "beam splitter order" and "beam splitter order" can be used interchangeably.

[0028] The present invention is based on the idea of ​​dividing the wavelength range of a process beam, particularly the visible wavelength range, into narrower wavelength bands and individually sensing the intensity of the process beam for each narrow wavelength band. For this purpose, the present invention provides a beam splitter array, with the help of which a partial beam corresponding to each narrow wavelength band is separated from the process beam and directed to a corresponding photosensor. The intensity of each partial beam is sensed by the corresponding photosensor, which then outputs a sensor signal corresponding to the sensed intensity.

[0029] The present invention allows for monitoring of a laser processing process over three or more wavelength ranges, preferably over four wavelength ranges, and particularly preferably over at least seven wavelength ranges, and particularly preferably over at least two wavelength ranges, preferably over three wavelength ranges, and particularly preferably over four wavelength ranges in the visible range, which allows for more precise monitoring of the laser processing process, since certain process errors can be better or less detected.

[0030] In addition, each wavelength range can be sensed and / or processed and / or evaluated separately and thus independently from one another. The sensor signals for the different wavelength ranges can, for example, be amplified separately and / or differently from one another. This allows each generated sensor signal to be subjected to an individual amplification. The individual amplification is important because the intensities of the partial beams often vary over several orders of magnitude. For example, laser back reflections usually exhibit very high intensities, while the intensity of infrared radiation is usually several orders of magnitude lower. According to the invention, an individual amplification of the sensor signals for the different wavelength ranges can be achieved over many orders of magnitude, for example 10-107 This is possible with a variety of magnifications.

[0031] In a further example, the optical imaging can be individually configured and adjusted for each partial beam or wavelength range. For this purpose, a beam splitter array can be configured to separate each of the partial beams with predetermined and / or individually adjustable optical imaging and couple it to a corresponding photosensor. The beam splitter array can include an imaging device. The imaging device can include an aperture for each partial beam. The opening of each aperture can be individually adjustable. The apertures can also be inverse apertures. The apertures can also be configured for opto-mechanical beam steering and / or blocking. Furthermore, the imaging device can include at least one optical element, such as a lens or lens system, for each partial beam, by which the imaging of the partial beam on the sensor surface of the corresponding photosensor is adjusted. Thus, the beam splitter array can be used for spatial optical filtering, beam steering, or beam blocking.

[0032] Alternatively or additionally, for each partial beam or wavelength range, the size of the sensor surface of the corresponding photosensor and / or its position along the beam axis can be selected or adjusted independently and / or differently with respect to the other partial beams or wavelength ranges, thereby making it possible to adjust the section of the process area from which the intensity of the partial beam or in the monitoring wavelength range is sensed.

[0033] In this way, the imaging of the individual wavelength ranges can be spatially optimized, i.e., the individual wavelength ranges can be spatially filtered, and for each partial beam or monitored wavelength range, an optimized imaging can be selected or adjusted at the corresponding photosensor.

[0034] Aspects of the present disclosure may include one or more of the optional features listed below.

[0035] The sensor device may have an optical entrance for introducing a process beam.

[0036] The beam splitter array can be configured to separate a plurality of partial beams having distinct wavelength ranges from the process beam. The wavelength ranges of the partial beams separated by the beam splitter array can be completely different from one another, i.e., they do not overlap. The wavelength ranges of the partial beams separated by the beam splitter array can be 50 nm to 200 nm or 50 to 100 nm wide.

[0037] The beam splitter arrangement can be configured to separate a back-reflected partial beam having a back-reflected wavelength range from the process beam.

[0038] The sensor device may include a third photosensor array that senses the intensity of the process beam in the back-reflected wavelength range, and the third photosensor array may include photosensors positioned to sense the intensity of the back-reflected partial beam.

[0039] The back-reflected wavelength range can include the wavelength of the laser beam and / or a wavelength range of 950 nm to 1150 nm, preferably 1000 nm to 1100 nm, or a wavelength range in the green or blue spectral range. The beam splitter array can be configured to direct the back-reflected partial beams to photosensors of the third photosensor array. The laser beam can have a wavelength in the infrared or visible, particularly in the green or blue spectral range.

[0040] The visible and infrared wavelength ranges, or the visible, infrared and back-reflection wavelength ranges, may be completely different from one another, i.e., non-overlapping.

[0041] The first photosensor array may include a plurality of photosensors that sense the intensity of the process beam in the visible wavelength range, and may include a photosensor for each visible partial beam separated from the process beam by the beam splitter array, thereby sensing the intensities of the multiple visible partial beams separately from each other.

[0042] The second photosensor array may include a plurality of photosensors that sense the intensity of the process beam in the infrared wavelength range, and may include a photosensor for each infrared component beam separated from the process beam by the beam splitter array, thereby sensing the intensities of the plurality of temperature radiation component beams separately from each other.

[0043] The beam splitter array can be configured to split a first visible partial beam having a first visible wavelength range and a second visible partial beam having a second visible wavelength range to couple each to one of the photosensors of the first photosensor array, the beam splitter array can be further configured to split a third visible partial beam having a third visible wavelength range to couple to a third photosensor of the first photosensor array, and the beam splitter array can be further configured to split a fourth visible partial beam having a fourth visible wavelength range to couple to a fourth photosensor of the first photosensor array.

[0044] The first photosensor array can include a first photosensor arranged to sense the intensity of the first visible partial beam and a second photosensor arranged to sense the intensity of the second visible partial beam. The first photosensor array can further include a third photosensor arranged to sense the intensity of the third visible partial beam. The first photosensor array can further include a fourth photosensor arranged to sense the intensity of the fourth visible partial beam.

[0045] Some of the visible wavelength ranges may be entirely contained within at least one other visible wavelength range, the visible wavelength ranges may be identical, or the visible wavelength ranges may be imaged differently onto corresponding photosensors.

[0046] The multiple visible wavelength ranges can be distinct and / or non-overlapping. If present, the first, second, third, and / or fourth visible wavelength ranges can be completely distinct, i.e., non-overlapping. The first, second, third, and fourth visible wavelength ranges can be distinct and / or non-overlapping, and / or adjacent to each other in that order. In particular, the first and second visible wavelength ranges can be adjacent to each other, and / or the second and third visible wavelength ranges can be adjacent to each other, and / or the third and fourth visible wavelength ranges can be adjacent to each other. By separately sensing the intensities in the multiple visible wavelength ranges, effects, processes, and errors in the laser processing process that were previously unaccounted for and / or unrecognized can be sensed and monitored.

[0047] The distinct wavelength ranges of the visible partial beam can be selected from 350 nm to 450 nm, 450 nm to 550 nm, 550 nm to 650 nm, and 650 nm to 850 nm. The plurality of visible wavelength ranges, in particular the first, second, third, and / or fourth visible wavelength ranges, can each comprise at least one wavelength selected from 400 nm, 500 nm, 600 nm, 700 nm, 750 nm, 800 nm, wavelengths associated with components of the workpiece processed by the laser processing process, in particular steel alloys or aluminum alloys, wavelengths of aluminum oxide radiation bands, wavelengths of iron oxide radiation bands, and wavelengths of atomic emission lines, in particular titanium, copper, aluminum, or iron. The first visible wavelength range can include 400 nm, and / or the second visible wavelength range can include 500 nm, and / or the third visible wavelength range can include 600 nm, and / or the fourth wavelength range can include 750 nm.

[0048] The beam splitter array can be configured to separate at least one infrared component beam having an infrared wavelength range from the process beam, and the sensor device can further include a second photosensor array for sensing intensity of the process beam in the infrared wavelength range with at least one photosensor positioned to sense intensity of the infrared component beam.

[0049] The beam splitter array can be configured to separate a first infrared component beam having a first infrared wavelength range and a second infrared component beam having a second infrared wavelength range and couple each of the separated components to one of the photosensors in the second photosensor array. The second photosensor array can be configured to sense the intensity of the process beam in the first infrared wavelength range and the second infrared wavelength range. The second photosensor array can include at least two photosensors. The second photosensor array can include at least two photosensors each positioned to sense the intensity of one of the infrared component beams. The second photosensor array can include a first photosensor positioned to sense the intensity of the first infrared component beam and a second photosensor positioned to sense the intensity of the second infrared component beam.

[0050] The first and second infrared wavelength ranges can be (completely) separate and / or adjacent to each other in that order. One of the infrared wavelength ranges can be completely contained within the other separate infrared wavelength range. The first and second infrared wavelength ranges can be identical. The first and second infrared wavelength ranges can be imaged differently onto corresponding photosensors.

[0051] The at least two infrared wavelength ranges, particularly the first and / or second infrared wavelength ranges, can each include at least one wavelength selected from 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, and 1900 nm. The first infrared wavelength range can include 1500 nm and / or represent a high temperature. The second infrared wavelength range can include 1900 nm and / or represent a low temperature. Sensing intensity in the two infrared wavelength ranges can better detect and monitor heat conduction (dissipation) effects. The second infrared beam can be used to monitor effects and processes occurring in a wider environment of the workpiece processing area, such as those occurring during laser welding at a greater distance from the keyhole or weld pool. Additionally, it can be used to detect and monitor dimly lit areas of the workpiece. The first infrared beam can be used to monitor effects and processes occurring at or within the workpiece or its processing point, for example, those occurring in or immediately adjacent to the keyhole and / or in the molten pool, and can be used to sense and monitor brightly lit areas of the workpiece.

[0052] The fourth visible wavelength range, the back-reflecting wavelength range, and the first infrared wavelength range can be non-overlapping and / or adjacent to one another in that order, particularly the fourth visible wavelength range and the back-reflecting wavelength range can be adjacent to one another, and the back-reflecting wavelength range and the first infrared wavelength range can be adjacent to one another.

[0053] The beam splitter array can be configured to split a plurality of partial beams from the process beam. The beam splitter array can include a plurality of beam splitters, particularly dichroic beam splitters. The beam splitters can be configured as partially transparent mirrors. Each of the beam splitters can have a wavelength-range-specific coating, such as a dichroic coating, which is reflective or transmissive in a given wavelength range. In particular, each of the beam splitters can have a different coating. As a result, each beam splitter splits a partial beam having a specific wavelength or wavelength range.

[0054] According to various embodiments, the beam splitter array may include at least three, at least four, at least five, or at least six beam splitters. The beam splitter array may include beam splitters with a first to third beam splitter order, i.e., first to third beam splitter orders. The beam splitter array may include beam splitters with a first to sixth beam splitter order, i.e., first to sixth beam splitter orders.

[0055] According to various embodiments, each beam splitter can be positioned on the beam axis of the process beam entering through the optical inlet and / or on the optical axis defined by the optical inlet and / or by the focusing optics. The beam splitters can be sequentially positioned along the beam axis of the process beam or along an axis parallel to the beam axis of the process beam.

[0056] The beam splitter array may have one primary, one secondary and one tertiary beam splitter. The beam splitter array may have exactly one primary, one secondary and one tertiary beam splitter. In turn, the beam splitter array may have exactly one beam splitter for each of the first, second and third beam splitter orders.

[0057] The beam splitter array can have one primary, one secondary, one tertiary, one quaternary, one quintic, one sixth, etc. beam splitter in the same order. The beam splitter array can have exactly one primary, exactly one secondary, exactly one tertiary, exactly one quaternary, exactly one fifth, exactly one sixth, etc. beam splitter. That is, the beam splitter array can have exactly one beam splitter for each of the first, second, third, fourth, fifth, and sixth beam splitter orders. In other words, the beam splitter array can have a series arrangement of beam splitters of the first through sixth beam splitter orders.

[0058] The beam splitter array may include first- to fourth-order beam splitters, i.e., first to fourth beam splitter orders. The beam splitter array may include a first-order beam splitter. The beam splitter array may further include a first-order beam splitter on the beam axis of the partial beam transmitted by the first-order beam splitter and a second-order beam splitter on the beam axis of the partial beam reflected by the first-order beam splitter. The beam splitter array may further include a first-order beam splitter on the beam axis of the partial beam transmitted by the first or second secondary beam splitter and a second-order beam splitter on the beam axis of the partial beam reflected by the first or second secondary beam splitter. The beam splitter arrangement may further comprise exactly one or at least one fourth-order beam splitter located on the beam axis of the partial beam reflected or transmitted by the first third-order beam splitter or by the second third-order beam splitter.

[0059] In an alternative beam splitter arrangement, the first and second tertiary beam splitters may be arranged to be distributed along two of the beam axes: the beam axis of the partial beam transmitted by the first secondary beam splitter, the beam axis of the partial beam reflected by the first secondary beam splitter, the beam axis of the partial beam transmitted by the second secondary beam splitter, and the beam axis of the partial beam reflected by the second secondary beam splitter. In other words, the first and second tertiary beam splitters may be arranged on the beam axis of the partial beam reflected by the secondary beam splitter or the beam axis of the partial beam transmitted by the secondary beam splitter, respectively.

[0060] The beam splitter array may include first- to fourth-order beam splitters. The beam splitter array may include a first-order beam splitter. The beam splitter array may further include a first secondary beam splitter located on the beam axis of the partial beam transmitted by the first-order beam splitter and a second secondary beam splitter located on the beam axis of the partial beam reflected by the first-order beam splitter. The beam splitter array may further include a first tertiary beam splitter, a second tertiary beam splitter, and a third tertiary beam splitter distributed along three of the beam axes: the beam axis of the partial beam transmitted by the first secondary beam splitter, the beam axis of the partial beam reflected by the first secondary beam splitter, the beam axis of the partial beam transmitted by the second secondary beam splitter, and the beam axis of the partial beam reflected by the second secondary beam splitter.

[0061] The beam splitter arrangement may comprise one, in particular exactly one, beam splitter of the first or first beam splitter order.

[0062] The beam splitter arrangement may comprise at least two beam splitters of a second or secondary beam splitter order and / or at least two beam splitters of an order higher than the second or secondary beam splitter order. The beam splitter arrangement may comprise beam splitters of first to fourth order, i.e., first to fourth beam splitter orders. Thus, instead of a serial arrangement, the beam splitter arrangement may comprise a branching arrangement of beam splitters, preferably of first to fourth beam splitter orders.

[0063] When the beam splitters are arranged in a branching configuration, the beam splitter array generates the same number of partial beams as a serial configuration, while reducing the total number of (optical) interactions of the partial beams with the beam splitters. This is advantageous because each optical interaction is associated with an intensity loss, which can lead to imaging errors. In other words, the optical yield of the beam splitter array can be improved with a branching beam splitter arrangement compared to a serial beam splitter arrangement. In addition, the branching configuration can be implemented in a more compact manner or with a smaller form factor, if necessary. In one embodiment, a sensor device can have, for example, six beam splitters generating seven partial beams to be measured.

[0064] In this embodiment, when the beam splitters are arranged in series, exactly one beam splitter can be incorporated into the first through sixth beam splitter orders. This means that the first partial beam undergoes one interaction (with the primary beam splitter), the second partial beam undergoes two interactions (one with the primary beam splitter and one with the secondary beam splitter), the third partial beam undergoes three interactions, and the fourth, fifth, sixth, and seventh partial beams undergo four, five, six, and six interactions, respectively. A total of 27 interactions are required to generate seven partial beams with a series arrangement of six beam splitters.

[0065] When the beam splitters are in a branching arrangement, this embodiment can incorporate one beam splitter of the first beam splitter order, two beam splitters of the second beam splitter order, and three beam splitters of the third beam splitter order. In this way, the first partial beam undergoes two interactions (one with the primary beam splitter and one with the secondary beam splitter), the second partial beam undergoes three interactions (one with the primary beam splitter, one with the secondary beam splitter, and one with the tertiary beam splitter), and each of the other partial beams also undergoes three interactions. A total of 20 interactions are required to generate seven partial beams with a branching arrangement of six beam splitters.

[0066] According to various embodiments, the beam splitter arrangement may comprise two beam splitters of a secondary or second beam splitter order and a tertiary or third beam splitter order, and one, in particular exactly one, beam splitter of a quaternary or fourth beam splitter order.

[0067] According to various embodiments, the beam splitter array may include beam splitters of a first or first beam splitter order and at least a second or second beam splitter order or more, so the beam splitter array may include beam splitters of a first or first beam splitter order, a second or second beam splitter order, etc.

[0068] According to embodiments, the beamsplitter array may comprise beamsplitters of a first or first beamsplitter order, a second or second beamsplitter order, a third or third beamsplitter order or higher, etc. Thus, the beamsplitter array may comprise beamsplitters of a first or first beamsplitter order, a second or second beamsplitter order, a third or third beamsplitter order, etc.

[0069] According to various embodiments, the beamsplitter array may comprise beamsplitters of a first or first beamsplitter order, a second or second beamsplitter order, a third or third beamsplitter order, a fourth or fourth beamsplitter order or higher, etc. Thus, the beamsplitter array may comprise beamsplitters of a first or first beamsplitter order, a second or second beamsplitter order, a third or third beamsplitter order, a fourth or fourth beamsplitter order, etc.

[0070] According to various embodiments, the second or second beamsplitter order and / or higher order beamsplitter arrays may have exactly 2, 4, 8 or 16 beamsplitters. For example, the second or second beamsplitter order beamsplitter array may have exactly 2 beamsplitters, and / or the third or third order beamsplitter order may have exactly 2 or exactly 4 beamsplitters, and the fourth or fourth order beamsplitter order may have exactly 2 or exactly 4 or exactly 8 or exactly 16 beamsplitters, etc.

[0071] This "branching" arrangement of beam splitters has the advantage that the total number of interactions of the individual partial beams with the beam splitter is reduced compared to a simple series arrangement of beam splitters. A series arrangement is characterized by the presence of exactly one beam splitter of each beam splitter order (first order, second order, third order, etc.). In contrast, in a branching arrangement, there can be several beam splitters of each beam splitter order (second order, i.e., after the second beam splitter order).

[0072] Each beam splitter can be a dichroic beam splitter. Each (primary or secondary) beam splitter can be configured to reflect (or transmit) radiation within a particular wavelength range. Each (primary or secondary) beam splitter can be configured to transmit (or reflect) radiation having wavelengths outside the particular wavelength range.

[0073] The beam splitter arrangement may include at least one filter arranged before or after one of the beam splitters. The beam splitter arrangement may have at least one filter specialized for a wavelength range. The at least one wavelength range-specialized filter may be arranged in the beam path of at least one partial beam of the process beam.

[0074] Each photosensor may comprise at least one of the following elements: an optical sensor, a photodiode, a photodiode array, a CCD chip, and a CMOS chip.

[0075] The sensor surfaces of the photosensors of the first photosensor array may be of different sizes.

[0076] At least two beam splitters of the beam splitter array can be arranged in the beam path from the light inlet to at least one photosensor. This means that for at least one photosensor, the process beam passes through at least two beam splitters of the beam splitter array before hitting that photosensor as a corresponding partial beam. That is, the process beam is split at least twice by the beam splitters before hitting that photosensor. This makes it easier to optimize the coating of the two beam splitters compared to splitting by a single beam splitter on the beam path to each photosensor. This is because the wavelength range that each beam splitter must cover can be narrower.

[0077] The sensor device can be arranged on the laser processing head. The sensor device can preferably be arranged on the housing of the laser processing head. In particular, the sensor device can be flange-mounted to the housing of the laser processing head or configured to be flange-mounted to the housing. In particular, the sensor device can be arranged on an observation port of the housing. In particular, the sensor device can be arranged coaxially with respect to the beam axis of the laser beam. Alternatively, the sensor device can be arranged off-axis with respect to the beam axis.

[0078] Alternatively, the sensor device can be fiber-coupled. The light-receiving optics of the sensor device can be provided inside or on the surface of the laser processing head. The light-receiving optics can be located outside the laser processing head. The light-receiving optics can be arranged coaxially with respect to the beam axis of the laser beam.

[0079] Alternatively, the sensor device can be formed inside the laser.

[0080] The sensor device may include at least one housing. The housing may include an optical inlet. The optical inlet may be configured such that a process beam enters the housing of the sensor device through the optical inlet. A beam splitter array and / or a photosensor array and / or a filter may be disposed inside the housing. The sensor device may further include a coupling device configured to couple the sensor device to a laser processing head. The coupling device may be attached to the housing. The coupling device may include, for example, a through-hole for a fastening means. The coupling device may be integrated with the housing or formed on the housing.

[0081] The sensor device may further comprise at least one focusing optic, in particular a focusing lens, which may be arranged in or on the light inlet or in the beam path of the process beam between the light inlet and the beam splitter arrangement. The focusing optic may thus be arranged in the beam path of the process beam before the first splitting of the process beam, so that the entire process beam entering or having entered the sensor device passes through the focusing optic.

[0082] The photosensor array and / or photosensor can each be configured to generate a sensor signal corresponding to the sensed intensity. The sensor signal, particularly the intensity of the sensor signal, can represent the intensity in its respective sensed wavelength range. The sensor signal can be an analog or digital signal, but is preferably generated by converting an analog signal. The sensor signal can be a voltage signal.

[0083] The laser processing system may further include a control unit. The control unit may be configured to receive and / or evaluate the sensor signals. In particular, the control unit may be configured to evaluate the sensor signals separately, compare them, and / or combine them. The control unit may also be configured to perform open-loop control of the laser processing process and / or closed-loop control of the laser processing process based on the sensor signals. In particular, the control unit may be configured to detect the presence of a process error in the laser processing process based on the sensor signals.

[0084] The control unit can be configured to evaluate and / or record the sensor signals. The sensor signals can be evaluated separately from one another, in particular for each sensor signal, meaning that each wavelength range can be evaluated and monitored separately. The control unit can be configured to convert the (analog) sensor signals into digital signals.

[0085] The control unit may be configured to combine the individual sensor signals of the first photosensor array into a combined sensor signal, which may represent a total or average intensity across the entire visible wavelength range. The combined sensor signal may also represent a total intensity of a subset of the visible wavelength range. Combining may be performed by adding the sensor signal values ​​of the individual sensor signals. The control unit may also be configured to compare at least two of the individual sensor signals with each other. Comparison may be performed by forming a quotient of the sensor signal values ​​of the two individual sensor signals and / or by subtracting them.

[0086] The photosensors may each have a sensor surface, and each photosensor may be positioned such that its sensor surface is at the focal point of a corresponding partial beam. The sensor device may be configured such that the focal point of the process beam coincides with the surface of each photosensor at the expected focal position of the process beam.

[0087] The laser processing system, and in particular its control unit, can be configured so that an individual amplification factor can be set for each sensor signal.

[0088] Laser machining processes can include laser engraving, laser welding, laser cutting, laser soldering, and laser cladding of a workpiece. The workpiece can be a metallic workpiece.

[0089] Embodiments of the present disclosure will now be described with reference to the drawings, in which: [Brief explanation of the drawings]

[0090] [Figure 1] FIG. 1 illustrates a laser processing system according to embodiments of the present disclosure. [Figure 2] 1A and 1B are diagrams illustrating a schematic external appearance of a sensor device according to various embodiments of the present disclosure. [Figure 3] 1A and 1B are diagrams illustrating a schematic external appearance of a sensor device according to various embodiments of the present disclosure. [Figure 4] FIG. 1 is a diagram illustrating a sensor signal related to process beam intensity during laser welding in a broadband wavelength range. DETAILED DESCRIPTION OF THE INVENTION

[0091] Unless otherwise noted, the same reference numerals are used for identical and equivalent elements. Redundant descriptions of recurring features are avoided. The various embodiments and features in the figures described below can be combined and should not be understood as a complete implementation.

[0092] FIG. 1 illustrates a laser processing system according to embodiments of the present disclosure.

[0093] Laser processing system 10 is configured to perform laser processing processes and includes a laser processing head 12. In performing laser processing processes, laser processing head 12, including focusing and beam shaping optics, radiates and focuses a laser beam (not shown) onto workpiece 14, thereby heating, melting, and optionally vaporizing material from workpiece 14. Laser processing processes may include laser welding, laser cutting, laser soldering, and laser metal deposition welding.

[0094] During processing, a process beam 16 is generated and enters the laser processing head 12, where it is separated from the beam path of the laser beam (not shown) by a beam splitter 17. The process beam 16 includes laser radiation back-reflected or scattered by the workpiece 14, radiation in the infrared wavelength range of light, such as thermal radiation, and radiation in the visible wavelength range of light, such as radiation from plasma produced by the processing or from metal vapors strongly excited by the laser beam.

[0095] To separate the process beam 16, the laser processing head 12 can include a first coupling device 18 and an optical outlet (not shown), which can be associated with the first coupling device 18. The process beam is separated via the optical outlet of the laser processing head 12.

[0096] Laser processing system 10 further includes a sensor device 20 that monitors the laser processing process by sensing the intensity of process beam 16 generated during the laser processing process, according to embodiments of the present disclosure. Sensor device 20 includes an optical input port (not shown) for introducing or coupling process beam 16 into sensor device 20. The optical input port may be located on a housing 22 of sensor device 20. Sensor device 20 may further include a second coupling device 24 that couples sensor device 20 to a laser processing head. The coupling device 24 may be associated with the optical input port.

[0097] The beam splitter 17 may be disposed after the focusing optical system on the beam path of the process beam 16 in the laser processing head 12. In this way, the process beam 16 can be coupled into the sensor device 20 in a collimated manner.

[0098] Workpiece 14 can be a metallic workpiece, particularly one containing a ferrous material such as a steel alloy or an iron or aluminum-containing material such as aluminum or an aluminum alloy.

[0099] The sensor device 20 will now be described in detail. Figure 2 shows a schematic external view of a sensor device according to various embodiments of the present disclosure.

[0100] The sensor device 20 may include a focusing optical system (not shown), such as a focusing lens, that focuses the process beam 16 coupled into the sensor device. The beam axis 27 of the process beam 16 coincides with the optical axis of the focusing optical system. By providing such a focusing optical system, the process beam 16 or a partial beam, as described below, may also be focused onto a photosensor, as described below. However, the present disclosure is not limited to this. The process beam 16 may also be collimated and enter the sensor device 20.

[0101] The sensor device 20 includes a beam splitter array 28, a first photosensor array 42 that senses the intensity of the process beam 16 in the visible wavelength range, and a second photosensor array 44 that senses the intensity of the process beam 16 in the infrared wavelength range. The sensor device 20 may further include a third photosensor array 46 that senses the intensity of the process beam 16 in the back-reflection wavelength range, as shown in FIG. 2 . Each photosensor array 42, 44, 46 includes at least one photosensor 42 a, 42 b, 42 c, 42 d, 44 a, 44 b, 46 a. The beam splitter array 28 splits the process beam 16, separating partial beams having distinct wavelength ranges from the process beam 16 and directing each of the partial beams to one of the photosensors of the photosensor arrays 42, 44, 46. The photosensors may be configured, for example, as photodiodes.

[0102] The beam splitter array 28 includes a plurality of beam splitters, each configured as a partially transparent mirror. Each beam splitter can have a reflective coating and / or a transparent coating specialized for a certain wavelength range. As a result, a partial beam having a specific wavelength range is reflected or transmitted by each beam splitter of the beam splitter array 28. The beam splitter array 28 can further include at least one filter (not shown) specialized for a certain wavelength range that is arranged in the beam path of at least one partial beam of the process beam.

[0103] The beam splitter array 28 shown in FIG. 2 includes, by way of example, a primary beam splitter 28a, a first secondary beam splitter 28b, and a first tertiary beam splitter 28c, which are arranged one after the other on a line or axis. The primary beam splitter 28a is the first beam splitter and is arranged after the focusing optics in the beam path of the process beam 16 along the beam axis 27. The primary beam splitter 28a splits the process beam 16 into two partial beams. The first portion of the process beam 16 is reflected as a first primary reflected partial beam 30a. The second portion of the process beam 16 is transmitted as a first primary transmitted partial beam 30b. The beam axis of the partial beam 30b after the beam splitter 28a can be substantially coincident with or parallel to the beam axis of the process beam 16 that entered the sensor device 20 before the primary beam splitter 28a.

[0104] The first secondary beam splitter 28b is disposed in the beam path of the partial beam 30b transmitted by the beam splitter 28a. The beam splitter 28b splits the transmitted partial beam 30b into two parts. The first part of the partial beam 30b is reflected as a first secondary reflected partial beam 32a. The second part of the partial beam 30b is transmitted as a first secondary transmitted partial beam 32b. The beam axis of the partial beam 32b after the beam splitter 28b can be substantially coincident with or parallel to the beam axis of the partial beam 30b before the beam splitter 28b and / or to the beam axis of the process beam 16 before the beam splitter 28a.

[0105] The first tertiary beam splitter 28c is disposed in the beam path of the partial beam 32b transmitted by the beam splitter 28b. The beam splitter 28c splits the transmitted partial beam 32b into two parts. A first part of the partial beam 32b is reflected as a first tertiary reflected partial beam 34a. A second part of the partial beam 32b is transmitted as a first tertiary transmitted partial beam 34b. The beam axis of the partial beam 34b after the beam splitter 28c can be substantially coincident with or parallel to the beam axis of the partial beam 32b before the beam splitter 28c and / or to the beam axis of the process beam 16 before the beam splitter 28a.

[0106] The beam splitter arrangement further comprises a second secondary beam splitter 29a, a second tertiary beam splitter 29b, and a fourth-order beam splitter 29c. The second secondary beam splitter 29a is arranged in the beam path of the partial beam 30a reflected by the primary beam splitter 28a. The beam splitter 29a splits the reflected partial beam 30a into two parts. The first part of the partial beam 30a is reflected as a second secondary reflected partial beam 36a. The second part of the partial beam 30a is transmitted as a second secondary transmitted partial beam 36b. The beam axis of the partial beam 36b after the beam splitter 29a can be substantially coincident with or parallel to the beam axis of the partial beam 30a before the beam splitter 29a.

[0107] The second tertiary beam splitter 29b is arranged in the beam path of the partial beam 32a reflected by the first secondary beam splitter 28b. The beam splitter 29b splits the reflected partial beam 32a into two parts: a first part of the partial beam 32a is reflected as a second tertiary reflected partial beam 38a; and a second part of the partial beam 32a is transmitted as a second tertiary transmitted partial beam 38b. The beam axis of the partial beam 38b after the beam splitter 29b can be substantially coincident with or parallel to the beam axis of the partial beam 32a before the beam splitter 29b.

[0108] The fourth-order beam splitter 29c is disposed in the beam path of the partial beam 34a reflected by the first third-order beam splitter 28c. The beam splitter 29c splits the reflected partial beam 34a into two parts: a first part of the partial beam 34a is reflected as a fourth-order reflected partial beam 40a; and a second part of the partial beam 34a is transmitted as a fourth-order transmitted partial beam 40b. The beam axis of the partial beam 40b after the beam splitter 29c can be substantially coincident with or parallel to the beam axis of the partial beam 34a before the beam splitter 29c.

[0109] Beam splitter array 28 is not limited to the embodiment shown in FIG.

[0110] A further embodiment of the sensor device is shown in Figure 3. Here, the beam splitter array 28 comprises six beam splitters, arranged one after the other along the beam axis 27 of the process beam 16 entering the sensor device 20. The sensor device of Figure 3 comprises a primary beam splitter 45a, a secondary beam splitter 45b, a tertiary beam splitter 45c, a quaternary beam splitter 45d, a fifth beam splitter 45e, and a sixth beam splitter 45f. Each of the primary to fifth beam splitters 45a to 45e splits the corresponding partial beams 36a, 36b, 38a, 38b, 40a, and 40b. The sixth beam splitter splits the partial beams 40b and 46a.

[0111] The partial beams 38a, 38b, 40a, and 40b have different visible wavelength ranges. These partial beams are used to sense the intensity of the process beam 16 in these different visible wavelength ranges and can therefore also be referred to as visible partial beams. For example, the first partial beam 38a may have a first visible wavelength range around 400 nm and be used to sense atomic emission lines, particularly those of aluminum or iron. The second partial beam 38b may have a second visible wavelength range around 500 nm and be used to sense molecular emission bands, such as those of aluminum oxide. The third partial beam 40a may have a third visible wavelength range around 600 nm and be used to sense molecular emission bands, such as those of iron oxide. The fourth partial beam 40b may have a fourth visible wavelength range around 750 nm. The fourth visible wavelength range may also extend into the near-infrared range.

[0112] The illustrated beamsplitter array 28 separates four visible partial beams, but the present disclosure is not so limited. The beamsplitter array 28 could, for example, separate only two visible partial beams, e.g., first visible partial beam 38a and second visible partial beam 38b, or first visible partial beam 38a and third visible partial beam 40a.

[0113] The partial beams 36a, 36b have different infrared wavelength ranges. These partial beams are used to sense the intensity of the process beam 16 in different infrared wavelength ranges and can therefore also be referred to as infrared partial beams. The first infrared partial beam 36a can have an infrared wavelength range around 1500 nm. This infrared partial beam 36a can be used to sense thermal radiation representing high temperatures. This can be used, for example, to monitor effects and processes occurring around the keyhole and / or melt pool. The second infrared partial beam 36b can have an infrared wavelength range around 1900 nm. This infrared partial beam 36b can be used to sense thermal radiation representing low temperatures. This can be used, for example, to monitor effects and processes affecting heat transfer from the laser beam point of incidence on the workpiece or from the keyhole or melt pool.

[0114] Partial beam 34b has the same wavelength as the laser beam and is used to sense the intensity of the back reflection of the laser beam from workpiece 14 as part of process beam 16, and therefore may also be referred to as back reflected partial beam 34b.

[0115] The beam splitter array 28 directs the partial beams 38a, 38b, 40a, and 40b to corresponding photosensors in a first photosensor array 42 to sense the intensity of the process beam 16 in the visible wavelength range. In the illustrated example, the first photosensor array 42 includes four photosensors 42a-42d. Each of the four photosensors 42a-42d is positioned to sense the intensity of exactly one of the partial beams 38a, 38b, 40a, and 40b. For example, the first photosensor 42a senses the intensity of the first visible partial beam 38a, and so on. Because the beam splitter array 28 is configured to separate the separate partial beams 38a, 38b, 40a, and 40b having separate visible wavelength ranges from the process beam 16, the intensities in the separate visible wavelength ranges can also be detected and monitored separately from one another.

[0116] The beam splitter array 28 directs each of the partial beams 36a, 36b to one of the photosensors of the second photosensor array 44 for sensing the intensity of the process beam 16 in the infrared wavelength range. In the illustrated example, the second photosensor array 44 includes two photosensors 44a, 44b. Each of the two photosensors 44a, 44b is positioned to sense the intensity of exactly one of the partial beams 36a, 36b. For example, the first photosensor 44a senses the intensity of the first infrared partial beam 36a, and so on. Because the beam splitter array 28 separates the separate partial beams 36a, 36b, which have separate visible wavelength ranges, from the process beam 16, the intensities in the infrared wavelength ranges can also be detected and monitored separately from each other. The two photosensors 44a, 44b may have different sensor surface sizes. In particular, the sensor surface of the first photosensor 44a may be limited to imaging the processing area, such as the keyhole or the melt pool, while the sensor surface of the second photosensor 44b may be capable of imaging the processing area and its surroundings. In other words, the second photosensor 44b may have a larger sensor surface than the first photosensor 44a.

[0117] The beam splitter array directs partial beam 34b to a third photosensor array 46 for sensing the intensity of process beam 16 in the back-reflected wavelength range. The third photosensor array 46 includes a photosensor 46a positioned to detect the intensity of back-reflected partial beam 34b.

[0118] Beamsplitter array 28, photosensor arrays 42, 44, 46, and optionally additional filters and optical elements, such as focusing optics, are disposed within housing 22 (not shown in FIG. 2).

[0119] Each photosensor in each of photosensor arrays 42, 44, and 46 is configured to generate a corresponding sensor signal, e.g., an analog voltage signal, based on the intensity sensed in each condition, such that the voltage level is a measure of the intensity of the wavelength range sensed in each condition.

[0120] The laser processing system 10 shown in FIG. 1 may include a control unit 50 that receives sensor signals from all of the photosensors. The control unit 50 may be configured to control the laser processing process based on the received sensor signals. In particular, the control unit may be configured to detect the occurrence of a process error in the laser processing process based on the received sensor signals. The control unit may further be configured to set an individual gain for each sensor signal.

[0121] The control unit can further be configured to evaluate and / or record the sensor signals, which can be evaluated separately for each sensor signal or independently of the other sensor signals, so that each wavelength range can be evaluated and monitored separately.

[0122] The present invention relates to a sensor device for process monitoring, particularly during welding of parts, by recording process radiation or process beams in multiple wavelength ranges. In one possible embodiment, the sensor device has four visible spectrum photodiodes for sensing process radiation in the extended visible wavelength range, one laser wavelength photodiode for measuring laser backreflection, and two photodiodes for sensing process radiation in the infrared or temperature spectral range. In one possible embodiment, the beam splitter arrangement of the sensor device will be configured in series so that there are three primary beam splitters and three secondary beam splitters that further split the already split light and direct it into two channels each.

[0123] The beam splitter array of the present invention allows for monitoring a laser processing process in multiple wavelength ranges while optimizing the optical imaging of each individual wavelength range or channel separately. The sensor device allows for the sensor surface size of each individual photodiode to be appropriately selected, thereby enabling the imaging configuration to be designed. In addition, the described apparatus allows for the sensor signals of each individual photodiode to be amplified separately from each other. The signal of the laser back reflection will typically be very intense. In contrast, the intensity of radiation in that temperature range will typically be several orders of magnitude lower. Typically, the partial beams will have signal intensities that differ by several orders of magnitude. Therefore, it would be advantageous to be able to adjust the photodiode signals separately from each other. This is possible with the sensor device of the present invention, something that is not achievable or easily achieved with typical spectrometers due to their CCD or CMOS design.

Claims

1. 1. A sensor device (20) for monitoring a laser beam laser processing process by sensing the intensity of a process beam (16) produced during the laser processing process, comprising: a beam splitter array (28) configured to separate at least four visible partial beams (38a, b, 40a, b) having distinct visible wavelength ranges from the process beam (16); a first photosensor array (42) for sensing the intensity of the process beam (16) in the visible wavelength range using a plurality of photosensors (42a-d) arranged to individually sense the intensity of one of the at least four visible partial beams (38a, b, 40a, b); the beam splitter array (28) is configured to separate a first visible partial beam (38a) having a first visible wavelength range, a second visible partial beam (38b) having a second visible wavelength range, a third visible partial beam (40a) having a third visible wavelength range, and a fourth visible partial beam (40b) having a fourth visible wavelength range, and couple each of the separated beams to one of the photosensors (42a-d) of the first photosensor array (42); The first photosensor array (42) a first photosensor (42a) positioned to sense the intensity of the first visible partial beam (38a); a second photosensor (42b) positioned to sense the intensity of the second visible partial beam (38b); a third photosensor (42c) positioned to sense the intensity of said third visible partial beam (40a); a fourth photosensor (42d) positioned to sense the intensity of the fourth visible partial beam (40b); A sensor device comprising:

2. 2. The sensor device of claim 1, wherein the beam splitter array (28) is further configured to separate a back-reflected partial beam (34b) having a back-reflected wavelength range from the process beam (16); the sensor device (20) further comprises a third photosensor array (46) for sensing the intensity of the process beam (16) in the back-reflected wavelength range, the third photosensor array (46) comprising at least one photosensor (46 a) positioned to be able to sense the intensity of the back-reflected partial beam (34 b); The back-reflection wavelength range includes the wavelength of the laser beam and / or is a wavelength range from 950 nm to 1150 nm, or the back-reflection wavelength range includes a wavelength range in the green spectral range or the blue spectral range.

3. 3. The sensor device according to claim 1, the beam splitter array (28) is further configured to separate at least one infrared component beam (36a, 36b) having an infrared wavelength range from the process beam (16); The sensor device (20) further comprises a second photosensor array (44) that senses the intensity of the process beam (16) in the infrared wavelength range with at least one photosensor (44a, b) positioned to sense the intensity of the infrared beam (36a, 36b).

4. The sensor device according to any one of claims 1 to 3, the plurality of visible wavelength ranges do not overlap with one another; and / or A sensor device wherein each of the plurality of visible wavelength ranges includes at least one wavelength selected from the group consisting of 400 nm, 500 nm, 600 nm, 700 nm, 750 nm, 800 nm, wavelengths of aluminum oxide radiation bands, wavelengths of iron oxide radiation bands, and wavelengths of atomic emission lines, particularly those of a workpiece processed by the laser processing process, particularly those of copper, aluminum, or iron.

5. 5. The sensor device according to claim 1, The sensor device, wherein the beam splitter array (28) is configured to separate and couple each of the plurality of partial beams to a corresponding photosensor with predetermined and / or individually adjustable optical imaging.

6. 6. The sensor device according to claim 1, A sensor device in which the beam splitter array (28) has an imaging device, which has an aperture for at least one partial beam and / or at least one optical element, such as a lens or lens system, for at least one partial beam, by which the imaging of that partial beam onto the sensor surface of the corresponding photosensor is adjusted.

7. 7. A sensor device according to claim 1, A sensor device in which the size of the sensor surface of the corresponding photosensor and / or the position of the sensor surface along the beam axis for each partial beam can be selected or adjusted independently and / or differently with respect to the other partial beams.

8. A sensor device according to any one of claims 1 to 7, the beam splitter array (28) is configured to separate a first infrared component beam (36a) having a first infrared wavelength range from a second infrared component beam (36b) having a second infrared wavelength range different from the first infrared wavelength range; The sensor device, wherein the second photosensor array (44) comprises at least two photosensors (44a, b) arranged to individually sense the intensity of one of the infrared beams (36a, b).

9. A sensor device according to any one of claims 1 to 8, The sensor device, wherein the at least one infrared wavelength range includes at least one wavelength selected from the group consisting of 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, and 1900 nm.

10. 10. The sensor device according to claim 1, The beam splitter array (28) A sensor device comprising at least three, or at least four, or at least five, or at least six beam splitters (28a-c).

11. A sensor device according to any one of claims 1 to 10, A sensor device in which the beam splitter array (28) comprises primary, secondary, tertiary, quaternary, quintic and sixth order beam splitters, preferably arranged sequentially along the beam axis (27) of the process beam (16).

12. A sensor device according to any one of claims 1 to 10, The sensor device, wherein the beam splitter array (28) comprises at least two beam splitters belonging to a second beam splitter order and / or a beam splitter order higher than the second beam splitter order, the beam splitter order indicating the maximum number of optical interactions the partial beams in the beam splitter array have with the individual beam splitters.

13. A sensor device according to any one of claims 1 to 10 and 12, The beam splitter array (28) a primary beam splitter; a first secondary beam splitter located on the beam axis of the partial beam transmitted by the first beam splitter, and a second secondary beam splitter located on the beam axis of the partial beam reflected by the first beam splitter; a first tertiary beam splitter and a second tertiary beam splitter, which are distributed along two of the beam axes consisting of a beam axis of a partial beam transmitted by the first secondary beam splitter, a beam axis of a partial beam reflected by the first secondary beam splitter, a beam axis of a partial beam transmitted by the second secondary beam splitter, and a beam axis of a partial beam reflected by the second secondary beam splitter; Equipped with a fourth-order beam splitter located on the beam axis of the partial beam reflected or transmitted by the first third-order beam splitter or the second third-order beam splitter; or a first tertiary beam splitter, a second tertiary beam splitter, and a third tertiary beam splitter, which are distributed along three beam axes among the beam axes of the partial beam transmitted by the first secondary beam splitter, the beam axis of the partial beam reflected by the first secondary beam splitter, the beam axis of the partial beam transmitted by the second secondary beam splitter, and the beam axis of the partial beam reflected by the second secondary beam splitter; A sensor device comprising:

14. A sensor device according to any one of claims 1 to 13, The sensor device, wherein each of the photosensors comprises at least one of the following elements: a photodiode, a photodiode array, a CCD chip, a CMOS chip, and an optical sensor.

15. A sensor device according to any one of claims 1 to 14, the beam splitter array (28) comprises at least one beam splitter having a coating specialized for a wavelength range; and / or the beam splitter arrangement comprises at least one filter, which is arranged in the beam path of at least one partial beam of the process beam (16) and which is specialized for a certain wavelength range; and / or A sensor device in which the process beam (16) strikes the photosensor as corresponding partial beams after passing through at least two beam splitters of the beam splitter array (28).

16. 16. A sensor device according to any one of claims 1 to 15, further comprising a housing (22), the housing having a light entrance for introducing the process beam, the beam splitter array (28) and the photosensor arrays (42-44) being disposed within the housing (22); and The sensor device (20) comprises a coupling device (24) for coupling the sensor device (20) to a laser processing head (12), the coupling device (24) being attached to the housing (22).

17. A laser processing system (10) for performing a laser processing process, comprising: a laser processing head (12) configured to emit a laser beam onto a workpiece (14) to perform a laser processing process; A sensor device (20) according to any one of claims 1 to 16, A laser processing system (10) comprising: The laser processing system includes at least one beam splitter (17) arranged to split a process beam (16) generated during the laser processing process and entering the laser processing head from the beam path of the laser beam and couple it to the sensor device (20).

18. 18. A laser processing system according to claim 17, each of the photosensors is configured to generate a corresponding sensor signal based on a sensed intensity; The laser processing system (10) further comprises a control unit (50) configured to evaluate a sensor signal from the photosensor.

19. 19. A laser processing system according to claim 18, The laser processing system, wherein the control unit (50) is configured to perform closed-loop control of the laser processing process based on received sensor signals.

20. 20. The laser processing system according to claim 18 or 19, The laser processing system, wherein the control unit (50) is configured to combine the individual sensor signals of the photosensors of the first, second and / or third photosensor arrays into a combined sensor signal, preferably by adding together the sensor signal values ​​of the individual sensor signals.

21. 21. A laser processing system according to claim 20, the combined sensor signal represents a total or average intensity across the visible wavelength range; or The laser processing system, wherein the combined sensor signal represents a sum of intensities of the subset of visible wavelengths.

22. 22. The laser processing system according to any one of claims 18 to 21, The laser processing system wherein the control unit (50) is configured to compare at least two of the individual sensor signals of the photosensors of the first, second and / or third photosensor arrays with each other, preferably by forming a quotient of the sensor signal values ​​of the two individual sensor signals and / or by subtracting them.

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