Imaging device, laser processing machine comprising imaging device, and method for determining process variable

Abstract

The invention relates to an imaging device (12) for imaging a process zone (14) of a laser processing machine (10), comprising an image sensor (28) and an optical imaging system (30) located between the process zone (14) and the image sensor (28). The optical imaging system (30) has: a system axis (32) extending between the image sensor (28) and the process zone (14); a first diaphragm (34) radially spaced from the system axis (32); and a second diaphragm (36). The light beams (40, 44) emitted from the process zone (14) at different imaging angles (38, 42) are bounded by diaphragms (34, 36). The optical imaging system (30) is configured to spatially separately image the first light beam (40) from the second light beam (44). The invention also relates to: a laser processing machine (10) comprising such an imaging device (12); and a method for determining a process variable using such an imaging device (12).

Description

Technical Field

[0001] The invention relates to an imaging device having an optical imaging system for imaging a process zone of a laser processing machine on an image sensor. The invention also relates to a laser processing machine having the imaging device and a method for determining process variables. Background Art

[0002] Such devices and methods are known in various embodiments from the prior art and are used for monitoring laser machining processes. Typically, imaging devices display a three-dimensional image of the process area as a two-dimensional image on an image sensor. Based on the analysis of the image of the process area, if the image is sufficiently accurate, important functions and control variables of common laser cutting machines can be derived, which can, for example, support feed control or cutting error detection during laser machining.

[0003] WO 2016 062636 A1 describes a device for measuring the depth of a weld seam when welding or joining workpieces by means of radiation. The device can be tilted relative to the processing beam as a function of the feed speed in order to be able to take into account the tilting of the weld seam as a function of the feed speed. However, representing the weld seam from only one angle (albeit a variable one) can only convey insufficient information about the process zone. For example, information can be lost due to a reduction in the imaging area.

[0004] WO 2016 181359A1 describes a laser processing device having at least one set of detector devices. The detector devices are arranged in a ring around the optical axis of the laser cutting device. The detector devices are configured to detect the process zone at various static angles. The described detector devices place considerable structural demands on the implementation of the described principle and require complex evaluation procedures for evaluating the detected information.

[0005] DE 10 2013 218 421 A1 describes a device for monitoring a laser cutting process on a workpiece using an image capture device, wherein an observation beam is formed at an observation angle oblique to the laser beam. The device can also have multiple observation directions with the same observation angle.

[0006] The aforementioned devices do have the possibility to image the process zone from different directions (e.g. by rotating the device). However, the device only images the process zone at a single predetermined angle. This means that the process zone can only be imaged in an inaccurate manner. For example, critical information cannot be imaged by the device at only one predetermined angle. The "geometric visibility" of the process zone usually depends on the nozzle diameter of the laser processing machine, the material thickness of the workpiece to be processed, the distance between the nozzle and the workpiece, and the emission characteristics of the laser processing process.

[0007] Purpose of the Invention

[0008] The object of the present invention is to provide a device for imaging a process zone of a laser processing device and an associated method thereof, which enable reliable determination of process variables from the image. Summary of the invention

[0009] According to the invention, this object is achieved by an imaging device having the features of claim 1. The object is also achieved by a laser processing machine having the features of claim 18 and a method having the features of claim 19. The dependent claims indicate preferred embodiments of the invention.

[0010] According to the present invention, an imaging device is provided. The imaging device is suitable for imaging a process area of ​​a laser processing machine. Typically, the process area is optically imaged by imaging light emitted from the process area.

[0011] The imaging device comprises an image sensor. The image sensor is usually configured for two-dimensional imaging of optical radiation, preferably in the spectral range from ultraviolet (UV) to short-wave infrared (SWIR), particularly preferably from 350 nm to 1800 nm. Preferably, the image sensor is semiconductor-based.

[0012] The imaging device further comprises an optical imaging system arranged between the process zone and the image sensor. The optical imaging system is preferably configured to guide and direct the light radiation emitted from the process zone to the image sensor. Further preferably, the optical imaging system is configured to deflect the processing beam of the laser processing device onto the workpiece to be processed.

[0013] The optical imaging system has a system axis extending between the image sensor and the process area. In order to simplify the description of the present invention, the system axis can be understood as an idealized axis. The idealized axis can replace the optical path commonly used in practice, which can consist of parts that are inclined to each other. A person skilled in the art can transfer the present invention from the system axis to the optical path, so that, for example, an offset between the process area and the image sensor can be achieved in structure.

[0014] The optical imaging system further comprises a first aperture radially spaced from the system axis. The first aperture is preferably configured perpendicular to the system axis. The first aperture limits a first light beam emitted from the process zone at a first imaging angle. In other words, the first aperture only allows light radiation emitted from the process zone to pass through at a certain angle.

[0015] The optical imaging system further comprises a second aperture. Preferably, the second aperture is configured perpendicular to the system axis. The second aperture can be spaced apart from the first aperture, in particular radially spaced apart relative to the system axis. The second aperture delimits a second light beam emitted from the process zone at a second imaging angle.

[0016] The optical imaging system further comprises a first imaging lens arranged between the aperture and the image sensor. In other words, the first imaging lens is arranged upstream of the first imaging lens in the beam path of the optical imaging system. The optical imaging system is thus configured for integrating additional optical components between the aperture and the first imaging lens. Additional optical components can be integrated into the optical imaging system, for example in the form of optical filters. This enables the optical imaging system to be used for performing optical measurement procedures, such as stereometry / stereoscopy, pyrometry, goniometric measurement or spectral analysis.

[0017] The first imaging lens is generally configured as a converging lens. The first imaging lens is configured to image at least the first light beam and the second light beam onto an image sensor.

[0018] According to the invention, the first imaging angle is different from the second imaging angle. In other words, the first light beam bounded by the first aperture has a different imaging angle than the second light beam bounded by the second aperture. The imaging angle is the angle enclosed between the respective light beam and the system axis. In other words, several light beams may have the same angle value but may be emitted from the process area in different directions. The imaging angle may be zero degrees.

[0019] The optical imaging system is also configured to image the first light beam and the second light beam separately in space. The first light beam and the second light beam are usually imaged on an image sensor.

[0020] In other words, the basic object is achieved in that the imaging device is designed for imaging the process zone simultaneously or in parallel at at least two different imaging angles, while the remaining light radiation emitted by the process zone is hidden, reflected or absorbed. In addition, the process zone is imaged from at least two directional imaging angles, thereby increasing the area of ​​the process zone that can be imaged by the imaging device. In addition, the simultaneous imaging of the two light beams on the image sensor is performed spatially separately, so that the images can be assigned to the imaging angles. By knowing the imaging angles, the images of the process zone can be used for geometric comparison. In other words, the process zone can be analyzed three-dimensionally. By means of the three-dimensional analysis, process variables such as the length of the processing front of the laser processing machine, spatially resolved temperature measurements and / or the temperature distribution in the process zone can be reliably determined. This makes it possible, for example, to detect the formation of plasma or metal vapor and to improve the quality of the laser processing by avoiding cutting errors.

[0021] In a preferred embodiment of the imaging device, the optical imaging system has a directional lens arranged between the process area and the aperture. The directional lens can align the light beam emitted from the process area parallel to the system axis onto the aperture. In other words, the imaging device can form a collimator. This enables the light beam to be delimited particularly accurately by the aperture.

[0022] Another preferred embodiment of the imaging device is that the optical imaging device has a third aperture. The third aperture can limit the third light beam emitted from the process area at a third imaging angle. The additional aperture can also improve the three-dimensional observation of the process area.

[0023] In a preferred further development of the imaging device, the third imaging angle is different from the first imaging angle and / or the second imaging angle. This enables a more precise determination of the process variables.

[0024] Particularly preferred is the following further development of the imaging device, in which the optical imaging system is designed to image the third light beam spatially separately from the first light beam and / or the second light beam on the image sensor. Preferably, all light beams are imaged spatially separately from one another on the image sensor. This enables an evaluation of the image with a clear assignment of the respective imaging angles.

[0025] In a preferred embodiment of the imaging device, the optical imaging system has a process zone aperture. The process zone aperture can be designed in particular as a processing nozzle of a laser processing machine. This makes it possible to limit the total number of light beams emitted from the process zone in the direction of the imaging device, thereby improving the imaging accuracy of the light beams.

[0026] In a preferred embodiment of the imaging device, the apertures are formed on a common aperture disk. The common aperture disk is preferably arranged perpendicularly or orthogonally to the system axis. The common aperture disk enables a particularly precise spacing of the apertures from one another, in particular when the apertures are moved. Preferably, the aperture disk can be designed as a coated glass substrate. Particularly preferably, the aperture disk transmits light radiation in the aperture region and attenuates, absorbs or reflects light radiation outside the aperture.

[0027] In a preferred further improvement of the imaging device, the aperture disc is configured to be rotatable about the system axis. Preferably, the aperture disc is configured to be rotatable according to the processing direction of the laser processing machine. This makes it possible to maintain the image of the light beam with respect to the formation of the process area depending on the processing direction. For example, when the direction of laser processing changes by 90 degrees, for example, if the aperture disc is also rotated by 90 degrees, a high-sharp image of the process area can be made clearer.

[0028] In a preferred further development of the imaging device, the optical imaging system has a first optical rotation decoupling element (Drehentkopplung) located downstream of the first aperture. The first optical rotation decoupling element is generally designed to image the first light beam on the image sensor accurately in terms of position, independently of the rotation of the aperture disk. In other words, the first light beam can be imaged on the same imaging area of ​​the image sensor independently of the processing direction of the laser processing machine. This makes it particularly easy to assign the imaging angle to the image. In addition, the size of the image sensor can be kept particularly compact.

[0029] Particularly preferred is the following further improvement of the imaging device, in which the system axis intersects the image sensor at an imaging intersection. Preferably, in this case, the first imaging lens is configured to image the first light beam centrally at the imaging intersection. By imaging the first light beam at the imaging intersection, static imaging of the first light beam can be achieved.

[0030] In a particularly preferred further development of the imaging device, in which the system axis passes centrally through the second aperture, the imaging device has at least one wedge arranged upstream of the first imaging lens and downstream of the second aperture. In other words, in this case, the second aperture delimits a second light beam extending coaxially with the system axis, which second light beam is optically independent of any rotation of the second aperture. The wedge is preferably configured to deflect the second light beam obliquely relative to the system axis onto the first imaging lens. By deflecting the second light beam, the position of the image on the image sensor can be determined. Preferably, the second light beam is imaged onto an imaging area on the image sensor that is eccentric or spaced apart from the imaging intersection. This enables position-accurate and rotation-independent imaging of the second light beam without a rotational decoupling.

[0031] Alternatively, in the following further development of the imaging device, in which the system axis extends centrally through the second aperture, it can be provided that the optical imaging system has a first optical subsystem with a second imaging lens. The first optical subsystem or the second imaging lens is preferably configured to positionally accurately image the second light beam on the image sensor. The second imaging lens can be used to avoid optical superposition of the light beams in the first imaging lens, thereby improving the imaging accuracy. By forming the optical subsystem, an optical path with different spectral transmission characteristics can be provided that is separate from the optical path of the first light beam. This enables the process area to be imaged with other spectral characteristics, which can further improve the analysis of the process area.

[0032] Particularly preferred is the following further development of the imaging device, in which the first optical subsystem has a first deflection mirror located downstream of the aperture, wherein the first deflection mirror is configured to deflect the second light beam. Preferably, the first deflection mirror is configured to deflect a specific wavelength of the second light beam. In particular, unwanted wavelengths can be filtered out. This enables a particularly precise imaging of the second light beam.

[0033] In a preferred further development of the imaging device in combination with a third aperture, it can be provided that the optical imaging system has a second optical subsystem located downstream of the third aperture. The second optical subsystem is preferably designed for positionally accurate imaging of the third light beam, in particular on an imaging image sensor, independently of a rotation of the aperture disk.

[0034] Particularly preferred is the following further improvement of the imaging device, in which the second optical subsystem has a second deflection mirror located downstream of the aperture. The second deflection mirror is preferably configured to deflect a specific wavelength of the third light beam. This enables the third light beam to be imaged within a predetermined spectral range.

[0035] In a preferred embodiment of the imaging device, the optical imaging system is configured to image the light beam onto a single image sensor.

[0036] The basic object is also achieved by a laser processing machine having an imaging device as described above and below.

[0037] The laser processing machine usually has a laser processing unit for forming a laser beam. In addition, the laser processing machine usually has a machine control system. The machine control system can be configured to control or adjust the laser processing unit and / or the imaging device.

[0038] Preferably, the machine control system has an evaluation unit. The evaluation unit is particularly preferably configured to evaluate the image on the image sensor.

[0039] Furthermore, the basic object is achieved by a method for determining a process variable of a process zone by means of an imaging device described above and below. The method comprises the following method steps:

[0040] In one method step, at least a first image and at least a second image of the process area are created. The images are usually created by a first light beam and a second light beam on an image sensor. Preferably, a third image can be generated by a third light beam.

[0041] In a further method step, at least a first imaging angle and a second imaging angle are provided.The imaging angles can be provided, for example, by a machine control and / or by an operator of the imaging device.

[0042] In a subsequent method step, at least the first image is compared with the second image. Preferably, the geometric contents of the images are compared with one another.

[0043] Based on the comparison, at least one process variable is determined or calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further features and advantages of the invention can be found in the description, the claims and the drawings. According to the invention, the features mentioned above and the features to be further described can be used alone or together in any desired advantageous combination in each case. The embodiments shown and described should not be understood as an exhaustive enumeration, but should be understood as having exemplary characteristics for describing the invention. In the drawings:

[0045] Figure 1A laser processing machine having a first embodiment of an imaging device according to the invention is shown in a schematic representation, wherein the imaging device has an image sensor and an optical imaging system;

[0046] Figure 2 A second embodiment of an imaging device is shown in schematic representation;

[0047] Figure 3 A third embodiment of an imaging device is shown in schematic representation;

[0048] Figure 4 The schematic diagram shows the Figure 3 Image sensor;

[0049] Figure 5 The schematic diagram shows the Figure 3 The aperture disk;

[0050] Figure 6 The method according to the invention is shown in a schematic representation. DETAILED DESCRIPTION

[0051] Figure 1 A laser processing machine 10 is shown having an imaging device 12 for imaging a process zone 14 of the laser processing machine 10. In the case shown, the process zone 14 is designed as a process or irradiation zone of a laser beam (not shown in greater detail) of the laser processing machine 12.

[0052] During the machining process, the laser beam passes through the machining nozzle 16 of the laser machining machine 10 in the direction of the workpiece 18 to be machined. For better machining, the workpiece 18 can be placed on a workpiece support 20 (preferably in the form of a mesh), as in the case shown. By irradiating the workpiece 18, it can be melted and / or at least partially vaporized within the effective range of the laser beam. For example, if the laser machining machine 10 moves in the machining direction 22, the workpiece 18 to be machined can be cut along the cutting edge 24. In the transition area between the workpiece 18 and the cutting edge 24, a machining front 26 is formed on the workpiece 18, depending on the irradiation duration of the laser beam. Important information about the machining process can be obtained from the formation of the machining front 26. Therefore, the design of the machining front 26 is crucial for controlling or regulating the laser machining machine 10 and must be monitored, for example to ensure a high machining speed and / or machining quality.

[0053] According to the embodiment shown, the imaging device 12 is arranged on the laser processing machine 10, preferably integrated into the laser processing machine 10. The imaging device 12 comprises an image sensor 28 and an optical imaging system 30 arranged between the process zone 14 and the image sensor 28. The optical imaging system 30 is arranged along a system axis 32, which extends between the image sensor 28 and the process zone 14. Preferably, the system axis 32 is configured as an optical axis of the optical imaging system 30. In other words, the optical imaging system 30 can be configured at least predominantly rotationally symmetrical with respect to the system axis 32. The system axis 32 is also preferably configured orthogonally to the workpiece 18 to be processed. The optical imaging system 30, in particular the entire imaging device 12, can be arranged orthogonally to the workpiece 18 to be processed.

[0054] The optical imaging system 30 has a first aperture 34 radially spaced apart from the system axis 32. In addition, the optical imaging system 30 has a second aperture 36. The second aperture 36 is arranged at a distance, in particular radially, from the first aperture 34. According to the embodiment shown, the second aperture 36 can be arranged centrally with respect to the system axis 32.

[0055] The first aperture 34 delimits a first light beam 40 emitted from the process zone 14 at a first imaging angle 38. The second aperture 36 delimits a second light beam 44 emitted from the process zone 14 at a second imaging angle 42. The imaging angles 38, 42 can be determined as the inclination of the respective light beam 40, 44 relative to the system axis 32. According to the embodiment shown, the second light beam 44 is emitted parallel to the system axis 32, which is why the second imaging angle 42 is zero degrees here. The magnitude of the first imaging angle 38 is different from the magnitude of the second imaging angle 42. Preferably, the first imaging angle is between three and four degrees.

[0056] The first light beam 40 and the second light beam 44 are spatially imaged by the optical imaging system 30, respectively, on the image sensor 28. This allows a perspective view of the process area 14. Purely for a more compact representation, the beam paths of the first light beam 40 and the second light beam 44 are shown interrupted by two horizontal lines 46.

[0057] According to the embodiment shown, the optical imaging system 30 can have a process zone aperture 48, here formed on the processing nozzle 16. The process zone aperture 48 limits the light beams emitted from the process zone 14, such as the first light beam 40 and the second light beam 44. This can reduce scattered radiation and improve the imaging of the first light beam 40 and the second light beam 44.

[0058] The optical imaging system 30 may have a directional lens 50. The directional lens 50 may be arranged between the process zones 14, in particular between the process zone aperture 48 and the first aperture 34 and / or the second aperture 36. Preferably, the directional lens 50 aligns the first light beam 40 and / or the second light beam 44 emitted from the process zone 14 parallel to the system axis 32. Thus, the imaging device 12 may remain compact in its radial dimension relative to the system axis 32.

[0059] The optical imaging system 30 has a first imaging lens 52. The first imaging lens 52 is arranged between the apertures 34, 36 and the image sensor 28. The first imaging lens 52 is generally configured to image the first light beam 40 and / or the second light beam 44 onto the image sensor 28. Figure 1 As shown, imaging lens 52 forms first light beam 40 in a first imaging region 54 and second light beam 44 in a second imaging region 56 on image sensor 28. First imaging region 54 is spatially separated from second imaging region 56.

[0060] According to the present embodiment, a single image sensor 28 is provided. Alternatively or additionally, the imaging device 12 may have a plurality of image sensors 28 for imaging the light beams 40, 44. For better illustration, the image sensor 28 and the imaging areas 54, 56 with the first light beam 40 and the second light beam 44 imaged on the image sensor 28 are shown in a detailed view as a top view.

[0061] according to Figure 1 , the first light beam 40 is tilted in the process direction 22, so that a "high-sharp image" (stechende Abbildung) of the process region 14 is generated. In other words, the "high-sharp image" enables an oblique observation of the process region 14 and the process front 26 in the process direction 22. Thus, for example, a first length 58 of the process front 26 can be determined depending on the first imaging angle 38.

[0062] The second light beam 44 is not tilted relative to the system axis 32, which results in a “center image” of the process zone 14. In other words, the “center image” enables a center view of the process zone 14 and the process front 26 independently of the process direction 22. Thus, for example, a second length 60 of the process front 26 can be determined depending on the second imaging angle 42.

[0063] In the geometric comparison of the ascertained lengths 58 , 60 of the processing front 26 , further geometric variables of the process zone 14 , such as the current penetration depth of the laser beam, can then be ascertained.

[0064] The optical imaging system 30 may have an aperture disk 62. For better illustration, the aperture disk 62 is shown in a further detailed view as a top view. The first aperture 34 and the second aperture 36 may be formed on a (common) aperture disk 62. This facilitates the precise positioning of the first aperture 34 relative to the second aperture 36, which has a beneficial effect on the imaging accuracy of the process area 14.

[0065] As indicated by arrow 64, the aperture disk 62 may be configured to be rotatable about the system axis 32. This enables the imaging device 12 to adapt to a changed processing direction 22 of the laser processing machine 10. For example, if Figure 1 If the process direction 22 is shown to be reversed, the optical imaging system 30 will image the process area 14 opposite to the process direction 22. This can be prevented by rotating the aperture disk 62 by 180 degrees.

[0066] As shown, the optical imaging system 30 can have a first rotational decoupling 66. The first rotational decoupling 66 is located downstream of the first aperture 34. According to the embodiment shown, the first rotational decoupling 66 is configured as a convergent lens, here in the form of an imaging lens 52, which is rotationally symmetrical about the system axis 32. The system axis 32 corresponds to the optical axis of the imaging lens 52. The first rotational decoupling 66 images the first light beam 40 bounded by the first aperture 34 in an imaging region 54 of the image sensor 28. The imaging region 54 is centered at an imaging intersection 68 of the system axis 32 and the image sensor 28, so that the first light beam 40 can be accurately positioned independently of any displacement or rotation of the first aperture 34 relative to the system axis 32 about the system axis 32. In other words, the first light beam 40 can be imaged in the fixed imaging region 54 independently of the rotation of the first aperture 34. Therefore, the position of the image on the image sensor 28 does not change.

[0067] according to Figure 1 In the embodiment shown, the optical imaging system 30 for spatially separately imaging the second light beam 44 on the image sensor 28 has a wedge 70. The wedge 70 is designed to direct the second light beam 44 obliquely relative to the system axis 32 to the imaging lens 52. The oblique illumination of the imaging lens 52 causes the second light beam 44 to be imaged on the image sensor 28 at a certain radial distance from the imaging intersection 70. Due to the central arrangement of the second aperture 36 on the system axis 32, the positionally accurate imaging of the second light beam 44 can be carried out in the imaging region 56 of the image sensor 28 independently of the rotation of the second aperture 36 about the system axis 32. In this embodiment, the rotational decoupling can be omitted.

[0068] Figure 2A second embodiment of the imaging device 12 is shown in a schematic representation. The optical imaging system 30 has a first rotational decoupling 66 which enables a rotationally independent and positionally accurate imaging of the first light beam 40 in the imaging region 54 on the image sensor 28 by means of the first imaging lens 52 .

[0069] In addition, the optical imaging system 30 has a first optical subsystem 72. The optical subsystem 72 is configured to image the second light beam 44 spatially separated from the first light beam 40 onto the image sensor 28. According to the embodiment shown, the first optical subsystem 72 has a first deflection mirror 74, a second deflection mirror 76, a second imaging lens 78, and an imaging prism 80.

[0070] The first deflection mirror 74 is disposed between the apertures 34, 36 and the first imaging lens 52, and is configured to deflect the second light beam 44. As shown, the second light beam 44 can be directed by the first deflection mirror 74, through the first imaging lens 52 to the second deflection mirror 76.

[0071] The second deflection mirror 76 may be configured to align the second light beam 44. Preferably, the second deflection mirror 76 aligns the second light beam 44 parallel to the system axis 32. In other words, the deflection mirrors 74, 76 cause a parallel displacement of the second light beam 44 to the system axis 32 or a radial spacing of the second light beam 44 from the system axis.

[0072] Then, the second light beam 44 may be imaged on the image sensor 28 by means of the second imaging lens 78 , so that the image quality may be improved.

[0073] In order to keep the size of the image sensor 28 small, it can be provided, as shown, that the radial spacing caused by the deflection mirrors 74 , 76 is partially or completely compensated by the imaging prism 80 .

[0074] Figure 3 A third embodiment of an imaging device 12 is shown in a schematic representation.

[0075] The optical imaging system 30 has a first aperture 34, a second aperture 36 and a third aperture 82 which are radially spaced apart from the system axis 32. The apertures 34, 36, 82 can be formed on a common aperture disk 62.

[0076] The first light beam 40 bounded by the first aperture 34 is imaged in a first imaging region 54 on the image sensor 28 by means of an imaging lens 52. Figure 2 The second light beam 44 is imaged in the second imaging area 56 on the image sensor 28 by means of the first optical subsystem 72 or the second imaging lens 78 .

[0077] The third aperture 82 can be arranged at a distance, in particular a radial distance, from the first aperture 34 and / or from the second aperture 36. The third aperture 36 is generally configured to bound a third light beam 84 emitted from the process area 14 at a third imaging angle 86. The third imaging angle 86 can be inclined opposite to the processing direction 22. The optical imaging system 30 is configured to image the third light beam 84 on the image sensor 28, in particular in a third imaging area 88.

[0078] As shown, the optical imaging system 30 may have a second optical subsystem 90 configured to image the third light beam 84 onto the image sensor 28. The second optical subsystem 90 may have a third deflecting mirror 92, a fourth deflecting mirror 94, a third imaging lens 96, and a second imaging prism 98.

[0079] The second optical subsystem 90 can be configured similarly to the first optical subsystem 72 for radially spacing the third light beam 84. To this end, a deflection of the first light beam 84 from a direction parallel to the system axis 32 and a subsequent re-parallel alignment of the deflected third light beam 84 relative to the system axis 32 can be provided. Thus, an image of the third light beam 84 can be generated in a positionally accurate manner in a third imaging region 88, in particular a stationary image, via the third imaging lens 96 and the imaging prism 98.

[0080] according to Figure 3 In the embodiment shown, the second optical subsystem 90 is also designed as a second rotation decoupling element 100. This makes it possible to image the third light beam 84 accurately in position even when the third aperture 82 or the aperture disk 62 is rotating.

[0081] The third deflection mirror 92 of the second optical subsystem 90 can be configured to be rotationally symmetric with respect to the system axis 32 in a plane orthogonal to the system axis 32. The third deflection mirror 92 can be circular in a plane orthogonal to the system axis 32, wherein the inner diameter is smaller than the minimum distance of the third aperture 82 from the system axis 32, and wherein the outer diameter is larger than the maximum distance of the third aperture 82 from the system axis 32. Preferably, the deflection mirror 92 is configured as a circumferential ring in a plane orthogonal to the system axis 32. In other words, the deflection mirror 92 has a size that corresponds at least to the surrounding projection surface of the third aperture 82 in a plane projected toward the system axis 32. This maximizes the independence from the rotation of the third aperture 82. If the apertures 34, 36, 82 each have radially spaced surrounding projection surfaces - in other words, if the surrounding projection surfaces of the apertures 34, 36, 82 do not overlap, the annular design of the third deflection mirror 92 enables the first light beam 40 and the second light beam 44 to pass optically unhindered.

[0082] Alternatively, if Figure 3As shown, it can be provided that the deflection mirror 92 is configured to deflect the light beam within a predetermined wavelength range, wherein the light beam outside the predetermined wavelength range is transmitted. To this end, it can be provided that at least one optical bandpass filter 102 is connected upstream of the deflection mirror 92. Preferably, the apertures 34, 36, 82 each have an optical bandpass filter 102, which predetermines the wavelength range of the corresponding light beam 40, 44, 84. This enables the light beams 40, 44, 84 with overlapping surrounding projection surfaces to be optically separated.

[0083] Further information can also be recorded based on the polarization properties. For this purpose, as an alternative or in addition to the optical bandpass filter 102, it can be provided that at least one of the apertures 34, 36, 82 has a polarization filter, for example for filtering s-polarized light beams and p-polarized light beams. With the help of the polarization filter, a correspondingly "polarized" image can be displayed and / or used for measurement purposes.

[0084] Figure 4 The schematic diagram shows the Figure 3 The imaging regions 54, 56, 88 are spatially spaced apart from one another and are arranged in fixed positions on the image sensor 28. In other words, when the processing direction 22 (see Figure 1 ) or the rotational position of the aperture disk 62 (see Figures 1 to 3 , Figure 5 ) changes, the positions of the imaging areas 54, 56, 88 on the image sensor 28 do not change.

[0085] The first imaging region 54 shows a "high-sharp image" of the process area 14 (see Figure 1 ), from which, for example, it is possible to determine the value that depends on the first imaging angle 38 (see Figure 1 ) of the processing front 26. In addition, the second imaging region 56 shows a "center image" of the process zone 14, from which, for example, the image can be determined depending on the second imaging angle 42 (see Figure 1 ) of the processing front 26. In addition, the third imaging area 88 shows the process area 14 caused by the third imaging angle 86 (see Figure 3 ) relative to the machining direction 22 (see Figure 3 ) by which, for example, the third length 104 of the machining front 26 can be determined.

[0086] The additional information about the third image can further improve the determination of the geometric dimensions of the process region 14 .

[0087] Figure 5 The schematic diagram shows the Figure 3 The aperture disk 62.

[0088] As indicated by arrow 64, aperture disk 62 is configured to be rotatable about system axis 32. Apertures 34, 36, 82 are formed spatially separated from one another on aperture disk 62. Second aperture 36 is formed on aperture disk 62 centrally with respect to system axis 32.

[0089] The first aperture 34 and the third aperture 82 are offset by 180 degrees on the aperture disk 62 and have different radial distances from the system axis 32 .

[0090] The track 106 indicated by the dotted circle of the first aperture 34 overlaps with the third aperture 82. This may result in an optical superposition of the first beam 40 and the third beam 84, thereby causing the image sensor 28 ( Figures 1 to 4 ) is not clear. In order to avoid optical superposition, it can be provided that the apertures 34, 36, 82 (here in particular the first aperture 34 and the third aperture 82) have an optical bandpass filter 102.

[0091] Figure 6 Schematically shows a method for using an imaging device 12 (see Figure 1 ) to obtain process area 14 (see Figure 1 ) of process variables, especially geometric process variables 108.

[0092] Method 108 has the following method steps (see also below Figure 1 ).

[0093] In one method step 110 , first and second images of the process area 14 are created. The first and second images are typically created by imaging the first and second light beams 40 , 44 in the first and second imaging regions 54 , 56 of the image sensor 28 .

[0094] In a further method step 112 , a first imaging angle 38 and a second imaging angle 42 are provided.

[0095] The subsequent method step 114 provides for a geometric comparison of the first image with the second image, wherein at least one process variable is ascertained or calculated by means of the geometric comparison.

[0096] In summary, the present invention relates to an imaging device (12) for imaging a process zone (14) of a laser processing machine (10), the imaging device comprising an image sensor (28) and an optical imaging system (30) located between the process zone (14) and the image sensor (28). The optical imaging system (30) comprises a system axis (32) extending between the image sensor (28) and the process zone (14), a first aperture (34) radially spaced from the system axis (32), and a second aperture (36). Light beams (40, 44) emitted from the process zone (14) at different imaging angles (38, 42) are bounded by the apertures (34, 36). The optical imaging system (30) is configured to image the first light beam (40) and the second light beam (44) spatially separately. The present invention also relates to a laser processing machine (10) having the imaging device (12) and a method for determining a process variable.

[0097] Reference numerals list

[0098] 10 Laser processing machine

[0099] 12 Imaging equipment

[0100] 14. Process Area

[0101] 16 Processing nozzle

[0102] 18 Workpiece

[0103] 20 Workpiece support

[0104] 22 Processing direction

[0105] 24 Cutting edge

[0106] 26 Processing Frontier

[0107] 28 Image Sensor

[0108] 30 Optical Imaging System

[0109] 32 System Axis

[0110] 34 First aperture

[0111] 36 Second Aperture

[0112] 38 First imaging angle

[0113] 40 The First Beam

[0114] 42 Second imaging angle

[0115] 44 Second Beam

[0116] 46 Horizontal Line

[0117] 48 Process zone aperture

[0118] 50 Directional Lens

[0119] 52 First imaging lens

[0120] 54 First imaging area

[0121] 56 Second imaging area

[0122] 58 First Length

[0123] 60 Second Length

[0124] 62 Aperture disk

[0125] 64 Arrow

[0126] 66 First rotation decoupling element

[0127] 68 Imaging intersection

[0128] 70 light wedge

[0129] 72 First optical subsystem

[0130] 74 First deflecting mirror

[0131] 76 Second deflecting mirror

[0132] 78 Second imaging lens

[0133] 80 Imaging Prism

[0134] 82 Third aperture

[0135] 84 The Third Beam

[0136] 86 The third imaging angle

[0137] 88 Third imaging area

[0138] 90 Second optical subsystem

[0139] 92 Third deflecting mirror

[0140] 94 Fourth deflecting mirror

[0141] 96 Third imaging lens

[0142] 98 Second imaging prism

[0143] 100 Second rotation decoupling element

[0144] 102 Optical Bandpass Filter

[0145] 104 Third Length

[0146] 106 Tracks

[0147] 108 Methods

[0148] 110 Methods and Steps

[0149] 112 Methods and Steps

[0150] 114 Methods and Steps

Claims

1. An imaging device (12) for imaging a process area (14) of a laser processing machine (10), the imaging device comprising an image sensor (28) and an optical imaging system (30) arranged between the process area (14) and the image sensor (28); in, The optical imaging system (30) comprises: - a system axis (32) extending between the image sensor (28) and the process zone (14); - a first aperture (34) radially spaced from the system axis (32), the first aperture delimiting a first light beam (40) emitted from the process zone (14) at a first imaging angle (38); - a second aperture (36) which delimits the second light beam (44) emitted from the process zone (14) at a second imaging angle (42); a first imaging lens (52), which is arranged between the aperture (34, 36, 82) and the image sensor (28), and is configured to image the light beam (40, 44, 84) onto the image sensor (28); The first imaging angle (38) is different from the second imaging angle (42); and the optical imaging system (30) is configured to image the first light beam (40) and the second light beam (44) separately in space.

2. The imaging device (12) according to claim 1, in, The optical imaging system (30) also has a directional lens (50), which is arranged between the process area (14) and the aperture (34, 36, 82), and directs the light beam (40, 44, 84) emitted by the process area (14) to the aperture (34, 36, 82) in parallel with the system axis (32).

3. The imaging device (12) according to claim 1 or 2, in, The optical imaging system (30) has a third aperture (82) which delimits the third light beam (84) emitted from the process zone (14) at a third imaging angle (86).

4. The imaging device (12) according to claim 3, in, The third imaging angle (86) is different from the first imaging angle (38) and / or the second imaging angle (42).

5. The imaging device (12) according to claim 3 or 4, in, The optical imaging system (30) is configured to image the third light beam (84) spatially separated from the first light beam (40) and / or the second light beam (44) onto the image sensor (28).

6. The imaging device (12) according to any one of the preceding claims, in, The optical imaging system (30) has a process zone aperture (48), in particular a process nozzle (16) of the laser processing machine (10), which is used to limit the light beam (40, 44, 84) emitted by the process zone (14).

7. The imaging device (12) according to any one of the preceding claims, in, The apertures (34, 36, 82) are formed on a common aperture disk (62).

8. The imaging device (12) according to claim 7, in, The aperture disk (62) is configured to be rotatable about the system axis (32).

9. The imaging device (12) according to claim 8, in, The optical imaging system (30) has a first optical rotation decoupling element (66) located downstream of the first aperture (34); wherein the first optical rotation decoupling element (66) is configured to accurately image the first light beam (40) on the image sensor (28) in terms of position, independently of the rotation of the aperture disk (62).

10. The imaging device (12) according to claim 9, in, The system axis (32) intersects the image sensor (28) at an imaging intersection (68); and wherein the first imaging lens (52) is configured to image the first light beam (40) centrally on the imaging intersection (68).

11. The imaging device (12) according to any one of claims 8 to 10, in, The system axis (32) extends centrally through the second aperture (36); the imaging device has a wedge (70) located upstream of the first imaging lens (52), and the wedge is configured to deflect the second light beam (44) obliquely relative to the system axis (32) onto the first imaging lens (52).

12. The imaging device (12) according to any one of claims 8 to 10, in, The system axis (32) extends centrally through the second aperture (36); wherein the optical imaging system (30) has a first optical subsystem (72) with a second imaging lens (78); and wherein the second imaging lens (78) is configured to perform positionally accurate imaging of the second light beam (44).

13. The imaging device according to claim 12, in, The first optical subsystem (72) has a first deflection mirror (74) located downstream of the aperture (34, 36, 82), wherein the first deflection mirror (74) is configured to deflect a specific wavelength of the second light beam (44).

14. An imaging device (12) according to any one of claims 8 to 13 in combination with any one of claims 2 to 4, in, The optical imaging system (30) has a second optical subsystem (90) located downstream of the third aperture (82) and having a third imaging lens (96); and wherein the third imaging lens (96) is configured to accurately image the third light beam (84) in a positional manner.

15. The imaging device (12) according to claim 14, in, The second optical subsystem (90) is constructed as a second optical rotation decoupling component (100); wherein the second optical rotation decoupling component (100) is constructed to accurately image the third light beam (84) in terms of position, independently of the rotation of the aperture disk (62).

16. The imaging device (12) according to claim 15, in, The second optical rotation decoupling element (100) has a third deflection mirror (92) located downstream of the aperture (34, 36, 82), wherein the third deflection mirror (92) is configured to deflect a specific wavelength of the third light beam (84).

17. The imaging device (12) according to any one of the preceding claims, having a single image sensor (28); in, The optical imaging system (30) is configured to image the light beam (40, 44, 84) onto the single image sensor (28).

18. A laser processing machine (10) having an imaging device (12) according to any one of the preceding claims.

19. A method (108) for determining process variables, in particular geometric process variables, of a process zone (14) by means of an imaging device (12) according to any one of claims 1 to 17, the method comprising the following steps: - creating (110) a first image and a second image of the process area (14); - providing (112) the first imaging angle (38) and the second imaging angle (42); - geometrically comparing the first image with the second image; in, At least one process variable is ascertained by means of the geometric comparison.

Images