A device for detecting scattered radiation, having a light guide channel.

Abstract

The present invention relates to a device (1) for detecting scattered radiation (170) in the beam path of a laser system, the device (1) having an annular body (5) having a light guide channel (14) inside, the body (5) having a first aperture (6) and a second aperture (7) spaced apart from each other within the wall of the body (5), more specifically along the inner circumference of the body (5), and each forming a passage for scattered radiation (170) in the shape of a light guide channel (14), the light guide channel (14) having a detection portion (3) capable of detecting the radiation intensity of scattered radiation (170) received by the light guide channel (14).

Description

Technical Field

[0001] The present invention relates to a device for detecting scattered radiation in the beam path of a laser system.

Background Art

[0002] Laser systems, specifically multi-axis laser systems, have become an essential technology in many industries in recent years. They offer high precision and flexibility, enabling the workpiece to be processed, i.e., efficiently cut, welded, and / or coated. Laser systems have various optical elements such as lenses, mirrors, and protective glasses. In order to enable efficient and process-adapted machining of each workpiece, the optical elements need to be free of any significant defects, e.g., caused by excessive contamination.

[0003] EP 3,978,179 A1 is known from the prior art. This discloses a processing head in which contamination appearing on the protective glass is detected by an optical sensor. For this purpose, the protective glass has an anti-reflection film on the surface running orthogonally to the laser beam and a reflective film on the surface running along the direction of the laser beam. Thus, when there is dirt on the protective glass, a signal is sent to the optical sensor. This signal is usually reflected several times by the protective glass before reaching the optical sensor.

[0004] Summary of the Invention Based on known prior art, an object of the present invention is to provide an improved device. A particular object of the present invention is to detect scattered radiation to determine the state of an optical interface, regardless of the location of the defective optical interface. A further object of the present invention is to provide a device that does not increase, or only slightly increases, the complexity of evaluating the detected signal. The present invention may also aim to enable the device to be integrated into existing laser systems without requiring additional electronic equipment. Furthermore, a particular object of the present invention is to ensure that the device can be reliably mass-produced.

[0005] This objective is achieved by a device for detecting scattered radiation in the beam path of a laser system, having the features of claim 1. Advantageous developments arise from the dependent claims, the detailed description of the invention, and the drawings.

[0006] Therefore, a device for detecting scattered radiation in the beam path of a laser system is proposed. This device may be called a state detection device because it may be suitable for detecting the state of the optical interface of a substantially rotationally symmetric optical element through which the laser beam is directed. The optical element may be a lens, a mirror, and / or protective glass. The optical interface may be smooth and therefore may be different from a diffractive optical element. Specifically, the laser beam may strike the optical element substantially orthogonally if the optical element is a lens and / or protective glass. The laser beam may also strike the optical element obliquely if the optical element is a mirror and / or lens. The detected scattered radiation can provide information about whether the optical interface is defective. For example, the degree of contamination of the optical interface can be detected. The device can communicate with a control unit, at least indirectly, to convey the detected state of the optical interface to the control unit. For example, if the detected state exceeds a limit, the control unit can inform the operator of the laser system via a user interface, so that the optical interface can be cleaned and / or replaced, for example. The beam path can represent the path along which a laser beam is guided through a laser system and its components. The beam path can be varied depending on the processing. The beam path can travel from the laser source through an optical fiber cable into a laser quill, and from there into the primary laser optics via a mobile unit. The path of the beam path is determined by optical elements, specifically mirrors and lenses.

[0007] This device has an annular body that forms a light guide channel inside. This annular body can be designed to transmit scattered radiation to a detection part, which is why it can also be called a transmission element. Specifically, the light guide channel is formed throughout the inside of the annular body. The annular body can define a hollow space through which the light guide channel runs.

[0008] The annular body has a first aperture and a second aperture, spaced apart from each other within the walls of the body, specifically along the inner circumference of the body, and each forming a passage for scattered radiation in the form of a light guide channel. The first and second apertures together may be referred to as an aperture unit. The aperture unit is configured and provided to receive scattered radiation reflected from the optical interface. The reflected scattered radiation may be due to defects in the optical interface. For example, the optical interface may be contaminated with metal dust or oil fumes, which, when interacting with the laser beam, cause Mie scattering. The contamination of the optical interface can be in the range of 0.5 μm to 10 μm, where Mie scattering is dominant. It can also have a larger range, where classical scattering according to Snell's law of refraction is dominant. The first and second apertures allow the reflected radiation to enter the annular body and its light guide channels. The laser beam directed to the optical interface may be reflected or diffracted by the defects so as to deviate from the intended path of the laser radiation, i.e., the beam path, and therefore reflect scattered radiation. The intensity and direction of scattered radiation depend on the size and internal characteristics of the defect. The larger the defect, the stronger the scattered radiation and the weaker the laser beam passing through the optical element.

[0009] The device's light guide channel has a sensing portion that can detect the radiation intensity of scattered radiation received by the light guide channel. The sensing portion may be adapted to house a detector, which is why it may also be referred to as a detector receptacle. Specifically, the sensing portion may be configured and provided to house a detector, which is in the form of a photodiode, for detecting scattered radiation. The sensing portion may have a shape such that the detector is housed in the sensing portion by shape fitting and / or press-fit. The sensing portion may be machined into the device. The detector may be a photodiode, which is particularly suitable for a laser beam formed as infrared radiation.

[0010] Therefore, an annular body can be configured and provided to transmit scattered radiation received by an aperture unit to a detection portion, specifically to a detector located therein, at least in a section along the circumferential direction of the optical element. As a transmission element, the body performs the function of transmitting reflected scattered radiation received by the aperture to the detection portion. This transmission takes place at least in a section along the circumferential direction of the body. The body can be designed as a hollow channel within the device. A substantially rotationally symmetric optical element has a circumferential direction about an axis of rotation. The fact that the received scattered radiation extends at least partially along the circumferential direction ensures that the detection portion and the aperture define an angular span with respect to the axis of rotation. Therefore, the received reflected scattered radiation does not reach the detection portion via the shortest path, which prevents the detection signal from being distorted by defects causing reflected scattered radiation very close to the detection portion. Scattered radiation received by the aperture can be transmitted to the detection portion at, for example, 60°, 90°, 120° and / or 180° along the circumferential direction of the body.

[0011] Thus, defects can be reliably detected at a comparable signal level regardless of their location relative to the detector and detection unit. The detected scattered radiation can be detected spatially homogenized regardless of location. This also enables reliable detection of minute defects. The intensity of the reflected scattered radiation impacting the aperture unit can be inversely proportional to the square of the radius with respect to the center of the optical interface, i.e., the axis of rotation. The further the defect is from the center of the optical interface, the higher the intensity of the reflected scattered radiation, which can distort the detection signal. In this respect, the transmission of the received scattered radiation provides relief, at least in sections along the circumferential direction of the main body. The detection unit can accommodate just one detector. On the one hand, this facilitates communication between the device and the control unit, as only one detector needs to be considered. Furthermore, the integration of the device into the processing head of the laser system is simplified by the fact that a single detector requires only one cable. Thus, this device contributes to detecting scattered radiation to determine the state of the optical interface, regardless of the location of the defect in the optical interface. Furthermore, it helps to ensure that the complexity of evaluating the detection signal does not increase, or increases only slightly. It can also be integrated into existing laser systems without requiring additional electronic equipment. Furthermore, it can be reliably mass-produced.

[0012] In one embodiment, the first and second apertures are spaced apart from each other along the circumferential direction of the annular body, specifically by an angular span of at least 60°, and more specifically, 120° along the circumferential direction. Thus, scattered radiation reflected from the optical interface can be received by the first and second apertures at two predetermined locations spaced apart from each other. This further contributes to the homogenization of the signal detected by the detection unit and the resulting detected state. The first and second apertures can each be positioned inside the annular body. The angular span in which the first aperture is spaced apart from the second aperture can also be 180°. This ensures the maximum distance between the first and second apertures, thereby ensuring that a defect resulting in biased reflected scattered radiation in the first aperture results in biased reflected scattered radiation in the second aperture, thus maintaining a balanced and distortion-free signal detected by the detector. The aperture angles of the first and second apertures are small compared to the inner circumference of the body. In this way, the sensor signal can be received almost independently of defects and their locations. Furthermore, particles with the same wavelength and size as the laser light can be detected in this manner with remarkable efficiency.

[0013] In one embodiment, the body has a third aperture spaced circumferentially from the first and second apertures by an angular span of at least 60° in each case, and specifically, 120° in each case, along the circumferential direction. The third aperture further contributes to the homogenization of the signal detected by the detector and the resulting detected state. The first, second, and third apertures can be evenly distributed circumferentially, i.e., offset from each other by 120°. This further reduces the undesirable weighting caused by the location of defects very close to the apertures. The third aperture can be located inside the body. The first, second, and third apertures may each have chamfered aperture inclinations that enable efficient detection of reflected scattered radiation. For example, these apertures can be chamfered at an angle of at least 30° with respect to the plane on which the optical interface travels. These angles have proven advantageous when the reflected scattered radiation is scattered radiation reflected by oil mist or metal dust. This is because they are reflected according to the concept of Mie scattering, in which case they have an angle of 15° to 30° with respect to the plane on which the optical interface travels. The first, second, and third apertures can be arranged so that the scattered radiation received by the aperture unit is transmitted from the main body and its light guide channel, and therefore the transmission element, to the detection portion entirely along the circumferential direction. This further contributes to the homogenization of the signal detected by the detection portion and the resulting detected state.

[0014] In one embodiment, the first aperture is the aperture furthest from the detection area, specifically positioned diametrically opposite to the detection area, and defines a larger aperture angle than the second aperture, specifically the second and third apertures. Since the furthest aperture defines the largest aperture angle, any attenuation loss of received scattered radiation within the body is reduced. The larger aperture angle causes the first aperture to receive more reflected scattered radiation than the second aperture, specifically the second and third apertures. This cancels out the attenuation that scattered radiation undergoes in the light guide channel on its way from the first aperture circumferentially towards the detection area. Specifically, the larger aperture angle is adapted to the position of the first aperture. The second aperture, specifically the second and third apertures, are closer to the detection area than the first aperture, so the scattered radiation received by them undergoes less attenuation. In this respect, the aperture angles of the second and third apertures are smaller than those of the first aperture, and this does not affect the detection signal. A larger aperture angle of the first aperture ensures that the signal received by the first aperture is weighted by the detection portion and, consequently, by the sum signal received by the detector, with weights corresponding to its intensity. A linear relationship may exist between the size of the aperture angle of each aperture and the distance of each aperture from the detection portion.

[0015] As a general rule, the opening cross-section and / or the opening angle of the opening can be defined as increasing with the distance from the detection portion of each opening in the circumferential direction of the main body.

[0016] In a configuration where only two apertures (i.e., a first aperture and a second aperture) are provided to the body, it may be preferable that these apertures are opposite to each other in the circumferential direction of the body, i.e., spaced 180° apart, and that both apertures are at the same distance from the detection portion, and have the same aperture cross-section and the same aperture angle. In one embodiment, the light guide channel has a reflective surface made of a non-ferrous metal, a noble metal and / or alloy. Also known as annular channels, the light guide channel can extend substantially 360° around the axis of rotation from the detection portion. It can have a constant radius. The reflective surface can be selected to ensure sufficiently high reflection at the wavelength of the laser beam. Sufficiently high reflection is characterized by the fact that it transmits the scattered radiation received by the aperture to the detection portion with comparable intensity. For example, more than 90%, specifically more than 95%, of the scattered radiation received by the aperture can be transmitted to the detection portion. The received scattered radiation may be scattered multiple times when transmitted. The scattering attenuation is determined by the reflectance T of the surface of the light guide channel, the number of scattering particles n, and the coefficient T. n This can be achieved. Specifically, copper can be selected as the non-ferrous metal. Copper can be processed by diamond milling. As a result, the light guide channel can be efficiently machined into a copper body. Brass can be selected as the alloy, and this can also be processed. As a result, the light guide channel can be efficiently machined into a brass body. Furthermore, specifically, not only the surface of the light guide channel, but the entire body or the entire device can be made of non-ferrous metals, precious metals and / or alloys. This increases the efficiency of producing the device.

[0017] In one embodiment, the reflective surface is a applied coating. This means that the material can be used in the device without worrying about the corresponding reflective properties. Therefore, only the surface of the light guide channel needs to be coated in order to ensure a sufficiently high transmission speed to the detection portion of the aperture unit.

[0018] In one embodiment, the light guide channel forms a circular cross-section. The circular shape has a positive effect on the reflective properties of the light guide channel, and as a transmission element, it may also be called an annular channel. Furthermore, the circular shape ensures efficient machining of the light guide channel. The circular cross-section of the light guide channel can have a constant diameter. Alternatively, the diameter of the circular cross-section in each aperture area may be larger than that in the remaining area.

[0019] In one embodiment, the device has an upper and lower section that form a first aperture, a second aperture, an optional third aperture, a detection section, and a light guide channel, and specifically, the structures of which are substantially identical. The upper and lower sections can be designed such that when joined together, the apertures, detection section, and light guide channel are designed as a hollow space. This allows for the efficient production of the device. Furthermore, the fact that the upper and lower sections are structurally identical further increases production efficiency. For example, the hollow spaces forming the apertures, detection section, and light guide channel can be machined into the upper and lower sections.

[0020] In one embodiment, the device further comprises an optical fiber cable, specifically in the form of a quartz optical fiber, extending within a light guide channel. The optical fiber cable may have light-receiving portions on its radially inward-facing sides, each of which is located in one of the openings of the body. For example, the surface of the quartz optical fiber may be cut to form the light-receiving portions.

[0021] This disclosure further relates to a state detection system, which includes the device described above. Furthermore, the state detection system includes a detector housed within a detection portion and provided for detecting reflected scattered radiation. Therefore, the detector disclosure relating to this device should apply to the state detection system. The detector of the state detection system is configured to receive transmitted scattered radiation as a sum signal. The sum signal is formed from scattered radiation received by an aperture and transmitted through a light guide channel. For example, a first signal of the sum signal from a first aperture, a second signal of the sum signal from a second aperture, and / or a third signal of the sum signal from a third aperture may be received. The sum signal is weighted by the corresponding aperture angles of each aperture, so that the state detected by the state detection system is independent of the location of each defect in the optical interface. By forming a sum signal, the arrangement of multiple sensors is no longer necessary. This facilitates both the construction of a state monitoring system and its integration into existing laser systems. Thus, the state detection system contributes to detecting scattered radiation to determine the state of the optical interface, regardless of the location of the defective optical interface. Furthermore, it helps ensure that the complexity of evaluating the detection signal does not increase, or only slightly. It can also be integrated into existing laser systems without requiring additional electronics. It can also be reliably mass-produced.

[0022] In one embodiment, the state detection system has an aperture unit provided to adjust scattered radiation arriving at the detector. The aperture unit ensures that scattered radiation transmitted from the body to the detector as a transmission element collides with the detector only from a predetermined direction. This facilitates objective evaluation of the detector because signals arriving from the side that may distort the sum signal are adjusted accordingly. The aperture unit can be made adjustable so that the adjustment it provides is suited to the optical interface being monitored. For example, the adjustment when detecting the state of a mirror may be different from the adjustment when detecting the state of a lens.

[0023] In one embodiment, the aperture unit has two tubular elements arranged circumferentially on both sides of the detector. This ensures that the detector detects only scattered radiation that strikes it perpendicularly. The tubular elements can be identical in structure to one another. They can be held in corresponding recesses of the device by press-fit and / or shape-fit.

[0024] In one embodiment, the state detection system further comprises optical elements that can direct a laser beam through its interior, specifically to lenses, mirrors, and protective glass, wherein the device and optical elements extend in planes parallel to each other, and the distance between the planes is selected such that scattered radiation reflected at the optical interface of the optical elements collides with the aperture unit at an angle of 15° to 30°. The span of the angle may result from the fact that the exact location of the defect causing the scattered radiation varies. Since the defect may be of a size corresponding to the wavelength of the laser beam, Mie scattering can be emitted from the defect. For particles with dimensions of 0.5 μm to 10 μm, a laser beam with an infrared laser can exhibit reflected scattered radiation that is 15° to 30° off from the plane through which the optical interface travels. In this respect, the state detection system is optimized for defects causing Mie scattering.

[0025] In one embodiment, the state detection system further includes a control unit to which the detector transmits the received sum signal, and the control unit determines the contamination degree of the optical interface from the received sum signal. For this purpose, a threshold value can be stored in the control unit for each optical interface, and if it is exceeded, the control unit classifies the contamination degree as critical. As soon as the contamination level of the optical interface is classified as critical, the control unit can transmit a corresponding alarm signal to the user interface so that the operator of the system is alerted to the corresponding contamination of the optical interface. A look-up table listing the critical contamination degrees for each optical interface can be stored in the control unit. The look-up table can have a predetermined value or can be modified by the operator.

[0026] The present disclosure further relates to a laser system, i.e., a laser processing device for aligning a laser beam with a workpiece. The laser system has a state detection system according to the above disclosure and a processing head for aligning the laser beam with the workpiece.

[0027] Preferred further embodiments of the present invention will be described in more detail by the following description of the drawings.

Brief Description of the Drawings

[0028] [Figure 1] Shows a schematic diagram of a laser system. [Figure 2] Shows a schematic cross-sectional view of a state detection system having a device, a detector, and an optical element. [Figure 3] Shows a schematic plan view of a device having a detector. [Figure 4] Shows a schematic perspective view of a device having an aperture unit and a detector connected to a control unit by a cable. [Figure 5] Shows a schematic plan view of a device having an aperture unit with three apertures. [Figure 6]This figure shows how the reflected scattered radiation transmitted to the detector is normalized to the actual reflected scattered radiation. [Modes for carrying out the invention]

[0029] Preferred exemplary embodiments are described below with reference to the drawings. In these cases, elements that are the same, similar, or have the same effect are given the same reference numerals in different drawings, and repeated descriptions of these elements are omitted in some cases to avoid redundancy.

[0030] Figure 1 shows a laser system 100 having a processing head 110 that aligns a laser beam 120 with a workpiece 130. The laser system 100 has a plurality of substantially rotationally symmetric optical elements 140. The optical elements 140 may be lenses, mirrors, and / or protective glass. At least one lens is provided to focus the laser beam 120. At least one mirror is provided to redirect the laser beam 120. At least one protective glass is provided to protect the processing head 110 and the laser optics located therein from external interference factors. Each optical element 140 may be located on the processing head 110 and / or on the laser quill 150. The laser beam 120 is provided by a laser light source (not shown), such as a disk laser, diode laser, or fiber laser. The laser light source can guide the laser beam 120 to a laser quill 150 via an optical fiber cable, where the laser beam 120 is directed by a lens, specifically a collimating lens. From the laser quill 150, the laser beam 120 is guided to a processing head 110, which houses a laser optical system. The processing head 110 is controlled according to the processing to ensure proper alignment of the laser beam 120 with the workpiece 130. The laser system 110 may be a system for laser cutting, laser welding, and / or laser deposition welding. Each individual optical element 140 has at least one optical interface 160 that forms a substantially smooth surface. If the optical interface 160 has defects, for example due to contamination of the optical interface 160, reflected scattered radiation 170 is emitted from each defect (see Figure 2).

[0031] Figure 2 shows a cross-sectional view along the diameter of the state detection device 1, also referred to as the state detection device 1, for detecting the state of at least one optical interface 160. The state detection device 1 has an aperture unit 2, namely a first aperture 6 and a second aperture 7, which receive scattered radiation 170 reflected by the optical interface 160. The state detection device 1 further has a detection section 3 which houses a detector 4, specifically in the form of a photodiode, for detecting and processing the scattered radiation 170. The state detection device 1 has a body 5, which may also be referred to as the transmission element 5, which transmits the scattered radiation 170 received by the aperture unit 2 to the detector 4 along the circumferential direction U of the optical element 140.

[0032] The laser beam 120 is substantially orthogonal to the optical interface 160. The optical element 140 having the optical interface 160 is located upstream of the state detection device 1 in the laser beam. The laser beam 120 passes through the optical element 140, which transmits the laser beam 120. There is a defect 180 in the optical interface 160 of the optical element 140 facing the state detection device 1. This could result, for example, from contamination of the optical element 140. The defect 180 interferes with the laser radiation 120, resulting in reflected scattered radiation 170. The larger the defect 180, the greater the reflected scattered radiation 170, and the smaller the laser radiation 120 induced through the laser system 100 along the intended beam path.

[0033] The reflected scattered radiation 170 is received by a first aperture 6 and a second aperture 7 of the aperture unit 2 of the state detection device 1. The first aperture 6 and the second aperture 7 are located inside the state detection device 1. The annular body 5 has a light guide channel 14 having a reflective surface 8. The reflective surface 8 guides the scattered radiation 170 received through the first aperture 6 and the second aperture 7 along the circumferential direction U of the optical element 140 to the detection portion 3 where the detector 4 is located. The reflective surface 8 can be part of the light guide channel 14 having a circular cross-section. The detector 4 detects the scattered radiation 170 received by the first aperture 6 and the scattered radiation 170 received by the second aperture 7 as a sum signal and transmits the sum signal to a control unit (not shown) via a cable 9. The first aperture 6 is further away from the detector 4 than the second aperture 7. Therefore, the scattered radiation 170 received by the first aperture 6 needs to travel a longer distance than the scattered radiation 170 received by the second aperture 7. Because the path from the first aperture 6 is longer, the attenuation of the scattered radiation 170 received by the first aperture 6 is greater than the attenuation of the scattered radiation 170 received by the second aperture 7. To offset this effect, where the attenuation increases with increasing distance from the detector 4, the first aperture 6 can have a larger aperture area than the second aperture 7, and therefore the first aperture 6 receives relatively more scattered radiation 170. Thus, the sum signal detected by the detector 4 is weighted in correlation with the respective distances of apertures 6 and 7. In this case, the defect 180 is eccentric towards the optical interface 160 side. Specifically, since the aperture unit 2 has the first aperture 6 and the second aperture 7, the position of the defect 180 does not affect the result detected by the detector 4.

[0034] The laser light source can generate a laser beam with a wavelength of, for example, 0.4 μm to 1.5 μm, specifically about 450 nm, about 515 nm, about 800 nm to about 1000 nm, or about 1030 nm, 1060 nm, or 1070 nm, specifically an infrared laser beam. The defect 180 may be approximately 0.5 μm to 10 μm in size. Therefore, the laser beam 120 may be elastically scattered at the defect 180 in the manner of Mie scattering. For a particle size of 0.5 μm to 10 μm, Mie scattering results in a scattering angle W of 15° to 30°. Therefore, the distance between the state device 1 and the optical interface 160 is selected so that the reflected scattered radiation is detected by the aperture unit 2 at the corresponding position of the defect 180 on the optical interface 160.

[0035] Figure 3 shows a plan view of the state detection device 1. The first aperture 6 is positioned diametrically opposite to the detection portion 3. The second aperture 7 is provided at a distance of 120° from the first aperture 6 along the circumferential direction U. The third aperture 10 is provided at a distance of 120° from the first aperture 6, in a direction deviating from the direction of the second aperture 7 along the circumferential direction U. The second aperture 7 and the third aperture 10 are each offset by 60° from the detection portion 3, while the first aperture 6 is offset by 180° from the detection portion 3. Therefore, the first aperture is the furthest aperture because it is located opposite the detection portion 3. Thus, the first aperture 6 defines a larger aperture area than the second aperture 7 and the third aperture 10. The first aperture 6, the second aperture 7, and the third aperture 10 form an aperture unit 2. The third opening 10 can be positioned similarly to the first opening 6 and the second opening 7 inside the state detection device 1.

[0036] The defect 180 is located on the optical interface 160, eccentrically from the rotation axis R. The scattered radiation 170 reflected by the defect 180 is received by the aperture unit 2, and therefore by the first aperture 6, the second aperture 7, and the third aperture 10, and then transmitted from the main body 5 to the detector 4 along the circumferential direction. Thus, the detector 4 receives three signals of the reflected scattered radiation 170, and specifically, from the intensity of each detection signal and the time it takes to receive each detection signal, it can determine the severity of the damage to the optical interface 160 caused by the defect 180. From the first aperture 6, the reflected scattered radiation 170 is transmitted to the detector 4 along the first scattered radiation path 171 and along the second scattered radiation path 172. In addition, the reflected scattered radiation is transmitted to the detector 4 from the second aperture 7 along the third scattered radiation path 173 and from the third aperture 10 along the fourth scattered radiation path 174. The first scattered radiation path 171 extends 180° from the first aperture 6 along the circumferential direction U of the optical element 140 to the detector 4. The second scattered radiation path 172 also extends 180° from the first aperture 6 along the circumferential direction U of the optical element 140 to the detector 4, but in the opposite direction to the first scattered radiation path 171. The third scattered radiation path 173 extends 60° from the second aperture 7 along the circumferential direction U of the optical element 140 to the detector 4, and the fourth scattered radiation path 174 extends 60° from the third aperture 10 along the circumferential direction U of the optical element 140 to the detector 4. The detector 4 receives the signals received according to each scattered radiation path 171, 172, 173, and 174 as a sum signal and transmits them to the control unit. The control unit can detect the state of the optical interface 160 from the received sum signal.

[0037] Figure 4 shows a perspective view of the state detection device 1. The first aperture 6 has a chamfered aperture surface to optimally capture scattered radiation 170 reflected by the optical interface 160. The chamfer angle may be, for example, at least 30° with respect to the plane on which the optical element 140 extends. In this way, Mie scattering reflected by the defect 170 is efficiently received by the first aperture 6. Similarly, the second aperture 7 and the third aperture 10 may have chamfered aperture surfaces with a chamfer angle of at least 30°. The aperture unit 11 is located in the area of ​​the detector 4. The aperture unit 11 adjusts the scattered radiation 170 arriving at the detector 4. It may consist of two tubular elements located on either side of the detector 4. Each tubular element may be embedded in the corresponding aperture of the state detection device 1. The scattered radiation 170 arriving at the detector 4 can be detected via the position and / or diameter of the tubular elements.

[0038] The main body 5 has an upper part 12 and a lower part 13. The upper part 12 and the lower part 13 can be connected to each other in a press-fit manner, specifically by screw fastening and / or by material bonding. Together, they form a light guide channel 14 having a circular cross-section. The upper part 12 and the lower part 13 can be identical to each other in structure. This increases the efficiency of producing the state detection device 1. The state detection device 1 can be made of a non-ferrous metal such as copper, with the light guide channel 14 being diamond milled. The state detection device 1 can also be made of a precious metal. The state detection device 1 can also be made of an alloy such as brass, with the light guide channel 14 being milled. Furthermore, the opening unit 2, and thus the opening and detection part 3, can be machined into the state detection device 1.

[0039] Figure 5 shows a cross-sectional plan view of the state detection device 1. The detection portion 3 is positioned diametrically opposite to the first aperture 6. The first aperture 6 extends along the aperture angle α. The aperture angle α results in the first aperture area of ​​the first aperture 6. Along both directions in the circumferential direction U, the second aperture 7 and the third aperture 10 are offset by 120° from the first aperture 6. They each extend along the aperture angle β. The aperture angle β results in the second aperture area of ​​the second aperture 7 and the third aperture area of ​​the third aperture 10, which is of the same size. Since the first aperture 6 is further away from the detection portion 3 than the second aperture 7 and the third aperture 10, the first aperture area is larger than the second and third aperture areas, and therefore the scattered radiation 170 detected by the first aperture area 6 is attenuated more than the scattered radiation 170 detected by the second aperture 7 and the third aperture 10. The first aperture 6, the second aperture 7, and the third aperture 10 are connected to the detection section 4 via the light guide channel 14, which extends in an annular manner around the rotation axis R, which is the center of the optical interface 160.

[0040] Figure 6 schematically shows how the reflected scattered radiation 170 transmitted to the detector 4 is normalized to the actual reflected scattered radiation 170. Each point 190 represents a measurement point. The outer diameter of the dashed line in Figure 6 corresponds to the inner diameter of the annular body 5. In the embodiment of Figure 6, the first aperture 6, the second aperture 7, and the third aperture 10 are arranged according to the embodiment of Figure 5. In the central region 200, the design of the aperture unit 2 allows the actually reflected scattered radiation 170 to be fully detected and transmitted to the detector 4. Even in the extended region 210 extending between the central region 200 and each of the apertures 6, 7, and 10, the arrangement of the aperture unit 2 according to this embodiment allows approximately 80% of the actually reflected scattered radiation 170 to be detected. In the region not covered by the central region 200 or the extended region 210, less than 80%, specifically less than 60%, of the actually reflected scattered radiation 170 is detected. This means that defects 180 located outside the central region 200 and the machined region 210 do not significantly affect the state detected by the state detection device 1, as they do not significantly affect the laser beam 120 and result in less intense scattered radiation 170. Therefore, the arrangement of the aperture unit 2 in this exemplary embodiment results in an optimal compromise between state detection and the number of apertures 6, 7, and 10. Too many apertures, for example, five or more, can be disadvantageous in certain configurations, as this results in increased reflection of scattered radiation that has left the light guide channel 14 before the reflected scattered radiation 170 reaches the detector 4.

[0041] To the extent applicable, all individual features presented in the exemplary embodiments may be combined with and / or substituted for each other without departing from the scope of the invention. [Explanation of Symbols]

[0042] 1. Device, state detection device 2 Opening Unit 3. Detection area 4 detectors 5 Main unit 6. First opening 7. Second opening 8 Reflective surfaces 9 Cables 10 Third opening 11 Aperture Units 12 Top 13 Lower part 14 light guide channels 100 Laser Systems 110 Machining Head 120 laser beams 130 Workpiece 140 optical elements 150 laser quills 160 Optical Interfaces 170 Scattered radiation 171 First scattered radiation path 172 Second scattered radiation path 173 Third Scattering Radiation Path 174 The fourth scattered radiation path 180 defects 190 measurement points 200 central area 210 Extended Area U circumferential direction W scattering angle R rotation axis α First aperture angle β Second aperture angle

Claims

1. A device (1) for detecting scattered radiation (170) in the beam path of a laser system, - It has an annular body (5) that forms a light guide channel (14) inside, - The main body (5) has a first opening (6) and a second opening (7) which are spaced apart from each other within the wall of the main body (5), specifically along the inner circumference of the main body (5), and each forms a passage for the scattered radiation (170) in the shape of the light guide channel (14), - A device (1) having a detection portion (3) that can detect the radiation intensity of the scattered radiation (170) received by the light guide channel (14).

2. The device (1) according to claim 1, wherein the first opening (6) and the second opening (7) are spaced apart from each other along the circumferential direction (U) of the annular body (5), specifically by an angular span of at least 60°, and specifically by an angular span of 120° along the circumferential direction (U).

3. The device (1) according to claim 1 or 2, wherein the main body (5) has a third opening (10) that is spaced apart from the first opening (6) and the second opening (7) along the circumferential direction (U), specifically at least 60° in each case, and specifically at least 120° in each case along the circumferential direction (U).

4. The device (1) according to any one of claims 1 to 3, wherein the first opening (6) is the opening furthest from the detection portion (3), specifically, it is positioned opposite to the detection portion (3) in the diametrical direction, and defines an opening angle (α) that is larger than that of the second opening (7), specifically, larger than that of the second opening (7) and the third opening (10).

5. The device (1) according to any one of claims 1 to 4, wherein the light guide channel (14) specifically has a reflective surface made of a non-ferrous metal, a noble metal and / or an alloy.

6. The device (1) according to claim 5, wherein the reflective surface is a coated surface.

7. The device (1) according to any one of claims 1 to 6, wherein the light guide channel (14) has a circular cross-section.

8. The device (1) according to any one of claims 1 to 7, wherein the device (1) forms the first aperture (6), the second aperture (7), the detection portion (3), and the light guide channel (14), and specifically has an upper (12) and a lower (13) whose structures are substantially identical to each other.

9. Specifically, the device (1) according to any one of claims 1 to 8 further comprises an optical fiber cable in the form of a quartz optical fiber, extending within the optical guide channel (14).

10. A state detection system, A device (1) according to any one of claims 1 to 9, The system includes a detector (4) housed within the detection portion (3) and provided for detecting the reflected scattered radiation (170), A state detection system in which the detector (4) is configured to receive the transmitted scattered radiation (170) as a sum signal.

11. The state detection system according to claim 10, further comprising an aperture unit (11) provided for adjusting the scattered radiation (170) that has arrived at the detector (4).

12. The state detection system according to claim 11, wherein the aperture unit (11) has two tubular elements arranged in the circumferential direction (U) of the main body (5) on both sides of the detector (4).

13. It further includes an optical element (140) that can direct a laser beam (120) through its interior, A state detection system according to any one of claims 10 to 12, wherein the device (1) and the optical element (140) extend in planes parallel to each other, and the distance between the planes is selected such that the scattered radiation (170) reflected at the optical interface of the optical element (140) collides with the aperture unit (2) at an angle of 15° to 30°.

14. The state detection system according to any one of claims 10 to 13, further comprising a control unit to which the detector (4) transmits the received sum signal, wherein the control unit determines the degree of contamination of the optical interface from the received sum signal.

15. A laser system (100) for aligning a laser beam (120) with a workpiece (130), A state detection system according to any one of claims 10 to 14, A laser system (100) having a processing head (110) that aligns a laser beam (120) with a workpiece (130).

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