Sensing arrangement for monitoring contaminants on a cover glass of a laser processing head

Abstract

A sensing device monitors a contaminant on a cap optic of a laser processing head, indicating a need to replace the cap optic. The device includes at least one reflector and at least one sensor disposed in the processing head adjacent a periphery of the cap optic. The reflector reflects radiation from the laser beam that is deflected from a contaminant on the cap optic and incident thereon. The sensor is offset from the reflector and detects at least a portion of the radiation reflected by the reflector. A controller in communication with the sensor can determine the contaminant on the cap optic based on the detected radiation.

Description

Technical Field

[0001] The subject of this disclosure relates to monitoring contaminants on optical components, and more specifically to monitoring contaminants on the cover glass of a laser processing head. Background Technology

[0002] In material processing, cover glass is used in laser processing heads to protect the internal laser-emitting optics. For example, a laser cutting head generates a laser beam that melts the target material. Assist gas is expelled from the molten material to form a cut in the workpiece. Especially when using lasers to penetrate materials, the pressure and volume of the assist gas must be carefully controlled. If the assist gas pressure is too high, excessive spatter can adhere to the nozzle and the cover glass of the laser processing head. Over time, the cover glass needs to be replaced to prevent contaminants from interfering with the laser beam.

[0003] Some laser-emitting operations and certain materials can generate more contaminants compared to others. For example, cutting galvanized materials can release tiny particles from the zinc coating, producing very fine dust. Furthermore, contaminants inside the laser processing head can accumulate on the inner surface of the cover glass and interfere with the operation.

[0004] It is understood that contaminants on the coverslip can alter the optical quality of the emitted laser beam. Furthermore, scattered light from the coverslip can heat and damage other components of the processing head, or interfere with their operation. Therefore, it is preferable to monitor for contamination so that the coverslip can be replaced before optical quality deteriorates.

[0005] To monitor coverslips, laser processing heads can use optical sensors to detect contaminants on the coverslip. In standard solutions for monitoring coverslips, stray light sensors can be used to monitor stray light from the edges of the coverslip. Unfortunately, the detected signal is highly dependent on the surface characteristics at the coverslip edges and sometimes also on the surface of the mounting hardware holding the coverslip. Some areas of the coverslip may not affect the detected stray light signal at all, meaning that measurements of contaminants on the coverslip may be inaccurate.

[0006] In another solution, a pyrometer sensor mounted above the coverslip can be used to monitor the coverslip directly from above. While this arrangement facilitates better observation of the coverslip's surface area, the sensor's orientation increases the required height and overall space for monitoring the coverslip. The space required for the pyrometer can complicate the arrangement of the laser emission optics, alter the distance between the coverslip and the laser emission process, and interfere with other parameters of the laser processing head.

[0007] The subject of this disclosure aims to overcome or at least reduce the impact of one or more of the aforementioned problems. Summary of the Invention

[0008] As disclosed herein, an apparatus is used for a laser processing head having a replaceable cover optics. The replaceable cover optics is configured to be aligned with the longitudinal axis of a laser beam emitted from the laser processing head during laser emission. The apparatus includes at least one reflector and at least one sensor. The at least one reflector is disposed peripherally adjacent to the replaceable cover optics. The at least one reflector is configured to reflect radiation generated by the interaction of the laser beam with contaminants on the replaceable cover optics and incident on the at least one reflector. The at least one sensor is disposed peripherally adjacent to the replaceable cover optics. The at least one sensor is configured to be offset relative to the at least one reflector. The at least one sensor is configured to detect at least a portion of the radiation reflected by the at least one reflector.

[0009] As disclosed herein, a laser processing head has a replaceable cover optics. The replaceable cover optics are configured to be in line with a laser beam emitted from the laser processing head. The head includes a receiver, at least one reflector, and at least one sensor. The receiver is disposed on the laser processing head for holding the replaceable cover optics.

[0010] At least one reflector is positioned adjacent to the receiver. The at least one reflector is configured to reflect radiation generated by the interaction of the laser beam with contaminants on the replaceable cover optics and incident on the at least one reflector. At least one sensor is positioned adjacent to the periphery of the receiver. The at least one sensor is configured to be offset relative to the at least one reflector. The at least one sensor is configured to detect at least a portion of the radiation reflected by the at least one reflector.

[0011] The method disclosed herein is used with a laser processing head having a replaceable cover optics. The replaceable cover optics is configured to be aligned with a laser beam emitted from the laser processing head. The method includes: reflecting radiation generated by the interaction of the laser beam with contaminants on the replaceable cover optics and incident on the at least one reflector disposed on the laser processing head adjacent to the replaceable cover optics; detecting at least a portion of the radiation reflected by the at least one reflector disposed on the laser processing head adjacent to the periphery of the replaceable cover optics and offset relative to the at least one reflector; and determining the level of contaminants on the replaceable cover optics based on the radiation detected by the at least one sensor.

[0012] The foregoing overview is not intended to summarize every potential implementation or aspect of this disclosure. Attached Figure Description

[0013] Figure 1 A perspective view of an example laser processing head according to this disclosure is shown.

[0014] Figure 2 An exploded view of the cover optics and housing for the laser processing head is shown.

[0015] Figure 3 The illustration shows elements of a laser processing head having the sensing device of this disclosure.

[0016] Figures 4A to 4B A flowchart is shown for a process used to monitor contaminants in sensing optics.

[0017] Figure 5A A side view of the sensing device of this disclosure adjacent to the cover optics is shown.

[0018] Figure 5B A perspective view of the sensing device of this disclosure adjacent to the cover optics is shown.

[0019] Figures 6A to 6B A side view of the additional sensing arrangement of the present disclosure adjacent to the cover optics is shown.

[0020] Figure 7 A diagram showing an exemplary coverage area of ​​the sensing device of the disclosed cover optics is provided.

[0021] Figure 8 A suggested shape for the reflector of the sensing device is shown.

[0022] Figures 9A to 9C The arrangement of a laser processing head having the sensing device of this disclosure is schematically shown. Detailed Implementation

[0023] Figure 1 A perspective view of an example laser processing head 10 according to the present disclosure is shown. The laser processing head 10 includes a housing 12 for internal optics. A connection 14 at one end of the housing 12 can be coupled to a laser cable that conducts laser energy into the head 12. An output portion or nozzle 16 at the other end of the housing 12 allows a focused laser beam to be emitted from the housing 12 for laser emission operations such as welding, additive manufacturing, cutting, etc. This particular arrangement with the nozzle 16 is a cutting head 10. Generally, the cutting head 10 can benefit more from the features disclosed herein than welding or other types of heads.

[0024] To protect the internal optics within the housing 12, the head 10 includes a cover glass cassette 20 that holds replaceable cover optics, cover glass, or protective window 30. The cover optics 30 serves as a transparent window between the interior of the housing 12 (containing the internal optics) and the external environment (exposed to the laser emission process). Removal and replacement of the cassette 20 can be performed through an access door 18 on one side of the head 10. Typically, the cover optics 30 is made of a transparent material, such as suitable glass, which allows the laser beam to pass through but prevents contaminants from penetrating the housing 12 into the head.

[0025] The cover optics 30 are placed inside the head housing 12 below the focusing lens and are housed in a replacement-friendly cassette 20. To replace the cover optics 30, the access door 18 can be opened, and the cassette 20 holding the cover glass 30 can be pulled out of the head 10, exposing the internal optics of the cutting head 10 to the atmosphere and potential contaminants. Another cassette 20 with a new cover glass 30 can then be installed in the head 10 to continue laser emission operations.

[0026] Figure 2 An exploded view of a typical coverslip cassette 20 for the laser head of this disclosure is shown. The cassette 20 includes a tray 22 with a central opening in which a cover optics 30 is positioned. Seals 26 and 28, a cover plate 24, and fasteners hold the cover optics 30 in place within the tray 22. When the cassette 20 is installed in the head 10, the cover optics 30 acts as a protective cover for the internal optics of the head (10), preventing dust and other debris from interfering with the generated laser beam. Over time, the cover optics 30 needs to be replaced due to the accumulation of contaminants on it. Therefore, the cover optics 30 is replaceable in both the cassette 20 and the head 10.

[0027] In order to determine the level of contamination on the cover optics 30 and whether it needs to be removed and replaced, the processing head 10 includes a sensing device to monitor the contamination on the cover optics 30. Figure 3 The illustration shows the components of a laser processing head 10 having the sensing device 50 of this disclosure. The internal optics of the head 10 are shown, including a laser input device 40, a collimating lens 42, and a focusing lens 44. From there, a replaceable cover optics 30 is arranged to be aligned with the longitudinal axis A of the laser beam B emitted from the laser processing head 10 to the workpiece WP.

[0028] A sensing device 50 for monitoring the cover optics 30 is mounted in the head 10. The sensing device 50 includes at least one reflector 52 and at least one detector 54. The at least one detector 54 can be connected to a controller 60 having one or more processors 62 and a memory 64 to achieve the purpose of monitoring the cover optics 30 as disclosed herein. The controller 60 can be a controller independent of other control components of the laser processing head 10. Alternatively, the functionality of the controller 60 can be integrated into all control components of the laser processing head 10.

[0029] The evaluation electronics for controller 60 may not necessarily require a general-purpose central processing unit (CPU) and random access memory (RAM). Overall, the required electronics depend on cost and implementation details, which may be influenced by other subsystems of processing head 10, such as whether a general-purpose CPU is needed for other functions, etc.

[0030] Due to the sensitivity of the components of the sensing device 50, the sensor 54 and reflector 52 are preferably mounted inside the housing 12 of the processing head 10, protected by the cover optics 30. If feasible, the sensing device 50 or an additional sensing device can be used on the other side of the cover optics 30, but this may expose the components to the laser emission process. In some arrangements, the processing head may have two cover optics 30 with a space between them. In practice, the sensing device 50 of this disclosure can be disposed in the space between two cover optics to image either or both of them.

[0031] The laser input device 40 can provide a high-power laser transmission fiber for emitting a high-power laser beam B. A collimating lens 42 collimates the beam B, and a focusing lens 44 focuses the beam B passing through the protective cover optics 30. The focused beam B strikes the workpiece WP to perform the laser emission operation.

[0032] During operation, the area on the cover optics 30 is irradiated by the laser beam B. This area includes not only the surfaces of the optics 30 inside the head 10 that face the laser-emitting optics 40, 42, and 44, but also the opposing surfaces of the optics 30 that face outward from the head 10 and are directly exposed to contaminants from the laser emission process.

[0033] At least one detector 54 detects radiation during operation. Several different types of radiation may exist and occur during operation, and at least one detector 54 may or may not detect them. Generally, at least one detector 54 can detect scattered light (stray light) from the laser. In addition, at least one detector 54 can detect thermal radiation from the cover optics 30 itself. For example, contaminants can heat the cover optics 30 itself, and thus radiate radiation.

[0034] Furthermore, at least one detector 54 can detect visible and thermal radiation from contaminants on the irradiated area of ​​the cover optics 30. Visible and thermal radiation can be caused by heated irradiated contaminants. For example, any contaminants in the area of ​​the cover optics 30 irradiated by beam B can emit radiation, which is reflected by at least one reflector 52 to at least one detector 54. At least one detector 54 detects visible and thermal radiation from contaminants associated with the irradiated area of ​​the cover optics 30.

[0035] The type of radiation detected by at least one detector 54 can be distinguished. For example, at least the time-varying intensity modulation of the laser emission process itself can be filtered out, causing the sensing device 50 to tend to react only to actual contaminants, and not just to stray light from the laser. This filter can be used as hardware filtering or signal processing filtering.

[0036] In another variation, at least one detector 54 of device 50 may use a sensor or filter / sensor combination that detects only radiation above a certain wavelength associated with the composition of cover optics 30. For example, cover optics 30 may be made of fused silica, and the transmittance of fused silica decreases significantly above a wavelength range of about 4 μm. With this threshold configuration, sensing device 50 may be insensitive to anything occurring below cover optics 30 or above focusing lens 44. In effect, the configured sensing device 50 may only see thermal radiation within the space between the two optical elements 30, 44.

[0037] The controller 60 processes the radiation detected by the sensor 54 to monitor the contamination level on the cover optics 30 and indicate the necessity of replacing the cover optics 30. For example, the memory 64 may store threshold levels of contamination. (As mentioned above, although more complex electronics can be used, the sensing device 50 can actually use a simple dual in-line package switch with several predefined levels on the electronics box of the head.) One or more processors 62 may be configured to compare the detected radiation with the threshold levels and, in response to the comparison, indicate when the replaceable cover optics 30 needs to be replaced.

[0038] The algorithm used to make the decision to replace the cover optics 30 can be largely dependent on the type of laser emission process being performed. Some laser emission processes perform well under conditions with more contaminants than others. Generally, the controller 60 operates with an algorithm in which sensing devices 50 (i.e., reflectors 52, sensors 54, etc.) are calibrated to different contaminant levels relative to a given cover optics 30. The sensed response is normalized, thereby associating the contaminant level with the amount, pattern, intensity, frequency, or other characteristics of the detected radiation. For one or more given types of laser emission processes, a threshold level for an acceptable amount of contaminant on the cover optics 30 is defined. When the controller 60, used for the first 10, subsequently monitors the operation of a given laser emission process, the detected radiation can be equated to the associated contaminant level, which can be compared to a stored threshold. Thus, the contaminant level can be monitored on an ongoing or periodic basis to determine whether the threshold has been reached. If so, the controller 60 can instruct that the cover optics 30 needs to be replaced using any acceptable interface of the associated processing equipment.

[0039] According to the implementation method, direct or more integrated algorithms can be implemented to monitor contaminants on the cover optics 30. For example, Figure 4A A process (90) for monitoring contaminants on the cover optics 30 is illustrated. When the laser is operating, radiation is reflected and detected by a sensing device 50. The device 50 monitors the radiation level and determines whether the level exceeds a defined threshold. If so, the device can indicate that the cover optics 30 needs to be replaced. If the contamination is severe enough, the laser emission operation can be proactively modified.

[0040] In another example, Figure 4B The process of monitoring contaminants on the cover optics 30 when the head 10 has a zoom function is illustrated (95). The beam diameter on the cover optics 30 varies with the currently set magnification, thereby altering the signal from at least one detector 54. The device 50 for monitoring contaminants can be integrated with the zoom function and acquires the current magnification during operation. When this level is detected, the device 50 can normalize the signal from at least one detector 54 to an actual power density based on the magnification. This normalization then allows the resulting signal from at least one detector 54 to be more readily used for monitoring contaminants, while taking into account the variation due to the magnification.

[0041] Preferably, the cover optics 30 is positioned as far away as possible from the focal point FP of the laser beam B used during laser emission. This increased distance reduces the wear and tear on the cover optics 30 during laser emission and reduces the frequency of replacements. Simultaneously, and particularly for cutting applications, the total track length of the laser processing head 10 is preferably minimized, allowing for a shorter focal length for the focusing lens 44. For these reasons, the height H of the sensing device 50 from the optics 30 can have an advantageously low profile, thereby minimizing the amount of space required in the laser processing head 10.

[0042] In some arrangements, another cover optic (not shown) may be positioned above the collimating lens 42 to protect the internal optics when it is necessary to remove the head 10 from other components. This other cover optic may have a comparable sensing device as disclosed herein, if advantageous for a given embodiment.

[0043] exist Figures 5A to 5B Further details about the sensing device 50 are provided. For example... Figure 5A As shown in the side view, at least one reflector 52 is disposed in the laser processing head (10) adjacent to the periphery of the replaceable cover optics 30.

[0044] As disclosed herein, sensing device 50 senses contaminants on cover optics 30. These contaminants cause temperature gradients within optics 30 and can lead to a focus shift in the laser beam B. This can negatively impact the laser emission process and may ultimately damage cover optics 30.

[0045] At least one reflector 52 is configured to reflect radiation generated by scattering and / or absorption of the laser beam at a contaminant location on the replaceable cover optics 30 and incident on at least one reflector 52. The radiation can be caused by contaminants on either side of the cover optics 30 (e.g., inside or outside the head). Overall, the cover optics 30 is made of a transparent material and can be relatively thin compared to its surface area. Therefore, the sensing device 50 can sense the overall effect of contaminants on the cover optics 30.

[0046] At least one sensor 54 is disposed in the laser processing head adjacent to the periphery of the replaceable cover optics 30 and is positioned offset relative to at least one reflector 52. As shown, at least one reflector 52 and at least one sensor 54 are disposed on a lateral plane parallel to a short height H of the replaceable cover optics 30. At least one sensor 54 is guided along this lateral plane parallel to the replaceable cover optics 30. Thus, at least one sensor 54 is configured to detect at least a portion of the radiation reflected by the at least one reflector 52 opposite it.

[0047] As previously described, the controller 60 communicates with at least one sensor 54 and is configured to determine contaminants on the replaceable cover optics 30 based on radiation detected by at least one sensor 52.

[0048] If needed, the sensing device 50 can also be used with one or more additional sensing elements, such as a temperature sensor 55a associated with the housing (20) supporting the cover optics 30. When contaminants accumulate on the cover optics 30, the temperature of the cover optics 30 tends to rise, which can be detected in the housing (20) supporting the cover optics 30. Additionally, one or more edge sensors 55b for measuring stray light can be arranged around the edges of the cover optics 30 to measure contaminants. These additional sensing elements can be monitored by the controller 60.

[0049] To enhance monitoring of the illuminated area of ​​the cover optics 30, more than one reflector 52 and sensor 54 can be used. For example, Figure 5B The arrangement of a device 50 having several reflectors 52a-c and several sensors 54a-c is shown.

[0050] Several sensors 54a-c are arranged above the optics 30, with their fields of view parallel to the surface of the optics 30. The sensors 54a-c can image the optics 30 via several polished freeform surface reflectors 52a-c. The reflectors 52a-c can be largely convex, thus allowing them to distort and expand the field of view of the sensors 52a-c to cover as much of the illuminated area of ​​the optics 30 as possible. In one configuration, the surface of the reflector 52 can be an annular cross-section. If the freeform surface of the reflector 52a-c itself is insufficient to cover the entire optics 30, several sensors 54a-c can be combined to maximize the coverage of the surface area of ​​the optics. The sensors 54a-c image the optics 52 at a steep angle. Absorbing surfaces or more complex geometric arrangements can be used to minimize stray light from other parts of the optomechanical system to the sensors 54a-c.

[0051] exist Figure 6A In one variant shown, lens 56 can be positioned directly in front of detector 54, between detector 54 and reflector 52, to reduce the field of view of detector 54, thereby more closely matching the reflector size and enhancing the signal. Furthermore, an intermediate focal point 58 can be formed between detector 54 and reflector 52, so detector 54 can actually be closer to the surface of the cover optics.

[0052] These lens arrangements can influence the desired curvature C of reflector 52, even to the point where no curvature C on reflector 52 is required. Specifically, the field of view of sensor 54 (with photodiode) is typically divergent. By adding an additional positive lens 56, sensor 54 is effectively moved closer to reflector 52. In this case, the curvature C of reflector 52 can be adapted to match the new virtual position of sensor 54. Essentially, sensor 54 has a more useful field of view. Furthermore, the closer field of view of sensor 54 can reduce the influence of unwanted stray light from surrounding mechanisms (or, in the case of a thermal sensor, unwanted thermal radiation from parts that have heated up for other reasons).

[0053] exist Figure 6B In another variation, a concave reflector 52 with a very small radius of curvature C can be used, and this concave reflector can also be used in conjunction with a lens (not shown). These variations can produce an intermediate focal point in the field cone from the detector 54 to the cover optics 30, after which the cone will rapidly expand due to the small radius of curvature. Figure 6B In this case, an intermediate focus is generated after reflector 52.

[0054] Figures 5A to 5B and Figures 6A to 6B The arrangement illustrates why the system can have a reflector 52, which has a surface that is not merely purely annular. Generally, the ray density at the edge / side 31a adjacent to the reflector 52 on the cover glass 30 is higher than the ray density on the opposite edge 31b. The corresponding sensor 54 therefore tends to see more of the adjacent edge / side 31a. To make the ray density more uniform in this plane, the curvature C of the reflector 52 can vary along the height of the reflector 52. Therefore, in Figure 6A In, for example, the curvature C of the convex reflector 52 can be larger towards the bottom 53b and smaller towards the top 53a. Figure 6B In the concave reflector 52, the curvature C can be smaller towards the bottom 53b and larger towards the top 53a.

[0055] To achieve consistency in the published examples, such as in Figure 5B In the diagram, three reflectors 52a-c are shown arranged at 120-degree angles to each other around the periphery of the cover optics 30, and three sensors 54a-c are arranged at 120-degree angles to each other around the periphery of the cover optics 30 and are offset relative to the three reflectors 52a-c. In an exemplary geometry with three sensors 54a-c and three annular reflectors 52a-c, the reflectors 52a-c may have a height H of about 6 mm or less from the cover optics 30.

[0056] It is understood that one or more sensors 54 and one or more reflectors 52 can be used to adapt to the implementation. Therefore, more or fewer of each of the reflectors 52 and sensors 54 can be used. For example, a sensor 54 can be used with a large reflector 52, a sensor 54 can be used with multiple reflectors 52 arranged around the periphery, multiple sensors 54 can be used with a ring reflector 52, and so on. In a particular example, a single ring reflector 52 can surround the periphery of the cover optics 30 with a small height H, and multiple sensors 54 can be positioned in an observation slot defined around the periphery of the ring reflector 52. In general, any suitable combination of sensor and reflector configuration best suited to the type of laser processing head and the laser emission process being performed can be used.

[0057] Figure 7 It shows Figure 4B A diagram illustrating an exemplary coverage area of ​​the sensing device 50. To illustrate the field of view in this example, incoherent irradiance is plotted along the X and Y coordinates across the plane of the cover optics 30. The resulting coverage area can be altered by modifying the arrangement of the sensors 54, the surface shape of the reflectors 52, the number of sensors 54, the number of reflectors 52, etc. These details can be configured for a given implementation.

[0058] In the sensing device 50, at least one sensor 54 may include a photodiode, a pyrometer, a stray light sensor, or other radiation detector. Generally, the sensor 54 can perform measurements in the visible and near-infrared spectra. In a preferred arrangement, at least one sensor 54 is a pyrometer that can measure information related to the temperature of the cover optics 30 and is less affected by stray light from the process.

[0059] At least one reflector 52 may include a freeform mirror or other reflective surface. At least one reflector 52 may be coated with a highly reflective material, such as gold, so that reflector 52 will reflect most of the radiation and will tend not to absorb radiation, so that reflector 52 will not heat up during operation.

[0060] Generally, at least one reflector 52 can be a curved, convex, aspherical, or non-rotationally symmetric surface to reflect more radiation from the cover optics 30. For example, as Figure 8 As shown in one particular configuration, reflector 52 can be part of an annular torus 80. Thus, reflector 52 can define a first radius of curvature R along the lateral dimension and a second radius of curvature r along the longitudinal dimension. The first radius R will define a portion of the larger radius R of the annular torus 80, and the second radius r will define a portion of the smaller radius r of the annular torus 80.

[0061] Figures 9A to 9C The arrangement of a laser processing head 10 having the sensing device 50 of this disclosure is schematically shown. Figure 9A In this document, a replaceable cover optics 30 is shown in box 20, which can be inserted into and removed from the housing 12 of the head as previously described. Here, a sensing device 50 having one or more components for the reflector (52), sensor (54), lens (56), etc., disclosed herein can be incorporated into portion 90 of box 20. Other components such as the reflector (52), sensor (54), lens (56), etc., disclosed herein can be incorporated into housing 12 adjacent to box 20.

[0062] exist Figure 9B In the case 20, a replaceable cover optics 30 is shown, which can be inserted into and removed from the housing 12 of the head as previously described. Here, a sensing device 50 having one or more components for the reflector (52), sensor (54), lens (56), etc., disclosed herein can be incorporated into its own replaceable housing 92. Other components such as the reflector (52), sensor (54), lens (56), etc., disclosed herein can be incorporated into the housing 12.

[0063] exist Figure 9C In the diagram, a replaceable cover optics 30 is shown in box 20, which can be inserted into and removed from the housing 12 of the head as previously described. Here, the sensing device 50 disclosed herein, having one or more components for a reflector (52), sensor (54), lens (56), etc., can be incorporated into the head 10 and contained within the housing 12. Internal mechanical structures 94, etc., can support the components. Figures 9A to 9C As shown in these arrangements, the device 50 of this disclosure can be combined in a variety of ways for use in the laser processing head 10 relative to the replaceable cover optics 30.

[0064] As disclosed herein, the sensing device 50 has a low profile in the parallel plane adjacent to the cover optics 30. This configuration is particularly advantageous compared to an arrangement in which a sensor (e.g., a pyrometer) is used in the housing 12 of the head 10 directly above the cover optics 30. Such an arrangement would require more space to accommodate it.

[0065] Furthermore, the configuration of the disclosed device 50 is more reliable than an arrangement that uses stray light sensors only at the edge of the cover optics 30 within the head. Here, the geometry of the sensing device 50 allows the sensor 54 to detect more radiation from the irradiated area of ​​the cover optics 30 without requiring excessive space inside the laser processing head 10.

[0066] The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concept conceived by the applicant. It will be understood, with the benefit of this disclosure, that the foregoing features of any embodiment or aspect of the disclosed subject matter may be used alone or in combination with any other described feature of any other embodiment or aspect of the disclosed subject matter.

[0067] In exchange for the disclosure of the inventive concepts contained herein, the applicant expects all patent rights provided by the appended claims. Therefore, the appended claims are intended to cover all modifications and variations falling within the scope of the appended claims or their equivalents.

Claims

1. An apparatus for a laser processing head having a replaceable cover optics, the replaceable cover optics being configured to be aligned with the longitudinal axis of a laser beam emitted from the laser processing head onto a workpiece during laser emission, the replaceable cover optics including a laser-side surface and a workpiece-side surface, the laser beam being incident on the laser-side surface, the workpiece-side surface being opposite to the laser-side surface and located between the laser-side surface and the workpiece, the apparatus comprising: At least one reflector is disposed adjacent to the periphery of the replaceable cover optics, and the at least one reflector is configured to reflect radiation generated by the interaction of the laser beam with contaminants on the replaceable cover optics and incident on the at least one reflector. as well as At least one sensor is disposed adjacent to the periphery of the replaceable cover optics, the at least one sensor being offset relative to the at least one reflector, the at least one sensor being configured to detect at least a portion of the radiation reflected by the at least one reflector, wherein the at least one reflector and the at least one sensor are located on the same side of the replaceable cover optics as the side on which the laser beam is incident on the replaceable cover optics, and on the opposite side of the replaceable cover optics to the side where the workpiece is located, wherein the optical path maintained by the detected radiation portion is located on the opposite side of the workpiece side surface. The replaceable cover optics are optically located between the laser beam and the at least one reflector, and the at least one reflector is optically located between the replaceable cover optics and the at least one sensor.

2. The device of claim 1, wherein the at least one reflector is configured to reflect radiation generated by scattering and / or absorption of the laser beam by contaminants on the replaceable cover optics.

3. The device of claim 1, wherein the at least one sensor includes a filter configured to filter out radiation associated with the wavelength of the laser emission process.

4. The device of claim 1, wherein the device includes a circuit system configured to filter out radiation associated with time-varying intensity modulation of the laser emission process.

5. The device of claim 1, further comprising a lens disposed between the at least one reflector and the at least one sensor.

6. The device of claim 1, wherein the at least one reflector comprises at least three reflectors arranged at equidistant angles around the periphery of the replaceable cover optics.

7. The device of claim 6, wherein the at least one sensor comprises at least three sensors disposed around the periphery of the replaceable cover optics at an angle equidistant from the at least three reflectors.

8. The device of claim 1, wherein the at least one reflector defines a first radius of curvature along the lateral dimension and a second radius of curvature along the longitudinal dimension.

9. The device of claim 8, wherein the first radius of curvature defines at least a portion of the larger radius of the toroidal body; and wherein the second radius of curvature defines at least a portion of the smaller radius of the toroidal body.

10. The device of claim 1, wherein the at least one reflector defines a curvature that varies from the top to the bottom of the at least one reflector.

11. The device of claim 1, wherein the at least one reflector and the at least one sensor are disposed on a lateral plane parallel to the replaceable cover optics.

12. The device of claim 11, wherein the at least one sensor is guided along the lateral plane parallel to the replaceable cover optics.

13. The device of claim 1, wherein the at least one reflector comprises a reflective coating disposed thereon.

14. The device of claim 1, wherein the at least one sensor comprises a pyrometer.

15. The device of claim 1, wherein the at least one sensor and the at least one reflector are disposed inside the laser processing head, adjacent to the inner surface of the cover optics.

16. The device of claim 1, further comprising a controller that communicates with the at least one sensor and is configured to determine the level of the contaminant on the replaceable cover optics based on the radiation detected by the at least one sensor.

17. The device of claim 16, wherein the controller includes one or more processors and a memory, the memory storing at least one threshold, the one or more processors being configured to: correlate the level of the contaminant with detected radiation, compare the correlated level with the at least one threshold, and in response to the comparison indicate replacement of the replaceable cover optics.

18. The device of claim 17, wherein the at least one threshold stored in the memory is one of a plurality of thresholds stored in the memory, each threshold depending on a given one of the laser emission processes.

19. The device as claimed in claim 1, wherein, The at least one reflector is convex in shape and faces the at least one sensor.

20. The device as claimed in claim 5, wherein, The lens is configured to optically provide an intermediate focal point for the at least one sensor between the at least one reflector and the at least one sensor.

21. The device as claimed in claim 1, wherein, The at least one reflector is concave in shape and faces the at least one sensor.

22. The device as claimed in claim 21, wherein, The at least one reflector and the at least one sensor are configured such that the at least one reflector is optically located between the intermediate focal points of the at least one sensor and the at least one sensor.

23. A laser processing head for processing a workpiece by emitting a laser, the laser processing head having a replaceable cover optics arranged in a straight line with a laser beam emitted from the laser processing head, the replaceable cover optics including a laser-side surface and a workpiece-side surface, the laser beam being incident on the laser-side surface, the workpiece-side surface being opposite to the laser-side surface and located between the laser-side surface and the workpiece, the laser processing head comprising: A receiver is disposed on the laser processing head for holding the replaceable cover optics; At least one reflector is disposed adjacent to the receiver, and the at least one reflector is configured to reflect radiation generated by the interaction of the laser beam with contaminants on the replaceable cover optics and incident on the at least one reflector; as well as At least one sensor is disposed adjacent to the periphery of the receiver, the at least one sensor is configured to be offset relative to the at least one reflector, the at least one sensor is configured to detect at least a portion of the radiation reflected by the at least one reflector, wherein the at least one reflector and the at least one sensor are located on the same side of the replaceable cover optics as the side on which the laser beam is incident, and on the opposite side of the replaceable cover optics to the side where the workpiece is located, wherein the optical path maintained by the detected radiation portion is located on the opposite side of the workpiece side surface. The replaceable cover optics are optically located between the laser beam and the at least one reflector, and the at least one reflector is optically located between the replaceable cover optics and the at least one sensor.

24. A method for use with a laser processing head having a replaceable cover optics, the replaceable cover optics being configured to be aligned with a laser beam emitted from the laser processing head toward a workpiece, the replaceable cover optics including a laser-side surface and a workpiece-side surface, the laser beam being incident on the laser-side surface, the workpiece-side surface being opposite to the laser-side surface and located between the laser-side surface and the workpiece, the method comprising: Radiation generated by the interaction between the laser beam and contaminants on the replaceable cover optics and incident on the at least one reflector is reflected by at least one reflector disposed on the laser processing head adjacent to the replaceable cover optics. At least one sensor, disposed on the laser processing head adjacent to the periphery of the replaceable cover optics and offset relative to the at least one reflector, detects at least a portion of the radiation reflected by the at least one reflector, wherein the at least one reflector and the at least one sensor are located on the same side of the replaceable cover optics as the side where the laser beam is incident on the replaceable cover optics, and on the opposite side of the replaceable cover optics to the side where the workpiece is located, wherein the optical path maintained by the detected radiation portion is located on the opposite side of the workpiece side surface, wherein the replaceable cover optics is optically located between the laser beam and the at least one reflector, and the at least one reflector is optically located between the replaceable cover optics and the at least one sensor; and The level of contaminants on the replaceable cover optics is determined based on the radiation detected by the at least one sensor.

Images