A method and apparatus for rapid detection of laser field mirror protective mirror damage

Abstract

The application discloses a kind of quick detection method and device of laser field mirror protective mirror damage.It is realized based on laser processing system, including: in detection state, laser source provides detection laser and is shaped as flat top light by diffractive optical element, flat top light is incident along processing light path and is transmitted by protective mirror, and transmission light intensity distribution image is collected by CCD camera after transmission;Transmission image is divided by undamaged reference image pixel by pixel, and the transmission rate distribution map of the full width of protective mirror is obtained;Damage area is identified as the area where transmission rate is lower than preset damage threshold;According to the overall characteristics of transmission rate distribution map, if the discrete degree of full width transmission rate is less than the preset uniformity threshold, it is determined as uniform attenuation, if there is local area transmission rate lower than preset local anomaly threshold and difference value exceeds preset difference threshold with adjacent area, it is determined as local anomaly.The application can detect the full width transmission rate distribution of protective mirror in situ quickly, and the detection result directly corresponds to processing effect, to realize accurate maintenance.

Description

Technical Field

[0001] This invention relates to the field of micro-nano fabrication technology, specifically to a microstructure device and its fabrication method, and more particularly to a microstructure reverse etching fabrication method based on pattern reversal and mechanical polishing. Background Technology

[0002] In laser processing (laser marking, welding), galvanometer scanning systems are frequently used to control the movement of the laser beam. These systems mainly consist of a galvanometer and a field lens. To protect the field lens, a replaceable protective lens is typically installed at its front end to block molten slag, fumes, and vapor contaminants generated during processing, preventing them from directly adhering to or damaging the expensive field lens. The protective lens is usually coated with an anti-reflection film. During use, this anti-reflection film gradually deteriorates, leading to a decrease in transmittance. This, in turn, reduces the laser power density during processing, affecting the consistency of the processing results.

[0003] There are currently three main approaches to inspecting the condition of protective mirrors:

[0004] 1. Visual inspection and regular replacement

[0005] Operators periodically remove the protective lens and visually inspect its surface for any visible contamination or damage. If contamination is found, the protective lens is cleaned or replaced. This method relies entirely on manual experience, making it impossible to quantitatively assess the condition of the protective lens. Furthermore, frequent disassembly and reassembly may introduce secondary contamination or installation errors.

[0006] 2. Visual Slag Recognition Method Based on Reflection Images

[0007] The welding head is moved to the inspection station, and a coaxial lighting and inspection camera are used to capture the reflected image on the surface of the protective mirror. The size and quantity of welding slag are determined based on visual recognition, and a cleaning strategy is implemented if the slag exceeds the threshold.

[0008] 3. Defect detection method based on reflected light

[0009] A collimated probe light is emitted towards the protective mirror, and the reflected light from the protective mirror is received to form a detection image. The image is used to determine whether there are any defects on the protective mirror, and if there are defects, it is replaced.

[0010] However, the aforementioned existing technologies still have the following drawbacks:

[0011] 1. Manual visual inspection can only identify macroscopic black spots visible to the naked eye. It is completely insensitive to uniformly distributed hazy pollution. Whether the protective goggles need maintenance depends entirely on the operator's experience and judgment, and there is a lack of objective quantitative standards.

[0012] 2. Methods for identifying weld slag using reflected images and for determining defects using reflected light are affected by various factors such as weld slag morphology, color, and scratches. These factors cannot be directly converted into the transmittance loss of the protective mirror, nor can they be used to deduce the loss of laser power density during processing, a parameter that directly impacts the processing outcome.

[0013] 3. The above solution cannot distinguish whether the damage to the protective mirror is due to uniform attenuation or local anomaly. If the defects or weld slag are evenly distributed and the transmittance loss of the protective mirror is evenly distributed, the processing effect can be restored by increasing the laser output power without stopping the machine for maintenance. Summary of the Invention

[0014] The purpose of this invention is to propose a rapid detection method for damage to the protective mirror of a laser field mirror. This method can quickly and accurately obtain the full-area transmittance distribution of the protective mirror at the front end of the field mirror under the condition that the laser galvanometer processing system is in place, and determine whether the power attenuation in the processing area is uniform based on the transmittance distribution.

[0015] To achieve the aforementioned objective, this invention provides a rapid detection method for damage to a protective mirror of a laser field lens. The method is based on a laser processing system, which includes a laser source, a galvanometer, a field lens, and a protective mirror to be tested disposed at the front end of the field lens. The method includes:

[0016] In the detection state, the laser source provides a detection laser, which is shaped into a flat-top light by a diffractive optical element. The light intensity distribution on the cross-section of the flat-top light is uniform, and the wavelength is consistent with the working wavelength of the processing laser provided by the laser source in the processing state. The flat-top light enters the galvanometer along the same incident direction as the processing optical path, and after being reflected by the galvanometer, it passes through the field lens and the protective lens in sequence, and fully covers the effective light transmission aperture of the protective lens.

[0017] The CCD camera is used to acquire an image of the intensity distribution of the flat-top light after it has passed through the protective lens;

[0018] The transmittance distribution map of each region of the protective mirror is obtained by dividing the flat-top light intensity distribution image by the pre-stored non-damage reference flat-top light intensity distribution image pixel by pixel.

[0019] Based on the transmittance distribution map, areas with transmittance below a preset damage threshold are identified as damaged or contaminated areas, and their location coordinates, area, and attenuation value are recorded; and

[0020] The determination is performed based on the overall characteristics of the transmittance distribution map: if the dispersion of the full-area transmittance is less than the preset uniformity threshold, it is determined to be uniform attenuation; if there is a local area where the transmittance is lower than the preset local anomaly threshold, and the transmittance difference between this area and the adjacent area exceeds the preset difference threshold, it is determined to be a local anomaly.

[0021] Furthermore, the laser source can be a single laser, which outputs a high-power processing laser in processing mode and switches to a low-power mode to output the detection laser in detection mode. Alternatively, the laser source can include an independent main laser and a detection laser, where the main laser outputs the processing laser and the detection laser outputs the detection laser. The main laser and the detection laser operate at the same wavelength, and their output optical paths share the same path to the galvanometer after beam combining or switching.

[0022] Furthermore, the diffractive optical element is inserted into the output optical path of the laser in the detection state and cut out of the output optical path in the processing state.

[0023] Furthermore, the output power of the laser source in the detection state ranges from 0.1mW to 50mW.

[0024] Furthermore, the uniformity of light intensity distribution on the flat-top light cross-section is better than ±2%.

[0025] Furthermore, the power configuration of the flat-top light is as follows: when the CCD camera positioned on the imaging surface behind the protective lens uses fixed exposure parameters, the grayscale value of the image obtained by illuminating the undamaged reference protective lens is within a preset proportion range of the CCD's full scale, and the power stability is better than a preset stability; more specifically, the preset proportion range is 60% to 80%. The preset stability is a power stability better than ±1%.

[0026] Furthermore, the preset damage threshold is a transmittance of less than 90%.

[0027] Furthermore, the preset uniformity threshold is that the standard deviation of the full-area transmittance is less than 2%.

[0028] Furthermore, the preset local anomaly threshold is a transmittance of less than 80%; the preset difference threshold is a transmittance difference between the region and its adjacent regions that is greater than 5%.

[0029] Furthermore, the operating wavelength of the laser source can be one of the infrared band, visible light band, or ultraviolet band.

[0030] Furthermore, the undamaged reference flat-top light intensity distribution image is a reference image pre-acquired and stored under the same lighting conditions and acquisition parameters when the protective mirror is brand new or has been cleaned and confirmed to be undamaged.

[0031] Furthermore, the transmittance distribution map is obtained by dividing the gray values ​​pixel by pixel, and its pixel spatial resolution is determined by the pixel size of the CCD camera and the magnification of the imaging optical system.

[0032] Furthermore, the location coordinates of the damaged or contaminated area can be mapped to the physical coordinate system of the protective mirror, or to the processing area coordinate system of the laser processing system.

[0033] Furthermore, the attenuation value is the percentage or absolute difference in transmittance within the region relative to the undamaged reference transmittance.

[0034] Furthermore, the dispersion of the full-area transmittance is characterized by the standard deviation, which is calculated based on the transmittance values ​​of all effective pixels in the transmittance distribution map.

[0035] Furthermore, when a local anomaly is determined, the method further includes generating an alarm signal containing the coordinates, area, and attenuation value of the region, and sending the alarm signal to the control terminal or remote monitoring platform of the laser processing system.

[0036] Furthermore, in the detection state, the laser emitted from the laser source is attenuated by an attenuator before being incident on the diffractive optical element.

[0037] Furthermore, the laser emitted from the laser source is attenuated by an attenuator and then expanded by a beam expander before being incident on the diffractive optical element; the diameter of the flat-top light spot is 50mm to 60mm.

[0038] Furthermore, the laser source controls the reflector to move out of or into the optical path via an electrically controlled displacement stage, thereby switching between processing and detection states.

[0039] Furthermore, in the detection state, the laser emitted from the laser source is attenuated to 5mW by an attenuator, and after passing through a beam expander and diffractive optical elements, it forms a flat-top light spot with a diameter of 55mm. The uniformity of the flat-top light is better than ±2%, and the power stability is better than ±1%.

[0040] This invention also provides a rapid detection device for damage to a laser field lens protective mirror used to perform the above-described method. The device is integrated into a laser processing system, which includes a laser source, a galvanometer, a field lens, and a protective mirror disposed at the front end of the field lens. The detection device includes: a diffractive optical element movably disposed on the output optical path of the laser source; in the detection state, it enters the output optical path to shape the detection laser provided by the laser source into a flat-top beam with uniform intensity distribution across its cross-section; in the processing state, it exits the output optical path, allowing the processing laser provided by the laser source to propagate along the original optical path; the wavelength of the flat-top beam is consistent with the operating wavelength of the processing laser; a CCD camera disposed on the imaging surface behind the protective mirror to acquire an image of the intensity distribution of the flat-top beam after transmission through the protective mirror; and a processor to process the image acquired by the CCD camera and output a maintenance decision signal based on the processing result.

[0041] Furthermore, the detection device also includes multiple mirrors disposed in the optical path, each mirror being disposed on an electrically controlled displacement stage, the electrically controlled displacement stage being used to move each mirror out of or into the optical path; the diffractive optical element is linked to each mirror to switch so that the laser source switches between processing state and detection state.

[0042] Furthermore, the processor is communicatively connected to the control terminal or remote monitoring platform of the laser processing system, and is used to send an alarm signal when a local anomaly is determined.

[0043] Compared with existing technologies, the beneficial effects of this invention include: First, the detection results of this invention directly correspond to the processing effect. The transmittance distribution directly determines the actual power density distribution of laser processing; therefore, the detection results of this invention can be directly used to assess the degree of processing quality degradation. Second, flat-top light eliminates the systematic errors introduced by uneven illumination. Compared with Gaussian light or ordinary collimated light, flat-top light can directly obtain the true transmittance distribution without complex deconvolution or multiple calibrations, improving detection accuracy and reliability. Third, it enables precise maintenance based on the consistency of processing effects. By distinguishing between uniform attenuation and local anomalies, differentiated maintenance strategies can be implemented. Attached Figure Description

[0044] Figure 1 The optical path of the laser field lens protective mirror damage detection device provided in one embodiment of the present invention when applied to a laser processing system;

[0045] Figure 2 This is an exemplary schematic diagram of the reference transmitted light intensity grayscale image;

[0046] Figure 3 This is an exemplary schematic diagram of the transmittance distribution.

[0047] Figure 4 This is an exemplary schematic diagram of the transmittance distribution when the attenuation is uniform across the entire width.

[0048] Figure 5 This is an exemplary schematic diagram of the transmittance distribution under local anomalies;

[0049] Figure 6 A schematic diagram of the optical path principle of the laser field lens protective lens damage detection device provided in another embodiment of the present invention when applied to a laser processing system (reusing the processing light source). Detailed Implementation

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0051] This invention provides a rapid detection method and apparatus for damage to protective mirrors in laser field mirrors. It utilizes a flat-top beam with the same wavelength as the processing laser to transmit light through the protective mirror under test. By acquiring the transmitted light intensity distribution image and comparing it pixel-by-pixel with a non-damaged reference image, a transmittance distribution map of the entire protective mirror surface is obtained. Based on the overall characteristics of the transmittance distribution map, the damaged area can be quickly identified, and differentiated maintenance decisions can be made. This method can quickly complete the detection while the laser field mirror processing system is in place, without disassembling the protective mirror. It has high detection efficiency and can distinguish between two different damage modes: uniform attenuation and localized anomalies, thereby guiding operators to take targeted maintenance measures.

[0052] Specifically, the present invention adopts the following technical solution:

[0053] Step 1: Flat-top lighting

[0054] A flat-top beam is provided, which is obtained by the laser beam being emitted and shaped by a diffractive optical element. The uniformity of the light intensity distribution on its cross-section is better than ±2%, and the wavelength is consistent with the working wavelength of the laser processing system to which the protective mirror under test belongs.

[0055] The power configuration of the flat-top light needs to meet the following requirements: under the fixed exposure parameters of the subsequent CCD camera, the gray value of the image obtained by irradiating the non-damaging reference protective lens accounts for 60% to 80% of the full scale of the CCD, the absolute power range is 0.1mW to 50mW, and the power stability is better than ±1%.

[0056] The flat-top beam enters the galvanometer along the same incident direction as the processing optical path, then reaches the protective mirror, and completely covers the protective mirror at the front end of the field mirror under test. In the testing state, the main laser is off, and the galvanometer is locked in its initial position without moving. The flat-top beam passes sequentially through the galvanometer, field mirror, and protective mirror, and the transmitted image is received by the CCD.

[0057] Step 2: Acquisition of transmitted light intensity

[0058] On the imaging surface behind the protective mirror, a CCD camera is used to capture an image of the intensity distribution of the flat-top light transmitted through the protective mirror.

[0059] Step 3: Transmittance Distribution Calculation

[0060] Divide the light intensity distribution image obtained in step 2 pixel by pixel with the pre-stored non-damaging reference flat-top light intensity distribution image to obtain the transmittance distribution map of each region of the protective mirror.

[0061] Step 4: Damage Area Identification

[0062] Based on the transmittance distribution map, areas with transmittance below 90% are identified as damaged or contaminated areas, and their location coordinates, area, and attenuation value are recorded.

[0063] Step 5: Status Assessment and Maintenance Decision

[0064] The determination is made based on the overall characteristics of the transmittance distribution map:

[0065] If the standard deviation of the full-area transmittance is less than 2%, it is judged as uniform attenuation. At this time, the power density of each area within the processing area decreases synchronously. Only the output power of the laser needs to be increased, and no shutdown maintenance is required.

[0066] If a local area has a transmittance of less than 80%, and the transmittance difference between this area and the adjacent area is greater than 5%, it is judged as a local anomaly. At this time, the processing position corresponding to this area will have a low power density, and the processing effect will be different from the surrounding area. Output the coordinates of this area and perform cleaning, maintenance or replacement of the protective lens.

[0067] The above technical solution will be described in detail below through two specific embodiments.

[0068] Example 1

[0069] This embodiment uses a 1064nm laser marking system as an example to provide a detailed description of the rapid detection method and device for laser field lens protective mirror damage provided by the present invention. Figure 1 As shown, it illustrates the optical path principle of a laser field lens protective lens damage detection device applied to a laser processing system. In this embodiment 1, an independent detection light source is used.

[0070] In this embodiment 1, the laser processing system is a 1064nm fiber laser marking system, which includes a main laser 11 (laser 1), a galvanometer 12, a field lens 13, and a protective mirror 14 disposed at the front end of the field lens 13. The protective mirror 14 is a circular quartz substrate lens with a diameter of 50mm, and is coated with a 1064nm antireflection film on both sides to block the spatter, slag, fumes, and vapor contaminants generated during laser processing, preventing them from directly adhering to or damaging the expensive field lens.

[0071] The detection device includes a separate detection laser 21 (laser 2), a beam expander 22, a diffractive optical element 23 (DOE), a CCD camera 24, and a processor 26. The light source of the detection optical path 20 comes from the detection laser 21. After the detection light is expanded and collimated by the beam expander 22, it is incident on the diffractive optical element 23 and shaped into a flat-top light output with uniform light intensity distribution on the cross-section.

[0072] The system parameters are as follows:

[0073] The flat-top light source employs an independent 1064nm semiconductor laser 21 (laser 2), with continuous wave output, an output power of 5mW, and power stability better than ±1%. The laser emitted from laser 21 is expanded and collimated by beam expander 22 before being incident on a diffractive optical element (DOE). The DOE 23 then shapes the light into a flat-top beam with uniform intensity distribution across its cross-section. The diameter of the flat-top beam is 55mm, and the uniformity is better than ±2%.

[0074] CCD camera 24 employs an area-array CMOS image sensor with a resolution of 1280×1024 pixels, 12-bit grayscale output, and a frame rate of 30fps. This CCD camera 24 is positioned on the imaging surface behind the protective lens to acquire images of the light intensity distribution after transmission through the protective lens 14. Testing showed that at an exposure time of 5ms, the grayscale value of the transmitted image obtained after illuminating the undamaged reference protective lens was approximately 3000 (based on a 12-bit full-scale value of 4095), accounting for approximately 73% of the full-scale value, meeting the preferred range of 60%-80%.

[0075] The method for acquiring the reference transmission image is as follows: Before the first laser processing of the newly installed protective lens, i.e., when the protective lens 14 is in a brand new and undamaged state, the system is switched to detection mode. A flat-top light is emitted from the detection laser 21, and after transmission through the protective lens 14, the CCD camera 24 acquires an image of the transmitted light intensity distribution (e.g., ...). Figure 2 The image shown is a grayscale image of the reference transmitted light intensity. This image primarily focuses on the power fluctuations in the central 20×20 mm region (edge ​​areas are generally not used during processing and are therefore ignored), and is stored in the processor as a non-destructive reference flat-top light intensity distribution image. This reference image is used as a reference for each subsequent inspection.

[0076] The structure and detection process of the detection optical path 20 in this embodiment 1 are as follows:

[0077] The system automatically switches the optical path to detection mode upon daily power-on self-test or at preset self-test intervals. In detection mode, the main laser 11 (laser 1) stops emitting light, and the independent detection laser 21 (laser 2) emits light. The detection laser is collimated by the beam expander 22 and shaped by the DOE to form a flat-top beam. Simultaneously, the reflector 25, located in the main optical path, is moved out of the optical path by an electrically controlled translation stage, allowing the detection light to enter the main optical path. The light then enters the galvanometer mirror along the same incident direction as the processing optical path, and after reflection by the galvanometer mirror, passes sequentially through the field mirror and the protective mirror, fully covering the effective aperture of the protective mirror. The CCD camera 24 is moved by an electrically controlled displacement stage to be directly below the protective mirror 14, with its optical axis coaxial with the optical path after the flat-top beam is transmitted, enabling the simultaneous acquisition of a full-area transmitted image.

[0078] After the transmitted light intensity is acquired, the CCD camera 24 transmits the acquired flat-top light intensity distribution image to the processor 26. The processor 26 divides the real-time acquired light intensity distribution image pixel by pixel with the pre-stored non-destructive reference flat-top light intensity distribution image to obtain the transmittance distribution map of each region of the protective mirror (e.g., ...). Figure 3 The diagram shows the transmittance distribution.

[0079] The transmittance distribution map is calculated by dividing the pixel-by-pixel grayscale values. Specifically, for each pixel position (x, y) in the image, the transmittance T(x, y) = I_real(x, y) / I_ref(x, y), where I_real is the grayscale value of the real-time acquired image, and I_ref is the grayscale value of the reference image. The pixel spatial resolution of the transmittance distribution map is determined by the pixel size of the CCD camera and the magnification of the imaging optical system.

[0080] After obtaining the transmittance distribution map, processor 26 traverses all pixels across the entire area, marking all areas with transmittance below 90% as damaged or contaminated areas, and recording their location coordinates, area, and attenuation value. The location coordinates can be mapped to the physical coordinate system of the protective mirror or to the processing area coordinate system of the laser processing system for operator positioning. The attenuation value is the percentage or absolute difference in transmittance within that area compared to the undamaged baseline transmittance.

[0081] Finally, processor 26 performs a determination based on the overall characteristics of the transmittance distribution map:

[0082] If the standard deviation of the full-width transmittance is less than 2%, it is judged as uniform attenuation. Figure 4The diagram illustrates an exemplary transmission distribution under uniform attenuation across the entire area (the standard deviation of the transmission across this area is less than 2%, and the overall transmission is 95% with a standard deviation of 1.5%). In this case, the power density in each region within the processing area decreases synchronously, and the attenuation can be compensated simply by increasing the output power of the main laser, without requiring downtime maintenance. Specifically, the processor 26 outputs a maintenance recommendation: "For uniform attenuation, it is recommended to increase the output power of the main laser by x%, where x = 100 / average transmittance - 100". Optionally, the criteria for determining uniform attenuation may also include: the decrease in the average transmittance across the entire area relative to the undamaged reference transmittance does not exceed 5% to 10%.

[0083] If a local area has a transmittance below 80%, and the transmittance difference between this area and its adjacent areas is greater than 5%, it is considered a local anomaly. Figure 5 The diagram illustrates an exemplary transmission distribution under local anomalies (the standard deviation of transmission in the abnormal area is greater than 5%, while the standard deviation of transmission in the normal area is less than 2%. The normal area has a transmission rate of 90%, and the abnormal area has a transmission rate of 60%–80%). In this case, the processing position corresponding to this area will experience lower power density, resulting in a difference in processing quality compared to the surrounding area. Cleaning, maintenance, or replacement of the protective lens is required. The processor 26 outputs the location coordinates, area, and attenuation value of the local anomaly area, for example: "Local anomaly, location coordinates (X1, Y1)..., please clean or replace the protective lens," and sends an alarm signal to the control terminal or remote monitoring platform of the laser processing system.

[0084] In this embodiment, the galvanometer 12 is locked in its initial position and does not move. The flat-top light is reflected by the galvanometer 12 and incident on the field lens 13 and the protective lens 14 at a fixed angle. The optical axis of the CCD camera 24 is coaxial with the optical path after the flat-top light is transmitted, thereby realizing the one-time acquisition of the full-area transmission image without the need for galvanometer scanning or point-by-point acquisition. The detection speed is fast and suitable for online rapid detection needs.

[0085] Example 2:

[0086] The difference between Example 2 and Example 1 is that the flat-top beam is provided by the main laser of the processing system itself, rather than by a separately installed detection laser. For example... Figure 6 As shown, it illustrates the optical path principle of the provided laser field lens protective lens damage detection device when applied to a laser processing system. This embodiment reuses the processing light source.

[0087] In this embodiment 2, the laser processing system is also a 1064nm fiber laser marking system, including a laser 41, a galvanometer 42, a field lens 43, and a protective mirror 44 disposed at the front end of the field lens 43. The laser 41 outputs a high-power processing laser (power range of 10W to 10kW) in processing mode and switches to a low-power detection mode in detection mode, with an output power range of 0.1mW to 50mW. The laser 41 switches between processing and detection modes by adjusting the drive current or the pump power.

[0088] The specific optical path structure is as follows:

[0089] In the processing state, the laser 41 outputs a high-power processing laser, which is transmitted along the main optical path and reaches the surface of the workpiece after passing through the galvanometer 42, field mirror 43, and protective mirror 44. At this time, the diffractive optical element 53 (DOE) set in the optical path cuts out the optical path and does not participate in beam shaping.

[0090] When switching to detection mode, reflectors 55 and 56, which are set in the optical path, are moved out of the optical path by an electrically controlled displacement stage. At the same time, the laser in the main optical path is attenuated to 5mW by attenuator 57, and then formed into a flat-top beam after being expanded and collimated by beam expander 52 and shaped by diffractive optical element 53 (DOE). The flat-top beam has a diameter of 55mm, uniformity better than ±2%, output power of 5mW, and power stability better than ±1%.

[0091] In the above scheme, the diffractive optical element 53 enters the output light path of the laser 41 in the detection state and exits the output light path in the processing state. The diffractive optical element 53 is driven by a motor or electromagnetic drive to enter or exit the path. Simultaneously, reflectors 55 and 56 are respectively mounted on an electrically controlled displacement stage, which is used to move reflectors 55 and 56 out of or into the light path. The diffractive optical element 53 is linked to and switches with reflectors 55 and 56 to switch the laser 41 between the processing and detection states. When switching to the detection mode, the galvanometer 42 is locked in its initial position and does not move.

[0092] In this embodiment 2, the operating wavelength of the laser 41 is the same as in embodiment 1, which is 1064nm (infrared band). It can be understood that, depending on the actual processing requirements, the operating wavelength of the laser can also be either the visible light band or the ultraviolet band.

[0093] In the detection state, the flat-top light enters the galvanometer 42 along the same incident direction as the processing optical path. After being reflected by the galvanometer 42, it passes sequentially through the field mirror 43 and the protective mirror 44, fully covering the effective aperture of the protective mirror. A CCD camera 54, positioned on the imaging surface behind the protective mirror 44, acquires an image of the intensity distribution of the flat-top light after transmission through the protective mirror 44. After the transmitted light intensity is acquired, the CCD camera 54 transmits the acquired image of the flat-top light intensity distribution to the processor 58. The subsequent detection process (transmittance distribution calculation, damage area identification, status determination, and maintenance decision-making) is completely consistent with Example 1 and will not be repeated here.

[0094] This embodiment 2 reuses the processing light source as the detection light source, eliminating the need for an additional independent detection laser, further reducing system cost and optical path complexity, and is especially suitable for processing systems already equipped with high-power lasers.

[0095] In the above embodiments, the rapid damage detection device for laser field lens protective mirrors used to perform the detection method of the present invention is integrated into the laser processing system. This detection device includes diffractive optical elements, a CCD camera, and a processor.

[0096] The diffractive optical element is movably positioned in the output optical path of the laser source. In the detection state, it enters the output optical path to shape the detection laser provided by the laser source into a flat-top beam with uniform intensity distribution across its cross-section. In the processing state, it exits the output optical path, allowing the processing laser provided by the laser source to propagate along the original optical path. The wavelength of the flat-top beam is consistent with the operating wavelength of the processing laser.

[0097] The CCD camera is positioned on the imaging surface behind the protective mirror to capture images of the intensity distribution of the flat-top light after it has been transmitted through the protective mirror.

[0098] The processor communicates with both the CCD camera and the laser source, processing images acquired by the CCD camera and outputting maintenance decision signals based on the processing results. When a local anomaly is detected, the processor also generates an alarm signal containing the region's coordinates, area, and attenuation value, sending the alarm signal to the laser processing system's control terminal or remote monitoring platform. Furthermore, the processor controls the switching sequence of the laser source between processing and inspection states, automating the inspection process.

[0099] In the above embodiments, the uniformity of light intensity distribution on the flat-top light cross-section is better than ±2%, the power stability is better than ±1%, and the grayscale value of the image obtained by illuminating the undamaged reference protective lens under fixed exposure parameters of the CCD camera is between 60% and 80% of the CCD's full scale. These preferred ranges of parameters ensure the accuracy and repeatability of the detection results. Areas with transmittance below 90% are identified as damaged or contaminated areas, a full-area transmittance standard deviation of less than 2% is judged as uniform attenuation, and transmittance below 80% with a difference greater than 5% from adjacent areas is judged as local anomalies. The specific values ​​of the above thresholds can be adaptively adjusted according to the protective lens material, coating characteristics, and processing requirements, all of which fall within the protection scope of this invention.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rapid detection method for damage to a protective mirror of a laser field lens, the method being implemented based on a laser processing system, the laser processing system comprising a laser source, a galvanometer, a field lens, and a protective mirror to be tested disposed at the front end of the field lens; characterized in that, The method includes: In the detection state, the laser source provides a detection laser, which is shaped into a flat-top light by a diffractive optical element. The light intensity distribution on the cross-section of the flat-top light is uniform, and the wavelength of the flat-top light is consistent with the working wavelength of the processing laser provided by the laser source in the processing state. The flat-top light enters the galvanometer along the same incident direction as the processing optical path, and after being reflected by the galvanometer, it passes through the field lens and the protective lens in sequence, and fully covers the effective light transmission aperture of the protective lens. The intensity distribution image of the flat-top light after transmission through the protective mirror is acquired using a CCD camera; The transmittance distribution map of each region of the protective mirror is obtained by dividing the flat-top light intensity distribution image by the pre-stored non-damage reference flat-top light intensity distribution image pixel by pixel. Based on the transmittance distribution map, areas with transmittance below a preset damage threshold are identified as damaged or contaminated areas, and their location coordinates, area, and attenuation value are recorded; and The determination is performed based on the overall characteristics of the transmittance distribution map: if the dispersion of the full-area transmittance is less than the preset uniformity threshold, it is determined to be uniform attenuation; if there is a local area where the transmittance is lower than the preset local anomaly threshold, and the transmittance difference between this area and the adjacent area exceeds the preset difference threshold, it is determined to be a local anomaly.

2. The method according to claim 1, characterized in that, The laser source is a laser, which outputs a high-power processing laser in the processing state and switches to a low-power mode to output the detection laser in the detection state.

3. The method according to claim 1, characterized in that, The laser source includes a main laser and a detection laser that are independent of each other. The main laser is used to output the processing laser, and the detection laser is used to output the detection laser. The main laser and the detection laser have the same operating wavelength, and their output optical paths are combined or switched to share the same optical path to enter the galvanometer.

4. The method according to claim 1, characterized in that, The diffractive optical element is inserted into the output optical path of the laser in the detection state and cut out of the output optical path in the processing state.

5. The method according to claim 1, characterized in that, The output power of the laser source in the detection state ranges from 0.1mW to 50mW.

6. The method according to claim 1, characterized in that, The uniformity of light intensity distribution on the flat-top light cross section is better than ±2%.

7. The method according to claim 1, characterized in that, The power configuration of the flat-top light is as follows: when the CCD camera set on the imaging surface behind the protective mirror uses fixed exposure parameters, the grayscale value of the image obtained by illuminating the undamaged reference protective mirror is within the preset ratio range of the CCD's full scale, and the power stability is better than the preset stability.

8. The method according to claim 7, characterized in that, The preset ratio range is 60% to 80%.

9. The method according to claim 7, characterized in that, The preset stability is a power stability better than ±1%.

10. The method according to claim 1, characterized in that, The preset damage threshold is a transmittance of less than 90%.

11. The method according to claim 1, characterized in that, The preset uniformity threshold is that the standard deviation of the full-area transmittance is less than 2%.

12. The method according to claim 1, characterized in that, The preset local anomaly threshold is a transmittance of less than 80%; the preset difference threshold is a transmittance difference between the region and its adjacent regions that is greater than 5%.

13. The method according to claim 1, characterized in that, The laser source operates in the infrared band.

14. The method according to claim 1, characterized in that, The undamaged reference flat-top light intensity distribution image is a reference image that has been pre-acquired and stored under the same lighting conditions and acquisition parameters when the protective mirror is brand new or has been cleaned and confirmed to be undamaged.

15. The method according to claim 1, characterized in that, The transmittance distribution map is obtained by dividing the gray values ​​pixel by pixel, and its pixel spatial resolution is determined by the pixel size of the CCD camera and the magnification of the imaging optical system.

16. The method according to claim 1, characterized in that, The location coordinates of the damaged or contaminated area are mapped to the physical coordinate system of the protective mirror or to the processing area coordinate system of the laser processing system.

17. The method according to claim 1, characterized in that, The attenuation value is the percentage or absolute difference in transmittance within the region relative to the undamaged reference transmittance.

18. The method according to claim 1, characterized in that, The dispersion of the full-area transmittance is characterized by the standard deviation, which is calculated based on the transmittance values ​​of all valid pixels in the transmittance distribution map.

19. The method according to claim 1, characterized in that, When a local anomaly is determined, the method further includes generating an alarm signal containing the coordinates, area, and attenuation value of the region, and sending the alarm signal to the control terminal or remote monitoring platform of the laser processing system.

20. The method according to claim 1, characterized in that, In the detection state, the laser emitted from the laser source is attenuated by an attenuator and then incident on the diffractive optical element.

21. The method according to claim 20, characterized in that, The laser emitted from the laser source is attenuated by an attenuator and then expanded by a beam expander before being incident on the diffractive optical element; the diameter of the flat-top light spot is 50mm to 60mm.

22. The method according to claim 1, characterized in that, The laser source controls the reflector to move out of or into the optical path via an electrically controlled displacement stage, thereby switching between processing and detection states.

23. The method according to claim 21, characterized in that, In the detection state, the laser emitted from the laser source is attenuated to 5mW by an attenuator, and after passing through a beam expander and diffractive optical elements, it forms a flat-top light spot with a diameter of 55mm. The uniformity of the flat-top light is better than ±2%, and the power stability is better than ±1%.

24. A rapid detection device for damage to a laser field lens protective mirror used in performing the method as described in any one of claims 1 to 23, characterized in that, The device is integrated into a laser processing system, which includes a laser source, a galvanometer, a field lens, and a protective mirror disposed at the front end of the field lens; the detection device includes: A diffractive optical element is movably disposed in the output optical path of the laser source. In the detection state, it cuts into the output optical path to shape the detection laser provided by the laser source into a flat-top light with uniform intensity distribution on the cross-section. In the processing state, it cuts out the output optical path so that the processing laser provided by the laser source can be transmitted along the original optical path. The wavelength of the flat-top light is consistent with the working wavelength of the processing laser. A CCD camera, positioned on the imaging surface behind the protective mirror, is used to acquire an image of the intensity distribution of the flat-top light transmitted through the protective mirror; and The processor is used to process the images acquired by the CCD camera and output maintenance decision signals based on the processing results.

25. The apparatus according to claim 24, characterized in that, The detection device further includes multiple mirrors disposed in the optical path, each mirror being disposed on an electrically controlled displacement stage, the electrically controlled displacement stage being used to move each mirror out of or into the optical path; the diffractive optical element is linked to each mirror to switch so that the laser source switches between processing state and detection state.

26. The apparatus according to claim 24, characterized in that, The processor is communicatively connected to the control terminal or remote monitoring platform of the laser processing system and is used to send an alarm signal when a local anomaly is detected.

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