A method and device for monitoring a three-dimensional temperature field of a laser cladding molten pool

Abstract

The application discloses a kind of laser cladding molten pool temperature field three-dimensional monitoring method and device.The method comprises the following steps: S1, calibration is carried out to visible light imaging device, obtains distortion coefficient and projection mapping matrix, and infrared thermal imaging device and the observation field of visible light imaging device are registered alignment;S2, pseudo binocular image pair containing left and right virtual visual angle is obtained using visible light imaging device;S3, thermal radiation intensity distribution image is obtained using infrared thermal imaging device;S4, according to distortion coefficient, projection mapping matrix and pseudo binocular image pair, the three-dimensional point cloud data of molten pool surface topography is reconstructed;S5, according to spatial corresponding relationship, three-dimensional point cloud data is given with thermal radiation intensity value point by point, and three-dimensional temperature field reconstruction result is obtained.The device for realizing the monitoring method is also provided.The application realizes pseudo binocular imaging by single visible light imaging device, combines infrared thermal imaging and three-dimensional point cloud fusion, and realizes the accurate monitoring of molten pool area three-dimensional temperature field.

Description

Technical Field

[0001] This invention belongs to the field of laser manufacturing and additive manufacturing technology, and specifically relates to a method and device for three-dimensional monitoring of the temperature field of a laser cladding molten pool. Background Technology

[0002] Laser cladding technology, as an important additive manufacturing and surface modification process, has been widely applied in aerospace, automotive manufacturing, mold repair, mining machinery, and other fields. During laser cladding, a high-energy-density laser beam irradiates the substrate surface, causing the powder material or filament to melt simultaneously with the substrate, forming a solidified cladding layer with specific functional properties. The temperature distribution and dynamic evolution of the molten pool directly determine the comprehensive quality indicators of the cladding layer, such as its microstructure, residual stress, crack tendency, and rarefaction porosity. Therefore, accurate and real-time temperature field monitoring of the molten pool area is crucial for ensuring the quality of the cladding layer.

[0003] Currently, monitoring the temperature field of the molten pool mainly relies on two technical approaches: contact temperature measurement based on thermocouples and non-contact temperature measurement based on infrared thermal imaging devices. The former is used to obtain the temperature history of key locations, while the latter is used to capture the overall temperature distribution of the molten pool. Although contact thermocouple temperature measurement has high accuracy, the temperature sensing element cannot directly contact the high-temperature molten pool during the cladding process, and it can only measure the temperature change at a single point, making it unable to reflect the state of the entire molten pool. Therefore, researchers prefer to use non-contact infrared cameras to monitor the temperature field of the molten pool.

[0004] However, existing infrared thermal imaging monitoring technology has the following key problems: current methods for monitoring the temperature field of the molten pool are limited to two-dimensional imaging and have not yet achieved three-dimensional imaging, resulting in the loss of feature information in certain dimensions and incomplete monitoring of the molten pool. Therefore, the industry urgently needs a solution to achieve three-dimensional monitoring of the temperature field of the laser cladding molten pool. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a three-dimensional monitoring device and method for the temperature field of a laser cladding molten pool. The aim is to achieve in-situ measurement of the three-dimensional temperature field of the laser cladding molten pool, providing comprehensive and accurate data support for intelligent monitoring and quality control of the laser cladding process.

[0006] To achieve the above objectives, the specific solution of the present invention is as follows:

[0007] 1. A method for three-dimensional monitoring of the temperature field of a laser cladding molten pool, characterized by comprising the following steps:

[0008] S1, perform intrinsic parameter solving and distortion correction on the visible light imaging device to obtain the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device; and perform registration and alignment between the observation field of the infrared thermal imaging device and the observation field of the visible light imaging device to establish the spatial correspondence between the two observation fields at the pixel level.

[0009] S2, During the cladding process, the visible light imaging device described in S1 is used to acquire a pseudo-binocular image pair of the molten pool area, including a left virtual viewpoint and a right virtual viewpoint, through the following optical path: The processing laser beam is reflected by a dichroic mirror and then focused on the substrate surface by a focusing optical element to form a molten pool area; at the same time, the auxiliary illumination light emitted by the auxiliary illumination lamp directly illuminates the surface of the molten pool; the auxiliary illumination light reflected from the surface of the molten pool passes through the focusing optical element and the dichroic mirror in sequence and then enters the dichroic mirror. The dichroic mirror reflects the auxiliary illumination light band in the incident light to the telephoto macro optical component, the biprism sheet and the narrowband filter element, and then enters the visible light imaging device;

[0010] S3, During the cladding process, the infrared thermal imaging device described in S1 is used to obtain an image of thermal radiation intensity distribution through the following optical path: The infrared thermal radiation released from the molten pool area passes through the focusing optical element and the first dichroic mirror in sequence and then enters the second dichroic mirror. The second dichroic mirror transmits the infrared thermal radiation band in the incident light into the infrared thermal imaging device.

[0011] S4. Based on the radial distortion coefficient, tangential distortion coefficient, and projection mapping matrix obtained in S1, and the pseudo-binocular image pair obtained in S2, the three-dimensional point cloud data of the surface morphology of the molten pool region is reconstructed using a binocular vision three-dimensional reconstruction algorithm.

[0012] S5. Based on the spatial correspondence obtained in S1, the infrared thermal radiation intensity values ​​in the thermal radiation intensity distribution image obtained in S3 are assigned point by point to the corresponding spatial point coordinates in the three-dimensional point cloud data reconstructed in S4, thereby obtaining the three-dimensional temperature field reconstruction result of the molten pool region that integrates spatial geometric information and temperature distribution information.

[0013] Furthermore, the visible light imaging device and the infrared thermal imaging device described in step S1 are configured to have the same imaging frame rate.

[0014] Further, in step S2, the wavelength of the processing laser beam is 1080nm; the dichroic mirror reflects the wavelength of the 1080nm processing laser beam, transmits the wavelength of the auxiliary illumination light, and transmits the infrared thermal radiation band; the wavelength of the light emitted by the auxiliary illumination source is 808nm; the dichroic mirror reflects the wavelength of the 808nm auxiliary illumination source and transmits the 850nm infrared thermometry band.

[0015] Furthermore, the binocular vision 3D reconstruction algorithm described in step S4 reconstructs the 3D point cloud data of the surface morphology of the molten pool region, including the following steps:

[0016] S41. Construct an imaging model based on calibration data: Based on the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device obtained in S1, and combined with the virtual imaging pair introduced by the double prism, construct a pseudo binocular camera imaging geometric model with left virtual viewpoint and right virtual viewpoint.

[0017] S42. Pseudo-binocular molten pool image feature point extraction and matching: Extract molten pool contour and internal texture feature points from the image based on the Superpoint deep learning model, and obtain high-precision feature point matching pairs based on the LightGlue deep learning model;

[0018] S43. Calculation of 3D coordinates of feature points in the molten pool: Based on the pseudo-binocular camera imaging geometric model constructed in S41, the coordinate values ​​of all matched feature points in the 3D space are calculated using the matching pairs obtained in S42.

[0019] S44. Filtering and Reconstruction of 3D Point Cloud of Molten Pool: The 3D spatial coordinate set obtained by S43 is filtered based on the moving least squares method to eliminate outliers caused by noise. Then, the 3D spatial coordinates are fitted and interpolated based on the rolling sphere method and Loop mesh subdivision to generate continuous and complete 3D point cloud data of the surface morphology of the molten pool area.

[0020] A three-dimensional monitoring device for the temperature field of a laser cladding pool for implementing the method includes a laser for emitting a processing laser beam, an auxiliary lighting lamp for emitting auxiliary illumination light, a laser cladding head, a visible light imaging device, an infrared thermal imaging device, and a dichroic mirror II. The laser cladding head is provided with a dichroic mirror I and a focusing optical element arranged sequentially from top to bottom.

[0021] The processing laser beam emitted by the laser is incident on a dichroic mirror and reflected, then focused by a focusing optical element and irradiates the powder on the surface of the substrate to form a molten pool.

[0022] The auxiliary lighting lamp emits auxiliary lighting light that directly illuminates the surface of the molten pool;

[0023] The auxiliary illumination light reflected from the surface of the molten pool and the infrared thermal radiation released from the molten pool are sequentially transmitted through a focusing optical element and a dichroic mirror, and then incident on a dichroic mirror. The dichroic mirror reflects the auxiliary illumination light band to the visible light imaging device and transmits the infrared thermal radiation band to the infrared thermal imaging device.

[0024] Furthermore, the wavelength of the processing laser beam emitted by the laser is 1080nm, and the wavelength of the auxiliary illumination light emitted by the auxiliary illumination lamp is 808nm.

[0025] Furthermore, a telephoto macro optical component is provided between the dichroic mirror and the visible light imaging device. The telephoto macro optical component is used to magnify and image the molten pool area during the cladding process.

[0026] Furthermore, a double prism is provided between the telephoto macro optical component and the visible light imaging device. The double prism is used to split the single incident light into two outgoing light with a slight angular offset, so that a single visible light imaging device can simultaneously capture a pseudo binocular image pair containing a left virtual viewpoint and a right virtual viewpoint.

[0027] Furthermore, a narrowband filter element is disposed between the biprism sheet and the visible light imaging device. The narrowband filter element is a narrowband filter with a center wavelength of 808nm. The narrowband filter element is used to suppress background interference light of non-target wavelengths.

[0028] Advantages of the present invention

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] First, the present invention achieves the acquisition of pseudo-binocular image pairs containing left and right virtual perspectives by combining a telephoto macro optical component, a double prism lens and a single visible light imaging device, using only a single visible light imaging device, and then obtains a three-dimensional point cloud of the molten pool surface morphology based on a binocular vision three-dimensional reconstruction algorithm.

[0031] Secondly, through the ingenious arrangement of two dichroic mirrors, this invention achieves spectral separation of the laser processing optical path, the visible light imaging optical path, and the infrared thermal radiation acquisition optical path. The three optical channels are independent and do not interfere with each other, ensuring the purity and acquisition quality of the signals in each channel.

[0032] Third, this invention performs pixel-level registration and alignment of the observation fields of the infrared thermal imaging device and the visible light imaging device, thereby enabling precise mapping of two-dimensional thermal radiation intensity data onto a three-dimensional point cloud, achieving accurate reconstruction of the three-dimensional temperature field of the molten pool region, and providing comprehensive and accurate data support for intelligent monitoring and quality control of the cladding process. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the three-dimensional monitoring of the temperature field of the laser cladding molten pool according to the present invention.

[0034] Figure 2 This is a flowchart illustrating the binocular vision 3D reconstruction algorithm in step S4 of the present invention.

[0035] Figure 3 for Figure 1 Imaging results from a visible light imaging device.

[0036] Figure 4 for Figure 1 Imaging results from a mid-infrared thermal imaging device.

[0037] Figure 5 for Figure 1 Three-dimensional imaging results of the temperature field of the molten pool in the laser cladding head.

[0038] Figure 6 This is an imaging optical path diagram of the three-dimensional monitoring device for the temperature field of the laser cladding molten pool of the present invention.

[0039] In the picture:

[0040] 1. Visible light imaging device; 2. Narrow band filter element; 3. Biprism sheet; 4. Telephoto macro optical component; 5. Dichroic mirror II; 6. Infrared thermal imaging device; 7. Laser cladding head; 8. Dichroic mirror I; 9. Focusing optical element; 10. Powder; 11. Molten pool; 12. Laser; 13. Auxiliary lighting lamp; 14. Substrate. Detailed Implementation

[0041] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. It should be noted that the specific embodiments are not intended to limit the scope of the present invention.

[0042] like Figures 1 to 5 As shown, a three-dimensional monitoring method for the temperature field of a laser cladding molten pool 11 includes the following steps:

[0043] S1. Before the optical measurement channel is used for the first time, perform the following calibration and registration steps:

[0044] First, the intrinsic parameters of the visible light imaging device 1 are calibrated: using a checkerboard calibration plate, the Zhang calibration is used to solve the intrinsic parameters and correct the distortion of the visible light imaging device 1, and obtain the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device 1, so as to obtain the distortion parameters and projection matrix of the camera, and provide basic parameters for subsequent three-dimensional space reconstruction calculations.

[0045] Then, the infrared thermal imaging device 6 and the visible light imaging device 1 are registered: based on the principle of perspective mapping, the observation field of the infrared thermal imaging device 6 and the observation field of the visible light imaging device 1 are registered and aligned to establish the spatial correspondence between the two observation fields at the pixel level.

[0046] The visible light imaging device 1 and the infrared thermal imaging device 6 are configured with the same imaging frame rate to ensure that the images acquired by the two devices can establish a strict one-to-one correspondence.

[0047] S2, during the cladding process, using the visible light imaging device 1 described in S1, a pseudo-binocular image pair of the molten pool 11 region, including a left virtual viewpoint and a right virtual viewpoint, is acquired through the following optical path:

[0048] A processing laser beam with a wavelength of 1080nm is reflected by a dichroic mirror 8 and then focused onto the surface of a substrate 14 by a focusing optical element 9, causing the powder material and the substrate 14 to melt and form a molten pool region 11. This optical path is a laser processing optical path. The dichroic mirror 8 can reflect the processing laser with a wavelength of 1080nm, while transmitting 808nm auxiliary illumination light and 850nm infrared thermal radiation signal, so that the laser processing optical path and the monitoring optical path are completely separated in space.

[0049] Simultaneously, auxiliary illumination light with a center wavelength of 808nm is activated to directly illuminate the surface area of ​​the molten pool 11 for supplementary illumination. The auxiliary illumination light reflected from the surface of the molten pool 11 passes sequentially through the focusing optical element 9 and the dichroic mirror 8 before entering the dichroic mirror 5. The dichroic mirror 5 reflects the 808nm auxiliary illumination light band of the incident light to the telephoto macro optical component 4, the biprism 3, and the narrowband filter element 2 with a center wavelength of 808nm, before entering the visible light imaging device 1. This optical path is the visible light imaging optical path for the molten pool 11. Among them, the dichroic mirror 5 can reflect the 808nm wavelength auxiliary illumination light while transmitting the 850nm wavelength infrared thermal radiation signal, so that the visible light imaging optical path and the infrared thermal radiation acquisition optical path remain spatially independent.

[0050] After passing through the double prism 3, the single incident light is split into two outgoing lights with a slight angular shift, enabling the visible light imaging device 1 to simultaneously capture a pseudo-binocular image pair of the molten pool 11 region, including both the left and right virtual viewpoints, such as... Figure 3 As shown. The acquired pseudo-binocular image pairs of the molten pool region 11 are used for the subsequent 3D point cloud reconstruction in step S4.

[0051] S3, during the cladding process, the infrared thermal imaging device 6 described in S1 is used to acquire a thermal radiation intensity distribution image via the following optical path: the 850nm infrared thermal radiation signal released from the molten pool 11 region passes sequentially through the focusing optical element 9 and the first dichroic mirror 8 before being incident on the second dichroic mirror 5. The second dichroic mirror 5 transmits the infrared thermal radiation band in the incident light into the infrared thermal imaging device 6, thereby acquiring a thermal radiation intensity distribution image, such as... Figure 4 As shown, this optical path is for infrared thermal radiation acquisition.

[0052] S4. Based on the radial distortion coefficient, tangential distortion coefficient, and projection mapping matrix obtained in S1, and the pseudo-binocular image pair obtained in S2, the three-dimensional point cloud data of the surface morphology of the molten pool 11 region is reconstructed using a binocular vision three-dimensional reconstruction algorithm.

[0053] The binocular vision 3D reconstruction algorithm reconstructs the 3D point cloud data of the surface morphology of the melt pool 11 region, specifically including the following steps:

[0054] S41. Construct an imaging model based on calibration data: Based on the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device 1 obtained in S1, and combined with the virtual imaging pair introduced by the double prism sheet 3, construct a pseudo binocular camera imaging geometric model with left virtual viewpoint and right virtual viewpoint.

[0055] S42. Pseudo-binocular molten pool 11 image feature point extraction and matching: Extract the contour and internal texture feature points of the molten pool 11 in the image based on the Superpoint deep learning model, and obtain high-precision feature point matching pairs based on the LightGlue deep learning model;

[0056] S43, Calculation of 3D coordinates of feature points in molten pool 11: Based on the pseudo binocular camera imaging geometric model constructed in S41, the coordinate values ​​of all matched feature points in 3D space are calculated using the matching pairs obtained in S42.

[0057] S44, 3D point cloud filtering and reconstruction of molten pool 11: The 3D spatial coordinate set obtained by S43 is filtered based on the moving least squares method to eliminate outliers caused by noise. Then, the 3D spatial coordinates are fitted and interpolated based on the rolling sphere method and Loop mesh subdivision to generate continuous and complete 3D point cloud data of the surface morphology of the molten pool 11 region.

[0058] S5, based on the spatial correspondence obtained in S1, the infrared thermal radiation intensity values ​​in the thermal radiation intensity distribution image obtained in S3 are assigned point by point to the corresponding spatial point coordinates in the three-dimensional point cloud data reconstructed in S4, thereby obtaining the three-dimensional temperature field reconstruction result of the molten pool 11 region that integrates spatial geometric information and temperature distribution information, such as... Figure 5 As shown, Figure 5 The colors in the image represent temperature information.

[0059] like Figure 6 As shown, a three-dimensional monitoring device for the temperature field of a laser cladding pool 11 that implements the above method includes a laser 12 for emitting a processing laser beam, an auxiliary lighting lamp 13 for emitting auxiliary illumination light, a laser cladding head 7, a visible light imaging device 1, an infrared thermal imaging device 6, and a dichroic mirror 2 5.

[0060] The laser cladding head 7 is a commercially available product. In this embodiment, the model LAMLH-TV is selected, and the product is from the Huirui brand. The Huirui brand laser cladding head 7 contains an original dichroic mirror and a focusing optical element 9 arranged sequentially from top to bottom. To achieve the wavelength selection function required in this application, as an improvement, this embodiment replaces the original dichroic mirror in the laser cladding head 7 with a dichroic mirror 8 as described in this embodiment. The dichroic mirror 8 is a model HIM-R990-1600T590-900-D50, sourced from Hengyang Optics. In this embodiment, the laser 12 is a model RFL-C6000, sourced from Raycus. The laser 12 emits a processing laser beam with a wavelength of 1080nm, which is incident on the dichroic mirror 8 and reflected. After being focused by the focusing optical element 9 in the laser cladding head 7, it irradiates the powder 10 on the surface of the substrate 14 to form a molten pool 11. In this embodiment, the auxiliary lighting lamp 13 is model FC-808, sourced from Changchun New Industries Optoelectronic Technology. The auxiliary lighting lamp 13 emits 808nm wavelength auxiliary lighting light that directly illuminates the surface of the molten pool 11. It can be seen that the dichroic mirror 8 in this embodiment reflects the wavelength of the 1080nm processing laser beam while transmitting the wavelength of the auxiliary lighting light and the infrared thermal radiation band, thus spatially separating the laser cladding processing channel from the monitoring channel.

[0061] The visible light imaging device 1 and the infrared thermal imaging device 6 are configured with the same imaging frame rate to ensure a strict one-to-one correspondence between the images acquired by the two devices. The visible light imaging device 1 is a model X213M from the Qianlilang brand. The infrared thermal imaging device 6 is a model MIKRON MCS640 from ADVANCEDENERGY.

[0062] Dichroic mirror 2.5 is a custom-designed 50mm diameter circle sourced from Green Laser. It transmits infrared thermometry light at 850nm and reflects auxiliary illumination light at 808nm, allowing the visible light imaging channel and the infrared thermal radiation acquisition channel to be spatially independent.

[0063] The auxiliary illumination light reflected from the surface of the molten pool 11 and the infrared thermal radiation released by the molten pool 11 are transmitted sequentially through the focusing optical element 9 and the dichroic mirror 8 and then incident on the dichroic mirror 5. The dichroic mirror 5 reflects the 808nm wavelength auxiliary illumination light band to the visible light imaging device 1 and transmits the 850nm wavelength infrared thermal radiation band to the infrared thermal imaging device 6.

[0064] From left to right, a telephoto macro optical component 4, a biprism sheet 3, and a narrowband filter element 2 are arranged between the dichroic mirror 2 5 and the visible light imaging device 1.

[0065] The telephoto macro optical assembly 4 includes an imaging lens group and a teleconverter group. The imaging lens group is a Sigma MACRO 105mm F2.8 EX DG model, and the teleconverter group is a Nikon AF-S TC-14E ​​III model. The imaging lens group and the teleconverter group have matching bayonet structures (e.g., both are Nikon F mounts), allowing them to be directly snapped together. The teleconverter group is mounted at the rear end of the image-side optical path of the imaging lens group. The teleconverter group is configured to extend the focal length of the imaging lens group by a preset magnification. The teleconverter group and the imaging lens group are detachably connected by a bayonet connection structure via a rotational snap-fit ​​mechanism. The telephoto macro optical assembly 4 is used to magnify and image the molten pool 11 area during the cladding process to clearly obtain the microscopic morphological details of the molten pool 11 area.

[0066] The biprism lens 3 is custom-made with a length of 5cm, a width of 5cm, a base angle α of 5°, and is made of K9 material, sourced from Jingyao Optoelectronics. The biprism lens 3 is used to split a single incident light beam into two outgoing beams with slight angular offsets, forming imaging beams with left and right viewing angles respectively. After passing through the narrowband filter element 2, these two imaging beams form two sub-images, left and right halves, on the photosensitive surface of the visible light imaging device 1. This allows a single visible light imaging device 1 to simultaneously capture a pseudo-binocular image pair containing both a left virtual viewing angle and a right virtual viewing angle.

[0067] Narrowband filter element 2 is a narrowband filter with a center wavelength consistent with the wavelength of the auxiliary illumination light, both being 808nm. In this embodiment, an 808nm bandpass filter, sourced from the brand "Juanrou," is selected for narrowband filter element 2. Narrowband filter element 2 effectively filters out background interference light outside the 808nm wavelength range to achieve high-quality imaging of the fused pool 11 and improve the imaging signal-to-noise ratio. The telephoto macro optical component 4, the biprism 3, and the narrowband filter element 2 can be considered as a single unit, facilitating easy adjustment of the imaging effect.

[0068] The monitoring device in this embodiment is highly versatile and can be adapted to any structure of the laser cladding head 7. In this system, the cladding head only serves as a carrier to provide basic working environments such as powder feeding, gas supply, and water cooling. The monitoring device can output the three-dimensional temperature distribution results of the molten pool 11 in real time, helping operators to intuitively grasp the processing status and quality; it can also be directly connected to existing processing equipment to use the three-dimensional temperature data to correct process parameters in real time, effectively improving the part forming quality.

Claims

1. A method for three-dimensional monitoring of the temperature field of a laser cladding molten pool, characterized in that, Includes the following steps: S1, perform intrinsic parameter solving and distortion correction on the visible light imaging device to obtain the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device; and perform registration and alignment between the observation field of the infrared thermal imaging device and the observation field of the visible light imaging device to establish the spatial correspondence between the two observation fields at the pixel level. S2, During the cladding process, the visible light imaging device described in S1 is used to acquire a pseudo-binocular image pair of the molten pool area, including a left virtual viewpoint and a right virtual viewpoint, through the following optical path: The processing laser beam is reflected by a dichroic mirror and then focused on the substrate surface by a focusing optical element to form a molten pool area; at the same time, the auxiliary illumination light emitted by the auxiliary illumination lamp directly illuminates the surface of the molten pool; the auxiliary illumination light reflected from the surface of the molten pool passes through the focusing optical element and the dichroic mirror in sequence and then enters the dichroic mirror. The dichroic mirror reflects the auxiliary illumination light band in the incident light to the telephoto macro optical component, the biprism sheet and the narrowband filter element, and then enters the visible light imaging device; S3, During the cladding process, the infrared thermal imaging device described in S1 is used to obtain an image of thermal radiation intensity distribution through the following optical path: The infrared thermal radiation released from the molten pool area passes through the focusing optical element and the first dichroic mirror in sequence and then enters the second dichroic mirror. The second dichroic mirror transmits the infrared thermal radiation band in the incident light into the infrared thermal imaging device. S4. Based on the radial distortion coefficient, tangential distortion coefficient, and projection mapping matrix obtained in S1, and the pseudo-binocular image pair obtained in S2, the three-dimensional point cloud data of the surface morphology of the molten pool region is reconstructed using a binocular vision three-dimensional reconstruction algorithm. S5. Based on the spatial correspondence obtained in S1, the infrared thermal radiation intensity values ​​in the thermal radiation intensity distribution image obtained in S3 are assigned point by point to the corresponding spatial point coordinates in the three-dimensional point cloud data reconstructed in S4, thereby obtaining the three-dimensional temperature field reconstruction result of the molten pool region that integrates spatial geometric information and temperature distribution information.

2. The method according to claim 1, characterized in that, The visible light imaging device and the infrared thermal imaging device described in step S1 are configured to have the same imaging frame rate.

3. The method according to claim 1, characterized in that, In step S2, the wavelength of the processing laser beam is 1080nm; the dichroic mirror reflects the wavelength of the 1080nm processing laser beam, transmits the wavelength of the auxiliary illumination light, and transmits the infrared thermal radiation band; the wavelength of the light emitted by the auxiliary illumination source is 808nm; the dichroic mirror reflects the wavelength of the 808nm auxiliary illumination source and transmits the 850nm infrared thermometry band.

4. The method according to claim 1, characterized in that, Step S4, which uses a binocular vision 3D reconstruction algorithm to reconstruct the 3D point cloud data of the surface morphology of the molten pool region, includes the following steps: S41. Construct an imaging model based on calibration data: Based on the radial distortion coefficient, tangential distortion coefficient and projection mapping matrix of the visible light imaging device obtained in S1, and combined with the virtual imaging pair introduced by the double prism, construct a pseudo binocular camera imaging geometric model with left virtual viewpoint and right virtual viewpoint. S42. Pseudo-binocular molten pool image feature point extraction and matching: Extract molten pool contour and internal texture feature points from the image based on the Superpoint deep learning model, and obtain high-precision feature point matching pairs based on the LightGlue deep learning model; S43. Calculation of 3D coordinates of feature points in the molten pool: Based on the pseudo-binocular camera imaging geometric model constructed in S41, the coordinate values ​​of all matched feature points in the 3D space are calculated using the matching pairs obtained in S42. S44. Filtering and Reconstruction of 3D Point Cloud of Molten Pool: The 3D spatial coordinate set obtained by S43 is filtered based on the moving least squares method to eliminate outliers caused by noise. Then, the 3D spatial coordinates are fitted and interpolated based on the rolling sphere method and Loop mesh subdivision to generate continuous and complete 3D point cloud data of the surface morphology of the molten pool area.

5. A three-dimensional monitoring device for the temperature field of a laser cladding pool, implementing the method of any one of claims 1 to 4, characterized in that, It includes a laser for emitting a processing laser beam, an auxiliary lighting lamp for emitting auxiliary illumination light, a laser cladding head, a visible light imaging device, an infrared thermal imaging device, and a dichroic mirror II. The laser cladding head is provided with a dichroic mirror I and a focusing optical element arranged sequentially from top to bottom. The processing laser beam emitted by the laser is incident on a dichroic mirror and reflected. After being focused by a focusing optical element, it irradiates the powder on the surface of the substrate to form a molten pool. The auxiliary lighting lamp emits auxiliary lighting light that directly illuminates the surface of the molten pool; The auxiliary illumination light reflected from the surface of the molten pool and the infrared thermal radiation released from the molten pool are sequentially transmitted through a focusing optical element and a dichroic mirror, and then incident on a dichroic mirror. The dichroic mirror reflects the auxiliary illumination light band to the visible light imaging device and transmits the infrared thermal radiation band to the infrared thermal imaging device.

6. The apparatus according to claim 5, characterized in that, The processing laser beam emitted by the laser has a wavelength of 1080nm, and the auxiliary illumination light emitted by the auxiliary illumination lamp has a wavelength of 808nm.

7. The apparatus according to claim 5, characterized in that, A telephoto macro optical component is provided between the dichroic mirror and the visible light imaging device. The telephoto macro optical component is used to magnify and image the molten pool area during the cladding process.

8. The apparatus according to claim 7, characterized in that, A double prism is provided between the telephoto macro optical component and the visible light imaging device. The double prism is used to split a single incident light into two outgoing light with a slight angular offset, so that a single visible light imaging device can simultaneously capture a pseudo binocular image pair containing a left virtual viewpoint and a right virtual viewpoint.

9. The apparatus according to claim 8, characterized in that, A narrowband filter element is disposed between the biprism sheet and the visible light imaging device. The narrowband filter element is a narrowband filter with a center wavelength of 808nm. The narrowband filter element is used to suppress background interference light of non-target wavelengths.

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