CN115008011B - Laser welding device integrated with self-adaptive OCT - Google Patents

Abstract

The invention discloses a laser welding device integrated with adaptive OCT. Including OCT structural imaging optical path, used for real-time guidance before laser welding and timely detection and evaluation of welding quality at the welding surface and weld position after laser welding; including electronically controllable adaptive optics module, which will enter the OCT before the laser welding module Beam spot shaping; including a visual imaging module, which is used to magnify and obtain the surface information of the laser welding sample in real time; including a laser welding module, which uses a two-dimensional vibrating mirror to enable a high-power laser to complete controllable large-area two-dimensional welding on the surface of the sample. In different usage scenarios of laser welding, especially the welding scenarios of long focal length field mirrors, the present invention adjusts the diameter of the spot before the OCT sample arm enters the laser welding module through the self-adaptive module, effectively improves the numerical aperture of the spot, and improves The lateral resolution of the OCT system improves the accuracy of guidance before laser welding and improves the effectiveness of welding quality evaluation after laser welding.

Description

A laser welding device integrating adaptive OCT

technical field

The invention relates to a laser welding device in the technical field of laser welding and self-adaptive OCT imaging, in particular to a laser welding device integrated with self-adaptive OCT.

Background technique

With the rapid development of high-power lasers, lasers, with their higher intensity, smaller heat-affected zone, higher precision, smaller deformation, and their compatibility with different metals, make laser welding widely used in manufacturing, The automotive industry, microelectronics industry, etc. have been widely used. Of course, the market demand has also put forward higher requirements for welding precision, and the quality inspection of laser welding has become particularly important.

As a non-contact and non-destructive optical industrial inspection method, OCT can monitor the depth position of laser welding in real time with its unique depth imaging capability, and plays an important role in the quality inspection after laser welding. However, in the traditional OCT-integrated laser welding device, considering the spatter generated during the welding process and the influence of the laser mode, the focal length of the field lens usually used for laser welding is large and the thickness is thick, resulting in the lateral resolution of OCT imaging. It is very poor, and the large dispersion introduced by the field lens will also lead to the decline of the axial resolution in OCT imaging, which will cause errors in the quality evaluation of OCT-guided laser welding and welding.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the present invention proposes a laser welding device integrating self-adaptive OCT, which solves the problems of low OCT lateral resolution and large dispersion in axial resolution under different laser welding scenarios , especially suitable for laser welding applications with long focal length field lenses.

Above-mentioned purpose of the present invention is achieved by following technical scheme:

The invention includes an OCT imaging module, an adaptive optics module, a visual imaging module, a laser welding module and an optical coupling module; the beam of the sample arm emitted from the OCT imaging module is incident on the On the surface of the sample to be welded, the beam of the sample arm is reflected on the surface of the sample to be welded and returns to the OCT imaging module along the original optical path for OCT scanning imaging; the visual imaging beam emitted by the visual imaging module is incident on the optical coupling module and the laser welding module. After welding the surface of the sample, the visual imaging beam returns to the visual imaging module along the original optical path for visual imaging after being reflected on the surface of the sample to be welded.

The adaptive optics module includes a beam expander structure using double lenses or multiple lenses.

The adaptive optics module includes a focusing lens and an electronically controlled adaptive optics lens; the beam of the sample arm emitted from the OCT imaging module sequentially passes through the focusing lens and the electrically controlled adaptive optics lens along the optical axis, and then enters the optical coupling module.

The laser welding module includes a laser light source, a dichroic mirror, a laser welding galvanometer and a laser welding field mirror;

The beam emitted from the optical coupling module enters the dichroic mirror, passes through the dichroic mirror and then enters the laser welding galvanometer, is reflected by the laser welding galvanometer and then enters the laser welding field mirror, and then passes through the laser welding field mirror After transmission, it converges to the surface of the sample to be welded; the laser light from the laser source is incident on the dichroic mirror, reflected by the dichroic mirror, and then incident on the laser welding galvanometer, reflected by the laser welding galvanometer, and then transmitted by the laser welding field mirror Incident to the surface of the sample to be welded and welded on the surface of the sample to be welded, the adjustment of the laser welding galvanometer changes the welding position of the sample to be welded.

The OCT imaging module includes a broadband light source, a fiber coupler, a polarization controller, a reference arm collimator, a reference arm focusing lens, a reference arm mirror, a sample arm collimator, an OCT scanning device, a spectrometer collimator, and a spectrometer reflective grating, spectrometer focusing lens and spectrometer camera;

The first branch end on one side of the fiber coupler is connected to the broadband light source, and the second branch end on the side of the fiber coupler is connected to the spectrometer camera after passing through the spectrometer collimator, the spectrometer reflective grating and the spectrometer focusing lens, and the fiber optic coupler is connected to the spectrometer camera. The first branch end on one side passes through the polarization controller, the reference arm collimator and the reference arm focusing lens in sequence, and then connects with the reference arm mirror, and the second branch end on the other side of the fiber coupler passes through the sample arm collimator and connects with the The OCT scanning device is connected, and the OCT scanning device is connected with the adaptive optics module.

The OCT scanning device is a galvanometer oscillating mirror.

The OCT imaging module adopts one of the following methods:

Time-domain OCT imaging method through mechanical scanning and changing the optical path of the reference arm;

Or a spectrometer OCT imaging method that records spectral interference signals through a spectrometer;

Or a frequency-sweeping OCT imaging method that uses a frequency-sweeping light source to line-scan and record spectral interference signals.

The visual imaging module is a visual imaging camera.

Beneficial effects and innovations of the present invention are as follows:

1. In different laser welding scenarios, especially in the working mode of the long focal length field lens, the lateral resolution of the OCT image will be limited. The adaptive optics module in the invention described in this paper can enter the laser when the beam of the OCT sample arm Before welding the device, the driving current value of the lens is changed by electronically controlling the adaptive optics lens, thereby changing the focal length of the electronically controlled lens, and at the same time adjusting the distance between the electronically controlled lens and the focusing lens, so that the beam is a collimated beam after beam expansion Enter the laser welding module, through the signal-to-noise ratio of the image ROI area, image quality feedback, determine the most suitable collimated spot size, and effectively improve the lateral resolution of the OCT system;

2. By means of digital iteration, the dispersion phase factor is added in the spectral domain to compensate the dispersion introduced by the laser welding module field mirror and optical coupling module in the sample arm, and improve the axial resolution of the OCT system, because there is no hardware dispersion Compensation simplifies the hardware configuration of the reference arm, and can also use a fixed-length optical fiber to replace the reference arm, reducing the system volume and saving system cost;

3. The OCT imaging module, vision module and laser welding module are designed with a common optical axis. Before laser welding, when the laser welding galvanometer is not working, two-dimensional imaging of the sample surface can be performed only through the OCT scanning device. , to obtain the surface information and depth information of the sample at any position of the metal to be welded; during the laser welding process, the OCT scanning device is reset, and under the two-dimensional rotation of the laser welding galvanometer, the depth information of the welding point position can be obtained in real time, and the keyhole Internal measurement is carried out to determine the actual welding penetration in real time; after the laser welding is completed, the OCT scanning device scans to quickly and effectively evaluate and analyze the welding quality of the welding surface, weld seam and other positions.

Description of drawings

Fig. 1 is the module schematic diagram of device of the present invention;

Fig. 2 is the structural representation of example device of the present invention;

Fig. 3 is a comparison chart of imaging experiment results of an exemplary embodiment of the present invention;

In the figure, 1-OCT imaging module; 2-adaptive optics module, 3-visual imaging module, 4-laser welding module, 5-optical coupling module, 6-sample to be welded, 101-broadband light source, 102-fiber coupler , 103-polarization controller, 104-reference arm collimator, 105-reference arm focusing lens, 106-reference arm mirror, 107-sample arm collimator, 108-OCT scanning device, 109-spectrometer collimator, 110-Spectrometer reflective grating, 111-Spectrometer focusing lens, 112-Spectrometer camera, 201-Focusing lens, 202-Electronic control adaptive optics lens, 301-Visual imaging camera, 401-Laser light source, 402-Dichroic mirror, 403- laser welding galvanometer, 404 laser welding field mirror.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, which form a part of this document. It should be noted that these descriptions and examples are illustrative only, and should not be construed as limiting the scope of the present invention. The protection scope of the present invention is defined by the appended claims, and any changes based on the claims of the present invention All are protection scope of the present invention.

In order to facilitate the understanding of the embodiments of the present invention, each operation is described as a plurality of discrete operations, however, the order of description does not represent the order in which the operations are performed.

As shown in Figures 1 and 2, the present invention includes an OCT imaging module 1, an adaptive optics module 2, a visual imaging module 3, a laser welding module 4, and an optical coupling module 5; The adaptive optics module 2, the optical coupling module 5 and the laser welding module 4 are incident on the surface of the sample 6 to be welded, the adaptive optics module 2 and the optical coupling module 5 have a common optical axis, and the light beam of the sample arm is reflected on the surface of the sample 6 to be welded Return to the OCT imaging module 1 along the original optical path for OCT scanning imaging to obtain OCT signals on the metal surface; the visual imaging beam emitted by the visual imaging module 3 is incident on the surface of the sample 6 to be welded after passing through the optical coupling module 5 and the laser welding module 4. After the imaging beam is reflected on the surface of the sample 6 to be welded, it returns along the original optical path to the visual imaging module 3 for visual imaging to obtain an image of the metal surface. In specific implementation, the sample 6 to be welded is metal.

According to the metal OCT signal obtained in the OCT imaging module 1, the laser welding module 4 is guided in real time to complete the laser welding at the preset position, and the inside of the keyhole is measured during the welding process to determine the actual welding penetration in real time, and after the welding is completed. Detect and evaluate the welding quality at the welding surface and the depth of the weld;

In the adaptive optics module 2, the sample arm beam emitted from the OCT imaging module 1 is shaped through the beam expander structure, that is, the numerical aperture of the spot is increased, and the lateral resolution of the OCT system is improved.

The visual imaging module 3 is used for real-time magnification and acquisition of surface information of the sample 6 to be welded;

The laser welding module 4 uses a two-dimensional vibrating mirror to enable a high-power laser to complete adjustable large-area two-dimensional welding on the surface of the sample 6 to be welded.

The optical coupling module 5 couples the OCT imaging module 1 and the visual imaging module 3 together. At this time, the OCT imaging module 1 and the visual imaging module 3 share a laser welding two-dimensional vibrating mirror and a laser welding focusing field lens, and the imaging object planes coincide, and the imaging center The location also coincides.

The OCT imaging module 1 adopts one of the following methods:

Time-domain OCT imaging method through mechanical scanning and changing the optical path of the reference arm;

Or a spectrometer OCT imaging method that records spectral interference signals through a spectrometer;

Or a frequency-sweeping OCT imaging method using a frequency-sweeping light source to line-scan and record spectral interference signals;

The OCT imaging module 1 includes a broadband light source 101, a fiber coupler 102, a polarization controller 103, a reference arm collimator 104, a reference arm focusing lens 105, a reference arm mirror 106, a sample arm collimator 107, an OCT scanning device 108, Spectrometer collimator 109, spectrometer reflective grating 110, spectrometer focusing lens 111 and spectrometer camera 112;

The first branch end on one side of the fiber coupler 102 is connected to the broadband light source 101, and the second branch end on the one side of the fiber coupler 102 passes through the spectrometer collimator 109, the spectrometer reflective grating 110 and the spectrometer focusing lens 111 successively, and connects with the spectrometer camera 112, the first branch end on the other side of the fiber coupler 102 is connected to the reference arm reflector 106 after passing through the polarization controller 103, the reference arm collimator 104 and the reference arm focusing lens 105, and the other side of the fiber coupler 102 The second branch end of the sample arm collimator 107 is connected to the OCT scanning device 108, and the OCT scanning device 108 is connected to the adaptive optics module 2. The OCT scanning device 108 is a galvanometer mirror.

In this embodiment, the OCT imaging module 1 is spectral domain OCT, the central wavelength of the broadband light source is 840nm, and the bandwidth is 45nm. The sample OCT signal is obtained in real time through the spectrometer camera and transmitted to the computer. The OCT scanning device is a galvanometer vibrating mirror. For controlling the scanning position of OCT structural imaging, raster scanning, circular scanning, sampling scanning, etc. can be realized.

The adaptive optics module 2 includes a beam expander structure using a double lens or a plurality of lenses.

The adaptive optics module 2 includes a focusing lens 201 and an electronically controlled adaptive optics lens 202;

The light beam of the sample arm emitted from the OCT imaging module 1 sequentially passes through the focusing lens 201 and the electronically controlled adaptive optics lens 202 along the optical axis, and then enters the optical coupling module 5 .

In this embodiment, the adaptive optics module 2 uses a combination of a focusing lens and an electronically controlled adaptive optics lens. Under different focal lengths of field lenses, especially in laser welding scenarios with long focal length and long focal depth, the drive of the lens can be changed. The electric current changes the focal length of the electric control lens, and then adjusts the distance between the focusing lens and the variable focus lens, so that the beam of the sample arm can enter the laser welding module with a larger spot size, and the most suitable one is determined through the image quality feedback mechanism. The magnified size to obtain the optimal OCT image can be applied to the laser welding scene without a focal length field lens.

The visual imaging module 3 is a visual imaging camera 301 .

The laser welding module 4 includes a laser light source 401, a dichroic mirror 402, a laser welding galvanometer 403 and a laser welding field mirror 404;

The light beam emitted from the optical coupling module 5 is incident on the dichroic mirror 402, transmitted through the dichroic mirror 402, and then incident on the laser welding galvanometer 403, reflected by the laser welding galvanometer 403, and then incident on the laser welding field mirror 404, After being transmitted by the laser welding field mirror 404, it is converged to the surface of the sample 6 to be welded; the high-power laser of the laser light source 401 is incident on the dichroic mirror 402, and then incident on the laser welding vibrating mirror 403 after being reflected by the dichroic mirror 402. The laser welding galvanometer 403 is reflected and then transmitted by the laser welding field lens 404 and then incident on the surface of the sample 6 to be welded and welded on the surface of the sample 6 to be welded. The adjustment of the laser welding galvanometer 403 changes the welding position of the sample 6 to be welded. The dichroic mirror 402 couples the OCT imaging module 1 , the visual imaging module 3 and the laser welding module 4 together, the welding position coincides with the imaging position, and the welding center coincides with the imaging center.

The broadband light source 101 emits an OCT beam. After the OCT beam passes through the fiber coupler 102, the reference arm beam emerges from the first branch end on the other side of the fiber coupler 102, and exits from the second branch end on the other side of the fiber coupler 102. The beam of the sample arm and the beam of the reference arm pass through the polarization controller 103 and the collimator 104 of the reference arm in turn, and then converge on the mirror 106 of the reference arm through the focusing lens 105 of the reference arm, and return along the original path of the optical path of the reference arm after being reflected by the mirror 106 of the reference arm to the fiber coupler 102 ; the beam of the sample arm is incident on the adaptive optics module 2 after passing through the sample arm collimator 107 and the OCT scanning device 108 . The sample arm beam emitted from the OCT scanning device 108 is incident on the optical coupling module 5 after being enlarged by the beam spot size of the adaptive optics module 2, and then incident on the laser welding vibrator after being transmitted by the optical coupling module 5 and the dichroic mirror 402. The mirror 403 is incident to the laser welding field mirror 404 after being reflected by the laser welding oscillating mirror 403. The laser welding field mirror 404 focuses the beam of the sample arm on the metal 6 to be welded, and the beam carrying the information of the metal 6 to be welded returns to the The fiber coupler 102, the reference arm beam returned by the reference arm mirror and the sample arm beam returned by the metal to be welded undergo weak coherent interference at the fiber coupler 102, and the interference signal enters the spectrometer collimator 109 and then enters the spectrometer reflective The grating 110, the spectrometer reflective grating 110 splits the interference signal according to the wavelength, and the split interference signal is then converged on the spectrometer camera 112 through the spectrometer focusing lens 111, and the computer analyzes and processes the spectral signal to obtain an OCT image.

The use steps of the present invention are as follows:

1. Before laser welding, when the laser welding galvanometer is not working, only the galvanometer galvanometer can perform two-dimensional imaging on the surface of the sample, and obtain the depth information and surface information of any position of the metal to be welded;

2. During the laser welding process, the galvanometer vibrating mirror is reset. Under the two-dimensional rotation of the laser welding vibrating mirror, the depth information of the position of the welding point can be obtained in real time, and the inside of the keyhole can be measured to determine the actual welding penetration in real time;

3. After laser welding, the welding quality of the welding surface, welding seam and other positions can be quickly and effectively evaluated and analyzed through the scanning of the galvanometer vibrating mirror.

The remarkable stabilizing effect of the present invention in practical application can be reflected in FIG. 3 . From Figure 3 a is the welding seam imaging picture after laser welding without adding the adaptive optics module of this paper, and Figure 3 b is adding the adaptive optics module of this paper, the welding seam imaging picture after laser welding, which is marked with the number 1 The picture above is the scanned physical picture, the black frame is the scanning area, the picture marked with number 2 is the projection picture of the weld after OCT scanning, and the tomogram corresponding to the dotted line position in the projection picture of the weld seam after OCT scanning is marked with the number 3 From the comparison of the left and right images in Figure 3, it can be found that after adding the adaptive optics module in this paper, the tomographic image is clearer, and the welded metal surface is sharper; the weld seam projection is clearer, and the weld seam outline is more prominent. The invention of the adaptive optics module effectively improves the lateral resolution and axial resolution of the OCT image in the application scenarios of laser welding with different focusing field lenses, especially under the long focal length field lens, and the effect is remarkable.

Claims (7)

1. A laser welding device integrating self-adaptive OCT, is characterized in that, comprises OCT imaging module (1), adaptive optics module (2), vision imaging module (3), laser welding module (4) and optical coupling module (5); the sample arm beam emitted from the OCT imaging module (1) is incident on the surface of the sample to be welded (6) after passing through the adaptive optics module (2), the optical coupling module (5) and the laser welding module (4) in sequence, The light beam of the sample arm returns to the OCT imaging module (1) along the original optical path after being reflected on the surface of the sample to be welded (6) for OCT scanning imaging; the visual imaging beam emitted by the visual imaging module (3) passes through the optical coupling module (5) and After the laser welding module (4) is incident on the surface of the sample to be welded (6), the visual imaging beam is reflected on the surface of the sample to be welded (6) and returns to the visual imaging module (3) along the original optical path for visual imaging; The adaptive optics module (2) includes a beam expander structure using double lenses or multiple lenses. 2. The laser welding device integrating adaptive OCT according to claim 1, characterized in that: the adaptive optics module (2) includes a focusing lens (201) and an electronically controlled adaptive optics lens (202); The light beam of the sample arm emitted from the OCT imaging module (1) is incident on the optical coupling module (5) after sequentially passing through the focusing lens (201) and the electronically controlled adaptive optics lens (202) along the optical axis. 3. The laser welding device integrating adaptive OCT according to claim 1, characterized in that: the laser welding module (4) includes a laser light source (401), a dichroic mirror (402), a laser welding vibrator mirror (403) and laser welding field mirror (404); The light beam emitted from the optical coupling module (5) enters the dichroic mirror (402), passes through the dichroic mirror (402), and then enters the laser welding galvanometer (403), and passes through the laser welding galvanometer (403). After reflection, it is incident on the laser welding field mirror (404), and then converged to the surface of the sample to be welded (6) after being transmitted by the laser welding field mirror (404); the laser light from the laser light source (401) is incident on the dichroic mirror (402), After being reflected by the dichroic mirror (402), it is incident on the laser welding galvanometer (403), after being reflected by the laser welding galvanometer (403), it is transmitted by the laser welding field lens (404) and then incident on the sample to be welded (6). The surface is also welded on the surface of the sample to be welded (6), and the adjustment of the laser welding galvanometer (403) changes the welding position of the sample to be welded (6). 4. A laser welding device integrating adaptive OCT according to claim 1, characterized in that: the OCT imaging module (1) includes a broadband light source (101), a fiber coupler (102), a polarization controller (103), reference arm collimator (104), reference arm focusing lens (105), reference arm mirror (106), sample arm collimator (107), OCT scanning device (108), spectrometer collimator ( 109), spectrometer reflective grating (110), spectrometer focusing lens (111) and spectrometer camera (112); The first branch end on one side of the fiber coupler (102) is connected to the broadband light source (101), and the second branch end on the side of the fiber coupler (102) passes through the spectrometer collimator (109) and the spectrometer reflection grating (110) in sequence. ) and the spectrometer focusing lens (111) are connected to the spectrometer camera (112), and the first branch end on the other side of the fiber coupler (102) passes through the polarization controller (103), the reference arm collimator (104) and the reference The arm focusing lens (105) is connected to the reference arm reflector (106), and the second branch end on the other side of the fiber coupler (102) is connected to the OCT scanning device (108) after passing through the sample arm collimator (107). The OCT scanning device (108) is connected to the adaptive optics module (2). 5. A laser welding device integrating adaptive OCT according to claim 4, characterized in that: the OCT scanning device (108) is a galvanometer vibrating mirror. 6. A kind of laser welding device integrating self-adaptive OCT according to claim 1, is characterized in that: what described OCT imaging module (1) adopts is one of the following methods: Time-domain OCT imaging method through mechanical scanning and changing the optical path of the reference arm; Or a spectrometer OCT imaging method that records spectral interference signals through a spectrometer; Or a frequency-sweeping OCT imaging method that uses a frequency-sweeping light source to line-scan and record spectral interference signals. 7. The laser welding device integrating adaptive OCT according to claim 1, characterized in that: the visual imaging module (3) is a visual imaging camera (301).

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