A real-time detection system for laser melting depth based on high-speed and high-precision motor with automatic optical path compensation

Abstract

The invention discloses a real-time detection system for laser penetration depth with automatic optical path compensation based on a high-speed and high-precision motor, which belongs to the technical field of laser welding detection and is characterized in that: a reference light passes through a collimator to collimate divergent light into parallel light, which is synthesized by a beam combiner and enters an automatic adjustment module for a reflector, and the distance or angle of the reflector is calculated and solved by obtaining a galvanometer scanning angle and a welding deflection position of a sample arm, so as to realize automatic adjustment of the distance or angle of the reflector, and keep the optical path difference between the reference light and the detection light less than 12 cm; the reference light in the reference arm and the detection light in the sample arm are reflected and returned to an interferometer to generate interference, and the signal is received by a photoelectric detector, and an imaging image is obtained by analysis; since the distance or angle adjustment of the reflector in the reference arm is increased, the optical path difference between the reference light and the detection light is kept less than a preset value, and the detection accuracy and precision are very high, so various requirements for real-time detection of laser penetration depth are met, and the quality of laser welding is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding detection, and relates to a laser welding depth real-time detection system, in particular to a laser welding depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation. Background Art

[0002] In laser welding, keyholes appear during the vaporization of the welded metal, and the instability of the keyholes can lead to internal voids and high weld porosity, which in turn leads to welding failure. Therefore, online monitoring of the penetration depth of laser welding is becoming increasingly important.

[0003] At present, the real-time detection system mainly adopts the laser welding penetration monitoring method based on optical coherence imaging (OCT). A near-infrared laser is introduced as the detection light source during the laser welding process, and it is divided into two beams by a spectroscope. The reference light enters the reference arm and is reflected back to the interferometer by the reflector. It interferes with the detection light also reflected back to the interferometer in the interferometer. The power spectrum density of the interference signal is processed by OCT through inverse Fourier transform to obtain the phase difference between the two beams of light, and then the keyhole depth is solved. Chinese Patent Publication No. CN112247382A "Laser welding penetration information monitoring system and method based on optical weak coherence imaging" provides a laser welding penetration information monitoring system based on optical weak coherence imaging. The detection light source emits detection light and transmits it to the optical fiber circulator and outputs it from its port. After being input into the optical fiber coupler, it is divided into two beams, which are used as detection light and reference light respectively. We can see that the technical solution still uses a conventional fixed and non-adjustable reference arm. However, during the welding process of the welding head, if there is no deflection amplitude, the reference light and the test light The optical path difference is stable in a certain range, and the interference signal is stable and accurate. During the welding process of the galvanometer system, the galvanometer welding system welds within the full-width area of ​​the field mirror. Since the galvanometer welding system has a large scanning area and a large deflection angle, the detection light follows the scanning of the galvanometer welding system. The variation amplitude of the optical path difference of the detection light increases, while the deflection position of the reference light is limited, resulting in an increase in the optical path difference between the reference light and the detection light, thereby causing the accuracy and sensitivity of the monitoring system to decrease. The smaller the optical path difference between the reference light and the detection light, the higher the accuracy. When the optical path difference between the reference light and the detection light is greater than 12 cm, the system accuracy drops sharply. Summary of the invention

[0004] The purpose of the present invention is to invent a real-time laser penetration detection system based on a high-speed and high-precision motor with automatic optical path compensation. A low-power near-infrared laser is introduced as a detection light source during laser welding, and enters the reference arm and the sample arm respectively through a spectroscope. The detection light in the sample arm is adjusted by a galvanometer, and is highly coaxial with the processing laser through optical path coupling, and acts on the welded material at the same time, directly hitting the bottom of the keyhole. The reference light in the reference arm is adjusted by automatic optical path compensation to reduce the optical path difference between the reference light and the detection light, and to achieve real-time optical path compensation to ensure that a larger-scale accurate value of penetration is obtained. The specific implementation plan is:

[0005] A real-time detection system for laser penetration depth based on a high-speed and high-precision motor with automatic optical path compensation is characterized in that: a tunable narrow-band laser is used as a detection light source, and the light is split by a spectroscope and enters a sample arm and a reference arm respectively. The light in the reference arm is called reference light, and the light in the sample arm is called detection light; the sample arm includes a detection light collimation module, a detection light galvanometer adjustment module, and a detection light reflector adjustment module. The detection light passes through the detection light collimation module to collimate the detection light from divergent light to parallel light, and the detection light galvanometer adjustment module and the reflector adjustment module adjust the parallel light and then enter the beam combiner. The beam combiner synthesizes the detection light reflection and the transmitted welding laser into one optical path and adjusts it to be coaxial. The detection light is focused by a focusing mirror and then Then it is reflected on the keyhole and surface of the product through the protective mirror and returned along the original optical path; the reference arm includes a reference light lens, a reference light beam combining mirror and a reference light reflector automatic adjustment module; the reference light passes through the lens to collimate the divergent light into parallel light, which is synthesized by the beam combining mirror and enters the reference light reflector automatic adjustment module; by obtaining the galvanometer scanning angle and welding deflection position of the sample arm, the distance or angle of the reflector is calculated and solved, and the distance or angle of the reflector is automatically adjusted to keep the optical path difference between the reference light and the detection light less than a preset value; the reference light in the reference arm and the detection light in the sample arm are reflected and returned to the interferometer to generate interference, and the signal is received by the photoelectric detector, and the imaging image is obtained by analysis.

[0006] The welding laser is output from the laser output head, and becomes parallel light after being collimated by the collimator. After the parallel light is transmitted through the beam combiner, the welding laser is focused by the focusing lens, and then hits the product through the protective lens to form a keyhole.

[0007] The detection light collimation module is composed of an optical fiber holder, a sleeve, a pressure ring, a lens sleeve, and a collimating lens. The sleeve has a stepped hole. The external thread of the optical fiber holder cooperates with the internal thread of the front end of the sleeve and is fixed at the front end of the sleeve through a threaded connection. The external thread of the lens sleeve cooperates with the internal thread of the rear end of the sleeve and is fixed at the rear end of the sleeve through a threaded connection. The external thread of the pressure ring cooperates with the internal thread of the lens sleeve. The collimating lens is installed in the lens sleeve and is tightened by the pressure ring.

[0008] The detection light galvanometer adjustment module includes an X-axis rotating galvanometer and a Y-axis rotating galvanometer driven by a high-speed and high-precision motor. The detection light reaches the Y-axis rotating galvanometer along the X-axis, is deflected, reaches the X-axis rotating galvanometer along the Z-axis, is deflected, and is output along the Y-axis to the reflector of the reference light reflector automatic adjustment module.

[0009] The detection light reflector adjustment module is composed of a reflector, a base, a mirror seat, a mirror cover, an axial adjustment screw, a pin and a radial adjustment screw. The mirror seat is a stepped shaft, the front end surface of the small shaft of the stepped shaft is an inclined surface, the inclined surface is preferably 45 degrees, a certain width of incision is cut at the step, and a plane notch is symmetrically opened on the circular surface of the large shaft of the stepped shaft. The mirror seat is placed in the base, and the reflector is fixedly installed on the inclined surface at the front end of the mirror seat. Through holes in the X and Y directions are opened on the base corresponding to the optical path of the reflector. The mirror cover is installed at the rear end of the mirror seat, and the screw The nail is fixed on the base, and the pin is fixed to the mirror seat by the pin through the opening of the mirror seat cutout. The axial adjustment screw is threadedly connected to the mirror seat. The front end face of the axial adjustment screw presses against the rear end face of the pin, and the outer end of the axial adjustment screw extends to the outside of the mirror cover. When the axial adjustment screw is rotated, the pin is pushed forward to enlarge the mirror seat cutout and adjust the pitch angle of the reflector. The radial adjustment screws on both sides are threadedly connected to the mirror cover and pass through the mirror cover to press against the plane notch. Rotating the radial adjustment screw makes the mirror seat rotate and adjusts the deflection of the reflector.

[0010] The beam combiner or the welding laser reflection and the detection light transmission are combined into one optical path and adjusted to be coaxial, and then adjusted by the scanning galvanometer. The welding laser is focused by the field lens and hits the product to form a keyhole, and the detection light is focused by the field lens and hits the keyhole and surface of the product and then reflected.

[0011] The scanning galvanometer includes an X-axis scanning galvanometer and a Y-axis scanning galvanometer driven by a high-speed and high-precision motor. The welding laser and the detection light are polarized by the X-axis scanning galvanometer to the Y-axis scanning galvanometer and then enter the field mirror.

[0012] The distance adjustment of the reference light reflector automatic adjustment module of the reference arm is achieved by driving the reflector in the reflector telescopic cylinder through a linear motor.

[0013] The angle adjustment of the reference light reflector automatic adjustment module of the reference arm is achieved by driving the reflector on the reflector frame with a rotating motor.

[0014] The reference light lens of the reference arm is a plano-convex lens, a biconvex lens or a compound lens, which plays the role of collimating and focusing the reference light.

[0015] The optical path difference between the reference light and the detection light is Δl=l 2 -l 1 =λ 2 / (4δ·λ), where l 2 is the optical path length of the detection light, l1 is the optical path of the reference light, δ is the resolution of the spectrometer, and λ is the main wavelength of the detection light source; the optical path of the detection light is l 2 =2n·d 2 , where n is the refractive index, d 2 is the sample arm length; the optical path of the reference light is l 1 = l 2 -Δl=2n·d 2 -λ 2 / (4δ·λ).

[0016] The adjustment distance of the reference light reflector automatic adjustment module of the reference arm is Δh=Δx·sinθ, wherein Δx is the scanning position of the galvanometer mirror, θ is the deflection angle of the galvanometer lens when the galvanometer mirror scans, and the automatic adjustment distance of the reflector in the reference arm is Δh.

[0017] The adjustment angle of the reference light reflector automatic adjustment module of the reference arm is cosα=l 1 / d 1 , where l 1 is the reference light path length, d 1 is the length from the reference arm to the reflector, and α is the deflection angle of the reflector.

[0018] The detection light of the sample arm and the reference light of the reference arm are returned to the photodetector, which receives the interference signal in time sequence by single-point detection, performs Fourier transform on the interference signal, obtains the phase difference between the two beams of light, and then solves the keyhole depth.

[0019] The positive and beneficial effects of the present invention are as follows: the galvanometer driven by a high-speed and high-precision motor can quickly scan the keyhole and the surface, the detection light galvanometer adjustment module and the reflector adjustment mechanism work together to achieve three-dimensional adjustment, and the detection light is quickly adjusted to keep it coaxial with the welding laser, thereby improving the scanning accuracy, thereby achieving a rapid response to obtain high-precision position information; at the same time, the adjustment of the reference arm is increased to ensure that the optical path difference between the reference light of the reference arm and the detection light of the sample arm is less than a preset value, the detection accuracy and precision are very high, meeting various requirements for real-time detection of laser penetration depth, and ensuring the quality of laser welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the penetration depth detection principle of the present invention.

[0021] Figure 2 This is a schematic diagram of the optical path of the welding head in Example 1 of the present invention.

[0022] Figure 3 This is a schematic diagram of the optical path of the welding head in Example 2 of the present invention.

[0023] Figure 4 It is a schematic diagram of the cross-sectional structure of the detection light collimation module of the present invention.

[0024] Figure 5 It is a schematic diagram of the optical path of the rotating galvanometer of the present invention.

[0025] Figure 6 It is a structural schematic diagram of the detection light reflector adjustment module of the present invention.

[0026] Figure 7 Schematic diagram of the distance adjustment optical path of the reference arm reflector of the present invention.

[0027] Figure 8 Schematic diagram of the light path for adjusting the inclination angle of the reference arm reflector of the present invention.

[0028] Fig. 9 This is a schematic diagram of single-point testing penetration in an embodiment of the present invention.

[0029] Fig.10 It is a schematic diagram of the penetration of continuous welding test according to an embodiment of the present invention.

[0030] In the figure, 001, detection light, 002, photoelectric detector, 003, interferometer, 004, reference arm, 005, welding head, 1, welding laser output head, 2, welding laser collimator, 3, beam combiner, 04, focusing mirror, 05, protection mirror, 4, X-axis scanning galvanometer, 5, Y-axis scanning galvanometer, 6, field mirror, 7, detection optical fiber, 8, detection light collimator, 9, X-axis rotating galvanometer, 10, Y-axis rotating galvanometer, 11, reflector, 12, keyhole, 13, high-speed and high-precision motor, 14, detection light collimation module, 1401, sleeve, 1402, Fiber optic holder, 1403, mirror sleeve, 1404, pressure ring, 15, two-dimensional adjustment mechanism, 1501, base, 1502, mirror holder, 1502-1, incision, 1502-2, notch, 1503, mirror cover, 1504, axial adjustment screw, 1505, pin, 1506, pin, 1507, radial adjustment screw, 1601, reference light lens, 1602, first reference light reflector, 1603, second reference light reflector, 1604, third reference light reflector, 1605, fourth reference light reflector, 1606, reflection grating. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, it is a schematic diagram of the principle of penetration detection of the present invention. The detection light 001 is a tunable narrow-band laser, which is divided into two paths through a beam splitter, one path enters the reference arm 004, and the other path enters the sample arm 005 (also called a welding head). After the two paths of light are reflected, interference is generated by the interferometer 003, and finally the signal is received by the detector 002, and then the imaging image is obtained by analysis.

[0032] like Figure 2 As shown, it is a schematic diagram of the optical path of the sample arm 005 of Example 1. The welding laser output head 1 outputs the welding laser, which is collimated by the welding laser collimator 2 to become parallel light and enter the beam combiner 3. The detection optical fiber 7 outputs the detection light, which is collimated by the detection light collimator 8 from divergent light to parallel light. The detection light reaches the Y-axis rotating galvanometer 10 along the X-axis and is deflected, and then reaches the X-axis rotating galvanometer 9 along the Z-axis and is deflected, and then output to the reflector 11 along the Y-axis. The reflector 11 adjusts the detection light to enter the beam combiner 3 by the two-dimensional adjustment mechanism 15. The beam combiner 3 transmits the welding laser and reflects the detection light to combine it into an optical path, and then focuses it through the focusing mirror 04 and the protective mirror 05, and hits the welding laser on the product to form a keyhole 12. After hitting the keyhole 12 and the surface of the product, the detection light returns along the original optical path.

[0033] like Figure 3 As shown, it is a schematic diagram of the optical path of the sample arm 005 of Example 2. The welding laser output head 1 outputs the welding laser, which is collimated by the welding laser collimator 2 and becomes parallel light and enters the beam combiner 3. The parallel light passes through the beam splitter 3 and then is polarized to the Y-axis scanning galvanometer 5 by the X-axis scanning galvanometer 4 driven by the high-speed and high-precision motor 13 and then reaches the field mirror 6. The detection optical fiber 7 outputs the detection light, which passes through the detection light collimator 8 to collimate the detection light from divergent light to parallel light. The detection light reaches the Y-axis rotating galvanometer 10 along the X-axis and is deflected along the Z-axis. The axis reaches the X-axis rotating galvanometer 9, which is deflected and then output to the reflector 11 along the Y axis. The reflector 11 is adjusted by the two-dimensional adjustment mechanism 15 to enter the beam combiner 3. The beam combiner 3 reflects the welding laser and transmits the detection light to one optical path. Then, it is polarized to the Y-axis scanning galvanometer 5 by the X-axis scanning galvanometer 4 driven by the high-speed and high-precision motor 13 and reaches the field mirror 6. The field mirror 6 hits the welding laser on the product to form a keyhole 12, hits the keyhole 12 and the surface on the product, and returns along the original optical path. We can see that after the detection light is adjusted by the galvanometer scanning twice, the detection light can detect the melting depth in an oblique direction, and the detection light will not be intercepted due to the complex shape of the keyhole, resulting in measurement deviation. Therefore, the keyhole measurement produced by the inclined laser welding is more accurate.

[0034] like Figure 4 As shown, it is a schematic diagram of the cross-sectional structure of the detection light collimation module 14, the external thread of the optical fiber holder 1402 cooperates with the internal thread of the front end of the sleeve 1401, and is fixed at the front end position of the sleeve 1401 through a threaded connection, the external thread of the lens sleeve 1403 cooperates with the internal thread of the rear end of the sleeve 1401, and is fixed at the rear end position of the sleeve 1401 through a threaded connection, the external thread of the pressure ring 1404 cooperates with the internal thread of the lens sleeve 1403, the detection light collimation lens 8 is installed in the lens sleeve 1403, and is pressed by the pressure ring 1404.

[0035] like Figure 5As shown, it is a schematic diagram of the rotating galvanometer optical path. The detection light 001 reaches the Y-axis rotating galvanometer 10 driven by the high-speed and high-precision motor 13 along the X-axis, deflects along the Z-axis to the X-axis rotating galvanometer 9, deflects and is output to the reflector 11 along the Y-axis.

[0036] like Figure 6 As shown, it is a schematic diagram of the structure of the two-dimensional adjustment mechanism 15, the mirror seat 1502 is placed in the base 1501, the reflector 11 is fixedly mounted on the inclined surface at the front end of the mirror seat 1502, the mirror cover 1503 is mounted on the rear end of the mirror seat 1502, and is fixed to the base 1501 by screws, and the pin 1505 is fixed to the mirror seat 1502 by a pin 1506 through the opening of the mirror seat cutout 1502-1, and the axial adjustment screw 1504 is threadedly connected to the mirror seat 1502. The front end surface is pressed against the rear end surface of the pin shaft 1505, and the outer end of the axial adjustment screw 1504 extends to the outside of the mirror cover 1503. When the axial adjustment screw 1504 is rotated, the pin shaft 1505 is pushed forward to enlarge the mirror seat cutout 1502-1 and adjust the pitch angle of the reflector 11. The radial adjustment screw threads 1507 on both sides are connected and pass through the mirror cover 1503 to press against the plane notch 1502-2. Rotating the radial adjustment screw 1507 causes the mirror seat 1502 to rotate and adjust the deflection of the reflector 11.

[0037] like Figure 7 As shown, it is a schematic diagram of the distance adjustment optical path of the reflector in the reference arm 004. When the reference light is collimated into parallel light by the reference light lens 1601 and then passes through the reference light beam combining mirror to the right-angled first reference light reflector 1602, the reference light is reflected to the reference light lens 1601 and focused to the second reference light reflector 1603. The second reference light reflector 1603 then reflects the reference light back along the original path. The adjustment distance of the reference light of the reference arm is Δh=Δx·sinθ.

[0038] like Figure 8 As shown, it is a schematic diagram of the angle adjustment optical path of the reflector in the reference arm 004. When the collimated reference light is reflected by the reflection grating 1606, it is collimated by the reference light lens 1601 and then by the reference light beam combining mirror to the planar third reference light reflector 1604. The reference light is then reflected to the reference light lens 1601 and focused to the reflection grating 1606. The reflection grating 1606 reflects the reference light to the fourth reference light reflector 1605. The fourth reference light reflector 1605 reflects the reference light back along the original path. The adjustment angle of the reference light of the reference arm is cosα=l1 / d1.

[0039] like Fig. 9As shown, it is a schematic diagram of single-point test penetration of the embodiment. During the experiment, 1 thick stainless steel plate + 10 thin stainless steel plates are overlapped and stacked. The thickness of 1 thick stainless steel plate is 0.2mm, the thickness of a single thin stainless steel plate is 0.02mm, and the total thickness of 10 thin stainless steel plates is 0.23mm. The thickness error caused by the gap between the steel plates has been corrected. The single-point test penetration is performed 20 times, and the test data is as follows:

[0040]

[0041] like Fig.10 As shown, the actual test penetration data of continuous welding and the cross-sectional metallographic diagram of the embodiment, the error of the measured OCT penetration monitoring and the cross-sectional metallographic diagram of the welded product is less than 10%.

[0042] To sum up, after the welding head is integrated with the penetration detection module, the penetration during the welding process can be detected online in real time, and the qualification of the product welding can be quickly and accurately judged according to the detection results, which eliminates the need for manual detection of welding penetration. At the same time, the penetration data can be quickly saved for traceability, providing a basis for adjusting the welding process parameters. The optical coherence tomography technology used in this case is a non-destructive test, which greatly saves costs. The two-directional rotating galvanometer and the two-dimensional adjustment mechanism of the reflective lens in this case work together to make it easier for the detection light to find the keyhole position, thereby ensuring the measurement accuracy.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser melting depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation, characterized in that: A tunable narrow-band laser is used as the detection light source. After being split by a spectroscope, the light enters the sample arm and the reference arm respectively. The light in the reference arm is called the reference light, and the light in the sample arm is called the detection light. The sample arm includes a detection light collimation module, a detection light galvanometer adjustment module and a detection light reflector adjustment module, wherein the detection light galvanometer adjustment module includes an X-axis rotating galvanometer and a Y-axis rotating galvanometer driven by a high-speed and high-precision motor, and the detection light reflector adjustment module is composed of a reflector, a base, a mirror seat, a mirror cover, an axial adjustment screw, a pin shaft and a radial adjustment screw. The mirror seat is a stepped shaft, the front end face of the small shaft of the stepped shaft is a 45° inclined surface, a certain width of incision is cut at the step, and a plane notch is symmetrically opened on the circular surface of the large shaft of the stepped shaft, the mirror seat is placed in the base, and the reflector is fixedly mounted on the inclined surface at the front end of the mirror seat. Through holes in the X and Y directions are provided in the optical path of the corresponding reflector. The mirror cover is installed at the rear end of the mirror seat and fixed on the base by screws. The pin shaft is fixed on the mirror seat by a pin passing through the opening of the mirror seat cutout. The axial adjustment screw is threadedly connected to the mirror seat. The front end surface of the axial adjustment screw presses against the rear end surface of the pin shaft. The outer end of the axial adjustment screw extends out of the mirror cover. When the axial adjustment screw is rotated, the pin shaft is pressed forward to enlarge the cutout of the mirror seat and adjust the pitch angle of the reflector. The radial adjustment screws on both sides are threadedly connected to the mirror cover and pass through the mirror cover to press against the plane notch. The radial adjustment screws are rotated to rotate the mirror seat and adjust the deflection of the reflector. The reference arm includes a reference light collimator, a reference light beam combiner and a reference light reflector automatic adjustment module, wherein the reference light reflector of the reference arm drives the reflector in the reflector telescopic tube through a linear motor to achieve distance adjustment, and drives the reflector on the reflector frame through a rotary motor to achieve angle adjustment; The optical path of the detection light has the following two paths: The first path: The detection light passes through the detection light collimation module to collimate the detection light from divergent light to parallel light. The detection light reaches the Y-axis rotating galvanometer along the X-axis, deflects along the Z-axis, reaches the X-axis rotating galvanometer along the Y-axis, deflects, and then outputs to the reflector along the Y-axis to adjust the pitch angle and deflection before entering the beam combiner. The beam combiner combines the reflected detection light and the transmitted welding laser into one optical path and adjusts it to be coaxial. The detection light is focused by the focusing mirror, then reflected by the protective mirror on the keyhole and surface of the product, and returns along the original optical path; The second path: The detection light passes through the detection light collimation module to collimate the detection light from divergent light to parallel light. The detection light reaches the Y-axis rotating galvanometer along the X-axis, deflects, reaches the X-axis rotating galvanometer along the Z-axis, deflects, and then is output to the reflector along the Y-axis to adjust the pitch angle and deflection before entering the beam combiner. The beam combiner combines the detection light welding laser reflection and the detection light transmission into one optical path and adjusts them to be coaxial. The welding laser and the detection light are polarized to the Y-axis scanning galvanometer by the X-axis scanning galvanometer driven by a high-speed and high-precision motor and then enter the field mirror for adjustment. The welding laser is focused by the field mirror and hits the product to form a keyhole. The detection light is focused by the field mirror and hits the keyhole and surface of the product, then reflects and returns along the original optical path. The optical path of the reference light is: the reference light passes through a collimator to collimate the divergent light into parallel light, is synthesized by a beam combiner, and then is reflected by a linear motor driving a reflector in a telescopic tube of the reflector to adjust the distance and by a rotary motor driving a reflector on a reflector frame to adjust the angle. By obtaining the scanning angle of the galvanometer of the sample arm and the welding deflection position, the distance or angle of the reflector is calculated and solved, and the distance or angle of the reflector is automatically adjusted to keep the optical path difference between the reference light and the detection light less than a preset value; The reference light in the reference arm and the detection light in the sample arm are reflected and returned to the interferometer to generate interference. The photoelectric detector receives the signal and analyzes it to obtain an imaging image.

2. A laser melting depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation as claimed in claim 1, characterized in that: The welding laser is output from the laser output head, and becomes parallel light after being collimated by the collimator. After the parallel light is transmitted through the beam combiner, the welding laser is focused by the focusing lens, and then hits the product through the protective lens to form a keyhole.

3. A laser melting depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation as claimed in claim 1, characterized in that: The detection light collimation module is composed of an optical fiber holder, a sleeve, a pressure ring, a lens sleeve, and a collimating lens. The sleeve has a stepped hole. The external thread of the optical fiber holder cooperates with the internal thread of the front end of the sleeve and is fixed at the front end of the sleeve through a threaded connection. The external thread of the lens sleeve cooperates with the internal thread of the rear end of the sleeve and is fixed at the rear end of the sleeve through a threaded connection. The external thread of the pressure ring cooperates with the internal thread of the lens sleeve. The collimating lens is installed in the lens sleeve and is tightened by the pressure ring.

4. A laser melting depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation as claimed in claim 1, characterized in that: The optical path difference between the reference light and the detection light is Δl=l2-l1=λ 2 / (4δ·λ), where l2 is the optical path of the detection light, l1 is the optical path of the reference light, δ is the resolution of the spectrometer, and λ is the main wavelength of the detection light source; the optical path of the detection light is l2=2n·d2, where n is the refractive index and d2 is the length of the sample arm; the optical path of the reference light is l1=l2-Δl=2n·d2-λ 2 / (4δ·λ); the adjustment distance of the reference light reflector automatic adjustment module of the reference arm is Δh=Δx·sinθ, wherein Δx is the scanning position of the galvanometer mirror, θ is the deflection angle of the galvanometer lens when the galvanometer mirror scans, and Δh is the automatic adjustment distance of the reflector in the reference arm; the adjustment angle of the reference light reflector automatic adjustment module of the reference arm is cosα=l1 / d1, wherein l1 is the reference light optical path, d1 is the length from the reference arm to the reflector, and α is the deflection angle of the reflector.

5. A laser melting depth real-time detection system based on a high-speed and high-precision motor with automatic optical path compensation as claimed in claim 1, characterized in that: The detection light of the sample arm and the reference light of the reference arm are returned to the photodetector, which receives the interference signal in time sequence by single-point detection, performs Fourier transform on the interference signal, obtains the phase difference between the two beams of light, and then solves the keyhole depth.

Images