Laser three-dimensional automatic focus following scanning processing optical system

Abstract

The invention relates to a laser three-dimensional automatic focus following scanning machining optical system which comprises a machining unit, a signal detection unit and a control unit, the signal detection unit and the control unit are connected, the machining unit comprises a laser, a lens module and a machining platform, the machining platform is used for bearing a workpiece, and the lens module comprises a dynamic focus lens set. Laser emitted by the laser can be forwardly emitted to a workpiece through the lens module; reflected light on the surface of the workpiece can reversely enter the signal detection unit through the lens module, the signal detection unit is used for transmitting collected reflected light information to the control unit, and the control unit regulates and controls the position of the dynamic focus lens set according to the reflected light information. Reflected light of laser on the surface of a workpiece serves as a feedback signal, the signal detection unit collects information of the reflected light, real-time feedback of defocusing information in the laser scanning machining process can be obtained, the signal detection unit transmits the information of the reflected light to the control unit, and the control unit regulates and controls the position of the dynamic focusing lens set according to the information of the reflected light. And laser automatic focus following is realized.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular to a laser three-dimensional automatic focus scanning processing optical system. Background Art

[0002] At present, laser processing systems are widely used in the semiconductor and microelectronics industries, automobile industry, shipbuilding industry, aerospace industry and other fields. Since lasers are focused for cutting, welding, drilling and other processing, the relative position of the laser beam focus and the surface of the workpiece being processed is also extremely important. Conventional laser focusing methods mainly include manual focusing, infrared camera method, pinhole scanning method, etc. Among them, manual focusing is the most commonly used, usually using conductive glass. However, the existing methods cannot achieve automatic focus, resulting in low processing efficiency. Summary of the invention

[0003] Based on this, it is necessary to provide a laser three-dimensional automatic focus scanning processing optical system to address the problem of automatic focus in the laser processing process.

[0004] A laser three-dimensional automatic focus scanning processing optical system, the laser three-dimensional automatic focus scanning processing optical system comprising:

[0005] A processing unit, comprising a laser, a lens module and a processing platform, wherein the processing platform is used to carry a workpiece, the lens module comprises a dynamic focusing lens group, and the laser emitted by the laser can be forwardly projected toward the workpiece through the lens module;

[0006] A signal detection unit and a control unit are communicatively connected, wherein the reflected light from the workpiece surface can be incident upon the signal detection unit through the lens module in the reverse direction, and the signal detection unit is used to transmit the collected reflected light information to the control unit, and the control unit adjusts the position of the dynamic focusing lens group according to the reflected light information.

[0007] In one embodiment, the lens module includes a polarization beam splitter prism, a quarter wave plate and a scanning lens; the laser light emitted by the laser can pass through the polarization beam splitter prism, the quarter wave plate, the dynamic focusing lens group, and the scanning lens in sequence to be emitted toward the workpiece; the reflected light can pass through the scanning lens, the dynamic focusing lens group, the quarter wave plate and the polarization beam splitter prism in sequence to be emitted into the signal detection unit.

[0008] In one embodiment, the dynamic focusing lens group includes a negative lens and a positive lens, and the laser energy emitted by the quarter-wave plate can be sequentially passed through the negative lens and the positive lens before being emitted into the scanning lens;

[0009] The laser three-dimensional automatic focus scanning processing optical system also includes a position adjustment unit connected to the control unit, and the position adjustment unit is connected to the negative lens to adjust the relative position of the negative lens and the positive lens.

[0010] In one of the embodiments, the position adjustment unit includes a driving source and a linear guide rail connected to each other, the linear guide rail is connected to the negative lens, and the moving direction of the linear guide rail is parallel to the optical axis.

[0011] In one embodiment, the focal length ratio of the negative lens to the positive lens is 1:3.

[0012] In one of the embodiments, when the linear guide rail drives the negative lens to move, the focus of the laser changes within a range of 0-10 microns.

[0013] In one embodiment, the processing unit further includes a scanning galvanometer group, the scanning galvanometer group includes a first blade and a first driving member connected to each other, and a second blade and a second driving member connected to each other, and the laser emitted by the dynamic focusing lens group passes through the first blade and the second blade in sequence and then enters the scanning lens;

[0014] The first driving member can drive the first blade to rotate around a first direction, and the second driving member can drive the second blade to rotate around a second direction, wherein the first direction is perpendicular to the second direction.

[0015] In one embodiment, the processing unit further includes a beam expander lens group, and the laser light emitted by the laser enters the polarization beam splitter prism after passing through the beam expander lens group.

[0016] In one embodiment, the signal detection unit includes a plurality of detectors, and the positions of the conjugate points of the plurality of detectors cover above, at and below the focus of the laser.

[0017] In one embodiment, the detector comprises an optical fiber head, and the optical fiber core diameter of the optical fiber head is within 1-10 microns.

[0018] The above-mentioned laser three-dimensional automatic focus scanning processing optical system sets the workpiece on the processing platform, and the laser emitted by the laser of the processing unit is forwardly directed to the workpiece through the lens module, so as to perform laser processing on the workpiece. By setting up a signal detection unit and a control unit, the reflected light of the laser on the surface of the workpiece can be reversely directed to the signal detection unit through the lens module. The reflected light of the laser on the surface of the workpiece is used as a feedback signal. The signal detection unit collects the reflected light information and can obtain real-time feedback of the defocus information of the laser scanning processing process. The signal detection unit transmits the reflected light information to the control unit, and the control unit adjusts the position of the dynamic focusing lens group according to the reflected light information to realize automatic laser focus. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic diagram of the structure of a laser three-dimensional automatic focus scanning processing optical system provided in an embodiment of the present application.

[0020] FIG. 2 is a schematic diagram of the structure of a polarization beam splitter prism and a quarter wave plate provided in an embodiment of the present application.

[0021] FIG. 3 is a schematic diagram of the structure of a dynamic focusing lens assembly provided in an embodiment of the present application.

[0022] FIG. 4 is a schematic structural diagram of a scanning galvanometer group and a scanning lens provided in an embodiment of the present application.

[0023] In the figure:

[0024] 100. Laser;

[0025] 200, polarization beam splitter prism;

[0026] 300, quarter wave plate;

[0027] 400, dynamic focusing lens group; 410, negative lens; 420, positive lens;

[0028] 500, scanning galvanometer group; 510, first blade; 520, first driving member; 530, second blade; 540, second driving member; 550, housing;

[0029] 600, scanning lens;

[0030] 700, processing platform;

[0031] 800, detection unit; 810, detector;

[0032] 900. Control unit; 910. Linear guide. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0034] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0035] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0037] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0038] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0039] Laser processing is one of the most promising areas for laser application. At present, more than 20 laser processing technologies have been developed at home and abroad, and some technologies are relatively mature. In modern industrial processing, the processing surface of the workpiece has gradually developed from a two-dimensional plane to a three-dimensional curved surface. The traditional two-dimensional galvanometer system can no longer meet the demand, and an efficient and high-precision three-dimensional galvanometer system is urgently needed. The traditional two-dimensional galvanometer system adopts a rear focusing method, which can achieve the minimum focal plane focus point, but cannot control the focal plane change well. Dynamic focusing technology changes the focusing method to front focusing, adds a group of movable lens groups in front of the galvanometer to change the focal plane of the optical path, and realizes a three-dimensional galvanometer system.

[0040] The existing three-dimensional surface laser processing methods mainly include:

[0041] (1) Two-dimensional galvanometer and multi-axis worktable linkage: This method has high requirements on the curvature continuity of the workpiece surface, poor precision, and requires the workpiece to be moved continuously, resulting in low processing efficiency.

[0042] (2) Manually adjust the focal plane of the dynamic focusing galvanometer, and the system provides zoom compensation: This method does not require the workpiece to be moved, which improves work efficiency, but has high requirements on the workpiece surface and can only provide plane processing.

[0043] (3) Using an automatically controlled dynamic focusing galvanometer and projection algorithm to calculate the processing trajectory: This significantly improves the processing speed and does not place high demands on the workpiece surface, allowing processing of most curved surfaces. However, for curved surfaces with high curvature changes or surfaces with discontinuous curvature, large distortion will occur, resulting in poor processing uniformity and severe deformation of the processed pattern.

[0044] In order to solve the above technical problems, the present application provides a laser three-dimensional automatic focus scanning processing optical system, as shown in Figures 1 to 4, the laser three-dimensional automatic focus scanning processing optical system includes a processing unit, a connected signal detection unit 800 and a control unit 900, the processing unit includes a laser 100, a lens module and a processing platform 700, the processing platform 700 is used to carry a workpiece, the lens module includes a dynamic focusing lens group 7400, the laser emitted by the laser 100 can pass through the lens module to shoot forward to the workpiece; the reflected light on the surface of the workpiece can pass through the lens module in the reverse direction to shoot into the signal detection unit 800, the signal detection unit 800 is used to transmit the collected reflected light information to the control unit 900, and the control unit 900 adjusts the position of the dynamic focusing lens group 400 according to the reflected light information.

[0045] In the above-mentioned laser three-dimensional automatic focus scanning processing optical system, the workpiece is set on the processing platform 700, and the laser emitted by the laser 100 of the processing unit is forwardly directed to the workpiece through the lens module, so as to perform laser processing on the workpiece. By setting up a signal detection unit 800 and a control unit 900, the reflected light of the laser on the surface of the workpiece can be directed to the signal detection unit 800 through the reverse radial lens module. The reflected light of the laser on the surface of the workpiece is used as a feedback signal. The signal detection unit 800 collects the reflected light information and can obtain real-time feedback of the defocus information during the laser scanning processing process. The signal detection unit 800 transmits the reflected light information, that is, the real-time feedback information, to the control unit 900. The control unit 900 adjusts the position of the dynamic focusing lens group 400 according to the reflected light information to realize the automatic focus of the laser.

[0046] Specifically, the lens module includes a polarization beam splitter prism 200, a quarter wave plate 300, and a scanning lens 600; the laser emitted by the laser 100 can sequentially pass through the polarization beam splitter prism 200, the quarter wave plate 300, the dynamic focusing lens group 400, and the scanning lens 600 to be emitted to the workpiece; the reflected light can sequentially pass through the scanning lens 600, the dynamic focusing lens group 400, the quarter wave plate 300, and the polarization beam splitter prism 200 to enter the signal detection unit 800. In the above-mentioned laser three-dimensional automatic focus scanning processing optical system, the workpiece is set on the processing platform 700, and the laser emitted by the laser 100 of the processing unit passes through the polarization beam splitter prism 200, the quarter wave plate 300, the dynamic focusing lens group 400, and the scanning lens 600 to be emitted to the workpiece, thereby performing laser processing on the workpiece. The reflected light of the laser projected on the surface of the workpiece can sequentially pass through the scanning lens 600, the dynamic focusing lens group 400, the quarter wave plate 300, and the polarization beam splitter prism 200 and then be reversely emitted to the signal detection unit 800.

[0047] Specifically, the processing unit further includes a beam expander lens group, and the laser light emitted by the laser 100 enters the polarization beam splitter prism 200 after passing through the beam expander lens group. By arranging the beam expander lens group between the laser 100 and the polarization beam splitter prism 200, the laser light emitted by the laser 100 enters the polarization beam splitter prism 200 after passing through the beam expander lens group, thereby changing the diameter and divergence angle of the laser beam to meet the requirements of the laser light entering the polarization beam splitter prism 200.

[0048] Specifically, the polarization beam splitter prism 200 is coated with a polarization film, which can selectively transmit or reflect laser light of a specific polarization state. The quarter wave plate 300 can change the polarization state of the laser light. The cooperation of the two allows the laser light emitted by the laser 100 to be transmitted through the polarization beam splitter prism 200, while the reflected light returning along the original optical path will be reflected and separated by the polarization beam splitter and directed to the signal detection unit 800 for easy detection and processing.

[0049] In order to more clearly illustrate the role of the polarization beam splitter prism 200 and the quarter wave plate 300, the following is analyzed in combination with the propagation direction of the light. As shown in FIG2 , the laser is incident on the polarization beam splitter prism 200 perpendicular to the optical axis. Under the action of the multi-layer polarization medium film on the hypotenuse of the polarization beam splitter prism 200, the horizontally polarized p light is transmitted, and the vertically polarized s light is reflected along the oblique surface of the prism (here, since the polarization ratio of the laser 100 is very high, it can be considered as horizontally linear polarized p light, so there is no reflected s light when it passes through the polarization beam splitter prism 200 for the first time). The laser emitted by the laser 100 The reflected light passes through the polarization beam splitter prism 200 and is directed to the quarter wave plate 300, and the reflected light reflected from the surface of the workpiece passes through the quarter wave plate 300 and is directed to the polarization beam splitter prism 200. In this process, the horizontally polarized light and the vertically polarized light produce a phase difference of Π / 2, and the originally horizontally polarized light p light is converted into vertically polarized light s light, and after passing through the polarization beam splitter prism 200 again, it is completely reflected and emitted in a direction perpendicular to the incident light, so that the reflected light is directed to the signal detection unit 800, thereby realizing the separation of the feedback light signal, which is convenient for subsequent collection and processing.

[0050] More specifically, the quarter wave plate 300 and the polarization beam splitter prism 200 are both placed perpendicular to the optical axis of the laser light emitted by the laser 100 .

[0051] Further, as shown in FIG. 1 and FIG. 3 , the dynamic focusing lens group 400 includes a negative lens 410 and a positive lens 420, and the laser energy emitted by the quarter wave plate 300 passes through the negative lens 410 and the positive lens 420 in sequence and then enters the scanning lens 600; the laser three-dimensional automatic focus scanning processing optical system also includes a position adjustment unit connected to the control unit 900, and the position adjustment unit is connected to the negative lens 410 to adjust the relative position of the negative lens 410 and the positive lens 420. The dynamic focusing lens group 400 composed of the negative lens 410 and the positive lens 420 connects the position adjustment unit to the negative lens 410, and the position of the negative lens 410 is adjusted by the position adjustment unit, thereby adjusting the back focal length of the laser.

[0052] Specifically, as shown in FIG. 1 and FIG. 3 , the position adjustment unit includes a connected driving source and a linear guide 910, the linear guide 910 is connected to the negative lens 410, and the moving direction of the linear guide 910 is parallel to the optical axis. The dynamic focusing lens group 400 composed of the negative lens 410 and the positive lens 420, the position of the positive lens 420 is fixed, and the negative lens 410 is located on the linear guide 910 and can move forward and backward along the optical axis. According to the imaging law of the lens, when the negative lens 410 moves toward the direction close to the positive lens 420, the focus of the dynamic focusing lens group 400 will move in the direction away from the positive lens 420. The relationship between the lens group distance change Δz and the focus change ΔS is related to the selected lens focal length and distance. As long as these two factors are reasonably controlled, the moving range of the focus can be changed. Without changing the lens, the back focal length of the laser can be adjusted by changing the lens group spacing, and the flexibility of laser focus adjustment is very good, which provides a large degree of freedom for the system.

[0053] More specifically, the lens group distance change amount Δz and the focus change amount ΔS are positively correlated.

[0054] More specifically, the driving source of the position adjustment unit is a voice coil motor. The moving direction of the linear guide 910 is parallel to the optical axis, and the negative lens 410 is always coaxial with the optical axis during the movement. When the negative lens 410 is located at the center of the travel range, the laser emitted from the positive lens 420 is parallel light.

[0055] Furthermore, the focal length, position and distance between the negative lens 410 and the positive lens 420 are variable, and the selection of the focal length, position and distance of the lenses must meet the following requirements: 1. A sufficiently large beam expansion ratio to ensure a smaller focused spot during processing; 2. When the negative lens 410 moves on the linear guide rail 910, the range of change of the laser focus must be large enough to meet the needs of actual three-dimensional processing.

[0056] Specifically, the focal length ratio of the negative lens 410 to the positive lens 420 is 1: 3. By limiting the focal length ratio of the negative lens 410 to the positive lens 420, a larger beam expansion ratio is obtained.

[0057] Specifically, when the linear guide rail 910 drives the negative lens 410 to move, the focus of the laser changes within a range of 0-10 microns. By limiting the maximum beam expansion of the negative lens 410 and the positive lens 420, the focus change range of the laser is also limited.

[0058] Furthermore, as shown in Figures 1 and 4, the processing unit also includes a scanning galvanometer group 500, which includes a first blade 510 and a first driving member 520 connected to each other, and a second blade 530 and a second driving member 540 connected to each other. The laser emitted by the dynamic focusing lens group 400 passes through the first blade 510 and the second blade 530 in sequence and then enters the scanning lens 600; the first driving member 520 can drive the first blade 510 to rotate around a first direction, and the second driving member 540 can drive the second blade 530 to rotate around a second direction, wherein the first direction is perpendicular to the second direction.

[0059] By setting the scanning galvanometer group 500, the laser emitted by the laser 100 passes through the polarization beam splitter prism 200, the quarter wave plate 300, the dynamic focusing lens group 400, the first blade 510, the second blade 530, and the scanning lens 600 in sequence and is directed to the workpiece, thereby laser processing the workpiece. The reflected light passes through the scanning lens 600, the second blade 530, the first blade 510, the dynamic focusing lens group 400, the quarter wave plate 300, and the polarization beam splitter prism 200 in sequence and then is directed back into the signal detection unit 800. The first blade 510 is connected to the first driving member 520, and the first driving member 520 drives the first blade 510 to rotate around the first direction, and the second blade 530 is connected to the second driving member 540, and the second driving member 540 drives the second blade 530 to rotate around the second direction, thereby controlling the deflection of the laser beam in the plane composed of the first direction and the second direction.

[0060] Specifically, the first driving member 520 and the second driving member 540 are both polarization motors.

[0061] Specifically, as shown in FIG. 1 and FIG. 4 , the scanning galvanometer group 500 includes a housing 550, and the first blade 510, the first driving member 520, the second blade 530 and the second driving member 540 are all arranged in the housing 550. The housing 550 is provided with an opening for laser injection, and the opening matches the spot of the laser emitted by the dynamic focusing lens group 400. The housing 550 is provided to accommodate the first blade 510, the first driving member 520, the second blade 530 and the second driving member 540. The housing 550 is provided with an opening, and the opening matches the spot of the laser emitted by the dynamic focusing lens group 400, so that the laser emitted by the dynamic focusing lens group 400 can be injected into the first blade 510 in the housing 550.

[0062] More specifically, as shown in FIG. 4 , the first blade 510 is connected to the first driving member 520 , and the second blade 530 is connected to the second driving member 540 , which control the movement of the laser in the plane formed by the first direction and the second direction. The scanning lens 600 is used to flatten the field, eliminate distortion, etc.

[0063] More specifically, the scanning lens 600 is a field lens.

[0064] Furthermore, as shown in FIG. 1 , the signal detection unit 800 includes a plurality of detectors 810. In the present application, the detectors use a method of spatial light coupling to an optical fiber to receive feedback light. The core diameter of the optical fiber is small enough so that only light within a very short focusing range in space can be coupled into the optical fiber and detected, thereby achieving a very high longitudinal resolution.

[0065] Specifically, the detector 810 includes an optical fiber head, and the optical fiber core diameter of the optical fiber head is within 1-10 microns. The optical fiber core diameter is within 1-10 microns, so as to couple into a light spot within 10 microns.

[0066] Specifically, as shown in FIG1 , the positions of the conjugate points of the multiple detectors 810 cover above, at, and below the laser focus. A plurality of detectors 810 are provided, and the positions of the conjugate points of the multiple detectors 810 cover above, at, and below the laser focus. The core diameter of the optical fiber of the detector 810 is small enough so that only light within a very short focusing range can be coupled into the optical fiber and detected, thereby achieving a very high longitudinal resolution. When the laser is defocused on the surface of the workpiece being processed, several groups of detectors 810 can reflect the defocus state of the laser and serve as feedback, so that the control unit 900 controls the movement distance of the negative lens 410.

[0067] Furthermore, the voice coil motor of the position adjustment unit and the multiple detectors 810 of the signal detection unit 800 are connected to the computer through the control card and controlled by the computer control unit 900. The reflected light returned from the workpiece surface according to the original optical path is divided into several groups of optical fiber heads with different focusing states coupled into the detectors 810, and the laser defocus state is determined according to the light intensity signals of the multiple groups of detectors 810. At the same time, the negative lens 410 is controlled to move along the optical axis to change the focal length, so that the laser focus moves toward the workpiece surface. The processing surface is always kept within the focal depth range through the dynamic adjustment of the position of the negative lens 410, thereby realizing the surface processing of three-dimensional objects, which can greatly improve the processing efficiency of three-dimensional workpieces.

[0068] In summary, the laser three-dimensional automatic focus scanning processing optical system of the present application includes a processing unit, a signal detection unit 800, a control unit 900 and a position adjustment unit. The processing unit includes a laser 100, a polarization beam splitter prism 200, a quarter wave plate 300, a dynamic focusing lens group 400, a scanning galvanometer group 500, a scanning lens 600 and a processing platform 700. The polarization beam splitter prism 200, the quarter wave plate 300 and the dynamic focusing lens group 400 are placed in sequence in front of the laser head of the laser 100 and are coaxially arranged with the laser head of the laser 100. The linear guide rail 910 of the position adjustment unit and the signal detection unit 800 are electrically connected to the control unit 900. The laser beam emitted from the laser 100 is focused on the surface of the workpiece through the polarization beam splitter prism 200, the quarter wave plate 300, the dynamic focusing lens group 400, the scanning galvanometer group 500, and the scanning lens 600. The reflected light on the surface of the workpiece returns along the original optical path, and passes through the scanning lens 600, the scanning galvanometer group 500, the dynamic focusing lens group 400, the quarter wave plate 300, and the polarization beam splitter prism 200. When the reflected light passes through the polarization beam splitter prism 200, the polarization direction is perpendicular to the original direction. After passing through the polarization beam splitter prism 200, it will be reflected and separated, and then coupled into several groups and received by the detector 810. The collected data is fed back to the control unit 900 by the detector 810. The control unit 900 determines the laser defocus state after analysis and processing, and dynamically adjusts the position of the negative lens 410 to achieve automatic focus tracking.

[0069] The present application can detect the reflected light of the laser on the surface of the workpiece during the laser processing, convert the optical signal into an electrical signal and send it to the control unit of the computer for processing and analysis. After determining the defocus information, the control unit 900 drives the linear guide 910 to move through the voice coil motor, thereby driving the negative lens 410 to move. In the process of movement, the signal is still detected, and the position of the negative lens 410 is dynamically adjusted according to the feedback to keep the workpiece within the focal depth range of the laser, thereby achieving real-time focusing of the laser on the surface of the three-dimensional workpiece and improving the processing efficiency of the three-dimensional workpiece. By improving the dynamic focusing lens group 400 and other components in the optical system, the dynamic focus range of the optical system can be changed to meet the application requirements of different occasions.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A laser three-dimensional automatic focus scanning processing optical system, It is characterized in that The laser three-dimensional automatic focus scanning processing optical system comprises: A processing unit, comprising a laser (100), a lens module and a processing platform (700), wherein the processing platform (700) is used to carry a workpiece, the lens module comprises a dynamic focusing lens group (400), and the laser light emitted by the laser (100) can be emitted forwardly toward the workpiece through the lens module; A signal detection unit (800) and a control unit (900) are communicatively connected, wherein the reflected light from the workpiece surface can be incident into the signal detection unit (800) in the reverse direction through the lens module, the signal detection unit (800) is used to transmit the collected reflected light information to the control unit (900), and the control unit (900) adjusts the position of the dynamic focusing lens group (400) according to the reflected light information.

2. The laser three-dimensional automatic focus scanning processing optical system according to claim 1, It is characterized in that The lens module comprises a polarization beam splitter prism (200), a quarter wave plate (300) and a scanning lens (600); the laser light emitted by the laser (100) can sequentially pass through the polarization beam splitter prism (200), the quarter wave plate (300), the dynamic focusing lens group (400) and the scanning lens (600) to be emitted toward the workpiece; and the reflected light can sequentially pass through the scanning lens (600), the dynamic focusing lens group (400), the quarter wave plate (300) and the polarization beam splitter prism (200) to be emitted into the signal detection unit (800).

3. The laser three-dimensional automatic focus scanning processing optical system according to claim 2, It is characterized in that The dynamic focusing lens group (400) comprises a negative lens (410) and a positive lens (420), and the laser energy emitted by the quarter wave plate (300) passes through the negative lens (410) and the positive lens (420) in sequence and then enters the scanning lens (600); The laser three-dimensional automatic focus scanning processing optical system also includes a position adjustment unit connected to the control unit (900), and the position adjustment unit is connected to the negative lens (410) to adjust the relative position of the negative lens (410) and the positive lens (420).

4. The laser three-dimensional automatic focus scanning processing optical system according to claim 3, It is characterized in that The position adjustment unit comprises a driving source and a linear guide rail (910) connected to each other, the linear guide rail (910) is connected to the negative lens (410), and the moving direction of the linear guide rail (910) is parallel to the optical axis.

5. The laser three-dimensional automatic focus scanning processing optical system according to claim 4, It is characterized in that The focal length ratio of the negative lens (410) to the positive lens (420) is 1:

3.

6. The laser three-dimensional automatic focus scanning processing optical system according to claim 4, It is characterized in that When the linear guide rail (910) drives the negative lens (410) to move, the focus of the laser changes within a range of 0-10 microns.

7. The laser three-dimensional automatic focus scanning processing optical system according to claim 2, It is characterized in that The processing unit further comprises a scanning galvanometer group (500), the scanning galvanometer group (500) comprising a first blade (510) and a first driving member (520) connected to each other, and a second blade (530) and a second driving member (540) connected to each other, and the laser emitted by the dynamic focusing lens group (400) passes through the first blade (510) and the second blade (530) in sequence and then enters the scanning lens (600); The first driving member (520) is capable of driving the first blade (510) to rotate around a first direction, and the second driving member (540) is capable of driving the second blade (530) to rotate around a second direction, wherein the first direction and the second direction are perpendicular.

8. The laser three-dimensional automatic focus scanning processing optical system according to claim 2, It is characterized in that The processing unit also includes a beam expander group, and the laser light emitted by the laser (100) passes through the beam expander group and then enters the polarization beam splitter prism (200).

9. The laser three-dimensional automatic focus scanning processing optical system according to claim 1, It is characterized in that The signal detection unit (800) comprises a plurality of detectors (810), and the positions of the conjugate points of the plurality of detectors (810) cover above, at and below the focus of the laser.

10. The laser three-dimensional automatic focus scanning processing optical system according to claim 9, It is characterized in that The detector (810) comprises an optical fiber head, and the optical fiber core diameter of the optical fiber head is within 1-10 microns.

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