Light spot real-time monitoring and feedback focusing system and method for laser processing

Abstract

The invention discloses a light spot real-time monitoring and feedback focusing system and method for laser processing. The system comprises a laser processing module, an emission light source module, a power monitoring module, a light spot monitoring module and an automatic control module. The emitting light source module is used for emitting laser beams; the power monitoring module is used for monitoring the laser power emitted by the emitting light source module; the light spot monitoring module is used for monitoring light spots of diffuse reflection light after the laser is emitted to the surface of the workpiece; the automatic control module sets reference signals of the following parameters: processing laser power and shape, position and size of a processing light spot; and according to the reference signal and the corresponding feedback signal, the laser emission parameter and the laser incident workpiece surface parameter are automatically adjusted, so that the error between the reference signal and the corresponding feedback signal is within a set precision range. According to the method, the light spot form and the light intensity in the machining process are dynamically monitored, and the light spot form and the energy in the laser machining process are adjusted in real time through feedback.

Description

Technical Field

[0001] The present invention relates to the field of laser processing and optical measurement, and in particular to a light spot real-time monitoring and feedback focusing system and method for laser processing. Background Art

[0002] At present, laser processing technology has become the core means of modern manufacturing due to its high precision, high efficiency and non-contact nature, and is widely used in many fields from macro material processing to micro precision manufacturing, including but not limited to automobile manufacturing, aerospace, electronics industry, medical equipment manufacturing, etc. Especially in applications such as micro-nano processing, 3D printing and laser engraving that require extremely high processing quality, the stability of the laser spot and the uniformity of the light intensity have a direct impact on the processing effect.

[0003] At present, one of the main difficulties of laser processing is how to ensure the stability of the shape and power of the laser spot during the processing. Factors such as thermal expansion and cooling of materials, surface reflection and absorption characteristics will cause the laser focal spot to shift and the light intensity to fluctuate, thus affecting the processing accuracy and quality. For example, in laser 3D printing, the laser melts the material through high energy and builds the target structure layer by layer. If the spot size and shape are inconsistent during this process, it will lead to reduced print accuracy, increased surface roughness, and even structural defects. Similarly, in laser cutting and marking, precise control of spot size, shape and light intensity is crucial to the quality of cutting or marking. Any deformation or power fluctuation may lead to processing errors, unclear lines, uneven edges and other problems.

[0004] Although current laser processing equipment is equipped with basic monitoring devices, most of them rely on pre-set static parameters and cannot reflect changes in the dynamic processing environment in real time. Especially when processing complex or irregular surfaces, traditional monitoring technology is difficult to cope with the impact of materials and environment on the light spot morphology and light intensity. Therefore, in order to achieve real-time control of light spot and light intensity in various processing environments, an intelligent, efficient and flexible laser monitoring system is needed, which can adjust and feedback the light spot and light intensity information in real time according to different materials and processing requirements, so as to improve the accuracy and consistency of laser processing. In addition, although some advanced laser processing equipment on the market has integrated some automatic focusing functions, it still has instability in complex working environments due to the lack of real-time spot size monitoring and intelligent feedback mechanism. Therefore, in response to the needs of real-time monitoring and focusing of focal spot defocus, a more intelligent, efficient and accurate solution is urgently needed. Summary of the invention

[0005] The present invention provides a real-time monitoring and feedback focusing system and method for a spot used in laser processing in order to solve the technical problems existing in the known technology.

[0006] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is:

[0007] A spot real-time monitoring and feedback focusing system for laser processing, comprising a laser processing module, an emission light source module, a power monitoring module, a spot monitoring module and an automatic control module;

[0008] The laser processing module is used to irradiate the laser beam onto the surface of the workpiece;

[0009] The emission light source module is used for emitting a laser beam;

[0010] The power monitoring module is used to monitor the laser power emitted by the emitting light source module in real time; it includes a focusing module and an optical power meter; the optical power meter is used to measure the optical power and is provided with a photosensitive target surface; the focusing module is used to converge the light beam, and its input is the laser beam from the emitting light source module, and it converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module;

[0011] The spot monitoring module is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and includes a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and includes an image sensor and an imaging module; the image sensor is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module is used to focus the light beam, and focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor; the image processing module is used to analyze the shape, position and size of the spot image acquired by the spot monitoring module, and feeds the analysis result back to the automatic control module as a processing spot feedback signal;

[0012] The automatic control module sets the reference signals of the following parameters: processing laser power and the shape, position and size of the processing spot; and automatically adjusts the laser emission parameters and the surface parameters of the laser incident workpiece according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range.

[0013] Furthermore, it also includes an optical path guiding module; on the one hand, the optical path guiding module divides the laser light beam output by the emitting light source module into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module in the power monitoring module; on the other hand, the optical path guiding module guides the diffuse reflected light from the surface of the workpiece to the imaging module in the spot monitoring module.

[0014] Furthermore, the optical path guiding module includes a beam splitter, and the beam splitter is a non-polarization beam splitter or a polarization beam splitter.

[0015] Furthermore, the automatic control module includes a controller and a beam adjustment module; the controller inputs a processing spot feedback signal and a processing laser power feedback signal and reference signals corresponding to the two, and outputs a control signal; the beam adjustment module includes a focusing module; the focusing module is used to shape the processing laser beam, and it automatically adjusts the focal length according to the control signal.

[0016] Furthermore, the controller includes a PID controller, which inputs a reference signal and a difference between a feedback signal corresponding to each other, and outputs a control signal so that the value of the feedback signal tracks the reference signal.

[0017] Furthermore, the laser processing module includes a first galvanometer, a second galvanometer and a field mirror which are optically connected in sequence; the first galvanometer and the second galvanometer cooperate to control the movement of the processing laser beam in the X-axis and Y-axis directions of the working plane; the field mirror is used to adjust the spot size so that the laser beam incident on the workpiece surface has the same focus within the entire laser processing working plane.

[0018] The present invention also provides a method for real-time monitoring and feedback focusing of a light spot for laser processing, which includes a laser processing module, an emission light source module, a power monitoring module, a light spot monitoring module and an automatic control module;

[0019] The laser processing module is used to irradiate the laser beam onto the surface of the workpiece;

[0020] The emission light source module is used for emitting a laser beam;

[0021] The power monitoring module is used to monitor the laser power emitted by the emitting light source module in real time; it is provided with a focusing module and an optical power meter; the optical power meter is used to measure the optical power, and is provided with a photosensitive target surface; the focusing module is used to converge the light beam, so that it inputs the laser beam from the emitting light source module, and converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module;

[0022] The spot monitoring module is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and is provided with a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and is provided with an image sensor and an imaging module; the image sensor is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module is used to focus the light beam so that it focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor; the image processing module is used to analyze the shape, position and size of the spot image acquired by the spot monitoring module, so that it feeds back the analysis result as a processing spot feedback signal to the automatic control module;

[0023] The automatic control module is set with reference signals for the following parameters: processing laser power and the shape, position and size of the processing spot; and the laser emission parameters and the surface parameters of the laser incident workpiece are automatically adjusted according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range.

[0024] Furthermore, an optical path guiding module is also provided; on the one hand, the optical path guiding module divides the laser beam output by the emitting light source module into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module in the power monitoring module; on the other hand, the optical path guiding module guides the diffuse reflected light from the surface of the workpiece to the imaging module in the light spot monitoring module.

[0025] Furthermore, the image processing module uses an edge detection algorithm to extract the edge of the light spot, and determines the contour of the light spot by calculating the grayscale gradient of the image; and fits the edge of the light spot by the least square method or the RANSAC algorithm to obtain the diameter of the light spot.

[0026] Furthermore, the automatic control module is provided with a controller and a beam adjustment module; the controller adopts a PID controller, and the difference between the processing spot feedback signal and the processing laser power feedback signal and the reference signals corresponding to the two are input into the PID controller; the PID controller outputs a control signal, so that the value of the feedback signal tracks the corresponding reference signal; the beam adjustment module is provided with a focusing module; the focusing module is used to shape the processing laser beam so that it automatically adjusts the focal length according to the control signal.

[0027] The advantages and positive effects of the present invention are as follows: the present invention proposes a real-time monitoring system and focusing method for spot and power for laser processing, which dynamically monitors the spot shape and light intensity during the processing and adjusts the spot shape and energy size during the laser processing in real time through feedback. The system integrates a variety of optical elements and sensor modules, and uses optical conjugation, imaging monitoring and non-contact sensing technologies to accurately measure the size, shape and light intensity of the spot. The present invention can monitor the spot shape and light intensity changes in laser processing in real time at milliseconds or microseconds to ensure processing quality and accuracy. And by selecting a high-precision sensor to detect the processing laser power and the shape, position and size of the processing spot, these detected signals are used as feedback signals, and image processing is combined with power monitoring to provide an intelligent real-time response mechanism for the spot and power changes during the processing. In addition, the optical path structure of the present invention is simple, and compatibility with a variety of optical elements, beam splitters and sensor types is achieved, so that it can be applied to different types of laser processing equipment and material processing requirements. Its highly automated control mechanism can significantly reduce manual intervention and reduce errors and instabilities caused by human factors during the processing process. The present invention is applicable to a variety of processing equipment and application environments, and can be expanded to various scenarios such as laser 3D printing, laser welding, engraving, cutting, medical surgery, etc. through modular configuration. The present invention can not only improve processing consistency, but also significantly reduce equipment adjustment and maintenance costs, providing an efficient, stable and intelligent solution for various laser processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of one embodiment of a method for real-time monitoring and feedback focusing of a spot for laser processing of the present invention;

[0029] Figure 2 This is a flow chart of a second embodiment of a method for real-time monitoring and feedback focusing of a spot for laser processing according to the present invention;

[0030] Figure 3 It is a structural schematic diagram of one embodiment of a spot real-time monitoring and feedback focusing system for laser processing of the present invention;

[0031] Figure 4 It is a structural schematic diagram of a second embodiment of a spot real-time monitoring and feedback focusing system for laser processing of the present invention;

[0032] Figure 5 A schematic diagram of diffuse reflection light generated when light is incident on a laser processing work plane;

[0033] Figure 6 A schematic diagram of the working optical path of a power monitoring module of a spot real-time monitoring and feedback focusing system for laser processing according to the present invention;

[0034] Figure 7 A schematic diagram of the working optical path of a spot monitoring module of a spot real-time monitoring and feedback focusing system for laser processing according to the present invention;

[0035] Figure 8 Schematic diagram of the spot size under different states;

[0036] Fig. 9 A schematic diagram of the size of a light spot monitored by a light spot monitoring module when the light spot is not out of focus;

[0037] Fig.10 This is a schematic diagram of the spot size monitored by the spot monitoring module when the spot is defocused by 10mm;

[0038] Fig.11 Schematic diagram of the spot size monitored by the spot monitoring module when the spot is defocused by 20mm.

[0039] Figure 1 , 2 middle:

[0040] S11-emitting light source module; S12-light path guiding module; S13-power monitoring module; S14-laser processing module; S15-spot monitoring module; S16-beam adjustment module.

[0041] The thinner solid line represents the laser light path used for laser processing, the thicker solid line is the diffuse reflection light path after the laser beam hits the workpiece surface, and the thinner dotted line represents the electrical signal. The arrow indicates the direction of light or electrical signal transmission.

[0042] Figure 3 , 4 middle:

[0043] 301-laser; 302-laser collimator; 303-optical power meter detector; 304-focusing module; 305-beam splitter; 306-imaging module; 307-image sensor; 308-focusing module; 309-first galvanometer; 310-second galvanometer; 311-field lens; 312-laser processing work plane; 313-focusing lens group.

[0044] Figure 6 , 7 Middle: Arrows indicate the direction of light transmission. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0046] In the description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. The terms "connected" and "connection" used in the present invention should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can also be an electrical connection or signal transmission; for those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0047] The Chinese meanings of the following English words, phrases and abbreviations are as follows:

[0048] CCD image sensor: Charge coupled image sensor, also known as charge coupled photosensitive element, is a semiconductor device that can convert optical images into digital signals.

[0049] CMOS image sensor: Complementary metal oxide semiconductor image sensor is a typical solid-state imaging sensor. CMOS image sensor usually consists of image sensitive unit array, row driver, column driver, timing control logic, AD converter, data bus output interface, control interface and other parts, which are usually integrated on the same silicon chip.

[0050] Canny edge detection: It is a classic edge detection algorithm proposed by John Canny in 1986. The core idea of ​​the algorithm is to accurately detect edges in an image through multi-stage processing while minimizing false detections and missed detections. The main steps of the Canny edge detection algorithm include noise suppression, calculation of gradient magnitude and direction, non-maximum suppression, dual threshold detection, and edge connection.

[0051] RANSAC algorithm: short for random sample consensus algorithm, it is an algorithm that calculates the mathematical model parameters of data based on a set of sample data sets containing abnormal data to obtain valid sample data. RANSAC algorithm is often used in computer vision.

[0052] PID controller: The full name is Proportional-Integral-Derivative Controller, which is a control loop feedback mechanism widely used in industrial control systems and other systems that require continuous modulation control. The PID controller achieves precise and timely control by continuously calculating the error value, that is, the difference between the desired set point and the measured process variable, and applying corrections based on the proportional (P), integral (I) and derivative (D) terms.

[0053] See also Figures 1 to 11 A spot real-time monitoring and feedback focusing system for laser processing includes a laser processing module S14, a light source module S11, a power monitoring module S13, a spot monitoring module S15 and an automatic control module.

[0054] The laser processing module S14 is used to irradiate the laser beam to the surface of the workpiece. The laser processing module S14 has different optical path settings according to different application scenarios; when used for scanning laser processing, the laser emitted by the emitting light source module S11 is output to the working surface through the galvanometer system and the field lens 311 in sequence. The galvanometer system and the field lens 311 ensure that the laser spot is accurately positioned on the processing object to achieve high-precision laser processing operations. When used for ordinary laser processing without scanning, the laser emitted by the emitting light source module S11 can be output to the laser processing work plane 312 through the focusing lens group 313.

[0055] The emission light source module S11 is used to emit laser beams; the emission light source module S11 is the core component of the laser processing light source, and can emit continuous laser or pulsed laser to meet different processing requirements. The laser emission module can achieve compatibility and applicability of different materials and process requirements by setting functions such as power output control and pulse frequency adjustment. For example, for application scenarios with high surface hardness of materials, the system can output high-power pulsed lasers; in scenarios with high precision requirements such as micro-machining and surface treatment, low-power stable output can be used to ensure delicate and stable processing effects.

[0056] The power monitoring module S13 is used to monitor the laser power emitted by the emitting light source module S11 in real time; it includes a focusing module 304 and an optical power meter; the optical power meter is used to measure the light power, and it is provided with a photosensitive target surface; the focusing module 304 is used to converge the light beam, and its input is the laser beam from the emitting light source module S11, and it converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module.

[0057] The power monitoring module S13 uses a highly sensitive optical power meter that can capture millisecond or microsecond power changes to ensure that the processing power is always within a stable range. Regardless of whether the laser power fluctuates due to environmental factors or equipment stability, the power monitoring module S13 can effectively sense the power changes to avoid processing errors caused by unstable power.

[0058] The spot monitoring module S15 is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and includes a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and includes an image sensor 307 and an imaging module 306; the image sensor 307 is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module 306 is used to focus the light beam, and focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor 307; the image processing module is used to perform shape, position and size analysis on the spot image acquired by the spot monitoring module S15, and feeds back the analysis result to the automatic control module as a processing spot feedback signal.

[0059] The light spot monitoring module S15 uses the optical conjugation principle to accurately project the shape and size of the processing light spot onto the photosensitive surface of the image sensor 307 through the imaging module 306. By collecting the shape, size and position of the light spot in real time, the changes of the light spot during the processing can be monitored. Through the image processing algorithm, the system can detect slight changes in the light spot, such as shape deformation, size fluctuation, etc., effectively ensuring that the light spot meets the processing requirements, thereby improving the processing accuracy.

[0060] The image processing module can use various existing image processing algorithms to analyze the spot image collected in real time and extract key parameters such as spot shape, position, area, etc. The image processing module can also adaptively adjust the detection parameters to meet the processing requirements of different materials or surface characteristics, thereby improving the flexibility and adaptability of the system.

[0061] Preferably, the image sensor 307 can be a CCD or CMOS image sensor, and the imaging module 306 is used to focus the light collected in the system to form a clear image. Specifically, the imaging module 306 refracts the light to focus the light diffusely reflected from the laser-processed working plane onto the photosensitive target surface of the CCD or CMOS image sensor. The CCD or CMOS image sensor can convert the optical signal into an electrical signal and generate a digital image signal to identify the focal spot morphology of the working plane.

[0062] The automatic control module sets the reference signals of the following parameters: processing laser power and the shape, position and size of the processing spot; and automatically adjusts the laser emission parameters and the surface parameters of the laser incident workpiece according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range. The automatic control module compares the feedback signal with the reference signal, and promptly identifies and records the state changes of the spot.

[0063] Preferably, it may also include an optical path guiding module S12; on the one hand, the optical path guiding module S12 divides the laser beam output by the emitting light source module S11 into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module 304 in the power monitoring module S13; on the other hand, the optical path guiding module S12 guides the diffuse reflected light from the workpiece surface to the imaging module 306 in the spot monitoring module S15.

[0064] Preferably, the optical path guiding module S12 may include a beam splitter 305, which may be a non-polarizing beam splitter or a polarizing beam splitter. The beam splitter 305 may be of various types, such as a non-polarizing beam splitter, a polarizing beam splitter, etc., so as to adapt to different laser light intensity conditions.

[0065] When the beam splitter 305 splits the laser beam output by the emission light source module S11 into two paths, the energy splitting ratios of the two beams are different. A beam splitter with a fixed splitting ratio can be selected, such as a flat plate or cubic prism type non-polarizing beam splitter, and a beam splitter with a larger energy splitting ratio value, such as 99:1 or 99.9:1, can be selected. The energy splitting ratio is 99:1, that is, 99% of the energy of the laser beam output by the emission light source module S11 is allocated to the optical path output to the surface of the workpiece to be processed; 1% of the energy is allocated to the optical path output to the power monitoring module S13. This can reduce the loss of energy after splitting.

[0066] Preferably, the automatic control module may include a controller and a beam adjustment module S16; the controller inputs a processing spot feedback signal and a processing laser power feedback signal and a reference signal corresponding to the two, and outputs a control signal; the beam adjustment module S16 may include a focusing module 308; the focusing module 308 may be used to shape the processing laser beam, and it may automatically adjust the focal length according to the control signal. The diffuse reflected light from the processing workpiece is reflected to the spot image acquisition module, and the spot image is analyzed in real time by the image processing module to calculate the degree of focus defocus. Finally, the automatic control module outputs a control signal to control the focusing module 308 to perform dynamic adjustment to ensure that the laser focus is always within the optimal working range.

[0067] Preferably, the controller may include a PID controller, which inputs a reference signal and a difference between the feedback signal and the reference signal corresponding to each other, and outputs a control signal so that the value of the feedback signal tracks the reference signal.

[0068] Preferably, the laser processing module S14 may include a first galvanometer 309, a second galvanometer 310 and a field lens 311 connected in sequence by optical paths; the first galvanometer 309 and the second galvanometer 310 cooperate to form a galvanometer system for controlling the movement of the processing laser beam in the X-axis and Y-axis directions of the working plane to achieve accurate marking of the material surface. The field lens 311 can be used to adjust the spot size so that the laser beam incident on the workpiece surface has the same focus within the entire laser processing working plane.

[0069] Specifically, the first galvanometer 309 and the second galvanometer 310 both include a servo motor and a reflector driven by the servo motor. The servo motor of the first galvanometer 309 is used to control the movement of the laser beam in the X-axis direction, and the servo motor of the second galvanometer 310 is used to control the movement of the laser beam in the Y-axis direction. The first galvanometer 309 and the second galvanometer 310 drive their respective reflectors to swing through the rapid rotation of their respective servo motors, so that the laser beam moves precisely in the X-axis and Y-axis directions to form the desired pattern or text.

[0070] The first galvanometer 309 and the second galvanometer 310 cooperate to form a pair of return mirrors. The automatic control module can output signals to control the operation of the servo motor. The encoder of the servo motor itself is used as a position sensor. It can be combined with the position feedback signal of the processing light spot fed back by the light spot monitoring module S15 to form a closed-loop control system, which can improve the scanning speed and repeated positioning accuracy of the laser processing module S14.

[0071] The field lens 311 ensures uniform focus and consistency in the entire laser processing working plane by correcting the beam path, thereby improving processing accuracy and efficiency.

[0072] Preferably, the laser processing module S14 may include a focusing lens group 313, and the focusing lens group 313 is used to converge the collimated light source to the laser processing format.

[0073] The present invention also provides a method for real-time monitoring and feedback focusing of a light spot for laser processing, which includes a laser processing module S14, an emission light source module S11, a power monitoring module S13, a light spot monitoring module S15 and an automatic control module;

[0074] The laser processing module S14 is used to irradiate the laser beam onto the surface of the workpiece;

[0075] The emission light source module S11 is used to emit laser beams; this module is the core component of the laser processing light source and can emit continuous laser or pulsed laser to meet different processing requirements. The laser emission module can achieve compatibility and applicability of different materials and process requirements by setting functions such as power output control and pulse frequency adjustment. For example, for application scenarios with high surface hardness of materials, the system can output high-power pulsed lasers; in scenarios with high precision requirements such as micro-machining and surface treatment, low-power stable output can be used to ensure delicate and stable processing effects.

[0076] The power monitoring module S13 is used to monitor the laser power emitted by the emitting light source module S11 in real time; it is provided with a focusing module 304 and an optical power meter; the optical power meter is used to measure the optical power, and is provided with a photosensitive target surface; the focusing module 304 is used to converge the light beam, so that it inputs the laser beam from the emitting light source module S11, so that it converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module;

[0077] The spot monitoring module S15 is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and is provided with a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and is provided with an image sensor 307 and an imaging module 306; the image sensor 307 is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module 306 is used to focus the light beam so that it focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor 307; the image processing module is used to analyze the shape, position and size of the spot image acquired by the spot monitoring module S15, so that it feeds back the analysis result as a processing spot feedback signal to the automatic control module;

[0078] The automatic control module is set with reference signals for the following parameters: processing laser power and the shape, position and size of the processing spot; and the laser emission parameters and the surface parameters of the laser incident workpiece are automatically adjusted according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range.

[0079] This method can monitor the defocus of the focal spot in real time during the processing, and automatically adjust the internal optical path of the laser according to the actual defocus amount, so that the defocus size of the focal spot is always controlled within the set range, thereby improving the quality and accuracy of laser processing.

[0080] Preferably, a light path guiding module S12 may also be provided; on the one hand, the light path guiding module S12 may divide the laser beam output by the emitting light source module S11 into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module 304 in the power monitoring module S13; on the other hand, the light path guiding module S12 may guide the diffuse reflected light from the surface of the workpiece to the imaging module 306 in the light spot monitoring module S15.

[0081] A stable collimated light beam is emitted by the emitting light source module S11, and after passing through the light path guiding module S12, one path is output to the surface of the workpiece to be processed; the other path is output to the focusing module 304 in the power monitoring module S13. The power monitoring module S13 monitors the stability of the reflected light, and the automatic control module includes a controller and a beam adjustment module S16; the light path guiding module S12 may include a beam splitter 305: the beam splitter 305 transmits a part of the stable collimated light beam emitted by the emitting light source module S11; and reflects a part. When the transmitted light is incident on the surface of the workpiece to be processed, the generated diffuse reflected light will be transmitted back to the beam splitter 305 through the laser processing module S14 and the beam adjustment module S16. At this time, after the diffuse reflected light is reflected and guided by the beam splitter 305, the reflected light enters the spot image acquisition module. The spot image signal is collected by the spot image acquisition module, and the spot image acquisition module outputs the spot image signal to the image processing module. The image processing module analyzes the spot image of the diffusely reflected light to determine the size of the focal spot defocus, which is then fed back to the feedback focusing module through the automatic control module to monitor and adjust the focal spot size of the laser processing plane in real time to improve the quality of laser processing.

[0082] Preferably, the image processing module can use an edge detection algorithm to extract the edge of the light spot, and determine the contour of the light spot by calculating the grayscale gradient of the image; the light spot edge can be fitted by the least squares method or the RANSAC algorithm to obtain the diameter of the light spot.

[0083] Preferably, the automatic control module can be provided with a controller and a beam adjustment module S16; the controller can adopt a PID controller, and the difference between the processing spot feedback signal and the processing laser power feedback signal and the reference signals corresponding to the two can be input into the PID controller; the PID controller can output a control signal, so that the value of the feedback signal tracks the corresponding reference signal; the beam adjustment module S16 can be provided with a focusing module 308; the focusing module 308 can be used to shape the processing laser beam so that it can automatically adjust the focal length according to the control signal.

[0084] The structure, working optical path and working principle of the present invention are further explained below with reference to several preferred embodiments of the present invention:

[0085] Please refer to Figure 1 , 3The present invention provides an embodiment of a spot real-time monitoring and feedback focusing system for laser processing, which is a scanning laser processing system, and its structure and working principle are as follows:

[0086] A spot real-time monitoring and feedback focusing system for laser processing includes an emission light source module S11, an optical path guiding module S12, a power monitoring module S13, a spot monitoring module S15, an automatic control module and a laser processing module S14.

[0087] The laser processing module S14 is used to irradiate the laser beam onto the surface of the workpiece; the laser processing module S14 includes a first galvanometer 309, a second galvanometer 310 and a field lens 311 which are optically connected in sequence; the first galvanometer 309 and the second galvanometer 310 cooperate to control the movement of the processing laser beam in the X-axis and Y-axis directions of the working plane; the field lens 311 can be used to adjust the spot size so that the laser beam incident on the surface of the workpiece has the same focus within the entire laser processing working plane.

[0088] The emission light source module S11 is used to emit a laser beam; it includes a laser 301 and a laser collimator 302 connected in sequence. The laser 301 and the laser collimator 302 together constitute the emission light source module S11, which is used to emit collimated light in the laser processing process and is used as a light source for power monitoring and focus monitoring.

[0089] It includes an optical path guiding module S12; the optical path guiding module S12 includes a beam splitter 305; on the one hand, the optical path guiding module S12 divides the laser beam output by the emitting light source module S11 into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module 304 in the power monitoring module S13; on the other hand, the optical path guiding module S12 guides the diffuse reflected light from the surface of the workpiece to the imaging module 306 in the spot monitoring module S15.

[0090] The power monitoring module S13 is used to monitor the laser power emitted by the emitting light source module S11 in real time; it includes a focusing module 304 and an optical power meter; the optical power meter is used to measure the light power, and it is provided with a photosensitive target surface; the focusing module 304 is used to converge the light beam, and its input is the laser beam from the emitting light source module S11, and it converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module.

[0091] In this way, the intensity and stability of the light source are monitored in real time by the optical power meter; the light is focused onto the photosensitive target surface of the optical power meter detector 303 by the focusing module 304 .

[0092] The spot monitoring module S15 is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and includes a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and includes an image sensor 307 and an imaging module 306; the image sensor 307 is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module 306 is used to focus the light beam, and focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor 307; the image processing module is used to perform shape, position and size analysis on the spot image acquired by the spot monitoring module S15, and feeds back the analysis result to the automatic control module as a processing spot feedback signal.

[0093] The automatic control module sets the reference signals of the following parameters: processing laser power and the shape, position and size of the processing spot; and automatically adjusts the laser emission parameters and the surface parameters of the laser incident workpiece according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range. The automatic control module includes a controller and a beam adjustment module S16; the controller inputs the processing spot feedback signal and the processing laser power feedback signal and the reference signals corresponding to the two, and outputs a control signal; the beam adjustment module S16 includes a focusing module 308; the focusing module 308 is used to shape the processing laser beam, and it automatically adjusts the focal length according to the control signal.

[0094] The light beam output by the laser 301 is collimated by the laser collimator 302 and then output to the beam splitter 305. The beam splitter 305 performs light splitting, with the purpose of dividing the original collimated light beam into two directions, one is reflected light and the other is transmitted light. The reflected light enters the power monitoring module S13, and the transmitted light is used for the laser processing module S14. The power monitoring module S13 can monitor the power stability of the laser to ensure that the output power is within the set range. In the actual laser processing process, the stability of the power is directly related to the quality and accuracy of the processing. If the power fluctuates, it may lead to a decrease in the processing quality or even damage the processing material. Therefore, the power monitoring module S13 monitors the reflected light and promptly feeds back to the system for necessary adjustments to ensure that the output power of the laser 301 is always kept within the set range, thereby improving the qualification rate and consistency of the processed products.

[0095] The beam adjustment module S16 performs dynamic adjustment according to the feedback signal of the spot image shape, position and size of the spot monitoring module S15. The role of the focusing module 308 in the beam adjustment module S16 is particularly important because the focal length of the laser processing plays a decisive role in the final processing effect. If the focal length is inaccurate, the spot may be defocused, resulting in the inability of the laser energy to be accurately focused on the surface of the material, thereby affecting the processing depth, width, and cutting or marking effect of the material. Through the dynamic adjustment of the focusing module 308, it can be ensured that the spot is always in the optimal focal length position, thereby achieving high-quality laser processing effects. Defocus here means that the focus is not accurately focused on the workpiece processing surface, causing the spot to diverge and become larger, thereby affecting the laser processing accuracy.

[0096] In the spot monitoring module S15, a high-precision imaging module 306 and a CCD or CMOS image sensor are used to determine the defocus size of the focal spot by analyzing the spot image of the diffusely reflected light. The data collected by the image sensor 307 is processed by an internal algorithm to calculate the defocus degree of the laser focal spot in real time, and is fed back to the focusing module 308 through an automatic control system.

[0097] like Figure 5 Specifically, the spot monitoring module S15 captures the spot image of diffuse reflected light generated by the laser on the surface of the processed material through the imaging module 306. Diffuse reflected light refers to the reflected light that is scattered in multiple directions when the light beam is irradiated on a rough surface due to the complexity and microscopic irregularities of the surface structure.

[0098] The diffuse reflected light generated by the laser on the surface of the processed material is incident on the photosensitive target surface of the image sensor 307 via the laser processing module S14, the beam adjustment module S16, the light path guide module S12, and the imaging module 306.

[0099] This diffuse reflected light can help the system better determine the specific position and size of the laser focal spot. The CCD or CMOS image sensor converts these spot images into digital signals and transmits them to the system for algorithm analysis and processing. These algorithms can accurately calculate the degree of deviation of the laser focal spot relative to the set focal length based on the shape and position of the spot image. This step is very important because it directly determines the working mode of the subsequent focusing module 308. Through the calculated defocus amount, the system can determine whether the focal spot is in the correct position within milliseconds or microseconds. If defocus is detected, the automatic control module will immediately send a control signal to the focusing module 308 based on the feedback signal. The focusing module 308 dynamically adjusts the position and size of the laser focal spot based on the control signal of the automatic control module to ensure that the spot always remains within the set focal length range, thereby improving the quality and accuracy of laser processing. The laser focal spot refers to the smallest spot area formed on the target surface after the laser beam is focused by the optical focusing system. The laser focal spot usually has the highest energy density and is used for material effects in the laser processing process, such as cutting, welding or marking.

[0100] When the focal spot is out of focus, the size of the spot will change, usually manifested as an increase in the diameter of the spot. The degree of defocus can be quantified by the change in the size of the spot. The image processing module accurately calculates the degree of deviation of the spot by extracting the edge of the spot image and calculating the spot diameter. The image processing module uses an edge detection algorithm (such as Canny edge detection) to extract the edge of the spot and determines the contour of the spot by calculating the grayscale gradient of the image. In the defocused state, the diameter of the spot will increase. The system fits the edge of the spot using the least squares method or the RANSAC algorithm to obtain the diameter of the spot. The defocus amount usually indicates the degree of deviation of the laser focal spot from the focal spot at the ideal focal position.

[0101] The calculation formula of defocus amount Δf is as follows:

[0102]

[0103] Among them, D 实际 is the spot diameter obtained after image processing module processing, D 理论 The ideal spot diameter calculated based on the optical design of the laser system. The percentage of defocus reflects the deviation between the spot and the ideal focus. This calculation method can accurately quantify the degree of defocus and provide the necessary reference data for subsequent focusing.

[0104] Once the defocus amount is calculated, the image processing module transmits the calculated feedback data to the automatic control module. The automatic control module outputs a control signal to the focusing module 308 according to the feedback signal and the reference signal. The focusing module 308 adjusts the focal length of the optical system according to the control signal to ensure that the laser spot is at the optimal focal length position. The adjustment process of the focusing module 308 adopts a feedback control algorithm, such as PID control, i.e., a proportional-integral-differential control method. The automatic control module adopts a PID controller to dynamically adjust the focal length according to the change in the defocus amount to maintain the optimal shape of the spot. The focusing module 308 adjusts the optical path through precise optical elements (such as a focusing lens group) so that the focus is accurately aligned to the processing surface. When the system detects defocus, the focusing module 308 can respond quickly and eliminate the deviation by dynamically adjusting the focal length to ensure that the focus is always on the surface of the processed workpiece. Through continuous image acquisition and real-time image processing, the system can respond to the offset of the focus in a short time. When the focal spot deviates from the ideal position, the system can adjust it in milliseconds. The spot monitoring module S15 and the image processing module monitor the change of the spot size in real time, and feed back the detected defocus amount to the automatic control module to form a closed-loop control to ensure that the focus during the laser processing process always remains at the set position.

[0105] The automatic control module can adapt to different processing environments and material characteristics to ensure real-time control of the laser focus during processing. This real-time monitoring and feedback closed-loop focusing control method greatly improves the accuracy and quality of laser processing.

[0106] Please refer to Figure 2 , 4 Another embodiment of the spot real-time monitoring and feedback focusing system for laser processing provided by the present invention is Figure 1 , 3 Compared with the embodiment shown in the figure, the difference is that the optical path structure of the laser processing module S14 is different:

[0107] The laser processing module S14 includes a focusing lens group 313, which is used to focus the collimated light source onto the laser processing area. In this embodiment, the spot position output by the laser module cannot move on the processing plane. If the processing position needs to be moved, the workpiece needs to be moved, such as the workbench moving in the X and Y axis directions of the processing plane.

[0108] The optical path transmission of this embodiment is as follows Figure 6 As shown, the light source module S11 emits collimated light, and after passing through the beam splitter 305, the reflected light is transmitted to the power monitoring module S13 for real-time monitoring of the output stability and specific intensity of the laser 301. The transmitted light is transmitted to the working plane through the laser processing module S14 to perform laser processing on the workpiece; Figure 7As shown, the diffuse reflection light on the surface of the workpiece is transmitted back to the beam splitter 305 through the laser processing module S14, and then received by the spot image acquisition module, and the spot analysis is performed by the image processing module. The spot monitoring module S15 receives the diffuse reflection light of the laser processing work plane, and dynamically monitors the position of the laser focal spot in real time to ensure that the laser focal spot is always kept within the optimal focal length range during the processing, thereby greatly improving the processing quality and accuracy. The whole process is highly automated, precise and intelligent, providing solid technical support for the efficiency and stability of laser processing.

[0109] like Figure 8 , 9 As shown in Figures 10 and 11, when defocus occurs during laser processing, the shape of the light spot at the working plane will change, and the degree of defocus is received and analyzed by the light spot monitoring module S15 and the image processing module, and finally the light spot of the working plane is maintained within a certain size range through the feedback focusing module to achieve high-quality laser processing.

[0110] The above-mentioned emitting light source module S11, optical path guiding module S12, power monitoring module S13, laser processing module S14, spot monitoring module S15, beam adjustment module S16, laser 301, laser collimator 302, optical power meter detector 303, focusing module 304, beam splitter 305, imaging module 306, CCD or CMOS image sensor, focusing module 308, first galvanometer 309, second galvanometer 310, field lens 311, laser processing working plane 312, and focusing lens group 313 can all adopt applicable elements, components and modules in the prior art, or adopt elements, components and modules in the prior art and construct them by conventional technical means.

[0111] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A spot real-time monitoring and feedback focusing system for laser processing, comprising a laser processing module, characterized in that: It also includes an emission light source module, a power monitoring module, a light spot monitoring module and an automatic control module; The laser processing module is used to irradiate the laser beam onto the surface of the workpiece; The emission light source module is used for emitting a laser beam; The power monitoring module is used to monitor the laser power emitted by the light source module in real time; it includes a focusing module and an optical power meter; the optical power meter is used to measure the optical power and is provided with a photosensitive target surface; The focusing module is used to converge the light beam. Its input is the laser beam from the emitting light source module. It converges the input laser beam onto the photosensitive target surface of the optical power meter. The optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module. The spot monitoring module is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and includes a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and includes an image sensor and an imaging module; the image sensor is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module is used to focus the light beam, and focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor; the image processing module is used to analyze the shape, position and size of the spot image acquired by the spot monitoring module, and feeds the analysis result back to the automatic control module as a processing spot feedback signal; The automatic control module sets the reference signals of the following parameters: processing laser power and the shape, position and size of the processing spot; and automatically adjusts the laser emission parameters and the surface parameters of the laser incident workpiece according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range.

2. The spot real-time monitoring and feedback focusing system for laser processing according to claim 1 is characterized in that: It also includes an optical path guiding module; on the one hand, the optical path guiding module divides the laser beam output by the emitting light source module into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module in the power monitoring module; on the other hand, the optical path guiding module guides the diffuse reflected light from the surface of the workpiece to the imaging module in the spot monitoring module.

3. The spot real-time monitoring and feedback focusing system for laser processing according to claim 2 is characterized in that: The optical path guiding module comprises a beam splitter, and the beam splitter is a non-polarization beam splitter or a polarization beam splitter.

4. The spot real-time monitoring and feedback focusing system for laser processing according to claim 1, characterized in that: The automatic control module includes a controller and a beam adjustment module; the controller inputs a processing spot feedback signal and a processing laser power feedback signal and reference signals corresponding to the two, and outputs a control signal; the beam adjustment module includes a focusing module; the focusing module is used to shape the processing laser beam, and it automatically adjusts the focal length according to the control signal.

5. The spot real-time monitoring and feedback focusing system for laser processing according to claim 4 is characterized in that: The controller includes a PID controller, which inputs a reference signal and a difference between a feedback signal corresponding to each other, and outputs a control signal to make the value of the feedback signal track the reference signal.

6. The spot real-time monitoring and feedback focusing system for laser processing according to claim 1, characterized in that: The laser processing module includes a first galvanometer, a second galvanometer and a field mirror which are optically connected in sequence; the first galvanometer and the second galvanometer cooperate to control the movement of the processing laser beam in the X-axis and Y-axis directions of the working plane; the field mirror is used to adjust the spot size so that the laser beam incident on the workpiece surface has the same focus within the entire laser processing working plane.

7. A method for real-time monitoring and feedback focusing of a spot for laser processing, wherein a laser processing module is provided, characterized in that: A transmitting light source module, a power monitoring module, a light spot monitoring module and an automatic control module are also provided; The laser processing module is used to irradiate the laser beam onto the surface of the workpiece; The emission light source module is used for emitting a laser beam; The power monitoring module is used to monitor the laser power emitted by the emitting light source module in real time; it is provided with a focusing module and an optical power meter; the optical power meter is used to measure the optical power, and is provided with a photosensitive target surface; the focusing module is used to converge the light beam, so that it inputs the laser beam from the emitting light source module, and converges the input laser beam onto the photosensitive target surface of the optical power meter; the optical power meter feeds back the detected laser power as a processing laser power feedback signal to the automatic control module; The spot monitoring module is used to monitor the spot of diffusely reflected light generated after the laser beam is irradiated onto the surface of the workpiece, and is provided with a spot image acquisition module and an image processing module; the spot image acquisition module is used to acquire the spot image of diffusely reflected light on the surface of the workpiece, and is provided with an image sensor and an imaging module; the image sensor is used to convert the light signal into an electrical signal and generate a digital image signal, and is provided with a photosensitive target surface; the imaging module is used to focus the light beam so that it focuses the diffusely reflected light from the surface of the workpiece onto the photosensitive target surface of the image sensor; the image processing module is used to analyze the shape, position and size of the spot image acquired by the spot monitoring module, so that it feeds back the analysis result as a processing spot feedback signal to the automatic control module; The automatic control module is set with reference signals for the following parameters: processing laser power and the shape, position and size of the processing spot; and the laser emission parameters and the surface parameters of the laser incident workpiece are automatically adjusted according to the reference signal and the corresponding feedback signal, so that the error between the reference signal and the corresponding feedback signal is within the set accuracy range.

8. The method for real-time monitoring and feedback focusing of a spot for laser processing according to claim 7, characterized in that: A light path guiding module is also provided; on the one hand, the light path guiding module divides the laser light beam output by the emitting light source module into two paths; one path is output to the surface of the workpiece to be processed; and the other path is output to the focusing module in the power monitoring module; on the other hand, the light path guiding module guides the diffuse reflected light from the surface of the workpiece to the imaging module in the light spot monitoring module.

9. The method for real-time monitoring and feedback focusing of a spot for laser processing according to claim 7, characterized in that: The image processing module uses an edge detection algorithm to extract the edge of the light spot, and determines the contour of the light spot by calculating the gray gradient of the image; the edge of the light spot is fitted by the least square method or the RANSAC algorithm to obtain the diameter of the light spot.

10. The method for real-time monitoring and feedback focusing of a spot for laser processing according to claim 7, characterized in that: The automatic control module is provided with a controller and a beam adjustment module; the controller adopts a PID controller, and the difference between the processing spot feedback signal and the processing laser power feedback signal and the reference signals corresponding to the two are input into the PID controller; the PID controller is provided with a control signal so that the value of the feedback signal tracks the corresponding reference signal; the beam adjustment module is provided with a focusing module; The focusing module is used to shape the processing laser beam so that it can automatically adjust the focal length according to the control signal.

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