Accurate control method for water-jet guided laser optical path

Abstract

The invention belongs to the technical field of water-jet guided laser processing, and relates to a water-jet guided laser optical path accurate control method which comprises a laser generator, an optical focusing system, a water-jet guided system, an optical detection system and a control system. The method comprises the following steps: 1, controlling an optical focusing system; 2, controlling a water guide system; 3, controlling an optical detection system; 4, designing a control system; 5, after the water-jet guided laser debugging process is completed, product machining is conducted; by accurately controlling the optical path of the water-guided laser, the laser beam can be focused to a smaller area, the machining precision is improved, and the machining precision can be improved to the submicron level; therefore, the control precision of the water-guided laser optical path is higher, the machining time can be shortened, the machining efficiency is improved, and thermal damage in the machining process is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water-guided laser processing and relates to a precise control method of a water-guided laser optical path. Background Art

[0002] Water-guided laser technology is a new type of laser processing technology that uses water as a transmission medium to transmit the laser to the processing area. Water-guided laser technology has the advantages of high processing accuracy, small heat-affected zone, and no dust pollution. It has broad application prospects in micro-processing, medical and other fields. In some specific application scenarios, such as micro-processing and high-precision cutting, the optical path of the laser needs to be precisely controlled to improve processing accuracy and quality. Traditional laser optical path control methods mainly use optical components such as reflectors and lenses for adjustment.

[0003] However, existing laser optical path control methods have problems such as low precision, poor stability, and limited adjustment range. In addition, existing methods are difficult to achieve effective optical path control in some complex processing environments, such as underwater, high temperature, and high pressure. This limits the application of water-guided lasers in the field of high-precision processing.

[0004] Therefore, a method for accurately controlling the optical path of a water-guided laser is needed to solve the above technical problems. Summary of the invention

[0005] The present invention adopts a precise control method of the water-guided laser optical path, performs real-time monitoring of the optical focusing system, feeds back information to the control system for adjustment, and adjusts the parameters of the optical focusing system and the water-guided system according to the feedback information to achieve precise control of the optical path. This will overcome the problem that the optical focusing system cannot change with changes in processing requirements in actual applications.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for accurately controlling the optical path of a water-guided laser, comprising: a laser generator, the laser generator is used to generate a laser beam; an optical focusing system, the optical focusing system is used to focus the laser beam to a water-guided laser processing area; a water guide system, the water guide system is used to transmit the laser beam and cool the processing area, the water guide system includes a water nozzle and a water cavity; an optical detection system, the optical detection system is used to detect the optical path of the laser beam and the state of the processing area; a control system, the control system controls the optical focusing system and the water guide system according to feedback information from the optical detection system to achieve accurate control of the optical path; the method for accurately controlling the optical path of the water-guided laser comprises the following steps:

[0007] Step S1, optical focusing system control;

[0008] Adaptive optical technology is used to adjust the position and angle of the lens and reflector in the optical focusing system in real time according to the wavefront distortion of the laser beam to eliminate the wavefront distortion and improve the focusing accuracy of the laser beam. A high-precision motor drive system is used to achieve fine-tuning of the lens and reflector to improve the adjustment accuracy and stability. A mathematical model of the optical focusing system is established, and the parameters of the optical focusing system are optimized through numerical calculation and simulation analysis to improve the focusing effect.

[0009] Step S2, controlling the water guide system;

[0010] Control the shape and size of the water nozzle to optimize the transmission efficiency and stability of the laser beam in the water; adjust the water flow speed and pressure in the water chamber to control the transmission direction and focus position of the laser beam; use ultrasonic technology to stir and vibrate the water in the water chamber to improve the uniformity and stability of the water, thereby improving the transmission accuracy of the laser beam;

[0011] Step S3, controlling the optical detection system;

[0012] Use high-precision optical sensors, such as interferometers and photoelectric detectors, to detect the optical path of the laser beam and the state of the processing area in real time; establish a mathematical model of the optical detection system, optimize the parameters of the optical sensor through numerical calculation and simulation analysis, and improve the detection accuracy and stability; use data fusion technology to fuse the detection information of multiple optical sensors to improve the accuracy and reliability of the detection results;

[0013] Step S4, design of control system;

[0014] Use advanced control algorithms, such as fuzzy control and neural network control, to achieve precise control of the optical focusing system and water guide system; establish a mathematical model of the control system, optimize the parameters of the control algorithm through numerical calculation and simulation analysis, and improve the control effect; use real-time monitoring and fault diagnosis technology to monitor and diagnose the control system in real time, and improve the reliability and stability of the system;

[0015] Step S5: After the water-guided laser debugging process is completed, product processing is performed.

[0016] Preferably, in step S1, the focusing formula of the laser beam in the mathematical model is:

[0017]

[0018] In formula (1), f represents the focal length, r represents the radius of curvature of the lens, and θ represents the incident angle of the laser beam;

[0019] The control formula of the adaptive optical system is:

[0020]

[0021] In formula (2), μ represents the control signal, a i represents the coefficients of the adaptive optics system, Represents the wavefront distortion function of the laser beam.

[0022] Preferably, in step S2, the transmission formula of the laser beam in water in the mathematical model is:

[0023] n1sinθ1=n2sinθ2 (3)

[0024] In formula (3), n1 and n2 represent the refractive index of air and water, respectively, and θ1 and θ2 represent the incident angle of the laser beam in air and water, respectively;

[0025] The shape and size of the water nozzle are calculated as follows:

[0026]

[0027] In formula (4), Q represents the water flow rate, d represents the diameter of the water nozzle, Indicates the flow rate of water.

[0028] Preferably, in step S3, the detection formula of the interferometer in the mathematical model is:

[0029]

[0030] In formula (5), represents the phase difference of the interference fringes, λ represents the wavelength of the laser, and Δl represents the displacement of the object being measured;

[0031] The detection formula of the photodetector is:

[0032] Ⅰ=KP (6)

[0033] In formula (6), I represents the output current of the photodetector, K represents the sensitivity of the photodetector, and P represents the power of the laser.

[0034] Preferably, in step S4, the calculation formula of the fuzzy control algorithm in the mathematical model is:

[0035]

[0036] In formula (7), u represents the control output, w i represents the weight of the fuzzy rule, x i represents input variables;

[0037] The calculation formula of the neural network control algorithm is:

[0038] y=f(wx+b) (8)

[0039] In formula (8), y represents the control output, f represents the activation function, w represents the weight matrix, x represents the input vector, and b represents the bias vector.

[0040] The beneficial effects of the present invention are:

[0041] 1. Improve processing accuracy: The present invention can focus the laser beam to a smaller area and improve processing accuracy by precisely controlling the optical path of the water-guided laser. Experimental results show that the processing accuracy can be improved to sub-micron level by using the method of the present invention.

[0042] 2. Improve processing quality: The present invention can reduce the scattering and reflection of the laser beam by precisely controlling the optical path, improve the energy utilization of the laser beam, and thus improve the processing quality. In addition, the water guide system can cool the processing area, reduce the heat-affected zone, and improve the processing quality.

[0043] 3. Expanding the processing range: The present invention can adapt to different processing requirements and expand the processing range. By adjusting the parameters of the optical focusing system and the water guide system, workpieces of different materials and shapes can be processed.

[0044] 4. Improve processing efficiency: The present invention can reduce processing time and improve processing efficiency. In addition, the water guide system can cool the processing area, reduce thermal damage during processing, and improve processing efficiency.

[0045] 5. Reduce processing costs: The present invention can improve processing accuracy and quality, reduce scrap rate, and reduce processing costs. In addition, the water guide system of the invention can cool the processing area, reduce tool wear, and reduce processing costs. DETAILED DESCRIPTION

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the relevant technologies in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] The method for precise control of the optical path of water-guided laser in this embodiment mainly includes the following parts:

[0048] 1. Laser generator: generates laser beam.

[0049] 2. Optical focusing system: focuses the laser beam to the water-guided laser processing area.

[0050] 3. Water guide system: including water nozzles, water chambers, etc., used to transmit laser beams and cool the processing area.

[0051] 4. Optical detection system: used to detect the optical path of the laser beam and the status of the processing area.

[0052] 5. Control system: According to the feedback information from the optical detection system, the optical focusing system and water guide system are controlled to achieve precise control of the optical path.

[0053] Its working principle is that the laser beam generated by the laser generator is focused by the optical focusing system and then enters the water guide system. The water nozzle in the water guide system transmits the laser beam to the processing area, and the water in the water cavity cools the processing area. The optical detection system detects the optical path of the laser beam and the state of the processing area in real time, and feeds back the detection information to the control system. The control system adjusts the parameters of the optical focusing system and the water guide system according to the feedback information to achieve precise control of the optical path.

[0054] The following is a detailed description of the method for implementing the present invention. The following implementation method is only used to describe the elements that are thought to achieve the purpose, and is not used as an essential element to limit the present invention. Various omissions, substitutions or changes in the structure can be made without departing from the scope of the present invention. The present invention is further described in detail in conjunction with an embodiment of a novel method for accurately controlling the optical path of a water-guided laser.

[0055] S1: Control of optical focusing system

[0056] -Adaptive optics technology is used to adjust the position and angle of the lens and reflector in the optical focusing system in real time according to the wavefront distortion of the laser beam to eliminate the wavefront distortion and improve the focusing accuracy of the laser beam. -High-precision motor drive system is used to achieve fine adjustment of the lens and reflector to improve the adjustment accuracy and stability.

[0057] -Establish a mathematical model of the optical focusing system, optimize the parameters of the optical focusing system through numerical calculation and simulation analysis, and improve the focusing effect.

[0058] Laser beam focusing formula: Where f is the focal length, r is the radius of curvature of the lens, and θ is the incident angle of the laser beam.

[0059] -Control formula of adaptive optical system: Where μ is the control signal, a i are the coefficients of the adaptive optics system, is the wavefront distortion function of the laser beam.

[0060] S2: Control of water guide system

[0061] -Control the shape and size of the water nozzle to optimize the transmission efficiency and stability of the laser beam in water.

[0062] - Adjust the water flow speed and pressure in the water chamber to control the transmission direction and focusing position of the laser beam.

[0063] -Using ultrasonic technology, the water in the water chamber is stirred and vibrated to improve the uniformity and stability of the water, thereby improving the transmission accuracy of the laser beam.

[0064] The transmission formula of laser beam in water is: n1sinθ1=n2sinθ2, where n1 and n2 are the refractive indices of air and water respectively, and θ1 and θ2 are the incident angles of the laser beam in air and water respectively.

[0065] -The shape and size of the water nozzle is calculated by: Where Q is the water flow rate, d is the diameter of the water nozzle, is the flow rate of water.

[0066] S3: Control of optical inspection system

[0067] -Use high-precision optical sensors, such as interferometers, photodetectors, etc., to detect the optical path of the laser beam and the status of the processing area in real time.

[0068] -Establish a mathematical model of the optical detection system, optimize the parameters of the optical sensor through numerical calculation and simulation analysis, and improve the detection accuracy and stability.

[0069] -Use data fusion technology to fuse the detection information of multiple optical sensors to improve the accuracy and reliability of the detection results.

[0070] -Interferometer detection formula: in is the phase difference of the interference fringes, λ is the wavelength of the laser, and ΔL is the displacement of the object being measured.

[0071] -The detection formula of the photodetector is: I=KP, where I is the output current of the photodetector, K is the sensitivity of the photodetector, and P is the power of the laser.

[0072] S4: Control system design

[0073] -Adopt advanced control algorithms, such as fuzzy control, neural network control, etc., to achieve precise control of the optical focusing system and water guide system.

[0074] -Establish a mathematical model of the control system, optimize the parameters of the control algorithm through numerical calculation and simulation analysis, and improve the control effect.

[0075] -Use real-time monitoring and fault diagnosis technology to monitor and diagnose the control system in real time to improve the reliability and stability of the system.

[0076] -Calculation formula of fuzzy control algorithm: Where u is the control output, w i is the weight of the fuzzy rule, x i is the input variable.

[0077] -The calculation formula of the neural network control algorithm is: y=f(wx+b), where y is the control output, f is the activation function, w is the weight matrix, x is the input vector, and b is the bias vector.

[0078] S5: Therefore, the entire water light debugging process is completed, and product processing can be carried out.

[0079] Example

[0080] First, the laser beam is shaped into parallel light through a beam shaping system (beam expander collimator). After passing through a quarter-wave plate, the polarized light of the laser beam line is converted into a circularly polarized beam state, providing uniform, high-quality light spots in various states for subsequent laser processing.

[0081] Then the light beam is folded under the first 45° beam splitter and enters the lens. The lens focuses the light beam into a non-diffraction light beam with a smaller diameter than the nozzle of the water jet coupling cavity, a longer collimation range, and a smaller central spot, and then propagates through total reflection in the water column.

[0082] When the laser beam reaches the optical focusing system, the optical detection system will detect the state of the beam (verticality, roundness, centering), etc. If it is detected that the laser beam does not meet the technical indicators. The control system will be started. Based on this information, the control system will start the high-precision motor drive system to fine-tune the lens and reflector in the optical focusing system. By accurately adjusting the angle of the 45° beam splitter, the reflector reflects the laser beam to the subsequent optical elements at a more precise angle. At the same time, the established coordinate system conversion mathematical model is used to perform numerical calculations and simulation analysis of the adjustment angle. The angle generated by the 45° reflector adjustment is brought into (x′=xcosθ+ysinθ, y′=ycosθ-xsinθ), and the optimal position adjustment amount of the lens can be determined to maximize the elimination of unsatisfied technical indicators, beam collimation, polarization state, spot roundness, etc. to improve the focusing accuracy of the laser beam, ensuring that it can be accurately focused on the water-guided laser processing area to meet the actual state required for water-light coupling.

[0083] Secondly, when the water jet coupling cavity and the nozzle are assembled and manufactured, the center of the nozzle and the center of the laser beam are not concentric. As a result, the position deviation causes the laser beam and the water column in the water jet coupling cavity to be unable to produce total reflection to propagate the beam, which will cause the nozzle in the water jet coupling cavity to be damaged or ablated. It is necessary to replace the new nozzle device, recalibrate the beam center and the nozzle, etc. Therefore, based on the above situation, a position detection system is used for calibration and adjustment. It includes a detection light source and a CCD camera. The light beam emitted by the detection light source passes through the second beam splitter at 45° and the first beam splitter at 45°, and passes through the lens to directly illuminate the upper surface of the nozzle of the water jet coupling cavity. According to the reversibility of the optical path, the CCD camera takes a picture of the center position of the nozzle and calculates the center position coordinates (x1, y1).

[0084] Third, the control system starts the micro-movement module to move the focusing module to a position farther away from the center of the nozzle, and at the same time controls the laser light to process the marking point on the alignment plate.

[0085] Fourth, the control system starts the CCD camera in the detection system to take a picture of the marking point to obtain the coordinates, and at the same time calculates the position coordinates (x2, y2) of the marking point.

[0086] Fifth, the deviation value (δx, δy) of the laser beam relative to the nozzle center position is calculated by detecting the nozzle center position and the position of the laser beam in the water jet coupling cavity.

[0087] Sixth, the control system starts the micro-motion module to move the focusing module (δx, δy) on the basis of the plane (x2, y2) so that the center of the focusing beam overlaps with the center position of the nozzle, thus completing the position calibration.

[0088] Seventh, under the power meter, the control system controls the height of the micro-movement module to adjust the focal position of the focusing module, so that the water-light coupling rate reaches the maximum, so that the laser power can be more fully applied in the processing.

[0089] Eighth, when the above steps are completed, the optical detection system begins to calibrate and adjust the verticality of the waterline. First, a three-dimensional water column diagram will be formed according to the coordinates of the waterline at different heights of the sensor. Then the theoretically formed water column diagram is compared with the actual water column diagram, and the angle and position formed are accurately calculated. Send it to the control system, and the control system will repeat the above steps to adjust the water-light coupling module.

[0090] Ninth, when the verticality of the water column is adjusted, the optical detection system installed under the coupling cavity will detect the state of the water column in real time. When the water column becomes shorter or stratified, the monitoring status will be fed back to the control system, and the control system will adjust the water pressure to maintain the state required during debugging.

[0091] Tenth, finally, when all factors reach the optimal set values ​​during debugging, the control system controls the laser, water supply system, etc. to perform corresponding parts processing according to the drawings.

[0092] Traditional water-guided laser technology has obvious limitations during operation and lacks effective means of adjustment. Specifically, it adopts a one-stop debugging mode, which is fixed after the initial debugging, and no longer performs focus detection and subsequent control and adjustment operations on the optical focusing system. This means that in the entire processing process, no feedback mechanism is established for the key parameters of the spot, such as position, verticality, spot size and roundness. The water beam fiber after laser focusing and coupling is simply mechanically moved to the specified position of the part to be processed, and the processing task is directly carried out.

[0093] This traditional method inevitably leads to many problems. Due to the lack of dynamic adjustment of the focusing system, it is difficult to always maintain the best application state. For example, during the processing, due to factors such as equipment vibration, ambient temperature changes or slight aging of optical components, the focusing effect of the laser will gradually deviate from the ideal state, but the system cannot automatically sense and correct it. This not only leads to low processing efficiency, but also makes the processing quality unstable, and it is easy to have defects such as substandard hole processing accuracy and increased cutting edge roughness, which seriously restricts the application efficiency of traditional water-guided laser technology in the field of high-precision processing.

[0094] In order to overcome the shortcomings of traditional methods, a precise control method of the water-guided laser optical path is now used. The core of this innovative method is to implement real-time monitoring of the optical focusing system. With the help of high-resolution optical sensors and advanced image processing technology, it can accurately capture the actual focused spot state and transmit this information to the control system online in real time. The control system uses a sophisticated algorithm to dynamically adjust the roundness, position and verticality of the spot based on the received spot state data. In this way, the visualization and clarity of the laser beam during transmission is effectively solved, allowing operators to intuitively understand the transmission characteristics of the beam and ensure that the optical system always maintains the best state in key links such as focusing, alignment and coupling.

[0095] In the specific operation process, the control system coordinates the parameters of the optical focusing system and the water guide system according to the feedback information. For example, when the roundness of the light spot is detected to be deviated, the control system will automatically fine-tune the lens position or curvature in the optical focusing system, and optimize the water flow pressure and flow rate of the water guide system to achieve precise regulation and parameter matching of water-light coupling. This refined adjustment strategy successfully overcomes a series of technical bottlenecks in traditional technologies, such as difficulty in focusing, coupling, and dimming.

[0096] The actual application effect is remarkable. The water-light coupling efficiency is improved by more than 30% compared with the traditional method, which means that more laser energy can be effectively transmitted to the processing area, thereby improving the processing speed and quality. In terms of debugging time, compared with the traditional method, it saves more than 50% of the operation time, greatly shortens the equipment preparation cycle, and improves production efficiency. More importantly, in the entire processing process, the optical focusing system can be adjusted dynamically in real time according to different processing requirements, and always maintains the best working state, so that the processing quality and accuracy are improved by more than 1.2 times compared with traditional technologies, providing strong technical support for precision processing in high-end manufacturing, and promoting the widespread application and development of water-guided laser technology in related fields.

[0097] In summary, the present invention can focus the laser beam to a smaller area and improve the processing accuracy by precisely controlling the optical path of the water-guided laser. The present invention can improve the processing accuracy to the sub-micron level; therefore, the control accuracy of the optical path of the water-guided laser of the present invention is higher.

[0098] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for accurately controlling the optical path of a water-guided laser, characterized in that: include: A laser generator, wherein the laser generator is used to generate a laser beam; An optical focusing system, wherein the optical focusing system is used to focus the laser beam into a water-conducting laser processing area; A water guide system, the water guide system is used to transmit the laser beam and cool the processing area, the water guide system includes a water nozzle and a water cavity; An optical detection system, the optical detection system is used to detect the optical path of the laser beam and the state of the processing area; A control system, wherein the control system controls the optical focusing system and the water guide system according to feedback information from the optical detection system to achieve precise control of the optical path; The method for accurately controlling the water-guided laser optical path comprises the following steps: Step S1, optical focusing system control; According to the wavefront distortion of the laser beam, the position and angle of the lens and reflector in the optical focusing system are adjusted in real time to eliminate the wavefront distortion and improve the focusing accuracy of the laser beam; a high-precision motor drive system is used to achieve fine-tuning of the lens and reflector to improve the adjustment accuracy and stability; a mathematical model of the optical focusing system is established, and the parameters of the optical focusing system are optimized through numerical calculation and simulation analysis to improve the focusing effect; Step S2, controlling the water guide system; Control the shape and size of the water nozzle to optimize the transmission efficiency and stability of the laser beam in water; Adjust the water flow speed and pressure in the water chamber to control the transmission direction and focusing position of the laser beam; Stirring and vibrating the water in the water chamber to improve the uniformity and stability of the water, thereby improving the transmission accuracy of the laser beam; Step S3, controlling the optical detection system; Real-time detection of the laser beam’s optical path and the status of the processing area; Establish a mathematical model of the optical detection system, optimize the parameters of the optical sensor through numerical calculation and simulation analysis, and improve the detection accuracy and stability; Fuse the detection information of multiple optical sensors to improve the accuracy and reliability of the detection results; Step S4, design of control system; Adopt control algorithm to realize precise control of optical focusing system and water guide system; Establish a mathematical model of the control system, optimize the parameters of the control algorithm through numerical calculation and simulation analysis, and improve the control effect; Real-time monitoring and fault diagnosis of the control system to improve the reliability and stability of the system; Step S5: After the water-guided laser debugging process is completed, product processing is performed.

2. The method for accurately controlling the optical path of a water-guided laser according to claim 1, characterized in that: In step S1, the focusing formula of the laser beam is: In formula (1), f represents the focal length, r represents the radius of curvature of the lens, and θ represents the incident angle of the laser beam; The control formula of the adaptive optical system is: In formula (2), μ represents the control signal, a i represents the coefficients of the adaptive optics system, Represents the wavefront distortion function of the laser beam.

3. The method for accurately controlling the optical path of a water-guided laser according to claim 1, characterized in that: In step S2, the transmission formula of the laser beam in water is: n1sinθ1=n2sinθ2 (3) In formula (3), n1 and n2 represent the refractive index of air and water, respectively, and θ1 and θ2 represent the incident angle of the laser beam in air and water, respectively; The shape and size of the water nozzle are calculated as follows: In formula (4), Q represents the flow rate of water, d represents the diameter of the water nozzle, and θ represents the flow velocity of water.

4. The method for accurately controlling the optical path of a water-guided laser according to claim 1, characterized in that: In step S3, the detection formula of the interferometer is: In formula (5), represents the phase difference of the interference fringes, λ represents the wavelength of the laser, and Δl represents the displacement of the object being measured; The detection formula of the photodetector is: I=KP (6) In formula (6), I represents the output current of the photodetector, K represents the sensitivity of the photodetector, and P represents the power of the laser.

5. The method for accurately controlling the optical path of a water-guided laser according to claim 1, characterized in that: In step S4, the calculation formula of the fuzzy control algorithm is: In formula (7), u represents the control output, w i represents the weight of the fuzzy rule, x i represents input variables; The calculation formula of the neural network control algorithm is: y=f(wx+b) (8) In formula (8), y represents the control output, f represents the activation function, w represents the weight matrix, x represents the input vector, and b represents the bias vector.

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