Fiber laser dichroic mirror synthesis control system and method based on multi-dimensional real-time feedback

Abstract

The invention provides a fiber laser dichroic mirror synthesis control system and method based on multi-dimensional real-time feedback. The method comprises the steps that all light sources output light beams with different wavelengths; each light source corresponds to a multi-dimensional adjustment module, and adjustment of multi-dimensional control parameters of each light beam is realized through the multi-dimensional adjustment module; the synthesis module realizes cascade synthesis of light beams through dichroic mirror arrays which are arranged according to the wavelength gradient of the light beams, outputs combined light beams, monitors the power, light spot morphology, spectrum and pointing data of the combined light beams in real time, and outputs monitoring data; and the feedback controller is used for converting the monitoring data into a multi-dimensional control vector and dynamically adjusting the multi-dimensional adjusting module corresponding to each light source to form multi-dimensional cooperative closed-loop control. According to the invention, the problem of light beam quality degradation caused by environmental disturbance of a traditional dichroic mirror synthesis system is solved, the anti-interference capability of the system is enhanced through multi-degree-of-freedom closed-loop control, modular expansion is supported at the same time, and rapid expansion can be realized when a synthesis laser unit needs to be newly added.

Description

Technical Field

[0001] The present invention mainly relates to the field of laser synthesis technology, and in particular to a fiber laser dichroic mirror synthesis control system and method based on multi-dimensional real-time feedback. Background Art

[0002] Fiber lasers have become a key development direction in the high-energy laser field due to their advantages such as high efficiency and high beam quality. Spectral synthesis technology based on dichroic mirrors utilizes the transmissive and reflective properties of dichroic mirrors to spatially combine multiple laser beams of different wavelengths, thereby overcoming the power limitations of single-fiber lasers.

[0003] However, the existing dichroic mirror synthesis system has the following technical defects. First, the ability to resist environmental disturbances is insufficient. External interferences such as temperature fluctuations and mechanical vibrations can easily lead to misalignment of the combined optical path, resulting in spatial position offset of the unit light beam, focus drift and optical axis angle deviation, which seriously affects the quality of the synthesized beam. However, traditional synthesis systems often adopt a pre-calibrated fixed installation method, lack a dynamic compensation mechanism, and cannot correct the optical path parameter deviation in real time. Secondly, the adjustment dimension of the existing synthesis system is single, and its adjustment device mostly focuses on a single optical axis tilt adjustment, which makes it difficult to achieve multi-degree-of-freedom coordinated control. In addition, due to the lack of a focusing device, it is impossible to compensate for focal spot mismatch, which affects the synthesis quality.

[0004] In addition, the scalability of existing dichroic mirror synthesis systems is limited: when the number of synthesis units is increased, the active control parameters of the light beams of different units are coupled, the cross-influence between the channels (especially the influence of optical axis tilt) is aggravated, and the existing architecture is difficult to maintain a stable synthesis effect.

[0005] Therefore, there is an urgent need to develop an intelligent synthesis control system that has multi-dimensional dynamic adjustment capabilities, can compensate for optical path errors in real time, and has an easily scalable synthesis scale. Summary of the Invention

[0006] In view of the limitations of the existing technology, the present invention proposes a fiber laser dichroic mirror synthesis control system and method based on multi-dimensional real-time feedback.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In one aspect, the present invention provides a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback, comprising:

[0009] More than one light source, each light source outputting a light beam of a different wavelength;

[0010] Each light source corresponds to a multi-dimensional adjustment module, and the multi-dimensional control parameters of each light beam are adjusted by the multi-dimensional adjustment module, wherein the multi-dimensional control parameters include two or more of displacement, axial focus, pitch angle and azimuth angle;

[0011] The synthesis module uses a dichroic mirror array arranged according to the wavelength gradient of the light beam to realize the cascade synthesis of the light beams and output the combined light;

[0012] The monitoring module monitors the power, spot shape, spectrum and pointing data of the combined light in real time and outputs the monitoring data;

[0013] The feedback controller receives the monitoring data output by the monitoring module, converts the monitoring data into a multi-dimensional control vector, and dynamically adjusts the multi-dimensional adjustment modules corresponding to each light source to form a multi-dimensional collaborative closed-loop control.

[0014] Preferably, the multi-dimensional adjustment module includes an electrically controlled translation device, an electrically controlled focusing device and an electrically controlled tilting device;

[0015] With the optical axis as the z-axis, the electrically controlled translation device realizes translation of the output light beam of the corresponding light source in the x-axis and y-axis directions perpendicular to the optical axis;

[0016] The electrically controlled focusing device is used to adjust the equivalent focal length of the output light beam of the corresponding light source along the optical axis;

[0017] The electrically controlled tilting device is used to adjust the pitch angle and azimuth angle of the light beam output by the corresponding light source.

[0018] Preferably, the electrically controlled translation device comprises: a motor-mechanical transmission mechanism for achieving coarse displacement adjustment of the light beam in a two-dimensional plane perpendicular to the optical axis; a piezoelectric material micro-displacement mechanism connected in series with the motor-mechanical transmission mechanism for high-frequency small-amplitude displacement compensation; the displacement directions of the motor-mechanical transmission mechanism and the piezoelectric material micro-displacement mechanism include translation in the x-axis and y-axis directions perpendicular to the optical axis;

[0019] The electrically controlled focusing device comprises: an adjustable focus lens group consisting of at least two collimating lenses; a precision linear motor driving the adjustable focus lens group to move along the optical axis to continuously adjust the equivalent focal length, and the axial focusing control of the electrically controlled focusing device corresponding to each light beam is independent of each other;

[0020] The electrically controlled tilting device includes: an electrically controlled rotating assembly for achieving large-angle deflection adjustment; a piezoelectric fast reflection mirror connected in series with the electrically controlled rotating assembly for rapid micro-angle correction; the tilt control device has dual-degree-of-freedom adjustment capabilities for pitch and azimuth angles, and the tilt control of the electrically controlled tilt devices corresponding to each light beam is independent of each other.

[0021] Preferably, assuming that there are n light sources, there are n-1 dichroic mirrors in the dichroic mirror array, and n light beams are combined and output through the n-1 dichroic mirrors in the dichroic mirror array. The first light beam and the second light beam are combined through the first dichroic mirror to obtain a first combined light beam, the first combined light beam and the third light beam are combined through the second dichroic mirror to obtain a second combined light beam, the second combined light beam and the fourth light beam are combined through the third dichroic mirror to obtain a third combined light beam, ..., and so on, until a combined light beam formed by combining n light beams of different wavelengths is obtained.

[0022] Preferably, the monitoring module includes a spectroscopic sampling mirror, a power meter and a synthetic effect detector. The spectroscopic sampling mirror divides the combined beam finally output by the dichroic mirror array into two parts, most of which is incident on the power meter, and the remaining small part enters the synthetic effect detector for detecting the light spot morphology, spectrum and pointing data.

[0023] Preferably, the combined effect detector includes a beam splitter group, a first four-quadrant high-speed detector, a beam converter, a second four-quadrant high-speed detector, a high-speed camera, a spectrometer, and a beam quality analyzer. The beam splitter group includes a plurality of beam splitters, which are used to split the combined beam incident on the combined effect detector into multiple paths and inject them into the first four-quadrant high-speed detector, the beam converter, the high-speed camera, the spectrometer, and the beam quality analyzer respectively.

[0024] The composite light beam injected into the beam converter is transformed into far-field information by the lens group inside the beam converter and then injected into the second four-quadrant high-speed detector again. The first four-quadrant high-speed detector is used to directly detect the near-field position error offset of the composite light beam, and the second four-quadrant high-speed detector is used to detect the far-field tilt error offset of the composite light beam after transformation by the beam converter; the high-speed camera is used to capture the spot images of lasers in different bands; the spectrometer is used to monitor the spectrum of the composite light beam; and the beam quality analyzer is used to monitor the beam quality of the composite light beam.

[0025] Preferably, the feedback controller includes a feature extraction module, a feedback control quantity solution module and a system monitoring and recording module;

[0026] The monitoring data obtained in real time by the synthetic effect detector is sent to the feature extraction module for data processing. The data processing obtains the information required for dimensional control and the information required for system monitoring. The information required for dimensional control is sent to the feedback control quantity solution module to generate the control command of the multi-dimensional adjustment module; the information required for system monitoring is sent to the system monitoring and recording module to judge the system working status. The system monitoring and recording module makes a real-time judgment on the feasibility of the control command obtained by the feedback control quantity solution module, and issues a system emergency shutdown command to each actuator in the multi-dimensional adjustment module and reinitializes the system to play a protective role when the system working status is abnormal. At the same time, a log of the abnormal system working situation is generated for subsequent troubleshooting; the feedback control quantity solution module and the system monitoring and recording module jointly control the actual execution parameters of each actuator in the multi-dimensional adjustment module through the control signal output wire, and the control command of the system monitoring and recording module has a higher priority.

[0027] On the other hand, a method for controlling fiber laser dichroic mirror synthesis based on multi-dimensional real-time feedback is provided, comprising the following steps:

[0028] (S1) constructing the above-mentioned fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback;

[0029] (S2) system initialization;

[0030] (S3) The monitoring module outputs the current monitoring data in real time;

[0031] (S4) judging whether the system working state is normal based on the current monitoring data, and issuing a system emergency shutdown command to each actuator in the multi-dimensional adjustment module when the system working state is abnormal, and returning to step (S2); if the system working state is normal, proceeding to (S5);

[0032] (S5) generating a current system evaluation function based on the current monitoring data, including: obtaining spatial translation errors Δx and Δy of light beams of different wavelengths in the x and y directions, extracting the defocus difference Δz of light beams of different wavelengths, and the angular deviations Δθx and Δθy of light beams of different wavelengths in the x and y directions; obtaining the current system evaluation function J = α(Δx 2 +Δy 2 )+β(Δz 2 )+γ(Δθx 2 +Δθy 2 ), where α, β, and γ are the weight coefficients of spatial translation error, defocus difference, and angular deviation, respectively;

[0033] (S6) Based on the current system evaluation function, a multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is generated through a multi-variable optimization algorithm, and the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified in real time. The process is iterated continuously until the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified, so as to generate a control signal for each actuator in the multi-dimensional adjustment module corresponding to each light source, and return to (S3).

[0034] Furthermore, the multivariable optimization algorithm is an algorithm that supports multi-dimensional parallel control, including genetic algorithm, hill climbing method, and SPGD algorithm.

[0035] Furthermore, if at least one of the following situations occurs, the system operating state is judged to be abnormal: the power fluctuation of the combined light detected by the monitoring module is greater than 10%; the spectral abnormality of the combined light detected by the monitoring module continues for a set number of control cycles; the beam quality of the combined light detected by the monitoring module deteriorates or the beam quality performance of the combined light is not improved within the set number of control cycles; the difference in the focal spot size corresponding to each light source exceeds the set limit.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention provides a fiber laser dichroic mirror synthesis control system and method based on multi-dimensional real-time feedback, which can realize real-time integrated control of optical axis translation, focus position adjustment and optical axis tilt correction for the unit laser beams involved in the synthesis.

[0038] This invention combines real-time multi-dimensional parameter monitoring, a multivariable optimization algorithm, and low- and high-frequency composite control to achieve coordinated compensation for spatial translation errors, defocus differences, and angular deviations in the composite beam, significantly improving the composite system's resistance to environmental disturbances and scalability. The independent control design of each actuator avoids cross-channel interference. Combined with the low- and high-frequency composite control mechanism and system monitoring and recording module, it balances control amplitude, response speed, and adjustment accuracy, ensuring the long-term stability of the composite beam quality and operational safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0040] Figure 1A schematic structural diagram of a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback provided by an embodiment;

[0041] Figure 2 Flowchart of a fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback provided in one embodiment;

[0042] Figure 3 A schematic structural diagram of a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback provided by an embodiment;

[0043] Figure 4 This is a comparison diagram of the translation control effect simulation of an embodiment of the present invention;

[0044] Figure 5 This is a comparison diagram of the defocus control effect simulation of an embodiment of the present invention;

[0045] Figure 6 This is a comparison diagram of the tilt control effect simulation of an embodiment of the present invention;

[0046] Figure 7 This is a comparison diagram of the simulation effects of translation, defocusing, and tilting three-dimensional control according to an embodiment of the present invention;

[0047] Numbers in the figure:

[0048] 1. Light source; 2. Electric-controlled translation device; 3. Electric-controlled focusing device; 4. Electric-controlled tilting device; 5. Dichroic mirror array; 6. Power meter; 7. Spectroscopic sampling mirror; 8. Synthetic effect detector; 8-1. Spectroscopic mirror group; 8-2. First four-quadrant high-speed detector; 8-3. Beam converter; 8-4. Second four-quadrant high-speed detector; 8-5. High-speed camera; 8-6. Spectrometer; 8-7. Beam quality analyzer; 9. Detector data transmission line; 10. Feedback controller; 10-1. Feature extraction module; 10-2. Feedback control quantity solution module; 10-3. System monitoring and recording module; 11. Control signal output wire. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] In one embodiment, the present invention provides a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback, comprising:

[0051] More than one light source 1, each light source outputs a light beam with a different wavelength; wherein the light source is a fiber laser.

[0052] Each light source 1 corresponds to a multi-dimensional adjustment module, and the multi-dimensional control parameters of each light beam are adjusted by the multi-dimensional adjustment module, wherein the multi-dimensional control parameters include two or more of displacement, axial focus, pitch angle and azimuth angle;

[0053] The synthesis module uses a dichroic mirror array arranged according to the wavelength gradient of the light beam to realize the cascade synthesis of the light beams and output the combined light;

[0054] The monitoring module monitors the power, spot shape, spectrum and pointing data of the combined light in real time and outputs the monitoring data;

[0055] The feedback controller 10 receives the monitoring data output by the monitoring module, converts the monitoring data into a multi-dimensional control vector, and dynamically adjusts the multi-dimensional adjustment module corresponding to each light source to form a multi-dimensional collaborative closed-loop control.

[0056] The optical axis direction is taken as the z-axis direction, where the multidimensional control parameters include the spatial translation X of the light source output beam in the x-axis direction perpendicular to the optical axis, the spatial translation Y of the light source output beam in the y-axis direction perpendicular to the optical axis, the equivalent focal length Z of the light source output beam along the optical axis, the pitch angle θx and the azimuth angle θy.

[0057] The monitoring data includes the power of the beam, the near-field position error offset, the far-field tilt error offset, the spot image, the spectrum and the beam quality.

[0058] Furthermore, a fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback includes the following steps:

[0059] (S1) Building the fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback described in the above embodiment;

[0060] (S2) system initialization, setting initial multi-dimensional control parameters;

[0061] (S3) The monitoring module outputs the current monitoring data in real time;

[0062] (S4) judging whether the system working state is normal based on the current monitoring data, and issuing a system emergency shutdown command to each actuator in the multi-dimensional adjustment module when the system working state is abnormal, and returning to step (S2); if the system working state is normal, proceeding to (S5);

[0063] (S5) generating a current system evaluation function based on the current monitoring data, including: obtaining spatial translation errors Δx and Δy of light beams of different wavelengths in the x and y directions, extracting the defocus difference Δz of light beams of different wavelengths, and the angular deviations Δθx and Δθy of light beams of different wavelengths in the x and y directions; obtaining the current system evaluation function J = α(Δx 2 +Δy 2 )+β(Δz 2 )+γ(Δθx 2 +Δθy 2 ), where α, β, and γ are weight coefficients of spatial translation error, defocus difference, and angular deviation, respectively, and can be set according to the actual situation of the system;

[0064] (S6) Based on the current system evaluation function, a multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is generated through a multi-variable optimization algorithm, and the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified in real time. The process is iterated continuously until the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified, so as to generate a control signal for each actuator in the multi-dimensional adjustment module corresponding to each light source, and return to (S3).

[0065] Reference Figure 1 In one embodiment, a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback is provided, comprising: a light source 1, an electrically controlled translation device 2, an electrically controlled focusing device 3, an electrically controlled tilting device 4, a dichroic mirror array 5, a power meter 6, a spectroscopic sampling mirror 7, a synthesis effect detector 8, a spectroscopic mirror group 8-1, a first four-quadrant high-speed detector 8-2, a beam converter 8-3, a second four-quadrant high-speed detector 8-4, a high-speed camera 8-5, a spectrometer 8-6, a beam quality analyzer 8-7, a detector data transmission line 9, a feedback controller 10, a feature extraction module 10-1, a feedback control quantity calculation module 10-2, a system monitoring and recording module 10-3, and a control signal output wire 11.

[0066] The light source 1 is a fiber laser, and the light source 1 has n light sources, which output n light beams with different wavelengths, namely λ1, λ2, λ3, ..., λ n . where λ1, λ2, λ3,...,λ n The intervals between them are all λ0. Each light source 1 is equipped with an independent temperature control device, and the wavelength stability meets certain requirements.

[0067] Each light source 1 corresponds to a multi-dimensional adjustment module, which adjusts the multi-dimensional control parameters of each light beam. Taking the optical axis as the z-axis, the multi-dimensional control parameters include the spatial translation X of the light source output beam in the x-axis direction perpendicular to the optical axis, the spatial translation Y of the light source output beam in the y-axis direction perpendicular to the optical axis, the equivalent focal length Z of the light source output beam along the optical axis, the pitch angle θx, and the azimuth angle θy.

[0068] The multi-dimensional adjustment module includes an electrically controlled translation device 2 , an electrically controlled focusing device 3 and an electrically controlled tilting device 4 .

[0069] With the optical axis as the z-axis, the electrically controlled translation device 2 achieves translation of the corresponding light source output beam in the x- and y-axis directions perpendicular to the optical axis. Specifically, the electrically controlled translation device 2 includes: a motor-mechanical transmission mechanism for achieving two-dimensional coarse displacement adjustment of the light beam perpendicular to the optical axis; and a piezoelectric material micro-displacement mechanism connected in series with the motor-mechanical transmission mechanism for high-frequency, small-amplitude displacement compensation. The displacement directions of the motor-mechanical transmission mechanism and the piezoelectric material micro-displacement mechanism include translation in the x- and y-axis directions perpendicular to the optical axis.

[0070] The electronically controlled focusing device 3 is used to adjust the equivalent focal length of the corresponding light source output beam along the optical axis. The electronically controlled focusing device 3 includes a focusable lens assembly consisting of at least two collimating lenses; and a precision linear motor that drives the focusable lens assembly along the optical axis to continuously adjust the equivalent focal length. The axial focusing control of the electronically controlled focusing device corresponding to each light beam is independent, preventing focusing coupling between different light beams.

[0071] The electrically controlled tilt device 4 is used to adjust the pitch and azimuth angles of the corresponding light source output beam. It includes an electrically controlled rotation assembly for large-angle deflection adjustment and a piezoelectric fast reflector connected in series with the electrically controlled rotation assembly for rapid micro-angle correction. The tilt control device has dual-degree-of-freedom adjustment capabilities for both pitch and azimuth, and the tilt control of the electrically controlled tilt device corresponding to each light beam is independent of each other.

[0072] There are n-1 dichroic mirrors in the dichroic mirror array 5. N light beams are combined and outputted through these n-1 dichroic mirrors. The first and second light beams are combined through the first dichroic mirror to produce the first combined light beam. The first combined light beam and the third light beam are combined through the second dichroic mirror to produce the second combined light beam. The second combined light beam and the fourth light beam are combined through the third dichroic mirror to produce the third combined light beam. This continues in this manner until a combined light beam consisting of n light beams of different wavelengths is obtained. The first dichroic mirror has high transmittance for the first light beam with a wavelength of λ1 and high reflectance for the second light beam with a wavelength of λ2. The first double mirror has high transmittance for the first combined light beam with wavelengths of λ1 and λ2 and high reflectance for the third light beam with a wavelength of λ3. And so on. The mirror coating bandwidth of each double mirror is designed to be 10nm to ensure that the specified number of beams can be combined in series.

[0073] The monitoring module includes a spectroscopic sampling mirror 7, a power meter 6 and a synthetic effect detector 8. The spectroscopic sampling mirror 7 has a high reflectivity (>99%) in the wavelength bands covered by all the light sources 1 used. After the combined light enters the spectroscopic sampling mirror 7, most of the energy of the combined light is reflected to the power meter 6. After the combined light enters the spectroscopic sampling mirror 7, only a small amount of the energy of the combined light is transmitted into the synthetic effect detector 8 for monitoring and control, and is used to detect monitoring data such as light spot morphology, spectrum and pointing data.

[0074] The combined effect detector 8 includes a spectrometer group 8-1, a first four-quadrant high-speed detector 8-2, a beam converter 8-3, a second four-quadrant high-speed detector 8-4, a high-speed camera 8-5, a spectrometer 8-6, and a beam quality analyzer 8-7. The spectrometer group 8-1 includes multiple 50:50 spectrometers, which split the combined light incident on the combined effect detector into five paths through the multiple 50:50 spectrometers and inject them into the first four-quadrant high-speed detector 8-2, the beam converter 8-3, the high-speed camera 8-5, the spectrometer 8-6, and the beam quality analyzer 8-7 respectively.

[0075] The composite light beam injected into the beam converter 8-3 is transformed into far-field information by the internal lens group of the beam converter 8-3 and then injected into the second four-quadrant high-speed detector 8-4 again. The first four-quadrant high-speed detector 8-2 is used to directly detect the near-field position error offset of the composite light beam, and the second four-quadrant high-speed detector 8-4 is used to detect the far-field tilt error offset of the composite light beam after transformation by the beam converter 8-3; the high-speed camera 8-5 is used to capture the spot image of lasers of different wavelength bands; the spectrometer 8-6 is used to monitor the spectrum of the composite light beam; and the beam quality analyzer 8-7 is used to monitor the beam quality of the composite light beam.

[0076] The feedback controller 10 includes a feature extraction module 10-1, a feedback control amount calculation module 10-2 and a system monitoring and recording module 10-3;

[0077] The monitoring data obtained in real time by the synthetic effect detector 8 is sent to the feature extraction module 10-1 via the detector data transmission line 9 for data processing. The data processing obtains the information required for dimensional control and system monitoring. The information required for dimensional control is sent to the feedback control quantity solving module 10-2 to generate a control command for the multi-dimensional adjustment module. The information required for system monitoring is sent to the system monitoring and recording module 10-3 to determine the system operating status. The system monitoring and recording module 10-3 makes a real-time judgment on the feasibility of the control command obtained by the feedback control quantity solving module 10-2. When the system operating status is abnormal, it issues a system emergency shutdown command to each actuator in the multi-dimensional adjustment module and reinitializes the system to provide protection. At the same time, a log of the system operating abnormality is generated for subsequent troubleshooting. The feedback control quantity solving module 10-2 and the system monitoring and recording module 10-3 jointly control the actual execution parameters of each actuator in the multi-dimensional adjustment module (i.e., the electrically controlled translation device 2, the electrically controlled focusing device 3, and the electrically controlled tilt device 4) via the control signal output wire 11, and the control command of the system monitoring and recording module 10-3 has a higher priority.

[0078] The feature extraction module 10-1 calculates the spatial translation error (i.e., Δx and Δy) and the angular deviation (i.e., Δθx and Δθy) of the light beam based on the collected data of the first four-quadrant high-speed detector 8-2 and the second four-quadrant high-speed detector 8-3, extracts the defocus difference (i.e., Δz) of lasers of different wavelength bands based on the spot images corresponding to the light sources 1 of different wavelengths collected by the high-speed camera 8-5, monitors the spectrum of the synthesized laser in real time based on the data of the spectrometer 8-6, determines the spectrum broadening or wavelength shift, and monitors the beam quality M of the synthesized laser based on the data of the beam quality analyzer 8-7. 2 Factor, based on the real-time information of the synthetic laser power collected by the power meter 6, determines whether the system is in a normal working state;

[0079] The feedback control quantity solution module 10-2 obtains a comprehensive evaluation function based on the calculation results of the data collected by the first four-quadrant high-speed detector 8-2, the second four-quadrant high-speed detector 8-3 and the high-speed camera 8-5 in the feature extraction module 10-1, and generates a multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source.

[0080] The system monitoring and recording module 10-3 records in real time the system working state obtained by judging the data collected by the power meter 6, high-speed spectrometer 8-6 and beam quality analyzer 8-7 in the feature extraction module 10-1, and at the same time judges whether the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source generated by the feedback control quantity solution module 10-2 is feasible (for example, voltage exceeds the limit, actuator exceeds the limit, etc.) and sends the system emergency shutdown command to the actuator through the control signal output wire 11 when the system working state is abnormal and re-initializes the system to play a protective role. At the same time, a log is generated for the abnormal working of the system for subsequent troubleshooting. When the system is working normally and the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source generated by the feedback control quantity solution module 10-2 is feasible, the specific execution command is sent to each actuator in the multi-dimensional adjustment module (the actuator is the electric control translation device 2, the electric control focusing device 3, and the electric control tilt device 4) through the control signal output wire 11. If at least one of the following situations occurs, the system operating status is judged to be abnormal: the power fluctuation of the combined light detected by the monitoring module is greater than 10%; the spectral abnormality of the combined light detected by the monitoring module continues for a set number of control cycles; the beam quality of the combined light detected by the monitoring module deteriorates or the beam quality performance of the combined light is not improved within the set number of control cycles; the difference in the focal spot size corresponding to each light source exceeds the set limit.

[0081] Furthermore, the feedback control quantity solving module 10-2 in the feedback controller 10 realizes real-time compensation of each control quantity based on a multivariable optimization control algorithm; its core is to first establish a dynamic relationship between the displacement / angle of each actuator and the beam parameters; then, through the multivariable optimization algorithm, the specific execution parameter settings of the actuator are iteratively optimized according to the synthetic effect obtained by calculating the data of the feature extraction module 10-1; in terms of the specific execution parameter settings, for the translation error component, the motor mechanical transmission mechanism is preferentially used for low-frequency and large-scale adjustment, and then high-frequency compensation is performed through piezoelectric micro-displacement; for the focusing error component, an axial displacement signal is generated to drive the linear motor to adjust the lens position; for the tilt error component, the large-angle deflection of the electrically controlled rotating component and the micro-angle correction of the piezoelectric reflector are combined.

[0082] The multivariable optimization algorithm can adopt various algorithms that support multi-dimensional parallel control, such as genetic algorithm, hill climbing method, SPGD algorithm, etc. Here, the iterative control process of the SPGD algorithm is briefly introduced as an example. The algorithm uses a bidirectional perturbation method to iteratively optimize the control vector u = (X, Y, Z, θx, θy) required by each actuator based on the system evaluation function J. The update formula of the control vector u is:

[0083]

[0084] Where δu is the perturbation amplitude, μ is the step gain, and the purpose of optimizing the system evaluation function J (the optimization direction is to gradually reduce the value of J, and ideally J is 0) and dynamically improving the synthetic control effect and enhancing the system's anti-interference ability is achieved by using a step-down method.

[0085] The system of the present invention is expandable. When a new light source 1 is needed, an independent multi-dimensional adjustment module is allocated and the parameters are initialized; a new dichroic mirror is inserted at the end of the dichroic mirror array 5, and its transmission / reflection band matches the wavelength of the old unit and the new unit; the number of channels of the multivariable control algorithm is updated; and finally, the new unit is incorporated into the closed-loop control system (each data line is connected).

[0086] Figure 3 This is a schematic diagram of the structure of a fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback provided in one embodiment. In this embodiment, there are three light sources 1, which output three beams of light with different wavelengths, namely λ1, λ2, and λ3. Each light source 1 corresponds to a multi-dimensional adjustment module. The other settings in this embodiment are basically the same as those in the previous embodiment.

[0087] Reference Figure 2 , which is a flow chart of a fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback provided in one embodiment, and its corresponding system structure is as follows Figure 1 or Figure 3 As shown, the whole process includes the following steps:

[0088] Step 1, system initialization:

[0089] Set the initial parameters of the electrically controlled translation device 2, the electrically controlled focusing device 3, and the electrically controlled tilting device 4; calibrate the wavelength gradient arrangement of the dichroic mirror array 5 and the synthesis effect detector 8; start each light source 1 to output a laser of a preset wavelength band; the light beam output by each light source 1 passes through the electrically controlled translation device 2, the electrically controlled focusing device 3, and the electrically controlled tilting device 4 and is incident on the dichroic mirror array 5 for dichroic mirror spectrum synthesis.

[0090] Step 2, real-time acquisition and preprocessing of multi-channel data: The synthetic beam is separated into 1:99 energy ratio by the spectroscopic sampling mirror 7, and the transmitted beam is divided into 5 monitoring channels by the 50:50 spectroscopic group 8-1; the first four-quadrant high-speed detector 8-2 collects the near-field spot position signal in real time; the beam converter 8-3 converts part of the beam into far-field distribution, and then the second four-quadrant high-speed detector 8-4 synchronously collects the far-field tilt signal; the high-speed camera 8-5 captures the spot image, and the programmable filter array is used to realize the separation and acquisition of each wavelength spot; the high-speed spectrometer 8-6 monitors the synthetic spectrum in real time, and the beam quality analyzer 8-7 continuously measures M 2factor; the power meter 6 collects the synthetic power data in real time to establish a power fluctuation curve; finally, the detection data of the synthetic effect detector 8 is sent to the feedback controller 10 via the detector data transmission line 9;

[0091] Step 3, multi-dimensional feature parameter extraction (system evaluation function generation): In the feature extraction module (10-1), the system evaluation function J (Δx, Δy, Δz, Δθx, Δθy) is obtained based on the collected data based on the first four-quadrant high-speed detector 8-2, the second four-quadrant high-speed detector 8-4, and the high-speed camera 8-5;

[0092] The spatial translation errors Δx and Δy can be obtained by sampling the near-field signal (V 1_1 ,V 1_2 ,V 1_3 ,V 1_4 ), the spatial translation errors Δx and Δy of the light spot in the x and y directions are obtained by the following two formulas:

[0093]

[0094] When there is a spatial translation error (Δx / Δy) between the light sources, the optical axes of the light beams emitted by different light sources have a low degree of overlap, the synthetic laser spot is larger, and the synthetic laser brightness is reduced; at the same time, when the spatial translation error of the light source is large, the dichroic mirror reflective surface will not be able to completely cover the incident light spot, resulting in energy loss and reducing the synthesis efficiency; in particular, if the spatial translation error (Δx / Δy) is greater than 1 / 3 of the collimated spot radius, the synthetic beam M 2 Factors will deteriorate significantly.

[0095] Based on the spot images of each wavelength captured by the high-speed camera 8-5 and the ellipse fitting, the wavelength λ is obtained. i The long axis of the laser spot a i With short axis b i Size, and then get the equivalent size of the spot r i =(a i +b i ) / 2, and compared with the ideal spot size r0, the defocus difference (Δz) corresponding to each light source 1 is obtained based on the mapping relationship between the defocus amount and the spot size. Here, the ideal fundamental mode Gaussian beam is taken as an example. The defocus difference (Δz) is related to the spot size r detected at the equivalent distance z on the target surface. i The relationship is:

[0096]

[0097] When there is a defocus difference (Δz) in the light beams emitted by each light source 1, the target spot size of the corresponding laser beams of each wavelength will be enlarged and different, resulting in a decrease in the spot overlap and the brightness of the synthetic laser, affecting the quality of the synthetic laser beam.

[0098] The angular deviations Δθx and Δθy can be obtained based on the far-field signal (V 2_1 ,V 2_2 ,V 2_3 ,V 2_4 ), the angular deviations Δθx and Δθy of the light spot in the x and y directions are obtained by the following two formulas, where M is the transformation coefficient, which can be adjusted according to the actual magnification parameters of the beam converter 8-3:

[0099]

[0100] When there is an angular deviation (Δθx / Δθy) between the light sources, the optical axis overlap of lasers of different wavelengths is not high, the relative size of the far-field spot of the synthesized beam will increase, and the brightness of the synthesized laser will decrease, affecting the power density of the synthesized laser at the target; if the angular deviation is large, the beam deflection angle will be too large when the synthesis scale is large, and it will not be able to match the subsequent synthesis system; in particular, if the angular deviation (Δθx / Δθy) is greater than 1 / 2 of the far-field divergence angle of the beam, the synthesized beam M 2 Factors will deteriorate significantly;

[0101] Finally, based on the above error measurement values, the evaluation function J of the system at this time is given to comprehensively evaluate the system synthesis effect and provide a reference for subsequent feedback control:

[0102] J=α(Δx 2 +Δy 2 )+β(Δz 2 )+γ(Δθx 2 +Δθy 2 )

[0103] Among them, α, β, and γ are the weight coefficients of spatial translation error, angular deviation, and defocus difference, which need to be set according to the actual situation of the system.

[0104] Step 4, multivariable optimization control signal solution generation: Based on the system evaluation function extracted by the feature extraction module 10-1, a multi-dimensional control vector u = (X, Y, Z, θx, θy) is generated through a multivariable optimization algorithm. The multivariable optimization algorithm can adopt a variety of algorithms that support multi-dimensional parallel control, such as genetic algorithm, hill climbing method, SPGD algorithm, etc. Here, the iterative control process of the SPGD algorithm is briefly introduced as an example. The algorithm uses a bidirectional perturbation method to iteratively optimize the control vector u = (X, Y, Z, θx, θy) required by each actuator based on the system evaluation function J, where the update formula of the control vector u is:

[0105]

[0106] Wherein δu is the perturbation amplitude, μ is the step gain, and the purpose of optimizing the system evaluation function J (the optimization direction is to gradually reduce the value of J, and ideally J is 0) and dynamically improving the synthetic control effect and enhancing the anti-interference ability of the system is achieved by a step-down method. The spatial translation error (Δx / Δy) is adjusted at a low frequency and in a large scale by the motor-mechanical transmission mechanism in the electrically controlled beam translation device 2, and then compensated at a high frequency by the piezoelectric micro-displacement mechanism to generate the control signals (X / Y) required by each motor-mechanical transmission mechanism and the piezoelectric micro-displacement mechanism; based on the defocus difference (Δz) of different light sources, the required signals (Z) for the linear motor displacement control in each electrically controlled focusing device 3 are generated respectively; based on the angular deviation (Δθx / Δθy), the large-angle deflection of the electrically controlled rotating component and the micro-angle correction of the piezoelectric mirror are combined to generate the required signals (θx / θy) for the rotation control of each motor and the piezoelectric mirror;

[0107] Step 5, system safety monitoring: the system monitoring and recording module 10-3 verifies in real time the feasibility of the execution parameters of each actuator corresponding to the multi-dimensional control vector generated by the feedback control quantity solving module 10-2 in step 4 (motor drive voltage, displacement tilt stroke); the system monitoring and recording module 10-3 also determines whether the system working status is normal based on the monitoring data of the synthetic effect detector 8, and performs an emergency shutdown when the following situations occur, and sends the shutdown command to each light source 1 and each actuator of the multi-dimensional adjustment module through the control signal output wire 11 and automatically records the fault event: the power fluctuation detected by the power meter 6 is greater than 10%; the spectrum is abnormal (such as drift, broadening) for a set number of control cycles; the beam quality deteriorates (the M2 factor increases to the set limit) or the beam quality performance is not improved within the set number of control cycles; the difference in the focal spot size corresponding to each light source 1 exceeds the set limit.

[0108] Step 6, dynamic collaborative closed-loop control: When the feasibility of the execution parameters generated by the feedback control quantity solution module 10-2 in the step 4 is verified by the step 5 and the system operates normally, the control signal generated in the step 4 is sent down to each actuator of the multi-dimensional adjustment module (electrically controlled beam translation device 2, electric controlled focusing device 3 and electric controlled tilting device 4) through the control signal output wire 11 for synchronous adjustment; the motor mechanism in the electric controlled beam translation device 2 performs coarse adjustment, and the piezoelectric mechanism performs fine adjustment to correct the spatial translation error in real time; the linear motor in the electric controlled focusing device 3 corrects the defocus difference in real time; the motor rotating assembly in the electric controlled tilting device 4 performs large angle coarse adjustment, and the piezoelectric mirror performs micro-radian level dynamic correction.

[0109] When the system is working normally, steps 2-6 are iteratively executed, and the control quantity is updated at fixed intervals according to the changes in the system evaluation function J generated in step 3, forming a closed-loop system with a certain control cycle, so that the control system evaluation function J is optimized in the direction of gradual reduction; the overall control is performed in the order of tilting, translation, and focusing, and a fixed time interval is set for adjacent actions.

[0110] Based on the above control method, Figure 3 For the structure shown, when only considering the single error effect in the three-way laser dichroic mirror synthesis system, a schematic diagram of the results of active control of spatial translation error (Δx / Δy), defocus difference (Δz) and angular deviation (Δθx / Δθy) can be generated in MATLAB simulation software. Figure 4 、 Figure 5 and Figure 6 As shown, Figure 4 This is a comparison chart of the translation control effect simulation;

[0111] Figure 5 This is a comparison chart of the defocus control effect simulation; Figure 6 This is a comparison chart of the tilt control effect simulation; Figure 4 、 Figure 5 and Figure 6 The left pictures in the figure are all synthetic spots without active control. Figure 4 、 Figure 5 and Figure 6 The right pictures in the figure are all the synthetic light spots after applying active control. It can be seen that the center of the synthetic light spot is aligned and the energy distribution is more concentrated after applying active control. When the influence of the three errors is considered at the same time, the following can be obtained: Figure 7 The control result comparison diagram shown in the figure is as follows: Figure 7 The left picture shows the synthetic light spot when no active control is performed. Figure 7The right picture shows the synthetic light spot after applying active control in all three dimensions. Compared with the state without active control, the synthetic effect is significantly optimized after applying active control. The center of the synthetic laser spot is aligned (indicating a high degree of optical axis overlap) and the size consistency of the three-way laser spot is also significantly improved.

[0112] In summary, this invention addresses the problem of beam quality degradation caused by environmental disturbances in traditional dichroic mirror synthesis systems, enhancing the system's anti-interference capabilities through multi-degree-of-freedom closed-loop control. Furthermore, the system supports modular expansion, enabling rapid expansion when additional synthetic laser units are needed.

[0113] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and such modifications and improvements are intended to fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

[0115] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback, characterized in that: include: More than one light source, each light source outputting a light beam of a different wavelength; Each light source corresponds to a multi-dimensional adjustment module, and the multi-dimensional control parameters of each light beam are adjusted by the multi-dimensional adjustment module, wherein the multi-dimensional control parameters include two or more of displacement, axial focus, pitch angle and azimuth angle; The synthesis module uses a dichroic mirror array arranged according to the wavelength gradient of the light beam to realize the cascade synthesis of the light beams and output the combined light; The monitoring module monitors the power, spot shape, spectrum and pointing data of the combined light in real time and outputs the monitoring data; The feedback controller receives the monitoring data output by the monitoring module, converts the monitoring data into a multi-dimensional control vector, and dynamically adjusts the multi-dimensional adjustment modules corresponding to each light source to form a multi-dimensional collaborative closed-loop control.

2. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 1, characterized in that: The multi-dimensional adjustment module includes an electrically controlled translation device, an electrically controlled focusing device, and an electrically controlled tilting device; With the optical axis as the z-axis, the electrically controlled translation device realizes translation of the output light beam of the corresponding light source in the x-axis and y-axis directions perpendicular to the optical axis; The electrically controlled focusing device is used to adjust the equivalent focal length of the output light beam of the corresponding light source along the optical axis; The electrically controlled tilting device is used to adjust the pitch angle and azimuth angle of the light beam output by the corresponding light source.

3. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 2, characterized in that: The electrically controlled translation device comprises: a motor-mechanical transmission mechanism for achieving coarse displacement adjustment of the light beam in a two-dimensional plane perpendicular to the optical axis; a piezoelectric material micro-displacement mechanism connected in series with the motor-mechanical transmission mechanism for high-frequency small-amplitude displacement compensation; the displacement directions of the motor-mechanical transmission mechanism and the piezoelectric material micro-displacement mechanism include translation in the x-axis and y-axis directions perpendicular to the optical axis; The electrically controlled focusing device comprises: an adjustable focus lens group consisting of at least two collimating lenses; a precision linear motor driving the adjustable focus lens group to move along the optical axis to continuously adjust the equivalent focal length, and the axial focusing control of the electrically controlled focusing device corresponding to each light beam is independent of each other; The electrically controlled tilting device includes: an electrically controlled rotating assembly for achieving large-angle deflection adjustment; a piezoelectric fast reflection mirror connected in series with the electrically controlled rotating assembly for rapid micro-angle correction; the tilt control device has dual-degree-of-freedom adjustment capabilities for pitch and azimuth angles, and the tilt control of the electrically controlled tilt devices corresponding to each light beam is independent of each other.

4. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 1, 2 or 3, characterized in that: Assume there are n light sources, then there are n-1 dichroic mirrors in the dichroic mirror array. N light beams are combined and output through the n-1 dichroic mirrors in the dichroic mirror array. The first light beam and the second light beam are combined through the first dichroic mirror to obtain a first combined light beam. The first combined light beam and the third light beam are combined through the second dichroic mirror to obtain a second combined light beam. The second combined light beam and the fourth light beam are combined through the third dichroic mirror to obtain a third combined light beam. And so on, until a combined light beam formed by combining n light beams of different wavelengths is obtained.

5. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 4, characterized in that: The monitoring module includes a spectroscopic sampling mirror, a power meter and a synthetic effect detector. The spectroscopic sampling mirror divides the combined beam output by the dichroic mirror array into two parts. Most of the power is incident on the power meter, and the remaining small part enters the synthetic effect detector for detecting the light spot morphology, spectrum and pointing data.

6. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 5, characterized in that: The combined effect detector includes a beam splitter group, a first four-quadrant high-speed detector, a beam converter, a second four-quadrant high-speed detector, a high-speed camera, a spectrometer, and a beam quality analyzer. The beam splitter group includes multiple beam splitters for splitting the combined beam incident on the combined effect detector into multiple paths and injecting the combined beam into the first four-quadrant high-speed detector, the beam converter, the high-speed camera, the spectrometer, and the beam quality analyzer respectively. The composite light beam injected into the beam converter is transformed into far-field information by the lens group inside the beam converter and then injected into the second four-quadrant high-speed detector again. The first four-quadrant high-speed detector is used to directly detect the near-field position error offset of the composite light beam, and the second four-quadrant high-speed detector is used to detect the far-field tilt error offset of the composite light beam after transformation by the beam converter; the high-speed camera is used to capture the spot images of lasers in different bands; the spectrometer is used to monitor the spectrum of the composite light beam; and the beam quality analyzer is used to monitor the beam quality of the composite light beam.

7. The fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback according to claim 1 or 2 or 3 or 5 or 6, characterized in that: The feedback controller includes a feature extraction module, a feedback control quantity calculation module, and a system monitoring and recording module; The monitoring data obtained in real time by the synthetic effect detector is sent to the feature extraction module for data processing. The data processing obtains the information required for dimensional control and the information required for system monitoring. The information required for dimensional control is sent to the feedback control quantity solution module to generate the control command of the multi-dimensional adjustment module; the information required for system monitoring is sent to the system monitoring and recording module to judge the system working status. The system monitoring and recording module makes a real-time judgment on the feasibility of the control command obtained by the feedback control quantity solution module, and issues a system emergency shutdown command to each actuator in the multi-dimensional adjustment module and reinitializes the system to play a protective role when the system working status is abnormal. At the same time, a log of the abnormal system working situation is generated for subsequent troubleshooting; the feedback control quantity solution module and the system monitoring and recording module jointly control the actual execution parameters of each actuator in the multi-dimensional adjustment module through the control signal output wire, and the control command of the system monitoring and recording module has a higher priority.

8. A fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback, characterized in that: The following steps are involved: (S1) constructing the fiber laser dichroic mirror synthesis control system based on multi-dimensional real-time feedback as described in claim 1; (S2) system initialization; (S3) The monitoring module outputs the current monitoring data in real time; (S4) judging whether the system working state is normal based on the current monitoring data, and issuing a system emergency shutdown command to each actuator in the multi-dimensional adjustment module when the system working state is abnormal, and returning to step (S2); if the system working state is normal, proceeding to (S5); (S5) generating a current system evaluation function based on the current monitoring data, including: obtaining spatial translation errors Δx and Δy of light beams of different wavelengths in the x and y directions, extracting the defocus difference Δz of light beams of different wavelengths, and the angular deviations Δθx and Δθy of light beams of different wavelengths in the x and y directions; obtaining the current system evaluation function J = α(Δx 2 +Δy 2 )+β(Δz 2 )+γ(Δθx 2 +Δθy 2 ), where α, β, and γ are the weight coefficients of spatial translation error, defocus difference, and angular deviation, respectively; (S6) Based on the current system evaluation function, a multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is generated through a multi-variable optimization algorithm, and the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified in real time. The process is iterated continuously until the feasibility of the multi-dimensional control vector of the multi-dimensional adjustment module corresponding to each light source is verified, so as to generate a control signal for each actuator in the multi-dimensional adjustment module corresponding to each light source, and return to (S3).

9. The fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback according to claim 8, characterized in that: The multivariable optimization algorithm is an algorithm that supports multi-dimensional parallel control, including genetic algorithm, hill climbing method, and SPGD algorithm.

10. The fiber laser dichroic mirror synthesis control method based on multi-dimensional real-time feedback according to claim 8, characterized in that: If at least one of the following situations occurs, the system operating status is judged to be abnormal: the power fluctuation of the combined light detected by the monitoring module is greater than 10%; the spectral abnormality of the combined light detected by the monitoring module continues for the set number of control cycles; the beam quality of the combined light detected by the monitoring module deteriorates or the beam quality performance of the combined light is not improved within the set number of control cycles; the difference in the focal spot size corresponding to each light source exceeds the set limit.

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