Laser processing temperature control method based on fiber beam combining and fiber transmission and integrated temperature control laser

Abstract

The application discloses a laser processing temperature control method and an integrated temperature control laser based on fiber beam combining and fiber transmission, power calibration, mode regulation and phase synchronization correction are performed on multiple paths of pump light, fiber core-cladding domain coaxial transmission is realized through a beam combiner; filtering, polarization correction and light intensity dynamic normalization processing are performed on the backhaul temperature measurement light signal, the light signal is converted into an electric signal, noise separation, baseline correction and segmented gain enhancement are performed, and then interference is removed through time domain correlation verification; temperature is calculated according to a temperature measurement formula, and improved PID without overshoot is adopted to realize hierarchical closed-loop regulation. The laser comprises a pump source, a beam combiner, a multi-clad optical fiber, a filter, an infrared detection module, a temperature processing module and a laser control card. The application is accurate, fast in response and stable in temperature control, solves the problems of optical field distortion, signal drift and interference misjudgment, and is suitable for high-precision laser processing.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, and particularly relates to a laser processing temperature control method based on fiber optic bundling and fiber optic transmission, and an integrated temperature-controlled laser. Background Technology

[0002] High-power fiber lasers have been widely used in precision material processing fields such as laser welding, cladding, and quenching. The temperature stability of the processing location directly determines the processing quality and forming effect. Existing laser processing temperature detection solutions mostly use infrared thermal imagers, thermocouples, or external fiber optic sensors. Infrared thermal imagers are easily affected by environmental dust and plasma interference, have low measurement accuracy, and are difficult to align precisely with the laser processing point. Thermocouples are contact-based measurements, with slow response speeds and interference with normal processing. Traditional fiber optic temperature measurement devices are difficult to integrate with lasers and cannot achieve coaxial synchronization of energy laser transmission and temperature detection.

[0003] While existing technologies employ fiber combiners and multi-clad fibers for laser transmission, they generally suffer from severe crosstalk between the energy beam and the temperature measurement signal beam, difficulty in coaxially aligning the temperature measurement spot and the processing spot, the need for repeated calibration during assembly and disassembly, and susceptibility to backlighting and stray light. Furthermore, traditional temperature control methods lack power consistency calibration of the pump source, segmented signal enhancement, and graded temperature deviation adjustment mechanisms, resulting in lag in temperature response, insufficient temperature control accuracy, and a tendency for overshoot and oscillation. These limitations make it difficult to meet the stringent requirements of high-precision laser processing for real-time performance, stability, and consistency. Summary of the Invention

[0004] The purpose of this invention is to provide a laser processing temperature control method and an integrated temperature control laser based on fiber optic bundling and fiber optic transmission, so as to solve the problems mentioned in the background art.

[0005] In view of this, the present invention provides a laser processing temperature control method based on fiber optic bundling and fiber optic transmission, the laser processing temperature control method based on fiber optic bundling and fiber optic transmission comprising:

[0006] The power consistency calibration and mode normalization of the energy light output from the N pump sources are performed. The processed multi-channel energy light and single-channel infrared temperature measurement signal light are input into the multi-channel pump single-signal combiner. Coaxial combining and core-cladding domain transmission are completed through the coupling region, so that the energy light is transmitted along the cladding of the multi-cladding fiber and the temperature measurement signal light is transmitted along the coaxial core.

[0007] The thermal radiation light signal generated at the processing location is collected and transmitted back along the fiber core. The transmitted light signal is then filtered for backlight, suppressed for stray bands, and corrected for polarization disturbance to obtain a purified temperature measurement light signal.

[0008] The purified thermometric optical signal is converted into an initial electrical signal. Noise separation, baseline drift correction, and segmented feature enhancement are performed on the initial electrical signal to extract a steady-state feature vector that is strongly correlated with temperature.

[0009] The real-time temperature at the processing position is calculated based on the steady-state feature vector and the preset mapping relationship. Based on the temperature deviation classification and overshoot-free adjustment strategy, the output power of each pump source is adjusted in a closed loop to stabilize the processing temperature within the target accuracy range.

[0010] The real-time processing temperature T is calculated using the following formula: T=Kln(U / U0)+T0, where K is the system calibration coefficient, U is the amplitude of the current characteristic electrical signal, U0 is the room temperature reference electrical signal, and T0 is the room temperature reference value.

[0011] In this invention, the power consistency calibration and mode normalization processing of the N-channel energy light includes: real-time acquisition of the output optical power of each pump source and calculation of the deviation value between the power of each channel and the mean.

[0012] The pump drive current of each channel is finely adjusted and registered according to the deviation value to ensure that the output power of multiple energy beams remains consistent.

[0013] The pump light is mode-normalized to ensure that it meets the mode matching conditions for cladding transmission in multi-clad optical fibers.

[0014] In this invention, further, the coaxial beam combining and core-cladding domain transmission through the coupling region includes: power combining of multiple energy beams within the coupling region and coupling them to the cladding of a multi-cladding fiber;

[0015] The temperature measurement signal light is independently coupled to the fiber core and spatially coaxial with the energy light;

[0016] This ensures that the temperature measurement spot and the processing spot always coincide, achieving in-situ, deviation-free temperature acquisition at the processing point.

[0017] In this invention, further, the noise separation, baseline drift correction and segmented feature enhancement of the initial electrical signal includes: using bandpass filtering and adaptive notch filtering to separate environmental noise and system noise;

[0018] Baseline drift is corrected based on multiple consecutive frames of signal to eliminate transmission loss and offset caused by detector aging.

[0019] The electrical signal is segmented and enhanced according to temperature range to improve the characteristic recognition of low temperature and high temperature ranges.

[0020] In this invention, the closed-loop regulation of pump source output power based on temperature deviation grading and overshoot-free regulation strategy includes: dividing the difference between real-time temperature and set temperature into three levels: slight deviation, mild deviation, and severe deviation.

[0021] Differentiated adjustment coefficients are adopted for different deviation levels, and smooth adjustment commands are output through PID algorithm;

[0022] The power of each pump is adjusted synchronously according to the gradient to avoid temperature overshoot and oscillation, and to ensure stable temperature during the processing.

[0023] An integrated temperature-controlled laser includes: N laser pump sources, a multi-channel pump single-signal combiner, a multi-clad output fiber, a filter, an infrared detection module, a temperature processing module, and a laser control card;

[0024] The laser pump source is connected to the pump input port of the multi-channel pump single-signal beam combiner, and the infrared detection module is connected to the signal input port.

[0025] The multi-clad output optical fiber is connected to the output end of the combiner. The fiber core transmits the temperature measurement signal light, and the cladding transmits the pump energy light.

[0026] The filter is located at the front end of the infrared detection module, and the temperature processing module is electrically connected to the infrared detection module and the laser control card respectively.

[0027] Furthermore, in this invention, the multi-channel pump single-signal combiner is fabricated using a fused taper process and has an internal isolation structure between the pump port and the signal port to prevent crosstalk between the pump light and the temperature measurement channel.

[0028] In this invention, the multi-clad output fiber is further described as having a double-clad or multi-clad structure, a core diameter of 10–200 μm, a multimode cladding structure with a diameter ≥100 μm, and a numerical aperture of 0.12–0.46.

[0029] In this invention, the infrared detection module further includes an infrared detector, a signal amplification circuit, and a filtering circuit, used to convert thermal radiation light signals into electrical signals.

[0030] Furthermore, in this invention, the temperature processing module incorporates an MCU or DSP chip and employs a PID algorithm. The laser control card adjusts the pump source power according to the instructions from the temperature processing module to achieve closed-loop temperature control.

[0031] The beneficial effects of this invention are:

[0032] This invention constructs a full-link closed-loop temperature control system through power consistency calibration, coaxial beam combining and domain-specific transmission, multi-level signal purification, and graded temperature deviation control. This system enables coaxial, non-interfering energy beam transmission and temperature detection, fundamentally solving the problems of temperature measurement point misalignment and inaccurate positioning with the laser processing point. The method employs noise separation, baseline drift correction, and segmented feature enhancement processing, combined with precise calculations using temperature measurement formulas, significantly improving temperature measurement response speed and linearity. The response time is no greater than 1ms, the temperature measurement range covers -50℃ to 3300℃, and the temperature control accuracy reaches within ±0.5℃. Through graded temperature deviation control and a no-overshoot adjustment strategy, temperature overshoot and oscillation are avoided, ensuring continuous temperature stability during processing. This greatly improves the consistency, reliability, and yield of laser processing, making it suitable for high-precision laser welding, cladding, quenching, and other similar applications.

[0033] This system employs an integrated structure combining a multi-pump single-signal combiner with multi-clad optical fiber. The pump light is transmitted through the cladding, while the temperature measurement signal light is transmitted through the fiber core. The optical paths are separated and coaxially output, eliminating the need for repeated calibration after assembly and disassembly, significantly improving ease of use. The combiner incorporates a port isolation structure, which, in conjunction with a front-end filter, effectively blocks crosstalk from the returning energy light, improving the signal-to-noise ratio of the temperature measurement signal and system stability. The entire device is built upon existing conventional laser components, featuring a compact structure, high integration, and strong compatibility. It requires no major modifications to existing laser equipment, resulting in lower costs and wider applicability. It can directly adapt to standard output connectors such as QBH, QD, and SMA905, demonstrating significant value for engineering and commercialization. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the method of the present invention;

[0035] Figure 2 This is a schematic diagram of a laser. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0037] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques known to those skilled in the art, laser processing temperature control methods and devices based on fiber optic bundling and fiber optic transmission may not be discussed in detail, but where appropriate, such techniques, laser processing temperature control methods and devices based on fiber optic bundling and fiber optic transmission should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0038] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, the first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0039] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0040] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, laser processing temperature control method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, laser processing temperature control method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, laser processing temperature control method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the laser processing temperature control method and apparatus based on fiber optic bundling and fiber optic transmission in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, for example, the described laser processing temperature control method based on fiber optic bundling and fiber optic transmission may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, the features described in some examples can be combined in other examples.

[0041] This embodiment provides a laser processing temperature control method based on fiber optic bundling and fiber optic transmission, including: after the system is started, the energy light output from the N pump sources is first calibrated for real-time power consistency and normalized for mode. The output light power of each pump source is synchronously acquired through the built-in optical power acquisition unit. The acquired power values ​​of each source are sent to the processing unit for average calculation to obtain the average output power of the N pump lights.

[0042] The power deviation value of each pump source is obtained by calculating the difference between the actual output power of each pump source and the average power. The drive current of each pump source is adaptively fine-tuned according to the power deviation value to keep the output power of all pump sources consistent and eliminate the power unevenness caused by device differences, temperature drift and drive fluctuation.

[0043] Simultaneously, the pump light is mode-normalized. The divergence angle and optical field distribution of the pump light are optimized through collimation and shaping structures, so that the pump light meets the mode matching conditions of multi-clad fiber cladding transmission, thereby improving coupling efficiency and reducing backlight interference.

[0044] In this embodiment, after mode normalization is completed, phase synchronization pre-correction is performed on each pump light: specifically, using the first pump source as the reference phase, phase micro-shift adjustment is applied to the driving current signals of the remaining N-1 pump sources, with an adjustment step size of 0.1π-0.5π for each source; the optical field intensity distribution at the output end of the combiner is acquired in real time, and when the multiple pump lights achieve in-phase superposition in the coupling region, the optical field uniformity is improved to the optimal level and remains stable; phase synchronization suppresses cladding mode fluctuations, local optical intensity distortion, and local overheating of the optical fiber caused by multi-beam interference; thereby solving the problems of local power spikes in the optical field, easy ablation of optical fibers, poor output stability, and inability to further improve the combining efficiency when multiple pump lights are combined due to phase randomness.

[0045] After calibration and normalization, the multi-channel energy beam and the single-channel infrared temperature measurement signal beam are synchronously input into the multi-channel pump single-signal combiner. The coaxial beam combining and core-cladding domain-separated transmission are completed through the coupling area formed by the fused tapered wire inside the combiner. This allows the energy beam to be transmitted at high power along the cladding of the multi-clad fiber, while the temperature measurement signal beam is transmitted coaxially along the core. This ensures that the energy beam path and the temperature measurement beam path are transmitted independently within the same fiber without crosstalk. From a physical structure perspective, this guarantees that the temperature measurement signal is not interfered with by the energy beam, and that the temperature measurement point and the laser processing point are always coaxially coincident.

[0046] Secondly, the thermal radiation light signal generated at the processing location under laser irradiation is collected, coupled into the core of the multi-clad fiber, and transmitted back along the core to the detection end. The returned temperature measurement light signal is subjected to backlight filtering, stray band suppression, and polarization disturbance correction. The pump light band is deeply attenuated and blocked through a bandpass filter structure, completely filtering out plasma stray light, ambient scattered light, and high-power backlight reflected from the fiber end face generated during processing. At the same time, the polarization state fluctuation generated during the transmission of the fiber core is compensated and stabilized in real time to eliminate signal fluctuations caused by polarization changes, resulting in a purified temperature measurement light signal with high purity, high linearity, and high signal-to-noise ratio, providing a reliable foundation for subsequent photoelectric conversion and temperature calculation.

[0047] In this embodiment, after polarization correction, the temperature measurement optical signal undergoes dynamic intensity normalization processing: the reference light intensity at the fiber input and output ends is acquired in real time, and the real-time transmission loss coefficient α is calculated; the intensity U of the returned temperature measurement optical signal is then normalized. raw Dividing by the loss factor α for intensity compensation yields the normalized light intensity U. norm =U raw / α; ensures that the amplitude of the optical signal input to the detector remains within the detector's linear range, unaffected by bending, swaying, or length differences; solves the problems of random attenuation of temperature measurement light intensity caused by fiber deformation, irregular drift in temperature measurement, and inability to compensate through fixed calibration.

[0048] The purified temperature-measuring optical signal is sent to the infrared detection module, where the infrared detector converts the optical signal intensity into a corresponding analog voltage signal, completing the photoelectric conversion and obtaining the initial electrical signal. Noise separation, baseline drift correction, and segmented feature enhancement are then performed on the initial electrical signal. First, hardware bandpass filtering and an adaptive digital notch filter algorithm are used to separate environmental electromagnetic noise, inherent circuit noise, power frequency interference, and the effective temperature measurement signal, eliminating invalid noise components. Next, based on multiple consecutive frames of sampled signals, moving averages and dynamic fitting are performed to correct baseline drift in real time, eliminating signal reference offsets caused by fiber bending loss, transmission distance variations, detector aging, and operating temperature changes. Furthermore, the electrical signal is segmented and its gain is adjusted according to three temperature ranges: low, medium, and high. Gain is increased for weak signals in the low-temperature range and compressed for strong signals in the high-temperature range, ensuring uniform and linear signal output with distinct characteristics across the entire temperature range. Finally, a steady-state feature vector with strong correlation to the processing temperature and high stability is extracted.

[0049] After extracting the steady-state feature vector, temporal correlation verification is performed on the feature vectors of multiple consecutive frames. Specifically, a feature sequence is formed by taking the feature vectors of 10 consecutive frames, and the Euclidean distance and correlation coefficient between adjacent frames are calculated. When the correlation coefficient is <0.6 and the Euclidean distance is > a set threshold, it is determined to be a transient interference mutation point and is directly removed. The remaining effective feature points are weighted and smoothed to obtain a feature sequence that truly reflects the changes in processing temperature. This solves the problem that plasma flash, dust, and splashes cause temperature measurement signal spikes and abrupt changes, and traditional filtering cannot distinguish between real temperature jumps and interference, leading to temperature control malfunctions.

[0050] The real-time temperature at the processing position is calculated based on the steady-state characteristic vector and the system's preset light intensity-temperature mapping relationship. Based on a temperature deviation grading and overshoot-free adjustment strategy, the output power of each pump source is adjusted in a closed loop to stabilize the processing position temperature within the set target accuracy range, avoiding temperature overshoot, oscillation, and control lag, ensuring continuous, stable, and controllable temperature during laser processing. The real-time processing temperature T is calculated using the following formula: T = K・ln(U / U0) + T0. Where: K is the system calibration coefficient, determined by fiber transmission loss, detector responsivity, beam combiner coupling efficiency, and optical path structure; U is the current characteristic electrical signal amplitude, directly reflecting the thermal radiation intensity at the processing point; U0 is the room temperature reference electrical signal, acquired after system power-on initialization; and T0 is the room temperature reference value, determined through system factory calibration. This formula accurately maps the electrical signal to the actual temperature, offering fast temperature response, good linearity, and high accuracy across the entire measurement range.

[0051] The power consistency calibration and mode normalization processing for the N-channel energy beams includes: real-time acquisition of the output optical power of each pump source; obtaining the actual output power of each pump beam through a high-sensitivity optical power acquisition unit; calculating the deviation between the power of each channel and the overall average power to obtain the degree of power deviation of each pump source; fine-tuning and registering the pump drive current of each channel based on the deviation value; adjusting the pump source drive current of each channel one by one through the laser control card to make the output power of multiple energy beams tend to be consistent, avoiding the decrease in coupling efficiency, output spot distortion and temperature control fluctuation caused by uneven power; and performing mode normalization processing on the pump beams to optimize the divergence angle and optical field distribution of the pump beams, so that the pump beams meet the mode matching conditions of multi-clad fiber cladding transmission, improve coupling efficiency, reduce backlight interference, and enhance transmission stability.

[0052] The process of achieving coaxial beam combining and core-cladding domain separation transmission through the coupling region includes: combining multiple energy beams within the coupling region and coupling them to the cladding of a multi-cladding fiber, utilizing the large aperture and high power carrying capacity of the cladding to achieve stable high-power energy transmission; independently coupling the temperature measurement signal beam to the fiber core and maintaining spatial coaxiality with the energy beam, ensuring that the temperature measurement optical path and the processing optical path are completely coaxial, with no angular deviation or positional offset; ensuring that the temperature measurement spot and the processing spot always coincide, achieving in-situ, deviation-free temperature acquisition at the processing point, eliminating the need for manual alignment and recalibration after disassembly and assembly, significantly improving temperature measurement consistency and ease of use.

[0053] The process of performing noise separation, baseline drift correction, and segmented feature enhancement on the initial electrical signal includes: using bandpass filtering and adaptive notch filtering to separate environmental and system noise, accurately filtering out power frequency interference, high-frequency electromagnetic interference, and low-frequency drift noise, while fully preserving the effective temperature measurement signal; correcting baseline drift based on multiple consecutive frames of signal, and eliminating signal reference offset caused by transmission loss, temperature changes, and device aging through moving average and dynamic fitting algorithms to ensure stable temperature measurement reference; specifically, using a moving average algorithm with a window length of M to smooth multiple consecutive frames of initial electrical signal, taking the signal data of the current frame and each (M-1) / 2 frames before and after it to form a local calculation window, and performing an arithmetic mean on all signal points within the window to obtain the moving average output value Y_avg(i)=(X(i-(M-1)). / 2)+X(i-(M-1) / 2+1)+…+X(i)+…+X(i+(M-1) / 2)) / M; Based on this, the least squares method is used to perform first-order linear dynamic fitting. The data points (x1,y1), (x2,y2)…(x_N,y_N) after N consecutive sets of moving averages are selected to construct the fitting line y=ax+b. The slope a=(N・Σx_jy_j−Σx_j・Σy_j) / (N・Σx_j²−(Σx_j)²) and the intercept b=(Σy_j−a・Σx_j) / N are obtained by calculation. The real-time baseline drift value is obtained based on the fitting line. Then, the original signal is subtracted from the corresponding baseline drift value to complete the dynamic correction and calibration of the signal baseline, and finally eliminate the signal offset caused by transmission loss, device aging and environmental changes.

[0054] The electrical signal is segmented and enhanced according to temperature range. The gain is increased for weak signals in the low temperature range and the gain is reasonably compressed for strong signals in the high temperature range. This improves the signal characteristic identification of the low temperature and high temperature ranges, so that the signal output is uniform and linear and the calculation accuracy is consistent throughout the entire temperature range.

[0055] The closed-loop adjustment of pump source output power based on temperature deviation grading and overshoot-free adjustment strategy includes: classifying the difference between real-time temperature and set temperature into three levels: slight deviation, minor deviation, and severe deviation, to achieve fine-grained grading of temperature deviation; adopting differentiated adjustment coefficients for different deviation levels, and outputting smooth adjustment commands through a PID algorithm, which allows for rapid adjustment when the deviation is large and fine-tuning when the deviation is small, taking into account both response speed and control stability; and adjusting the power of each pump according to the gradient synchronously to avoid temperature abrupt changes, overshoot, and oscillation, ensuring temperature stability during processing, and significantly improving the forming quality and consistency of laser welding, cladding, quenching, and other processing.

[0056] In another embodiment, a concrete physical product of the previous embodiment is provided, specifically including an integrated temperature-controlled laser, comprising: N laser pump sources, a multi-channel pump single-signal combiner, a multi-clad output fiber, a filter, an infrared detection module, a temperature processing module, and a laser control card; the N laser pump sources are used to output high-power pump energy light to provide energy for laser processing; the multi-channel pump single-signal combiner is used to achieve coaxial beam combining and transmission of multiple pump lights and one temperature measurement signal light; the multi-clad output fiber is used to achieve domain-specific coaxial transmission of cladding-transmitted energy light and core-transmitted temperature measurement signal light; the filter is used to filter out return pump light and stray interference light; the infrared detection module is used to convert thermal radiation light signals into electrical signals; the temperature processing module is used for signal processing, temperature calculation, and closed-loop control; and the laser control card is used to execute pump source power adjustment commands.

[0057] The laser pump source is connected to the pump input port of a multi-channel pump single-signal combiner, and the infrared detection module is connected to the signal input port, realizing independent input and unified beam combining of energy light and temperature measurement signal light. The multi-clad output fiber is connected to the output end of the combiner, with the fiber core transmitting the temperature measurement signal light and the cladding transmitting the pump energy light, achieving coaxial common path and independent domain transmission, completely solving the industry problems of non-axisymmetry, easy deviation, and difficulty in calibration between the temperature measurement optical path and the laser optical path. The filter is located at the front end of the infrared detection module to filter out the return pump light and stray light. The temperature processing module is electrically connected to the infrared detection module and the laser control card respectively, forming a complete closed loop of signal acquisition, processing, and control, ensuring fast system response and precise control.

[0058] The multi-channel pump single-signal combiner is fabricated using a fused taper process, resulting in high coupling efficiency, strong power carrying capacity, and stable and reliable structure. It has an internal isolation and filtering structure between the pump port and the signal port to prevent pump energy light crosstalk from entering the temperature measurement signal channel, thus preventing high-power light from damaging the detector and improving the signal-to-noise ratio of the temperature measurement signal.

[0059] The multi-clad output fiber has a double-clad or multi-clad structure with a core diameter of 10–200 μm. It is specifically designed for transmitting infrared temperature measurement signal light, with low transmission loss and high signal fidelity. The cladding has a multimode structure with a diameter ≥100 μm and a numerical aperture of 0.12–0.46, which provides high power carrying capacity and high coupling efficiency. It can stably transmit high-power pump energy light to meet the power requirements of various laser processing applications.

[0060] The infrared detection module includes an infrared detector, a signal amplification circuit, and a filtering circuit. The infrared detector is of the indium gallium arsenide or mercury cadmium telluride type, and its response band is matched with the temperature measurement signal light. It can convert the thermal radiation light signal into an analog electrical signal, and the signal is conditioned by the amplification and filtering circuit to output a stable and clear electrical signal to the temperature processing module, ensuring temperature measurement sensitivity and detection accuracy.

[0061] The temperature processing module has a built-in MCU or DSP chip and uses a PID algorithm, which has high-speed computing and real-time control capabilities. The laser control card adjusts the pump source output power in real time according to the instructions output by the temperature processing module to achieve closed-loop temperature control. The system response time is ≤1ms and the temperature control accuracy is within ±0.5℃, which can meet the stringent requirements of high-precision laser processing for temperature stability.

[0062] After the system is powered on, the pump energy light output from the N-channel laser pump source is input to the pump port of the multi-channel pump single-signal combiner after power consistency calibration; the infrared temperature measurement signal light output from the infrared detection module is input to the signal port of the combiner; the combiner couples the multi-channel energy light to the cladding of the multi-cladding fiber and couples the temperature measurement signal light to the fiber core, realizing coaxial common path and domain-specific transmission. The energy beam is transmitted through the cladding to the processing end and focused on the material surface to achieve laser heating, welding, or cladding. The thermal radiation light generated at the processing position travels back along the fiber core, and after being filtered by a filter to remove the returned energy beam and stray light, it enters the infrared detection module and is converted into an electrical signal. The electrical signal is then sent to the temperature processing module after noise reduction, correction, and segmented enhancement, where the real-time temperature is calculated according to the temperature measurement formula. Based on the temperature deviation classification results, the temperature processing module outputs adjustment commands to the laser control card through a PID algorithm. The laser control card synchronously adjusts the output power of each pump source to achieve high-precision closed-loop control of the processing temperature without overshoot or oscillation. Throughout the entire process, the temperature measurement spot and the laser processing spot remain coaxially aligned, requiring no calibration. The system is stable, has a fast response, accurate temperature measurement, and extremely high processing consistency.

Claims

1. A laser processing temperature control method based on fiber optic bundling and fiber optic transmission, characterized in that, The laser processing temperature control method based on fiber optic bundling and fiber optic transmission includes: The power consistency calibration and mode normalization of the energy light output from the N pump sources are performed. The processed multi-channel energy light and single-channel infrared temperature measurement signal light are input into the multi-channel pump single-signal combiner. Coaxial combining and core-cladding domain transmission are completed through the coupling region, so that the energy light is transmitted along the cladding of the multi-cladding fiber and the temperature measurement signal light is transmitted along the coaxial core. The thermal radiation light signal generated at the processing location is collected and transmitted back along the fiber core. The transmitted light signal is then filtered for backlight, suppressed for stray bands, and corrected for polarization disturbance to obtain a purified temperature measurement light signal. The purified temperature measurement optical signal is converted into an initial electrical signal. Noise separation, baseline drift correction and segmented feature enhancement are performed on the initial electrical signal to extract a steady-state feature vector that is strongly correlated with temperature. The real-time temperature at the processing position is calculated based on the steady-state feature vector and the preset mapping relationship. Based on the temperature deviation classification and overshoot-free adjustment strategy, the output power of each pump source is adjusted in a closed loop to stabilize the processing temperature within the target accuracy range. The real-time processing temperature T is calculated using the following formula: T=Kln(U / U0)+T0, where K is the system calibration coefficient, U is the amplitude of the current characteristic electrical signal, U0 is the room temperature reference electrical signal, and T0 is the room temperature reference value.

2. The laser processing temperature control method based on fiber optic bundling and fiber optic transmission according to claim 1, characterized in that, The power consistency calibration and mode normalization processing for the N-channel energy beams includes: real-time acquisition of the output optical power of each pump source and calculation of the deviation between the power of each channel and the mean. The pump drive current of each channel is finely adjusted and registered according to the deviation value to ensure that the output power of multiple energy beams remains consistent. The pump light is mode-normalized to ensure that it meets the mode matching conditions for cladding transmission in multi-clad optical fibers.

3. The laser processing temperature control method based on fiber optic bundling and fiber optic transmission according to claim 1, characterized in that, The method of completing coaxial beam combining and core-cladding domain-separated transmission through the coupling region includes: combining multiple energy beams within the coupling region and coupling them to the cladding of a multi-cladding fiber; The temperature measurement signal light is independently coupled to the fiber core and spatially coaxial with the energy light; This ensures that the temperature measurement spot and the processing spot always coincide, achieving in-situ, deviation-free temperature acquisition at the processing point.

4. The laser processing temperature control method based on fiber optic bundling and fiber optic transmission according to claim 1, characterized in that, The process of performing noise separation, baseline drift correction, and segmented feature enhancement on the initial electrical signal includes: using bandpass filtering and adaptive notch filtering to separate environmental noise from system noise; Baseline drift is corrected based on multiple consecutive frames of signal to eliminate transmission loss and offset caused by detector aging. The electrical signal is segmented and enhanced according to temperature range to improve the characteristic recognition of low temperature and high temperature ranges.

5. The laser processing temperature control method based on fiber optic bundling and fiber optic transmission according to claim 1, characterized in that, The closed-loop regulation of pump source output power based on temperature deviation classification and overshoot-free regulation strategy includes: classifying the difference between real-time temperature and set temperature into three levels: slight deviation, mild deviation, and severe deviation. Differentiated adjustment coefficients are adopted for different deviation levels, and smooth adjustment commands are output through PID algorithm; The power of each pump is adjusted synchronously according to the gradient to avoid temperature overshoot and oscillation, and to ensure stable temperature during the processing.

6. An integrated temperature-controlled laser, applied to the laser processing temperature control method based on fiber optic bundling and fiber optic transmission as described in any one of claims 1-5, characterized in that, include: N laser pump sources, multi-channel pump single-signal combiner, multi-clad output fiber, filter, infrared detection module, temperature processing module and laser control card; The laser pump source is connected to the pump input port of the multi-channel pump single-signal beam combiner, and the infrared detection module is connected to the signal input port. The multi-clad output optical fiber is connected to the output end of the combiner. The fiber core transmits the temperature measurement signal light, and the cladding transmits the pump energy light. The filter is located at the front end of the infrared detection module, and the temperature processing module is electrically connected to the infrared detection module and the laser control card respectively.

7. The integrated temperature-controlled laser according to claim 6, characterized in that, The multi-channel pump single-signal combiner is fabricated using a fused taper process and has an internal isolation structure between the pump port and the signal port to prevent crosstalk between the pump light and the temperature measurement channel.

8. The integrated temperature-controlled laser according to claim 6, characterized in that, The multi-clad output fiber has a double-clad or multi-clad structure, a core diameter of 10–200 μm, a multimode cladding structure with a diameter ≥100 μm, and a numerical aperture of 0.12–0.

46.

9. The integrated temperature-controlled laser according to claim 6, characterized in that, The infrared detection module includes an infrared detector, a signal amplification circuit, and a filtering circuit, which are used to convert thermal radiation light signals into electrical signals.

10. The integrated temperature-controlled laser according to claim 6, characterized in that, The temperature processing module has a built-in MCU or DSP chip and uses a PID algorithm. The laser control card adjusts the pump source power according to the instructions of the temperature processing module to achieve closed-loop temperature control.

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