A method of fiber coupling clamp positioning calibration

Abstract

The present application relates to the technical field of optical fiber coupling clamping positioning calibration, and discloses a kind of optical fiber coupling clamping positioning calibration method, optical fiber or lens clamping positioning is calculated with standard calibration piece theoretical coupling target position;With grating calibration plate establishes pixel mapping, calculates spatial displacement deviation;Generation multi-degree-of-freedom adjustment instruction controls five degrees of freedom and monitors coupling efficiency;Adopt random parallel gradient descent algorithm closed loop iteration until coupling efficiency reaches threshold value.The whole process closed loop control from initial clamping to final alignment of the optical fiber coupling clamping positioning calibration method improves coupling efficiency and repeat accuracy, calculates theoretical coupling target position by standard piece turnover measurement, thereby eliminating the system deviation of clamp and optical path, and accurate mapping of pixel and physical size is established using grating calibration plate, image distortion influence is eliminated, visual deviation is converted into spatial displacement deviation after driving adjustment, blind search is avoided.

Description

Technical Field

[0001] This invention relates to the field of optical fiber coupling clamping positioning and calibration technology, specifically to an optical fiber coupling clamping positioning and calibration method. Background Technology

[0002] Fiber optic coupling technology is a key process for achieving efficient transmission of optical signals between optical fibers and light sources, optical fibers and optical fibers, or optical fibers and optical chips. It is widely used in optical communication, fiber optic sensing, laser processing, medical optics and other fields. In the process of fiber optic coupling, clamping, positioning and calibration are the core links that determine the coupling efficiency.

[0003] In existing technologies, most methods separate the fixture clamping and positioning from the optical path calibration, lacking a complete process design from initial clamping to final alignment. This results in the inability to systematically identify and compensate for the clamping error of the fixture itself, affecting the repeatability accuracy. Secondly, when relying solely on visual images for fiber core positioning, positioning deviations are prone to occur due to distortion in the image acquisition system and unclear mapping relationships between pixel size and physical size. On the other hand, when relying solely on optical power feedback for active alignment, the algorithm converges slowly, especially when facing multiple error couplings such as radial deviation, end face tilt deviation, and axial deviation, making it prone to getting trapped in local optima. Therefore, it is necessary to invent a fiber optic coupled clamping, positioning, and calibration method to solve the above problems. Summary of the Invention

[0004] This invention provides the following technical solution: a fiber optic coupling clamping positioning and calibration method, characterized by comprising the following steps: S1. Place the optical fiber or lens element to be coupled in the predetermined clamping position of the fixture, and perform initial positioning through the pre-calibrated fixed reference surface to make the optical end face of the element roughly aligned with the optical path system. S2. Mount the standard calibration piece with the known geometric relationship between the optical center and the positioning surface on the same fixture, emit a collimated spot by driving the light source and collect the spot coordinates of the standard piece at different flip angles in sequence, calculate and store the theoretical coupling target position of the collimated spot to complete the system-level optical path calibration. S3. A high-resolution image acquisition device is used to capture images of the fiber core end face in real time. At the same time, a grating calibration plate with a known scribe line spacing is placed in the field of view. The pixel spacing of the grating scribe lines is identified by the image processing algorithm, and a mapping relationship between pixels and actual physical size is established. This mapping relationship is used to eliminate the distortion of the image acquisition system, and the pixel deviation between the current fiber core image center and the theoretical coupling target position is calculated and then converted into the actual spatial displacement deviation. S4. Based on the spatial displacement deviation calculated in step S3, generate multi-degree-of-freedom adjustment commands to independently control the micro-displacement of the optical fiber in five degrees of freedom: X-axis, Y-axis, Z-axis, pitch angle, and yaw angle. After each adjustment, immediately monitor and record the coupling efficiency value of the current optical path. S5. Using the coupling efficiency value obtained in step S4 as the optimization target, a stochastic parallel gradient descent algorithm is used for closed-loop iteration. In each iteration, independent random perturbations are applied to the control parameters of each degree of freedom, and the change in coupling efficiency after the perturbation is measured. The gradient direction of each degree of freedom is estimated based on the change. Then, the control parameters of all degrees of freedom are updated simultaneously along the gradient descent direction. The above iterative process is repeated until the coupling efficiency reaches the preset threshold. Finally, the set of control parameters is locked as the final coupling attitude.

[0005] Preferably, the calibration process of the standard calibration piece in step S2 specifically includes: firstly, clamping the standard piece in the forward orientation, recording the first coordinates P1=(x1, y1) of the collimated spot on the detector, then rotating the standard piece 180 degrees around the axis perpendicular to the optical axis and clamping it, recording the second coordinates P2=(x2, y2) of the collimated spot, and calculating the midpoint between the first coordinate and the second coordinate as the theoretical coupling target position P0 of the system optical axis.

[0006] Preferably, the initial positioning in step S1 includes: detecting the contact state between the fiber end face and the optical waveguide chip or lens by force sensing; when the contact force reaches a preset range, it is determined that the two are in a relatively close position, and this is used as the starting point for subsequent fine adjustment; if the contact force exceeds the preset range, an alarm is issued and the adjustment action is stopped.

[0007] Preferably, when calculating the deviation between the current fiber core and the target coupling position in step S3, it also includes an independent measurement and compensation step for the clamping error of the fixture itself: First, a known qualified standard fixture is used to clamp the reference fiber, and the reference position coordinates of the fiber core in the image field of view are captured and stored; then, the fixture under test clamps the end of the same reference fiber in the same posture, and the fiber core position coordinates are captured under the same image acquisition parameters; the offset of the fiber core coordinates under the fixture under test relative to the reference coordinates is calculated, and the offset is used as the inherent clamping error value of the fixture under test, and the error value is deducted from the measurement deviation in all subsequent coupling calculations.

[0008] Preferably, the iterative process of the stochastic parallel gradient descent algorithm in step S5 further includes: at the beginning of each iteration, reading the control parameter vector of the current five degrees of freedom. Generate a set of random perturbation vectors with zero mean and following independent and identical distribution. The amplitude of the perturbation is dynamically adjusted based on the current iteration step and coupling efficiency. Positive and negative perturbations are applied sequentially to each degree of freedom, or small-amplitude random perturbations are applied to all degrees of freedom simultaneously. The coupling efficiency before and after the perturbation is measured respectively. and The efficiency change difference for each degree of freedom is calculated, and the gradient estimate for that degree of freedom is obtained by dividing the difference by the perturbation magnitude. The above process is repeated until the coupling efficiency no longer increases significantly in consecutive iterations, or the preset maximum number of iterations is reached.

[0009] Preferably, before step S1, a coaxial optical path pre-calibration step is included: the output end of the light source and the input end of the optical fiber are respectively placed at both ends of the optical path system, and an auxiliary laser light source is connected to the output end of the optical fiber; the main light source and the auxiliary laser light source are turned on at the same time, and the main light spot and the laser light spot transmitted in the forward direction are observed respectively using a spot acquisition device at the input end of the optical fiber; by adjusting the installation posture of the light source or the optical fiber, the forward light spot and the reverse light spot are completely overlapped on the acquisition device, thereby confirming that the optical axis is in a coaxial state.

[0010] Preferably, the multi-degree-of-freedom adjustment command in step S4 is generated based on the following: the actual spatial displacement deviation calculated in step S3 is decomposed into five independent components: X-axis offset, Y-axis offset, Z-axis offset, pitch angle deviation around the X-axis, and yaw angle deviation around the Y-axis; the number of adjustment steps and direction required for each degree of freedom are calculated according to the sign and magnitude of each component; during the adjustment process, the adjustment is performed in the order of angle adjustment followed by translation adjustment, and coarse adjustment followed by fine adjustment: first, the pitch angle and yaw angle deviations are eliminated to make the fiber core end face perpendicular to the optical axis; then, the X-axis and Y-axis deviations are adjusted to make the fiber core center aligned with the center of the light spot; finally, the Z-axis deviation is adjusted to make the fiber core end face located at the focal point of the beam.

[0011] Preferably, the preset threshold in step S5 is set in stages according to the fiber type and coupling requirements: for single-mode fiber coupling, the threshold is set to a coupling efficiency of not less than 50%; for multimode fiber coupling, the threshold is set to a coupling efficiency of not less than 75%; for polarization-maintaining fiber coupling, in addition to meeting the coupling efficiency threshold, the polarization extinction ratio needs to be detected, and the calibration is considered complete only when the extinction ratio reaches a predetermined value; if the threshold is not reached within the set maximum number of iterations, the system automatically judges it as a coupling failure and outputs diagnostic information on the reason for the failure.

[0012] Preferably, it also includes error modeling and feedforward compensation steps: before starting the stochastic parallel gradient descent algorithm, the radial deviation is measured in advance. end face tilt deviation θ and axial deviation The impact curves of these three typical errors on coupling efficiency are used to fit the efficiency loss model under the individual effect of each error. In the actual iteration process, based on the real-time monitored deviations of each degree of freedom, the theoretical feedforward compensation amount for the current error combination is estimated using the efficiency loss model. .

[0013] Preferably, the real-time monitoring method for coupling efficiency is as follows: a photodetector is set at the output end of the optical path system. The detector converts the received optical power into an electrical signal, which is then sent to the controller after analog-to-digital conversion. The controller continuously reads the optical power value at a fixed sampling frequency and uses a moving average filtering algorithm to smooth the read sequence to eliminate interference from light source fluctuations and environmental noise. After each adjustment, the controller compares the current smoothed optical power value with the optical power value before adjustment. If the difference exceeds a preset threshold change, the adjustment is confirmed to be effective and optimization continues. If the difference is within the allowable fluctuation range, it is determined that the convergence region has been entered, and the amplitude of subsequent random disturbances is reduced.

[0014] Compared with the prior art, the present invention provides an optical fiber coupling clamping positioning and calibration method, which has the following beneficial effects: 1. This fiber optic coupling clamping and positioning calibration method features closed-loop control throughout the entire process from initial clamping to final alignment, improving coupling efficiency and repeatability. It calculates the theoretical coupling target position by rotating standard parts to eliminate system deviations in the clamps and optical paths. Furthermore, it establishes a precise mapping between pixels and physical dimensions using a grating calibration board, eliminating the influence of image distortion. Visual deviations are converted into spatial displacement deviations to drive adjustment, avoiding blind searching.

[0015] 2. This fiber optic coupling clamping positioning and calibration method estimates the gradient directions of five degrees of freedom in parallel using gradient estimation formulas and parameter update formulas. It introduces error modeling and feedforward compensation, pre-fits the influence curves of radial, tilt, and axial deviations, and solves the feedforward compensation amount superimposed on the initial control parameters. This allows the algorithm to start iterating from a state closer to the optimal point, reducing the average number of iterations from over 40 to less than 15. At the same time, it sets graded coupling thresholds for single-mode, multi-mode, and polarization-maintaining fibers, demonstrating good versatility.

[0016] 3. This fiber optic coupling clamping and positioning calibration method compares the fiber core coordinates of the standard fixture and the fixture under test, independently measures and deducts the clamping error of the fixture itself, so that the alignment accuracy is no longer limited by the repeatability of fixture manufacturing. It uses force sensing to detect the contact state to avoid visual blind spots and component damage. It achieves coaxial pre-calibration by judging the coincidence of forward and reverse light spots, follows the adjustment sequence of first angle and then translation, first coarse adjustment and then fine adjustment, and uses moving average filtering to eliminate light source fluctuation interference. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a technical solution: a fiber optic coupling clamping positioning and calibration method, characterized by comprising the following steps: S1. Place the optical fiber or lens element to be coupled in the predetermined clamping position of the fixture, and perform initial positioning through the pre-calibrated fixed reference surface to make the optical end face of the element roughly aligned with the optical path system. The initial positioning in step S1 includes: detecting the contact state between the fiber end face and the optical waveguide chip or lens by force sensing. When the contact force reaches a preset range, it is determined that the two are in a relatively close relative position, and this is used as the starting point for subsequent fine adjustment. If the contact force exceeds the preset range, an alarm is issued and the adjustment action is stopped to prevent damage to the fiber or chip.

[0019] Before step S1, a coaxial optical path pre-calibration step is also included: the output end of the light source and the input end of the optical fiber are respectively placed at both ends of the optical path system, and an auxiliary laser light source is connected to the output end of the optical fiber; the main light source and the auxiliary laser light source are turned on at the same time, and the main light spot of forward transmission and the laser light spot of reverse transmission are observed at the input end of the optical fiber using a spot acquisition device; by adjusting the installation posture of the light source or the optical fiber, the forward light spot and the reverse light spot are completely overlapped on the acquisition device, thereby confirming that the optical axis is in a coaxial state, thereby eliminating the coupling efficiency loss caused by the optical path being out of sync.

[0020] S2. Mount the standard calibration piece with the known geometric relationship between the optical center and the positioning surface on the same fixture, emit a collimated spot by driving the light source and collect the spot coordinates of the standard piece at different flip angles in sequence, calculate and store the theoretical coupling target position of the collimated spot to complete the system-level optical path calibration. The calibration process of the standard calibration piece in step S2 specifically includes: first, clamping the standard piece upright, recording the first coordinates of the collimated spot on the detector P1 = (x1, y1); then, rotating the standard piece 180 degrees around an axis perpendicular to the optical axis and clamping it again, recording the second coordinates of the collimated spot P2 = (x2, y2); and calculating the midpoint between the first and second coordinates as the theoretical coupling target position P0 of the system's optical axis, using the following formula:

[0021] When coupling all actual workpieces in the future, this theoretical position will be used as the alignment reference to eliminate the repeatability error of the fixture clamping and the inherent deviation of the optical path system.

[0022] S3. A high-resolution image acquisition device is used to capture images of the fiber core end face in real time. At the same time, a grating calibration plate with a known scribe line spacing is placed in the field of view. The pixel spacing of the grating scribe lines is identified by the image processing algorithm, and a mapping relationship between pixels and actual physical size is established. This mapping relationship is used to eliminate the distortion of the image acquisition system and to calculate the pixel deviation between the current fiber core image center and the theoretical coupling target position, which is then converted into the actual spatial displacement deviation. In step S3, when calculating the deviation between the current fiber core and the target coupling position, an independent measurement and compensation step for the clamping error of the fixture itself is also included: First, a known qualified standard fixture is used to clamp the reference fiber, and the reference position coordinates of the fiber core in the image field of view are captured and stored; then, the fixture under test clamps the end of the same reference fiber in the same posture, and the fiber core position coordinates are captured under the same image acquisition parameters; the offset of the fiber core coordinates under the fixture under test relative to the reference coordinates is calculated, and this offset is used as the inherent clamping error value of the fixture under test, and this error value is subtracted from the measurement deviation in all subsequent coupling calculations.

[0023] S4. Based on the spatial displacement deviation calculated in step S3, generate multi-degree-of-freedom adjustment commands to independently control the micro-displacement of the optical fiber in five degrees of freedom: X-axis, Y-axis, Z-axis, pitch angle, and yaw angle. After each adjustment, immediately monitor and record the coupling efficiency value of the current optical path. The multi-degree-of-freedom adjustment command in step S4 is generated based on the following: the actual spatial displacement deviation calculated in step S3 is decomposed into five independent components: X-axis offset, Y-axis offset, Z-axis offset, pitch angle deviation around the X-axis, and yaw angle deviation around the Y-axis; according to the sign and magnitude of each component, the required adjustment steps and directions for each degree of freedom are calculated respectively; during the adjustment process, the adjustment is performed in the order of angle first, then translation, and coarse adjustment first, then fine adjustment: first, eliminate the pitch angle and yaw angle deviations to make the fiber core end face perpendicular to the optical axis, then adjust the X-axis and Y-axis deviations to make the fiber core center aligned with the center of the beam spot, and finally adjust the Z-axis deviation to make the fiber core end face located at the beam focal point.

[0024] S5. Using the coupling efficiency value obtained in step S4 as the optimization target, a stochastic parallel gradient descent algorithm is used for closed-loop iteration. In each iteration, independent random perturbations are applied to the control parameters of each degree of freedom, and the change in coupling efficiency after the perturbation is measured. The gradient direction of each degree of freedom is estimated based on the change. Then, the control parameters of all degrees of freedom are updated simultaneously along the gradient descent direction. The above iterative process is repeated until the coupling efficiency reaches the preset threshold. Finally, the set of control parameters is locked as the final coupling attitude.

[0025] The iterative process of the stochastic parallel gradient descent algorithm in step S5 further includes: at the beginning of each iteration, reading the control parameter vectors of the current five degrees of freedom. Generate a set of random perturbation vectors with zero mean and following independent and identical distribution. The amplitude of the perturbation is dynamically adjusted based on the current iteration step and coupling efficiency. Positive and negative perturbations are applied sequentially to each degree of freedom, or small-amplitude random perturbations are applied to all degrees of freedom simultaneously. The coupling efficiency before and after the perturbation is measured respectively. and The efficiency change difference at each degree of freedom is calculated, and the gradient estimate for that degree of freedom is obtained by dividing the difference by the perturbation amplitude, as shown in the formula:

[0026] Where i = 1, 2, 3, 4, 5, the control parameters of each degree of freedom are adjusted in reverse according to the rule of multiplying the learning rate α by the gradient estimate, and the update formula is:

[0027] Repeat the above process until the coupling efficiency no longer increases significantly in consecutive iterations, or until the preset maximum number of iterations is reached.

[0028] The preset threshold in step S5 is set in stages according to the fiber type and coupling requirements: for single-mode fiber coupling, the threshold is set to a coupling efficiency of not less than 50%; for multimode fiber coupling, the threshold is set to a coupling efficiency of not less than 75%; for polarization-maintaining fiber coupling, in addition to meeting the coupling efficiency threshold, the polarization extinction ratio also needs to be detected, and the calibration is considered complete only when the extinction ratio reaches the predetermined value; if the threshold is not reached within the set maximum number of iterations, the system automatically judges it as a coupling failure and outputs diagnostic information on the reason for the failure.

[0029] Furthermore, it also includes error modeling and feedforward compensation steps: before starting the stochastic parallel gradient descent algorithm, the radial deviation is measured in advance. end face tilt deviation θ and axial deviation The impact curves of these three typical errors on coupling efficiency are used to fit the efficiency loss model under the individual effect of each error. In the actual iteration process, based on the real-time monitored deviations of each degree of freedom, the theoretical feedforward compensation amount for the current error combination is estimated using an efficiency loss model. The calculation method involves finding the compensation vector that minimizes the efficiency loss:

[0030] in, Indicates compensation amount The mapping relationship with the actual error is used to superimpose the feedforward compensation amount onto the initial control parameters of the stochastic parallel gradient descent algorithm, that is, to set the initial control parameters... This allows the algorithm to start iterating from an initial state that is closer to the optimal point, thereby reducing the number of iterations and improving convergence stability.

[0031] Furthermore, the real-time monitoring method for coupling efficiency is as follows: a photodetector is set at the output end of the optical path system. This detector converts the received optical power into an electrical signal, which is then sent to the controller after analog-to-digital conversion. The controller continuously reads the optical power value at a fixed sampling frequency and uses a moving average filtering algorithm to smooth the read sequence to eliminate interference from light source fluctuations and environmental noise. After each adjustment, the controller compares the current smoothed optical power value with the optical power value before adjustment. If the difference exceeds a preset threshold change, the adjustment is confirmed to be effective and optimization continues. If the difference is within the allowable fluctuation range, it is determined that the convergence region has been entered, and the amplitude of subsequent random disturbances is reduced to improve the adjustment accuracy.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fiber optic coupling clamping positioning and calibration method, characterized in that, Includes the following steps: S1. Place the optical fiber or lens element to be coupled in the predetermined clamping position of the fixture, and perform initial positioning through the pre-calibrated fixed reference surface to make the optical end face of the element roughly aligned with the optical path system. S2. Mount the standard calibration piece with the known geometric relationship between the optical center and the positioning surface on the same fixture, emit a collimated spot by driving the light source and collect the spot coordinates of the standard piece at different flip angles in sequence, calculate and store the theoretical coupling target position of the collimated spot to complete the system-level optical path calibration. S3. A high-resolution image acquisition device is used to capture images of the fiber core end face in real time. At the same time, a grating calibration plate with a known scribe line spacing is placed in the field of view. The pixel spacing of the grating scribe lines is identified by the image processing algorithm, and a mapping relationship between pixels and actual physical size is established. This mapping relationship is used to eliminate the distortion of the image acquisition system, and the pixel deviation between the current fiber core image center and the theoretical coupling target position is calculated and then converted into the actual spatial displacement deviation. S4. Based on the spatial displacement deviation calculated in step S3, generate multi-degree-of-freedom adjustment commands to independently control the micro-displacement of the optical fiber in five degrees of freedom: X-axis, Y-axis, Z-axis, pitch angle, and yaw angle. After each adjustment, immediately monitor and record the coupling efficiency value of the current optical path. S5. Using the coupling efficiency value obtained in step S4 as the optimization target, a stochastic parallel gradient descent algorithm is used for closed-loop iteration. In each iteration, independent random perturbations are applied to the control parameters of each degree of freedom, and the change in coupling efficiency after the perturbation is measured. The gradient direction of each degree of freedom is estimated based on the change. Then, the control parameters of all degrees of freedom are updated simultaneously along the gradient descent direction. The above iterative process is repeated until the coupling efficiency reaches the preset threshold. Finally, the set of control parameters is locked as the final coupling attitude.

2. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The calibration process of the standard calibration piece in step S2 specifically includes: first, clamping the standard piece in the forward direction, recording the first coordinate P1 = (x1, y1) of the collimated spot on the detector, then rotating the standard piece 180 degrees around the axis perpendicular to the optical axis and clamping it, recording the second coordinate P2 = (x2, y2) of the collimated spot, and calculating the midpoint between the first coordinate and the second coordinate as the theoretical coupling target position P0 of the system optical axis.

3. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The initial positioning in step S1 includes: detecting the contact state between the fiber end face and the optical waveguide chip or lens by force sensing; when the contact force reaches a preset range, it is determined that the two are in a relatively close position and this is used as the starting point for subsequent fine adjustment; if the contact force exceeds the preset range, an alarm is issued and the adjustment action is stopped.

4. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, When calculating the deviation between the current fiber core and the target coupling position in step S3, it also includes an independent measurement and compensation step for the clamping error of the fixture itself: first, use a known qualified standard fixture to clamp the reference fiber, take a picture of the reference position coordinates of the fiber core in the image field of view and store it. Then, the fixture under test clamps the end of the same reference fiber in the same posture, and the fiber core position coordinates are captured under the same image acquisition parameters; the offset of the fiber core coordinates under the fixture under test relative to the reference coordinates is calculated, and this offset is taken as the inherent clamping error value of the fixture under test, and this error value is subtracted from the measurement deviation in all subsequent coupling calculations.

5. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The iterative process of the stochastic parallel gradient descent algorithm in step S5 further includes: at the beginning of each iteration, reading the control parameter vector of the current five degrees of freedom. Generate a set of random perturbation vectors with zero mean and following independent and identical distribution. The amplitude of the perturbation is dynamically adjusted based on the current iteration step and coupling efficiency. Positive and negative perturbations are applied sequentially to each degree of freedom, or small-amplitude random perturbations are applied to all degrees of freedom simultaneously. The coupling efficiency before and after the perturbation is measured respectively. and The efficiency change difference for each degree of freedom is calculated, and the gradient estimate for that degree of freedom is obtained by dividing the difference by the perturbation magnitude. The above process is repeated until the coupling efficiency no longer increases significantly in consecutive iterations, or the preset maximum number of iterations is reached.

6. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, Before step S1, a coaxial optical path pre-calibration step is also included: the output end of the light source and the input end of the optical fiber are respectively placed at both ends of the optical path system, and an auxiliary laser light source is connected to the output end of the optical fiber; the main light source and the auxiliary laser light source are turned on at the same time, and the main light spot and the laser light spot transmitted in the forward direction are observed respectively using a spot acquisition device at the input end of the optical fiber; by adjusting the installation posture of the light source or the optical fiber, the forward light spot and the reverse light spot are completely overlapped on the acquisition device, thereby confirming that the optical axis is in a coaxial state.

7. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The multi-degree-of-freedom adjustment command in step S4 is generated based on the following: the actual spatial displacement deviation calculated in step S3 is decomposed into five independent components: X-axis offset, Y-axis offset, Z-axis offset, pitch angle deviation around the X-axis, and yaw angle deviation around the Y-axis; according to the sign and magnitude of each component, the required adjustment steps and direction for each degree of freedom are calculated respectively; during the adjustment process, the adjustment is performed in the order of angle adjustment followed by translation adjustment, and coarse adjustment followed by fine adjustment: first, eliminate the pitch angle and yaw angle deviations to make the fiber core end face perpendicular to the optical axis, then adjust the X-axis and Y-axis deviations to align the fiber core center with the beam spot center, and finally adjust the Z-axis deviation to position the fiber core end face at the beam focal point.

8. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The preset threshold in step S5 is set in stages according to the fiber type and coupling requirements: for single-mode fiber coupling, the threshold is set to a coupling efficiency of not less than 50%. For multimode fiber coupling, the threshold is set to a coupling efficiency of not less than 75%. For polarization-maintaining fiber coupling, in addition to meeting the coupling efficiency threshold, the polarization extinction ratio also needs to be detected. The calibration is considered complete only when the extinction ratio reaches the predetermined value. If the threshold is not reached within the set maximum number of iterations, the system automatically judges it as a coupling failure and outputs diagnostic information on the reason for the failure.

9. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, It also includes error modeling and feedforward compensation steps: before starting the stochastic parallel gradient descent algorithm, the radial deviation is measured in advance. end face tilt deviation θ and axial deviation The impact curves of these three typical errors on coupling efficiency are used to fit the efficiency loss model under the individual effect of each error. In the actual iteration process, based on the real-time monitored deviations of each degree of freedom, the theoretical feedforward compensation amount for the current error combination is estimated using the efficiency loss model. .

10. The fiber optic coupling clamping positioning and calibration method according to claim 1, characterized in that, The real-time monitoring method for the coupling efficiency is as follows: a photodetector is set at the output end of the optical path system. The detector converts the received optical power into an electrical signal, which is then sent to the controller after analog-to-digital conversion. The controller continuously reads the optical power value at a fixed sampling frequency and uses a moving average filtering algorithm to smooth the read sequence in order to eliminate interference from light source fluctuations and environmental noise. After each adjustment, the controller compares the current smoothed optical power value with the optical power value before adjustment. If the difference exceeds the preset threshold change, the adjustment is confirmed to be effective and optimization continues. If the difference is within the allowable fluctuation range, it is determined that the convergence region has been entered, and the amplitude of subsequent random disturbances is reduced.

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