A beam collimation method and system based on near-field reference

Abstract

This invention relates to a beam collimation method and system based on a near-field reference, belonging to the field of laser collimation technology. The method includes: setting a first detection plate with a limited aperture and a second detection plate without aperture limitation in the beam transmission optical path; acquiring a first position offset of the beam at the first detection plate, and adjusting the first reflector based on a pre-calibrated first mapping relationship between a first reflector adjustment amount and the beam offset at the first detection plate; acquiring a second position offset of the beam at the first detection plate and a third position offset at the second detection plate; and jointly adjusting the first and second reflectors based on the pre-calibrated second mapping relationship between the reflector adjustment amount and the beam offset at the detection plate, combined with the second and third position offsets, until the position deviation meets a preset collimation accuracy. This invention can stably and efficiently complete collimation under large deviation conditions without beam splitting and sampling.

Description

Technical Field

[0001] This invention belongs to the field of laser collimation technology, and specifically relates to a beam collimation method and system based on a near-field reference. Background Technology

[0002] With the rapid development of laser technology, laser systems are evolving towards larger scale, multi-path, and greater complexity. In large laser systems, the beam transmission path often stretches for tens or even hundreds of meters, containing numerous optical components such as mirrors, lenses, amplifiers, and spatial filters. Although each optical component is precisely aligned to the theoretical optical path during initial system assembly and adjustment, the actual beam transmission path inevitably deviates from the original design path during long-term operation due to multiple factors, including the slow drift of the oscillator output beam, thermal deformation of the mechanical structure caused by changes in ambient temperature, stress release and creep of the optical component support, and micro-vibrations of the foundation. Therefore, the optical path must be re-collimated before each system operation to ensure the beam has the correct spatial position and pointing angle, thereby guaranteeing the normal operation and output performance of the laser system.

[0003] Currently, optical path collimation in large laser systems generally employs a dual-reference strategy of "far-field reference + near-field reference." The near-field reference is used to monitor and correct the lateral positional deviation of the beam on a specific cross-section. This is typically achieved by inserting a beam splitter or wedge mirror into the optical path to divert a small portion of the main beam's energy onto a near-field detector. The far-field reference, on the other hand, is used to monitor and correct the beam's pointing angle deviation. This usually requires focusing the sampled beam through a long focal length lens to form a far-field spot on the focal plane, and the beam's direction is determined by the position of this spot. However, this traditional approach has significant limitations: firstly, the introduction of beam splitters or sampling elements increases the complexity of the optical path and insertion loss; secondly, to obtain sufficiently sensitive far-field angular resolution, a relatively long focusing optical path is often required, which places high demands on the system's spatial layout. Summary of the Invention

[0004] To address the shortcomings of existing technologies, a beam collimation method and system based on a near-field reference is proposed, which achieves fast and reliable beam collimation without increasing the complexity of the optical path.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a beam collimation method based on a near-field reference, comprising: S100. A first detection plate with a limited aperture and a second detection plate without a limited aperture are provided in the transmission optical path of the beam. S200: Obtain the first position offset of the beam at the first detection plate, and adjust the first reflector based on the first mapping relationship between the adjustment amount of the first reflector and the beam offset at the first detection plate, so as to eliminate the light transmission blockage of the beam at the first detection plate. S300: Obtain the second position offset of the beam at the first detection plate and the third position offset at the second detection plate; S400. Based on the second mapping relationship between the pre-calibrated adjustment amount of the reflector and the beam offset at the detection plate, and in combination with the second position offset and the third position offset, the first reflector and the second reflector are jointly adjusted until the position deviation of the beam at the first detection plate and the second detection plate meets the preset collimation accuracy.

[0006] The technical solution is further configured such that the first detection plate is a perforated plate, the second detection plate is a blind plate, and the distance between the perforated plate and the blind plate is determined based on a preset collimation accuracy.

[0007] The technical solution is further configured such that the light-transmitting hole structure of the small hole plate is either a single hole structure in the middle or a four-hole structure around the perimeter, and the aperture of the light-transmitting hole of the small hole plate is smaller than the aperture of the light beam. When the light-transmitting aperture structure is a four-hole structure, the position of the light beam at the small aperture plate is the average value of the light spot positions at the four light-transmitting apertures.

[0008] The technical solution is further configured such that the first mapping relationship and the second mapping relationship are obtained by decoupling the motion of the first reflector and the second reflector in two mutually orthogonal dimensions and then calibrating them.

[0009] This technical solution is further configured such that the calibration process includes: S01. Under the initial posture, acquire the initial spot position of the beam at the first detection plate and the second detection plate; S02. Control the first reflector to move by a preset step length in the two dimensions respectively, collect the position of the first spot of the beam at the first detection plate, and after moving the first detection plate out of the transmission optical path, control the first reflector to move by a preset step length in the two dimensions respectively, collect the position of the second spot of the beam at the second detection plate. S03. Control the second reflector to move by a preset step length in the two dimensions respectively, collect the third spot position of the beam at the second detection plate, and after the first detection plate is moved back into the transmission optical path, collect the fourth spot position of the beam at the first detection plate. S04. Based on the initial spot position, the first spot position, the second spot position, the third spot position, and the fourth spot position, determine the first mapping relationship and the second mapping relationship.

[0010] The technical solution is further configured such that the execution order of step S02 can be adjusted to after step S03.

[0011] This technical solution is further configured such that, before the light beam enters the transmission optical path, the method also includes: The beam is shaped into a pinhole beam.

[0012] This technical solution is further configured such that shaping the light beam into a pinhole light includes: The light beam is shaped using an aperture or a liquid crystal light modulator.

[0013] This technical solution is further configured such that the joint adjustment of the first reflector and the second reflector satisfies the following relationship: , Wherein, ΔP1_x and ΔP1_y are the positional offsets of the beam at the first detection plate in the x and y directions, respectively; ΔP2_x and ΔP2_y are the positional offsets of the beam at the second detection plate in the x and y directions, respectively; ΔM1_x and ΔM1_y are the required adjustment amounts of the first reflector in the x and y directions, respectively; ΔM2_x and ΔM2_y are the required adjustment amounts of the second reflector in the x and y directions, respectively; and M is the mapping matrix corresponding to the second mapping relationship. .

[0014] Secondly, the present invention provides a beam collimation system based on a near-field reference for implementing the method, comprising: Beam shaping module, used to shape the beam into a pinhole beam; The first detection plate is disposed in the transmission optical path of the light beam, and has a through hole corresponding to the pinhole light. The second detection board is disposed in the optical path downstream of the first detection board and serves as a blind board; The first and second reflectors are disposed in the optical path between the beam shaping module and the first detection plate, and are used to adjust the direction and position of the beam. The position detection module is used to collect the position of the light spot at the first detection plate and the second detection plate. The beneficial effects of this invention are: By combining a first detection plate with a limited aperture and a second detection plate without aperture limitation in the transmission optical path, the reliance on beam splitting or leakage sampling devices is completely eliminated, significantly simplifying the optical path structure and assembly complexity of the laser system. The step-by-step adjustment strategy of first eliminating light obstruction and then performing joint correction effectively solves the problem of data distortion and collimation failure caused by beam obstruction under large deviation conditions. Simultaneously, through orthogonal decoupling calibration and matrix-based joint adjustment, precise mapping between mirror adjustment and beam offset is achieved, greatly improving collimation convergence speed and stability, making it particularly suitable for the efficient operation and maintenance of large and complex laser systems. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the beam collimation method in an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical path arrangement of the beam collimation device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first detection plate in an embodiment of the present invention; Figure 4 This is a schematic diagram of another embodiment of the first detection plate in this invention.

[0016] In the attached diagram: 1. Shaping aperture; 2. First reflector; 3. Second reflector; 4. First detection plate; 5. Second detection plate. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0018] Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides a beam collimation method based on a near-field reference. This method, through a combination of dual detection plates and a step-by-step adjustment strategy, mainly includes the following steps: In step S100, a first detection plate 4 with a limited aperture and a second detection plate 5 without a limited aperture are set in the transmission optical path of the light beam.

[0019] Specifically, combined Figure 2The diagram shows the optical path arrangement. The first detection plate 4 is located upstream of the optical path and has a specific light-transmitting aperture. The second detection plate 5 is located downstream of the first detection plate 4 and has no light-transmitting limiting structure on its surface (e.g., a blind plate), enabling it to receive the complete light spot signal. Together, they can simultaneously detect the light spots at two locations: the first detection plate 4 and the second detection plate 5. This simplifies the collimation operation and saves collimation time.

[0020] Step S200: Obtain the first position offset of the beam at the first detection plate, and adjust the first reflector based on the first mapping relationship between the adjustment amount of the first reflector and the beam offset at the first detection plate to eliminate the light obstruction of the beam at the first detection plate.

[0021] Specifically, when the system starts up or the beam drift is large, the beam may not completely pass through the aperture of the first detection plate 4, resulting in weakened or even completely blocked light intensity reaching the second detection plate 5. If the data from the second detection plate 5 is used directly for calculation in this case, it will produce huge errors and may even cause the algorithm to diverge. Therefore, this step prioritizes using the first position offset measured at the first detection plate 4, combined with the first mapping relationship established only for the first reflector 2, to drive the first reflector 2 to perform independent adjustment. The goal of this adjustment is to guide the beam back within the aperture range of the first detection plate 4, thereby eliminating the light obstruction phenomenon. This preliminary step ensures that the second detection plate 5 can receive a complete and accurate light spot signal in subsequent stages, laying a reliable data foundation for high-precision joint adjustment.

[0022] Step S300: Obtain the second position offset of the beam at the first detection plate and the third position offset at the second detection plate.

[0023] Specifically, after step S200 eliminates the light-transmitting obstruction, the light beam successfully passes through the first detection plate 4 and is projected onto the second detection plate 5. At this time, the system simultaneously acquires the position information of the light spot on both detection plates. Since the obstruction has been eliminated, the second and third position offsets acquired at this time reflect the true transmission state of the light beam, rather than artifacts caused by truncation. These two offsets characterize the positional deviation of the light beam on two different cross-sections in the near field, and together determine the current actual position and pointing angle of the light beam.

[0024] Step S400: Based on the second mapping relationship between the pre-calibrated adjustment amount of the reflector and the beam offset at the detection plate, and combined with the second position offset and the third position offset, the first reflector and the second reflector are jointly adjusted until the position deviation of the beam at the first detection plate and the second detection plate meets the preset collimation accuracy.

[0025] Specifically, since the positional and pointing deviations of the beam are coupled, adjusting only a single reflector usually only corrects one dimension or increases the deviation in the other dimension. Therefore, this step utilizes a second mapping relationship that encompasses the combined influence of the first reflector 2 and the second reflector 3 on the two detection plates. Using the second and third positional offsets as inputs, it calculates the required adjustment amounts for each of the first and second reflectors 2 and 3, driving them to work together. Through this joint adjustment mechanism, the system can simultaneously decouple and correct the position and pointing of the beam, achieving rapid convergence. In practice, this step is typically performed iteratively. After each joint adjustment, the offset is re-detected. If the preset collimation accuracy (such as micrometer-level positional deviation and microradian-level pointing deviation) is still not met, the step is repeated iteratively. This step-by-step strategy fundamentally avoids the iterative divergence problem caused by data distortion under large deviations, significantly improving the success rate and robustness of collimation.

[0026] Example 2 In this embodiment, the first detection plate 4 is a pinhole plate, and the second detection plate 5 is a blind plate. The distance between the pinhole plate and the blind plate is determined based on a preset collimation accuracy. Specifically, combined with Figure 2 The optical path arrangement shown uses a small aperture plate (4) as the first detection plate with limited light-transmitting aperture, whose core function is to provide a high-precision position reference. A blind plate (5) as the second detection plate without light-transmitting limitations is mainly used to provide a position reference for the complete light spot. According to the principles of geometric optics, under the same positional deviation, the larger the distance between the two plates, the more significant the light spot displacement caused by changes in beam direction, thus improving the resolution of direction adjustment. However, excessively large distances also lead to an increase in the optical path volume and increased sensitivity to environmental disturbances. Therefore, this distance should be designed with a trade-off based on the preset collimation accuracy required by the system.

[0027] Furthermore, the light-transmitting hole structure of the first detection plate 4 is a single-hole structure in the middle (e.g., Figure 4 (as shown) or a four-hole structure (such as) Figure 3 As shown in the figure, the aperture of the aperture plate is smaller than the aperture of the light beam; when the aperture structure is a four-hole structure, the position of the light beam at the first detection plate 4 is the average of the positions of the light spots at the four apertures. Figure 3 In the four-quadrant four-aperture structure shown, the four apertures are symmetrically distributed in the four quadrants of the beam cross-section, and each aperture samples only a portion of the energy at the edge of the beam. After the beam passes through these four apertures, four separate sub-spots are formed on the second detection plate 5. The centroid coordinates of these four sub-spots are calculated, and their geometric average is taken as the equivalent position of the beam at the second detection plate 5.

[0028] Example 3 In this embodiment, the first and second mapping relationships are obtained by decoupling the movements of the first reflector 2 and the second reflector 3 in two mutually orthogonal dimensions and then calibrating them. During calibration, the independent movements of the first reflector 2 and the second reflector 3 in the X and Y directions, respectively, are strictly controlled.

[0029] Furthermore, the above calibration process specifically includes the following steps to ensure the accuracy and feasibility of obtaining the mapping relationship: Step S01: Under the initial posture, acquire the initial spot positions of the light beam at the first detection plate 4 and the second detection plate 5. Specifically, firstly, adjust the first reflector 2 and the second reflector 3 to the preset reference zero position or the current working point. At this time, the light beam should be in an ideal transmission state or a known reference state. The system synchronously records the initial position coordinates {P10_x, P10_y} (reference point 1) of the light beam at the first detection plate 4 and the initial position coordinates {P20_x, P20_y} (reference point 2) of the light beam at the second detection plate 5.

[0030] Step S02: Control the first reflecting mirror 2 to move by a preset step length in two dimensions respectively, and collect the first spot position of the light beam at the first detection plate 4. Specifically, keep the second reflecting mirror 3 stationary, and drive the first reflecting mirror 2 to move by a preset step length N in the X direction, recording the spot position P1_m1x on the first detection plate 4; after resetting, drive the first reflecting mirror 2 to move by a preset step length N in the Y direction, recording the spot position P1_m1y on the first detection plate 4. This step aims to extract the direct influence coefficient of the first reflecting mirror 2 on the beam position at the first detection plate 4.

[0031] After the first detection plate 4 is moved out of the transmission optical path, the position of the second spot of the beam at the second detection plate 5 is acquired. Specifically, when it is necessary to calibrate the influence of the first reflector 2 on the downstream second detection plate 5, if the first detection plate 4 is kept in the optical path, the adjustment of the first reflector 2 will change the angle and position of the beam entering the first detection plate 4, which can easily cause the beam to be blocked by the first detection plate 4, resulting in the spot reaching the second detection plate 5 being incomplete or even completely disappearing, thus causing the calibration data to fail. Therefore, before performing this step, the first detection plate 4 must be moved out of the beam transmission path by a mechanical translation or rotation mechanism so that the beam is projected onto the second detection plate 5 without obstruction. Subsequently, the first reflector 2 is controlled to move in the X and Y directions by a preset step size N, and the positions of the spots P2_m1x and P2_m1y on the second detection plate 5 are recorded respectively.

[0032] Step S03: Control the second reflector 3 to move by a preset step length in both dimensions, and collect the position of the third light spot on the second detection plate 5. Specifically, keep the first reflector 2 stationary, drive the second reflector 3 to move by a preset step length N in the X and Y directions respectively, and record the light spot positions P2_m2x and P2_m2y on the second detection plate 5.

[0033] After moving the first detection plate 4 into the transmission optical path, the position of the fourth spot of the beam at the first detection plate 4 is acquired. Specifically, in order to calibrate the influence of the second reflector 3 on the beam position at the first detection plate 4 (i.e., the cross-coupling term), the first detection plate 4 must be moved back into the optical path and precisely reset to its initial reference position. This is because only when the first detection plate 4 is present in the optical path can the effect of adjusting the second reflector 3 on the beam's passage through the first detection plate 4 be observed. In this state, the second reflector 3 is controlled to move in the X and Y directions by a preset step size N, and the positions of the spots P1_m2x and P1_m2y on the first detection plate 4 are recorded.

[0034] It should be noted that the execution order of step S02 can be adjusted to after step S03, that is, the execution order of steps S02 and S03 can be interchanged without affecting the accuracy and feasibility of the calibration results, thus giving the operation process greater flexibility.

[0035] Step S04: Based on the initial spot position, the first spot position, the second spot position, the third spot position, and the fourth spot position, determine the first mapping relationship and the second mapping relationship. Specifically, using the position data collected in the above steps and the corresponding preset step size N, the elements in the mapping matrix M can be obtained through differential calculation. For example, the transfer coefficient of the first reflector 2 to the first detection plate 4 in the X direction can be calculated by (P1_m1x - P10_x) / N. By traversing all dimension combinations, a complete 4×4 system transfer matrix (i.e., the second mapping relationship) and a first mapping relationship submatrix used in the coarse adjustment stage can be constructed.

[0036] Specifically, the mapping matrix M is represented as: .

[0037] Example 4 In this embodiment, before the light beam enters the transmission optical path, the beam is shaped into a pinhole shape. Specifically, this step is typically performed after the beam exits from the light source or oscillator and before entering the main transmission optical path containing the first reflector 2 and the second reflector 3. In actual large-scale laser systems, the original light beam often has a large aperture. By pre-shaping the beam into a pinhole shape that matches the light transmission structure of the first detection plate 4, the spatial cross-section of the incident beam can be precisely controlled, ensuring that its energy concentration area highly coincides with the sensitive area of ​​the detection plate.

[0038] Furthermore, specific methods for shaping the light beam into pinhole light include using an aperture or a liquid crystal light modulator to shape the beam. For example... Figure 2 As shown, the shaping aperture 1, as a typical passive optical element, is usually made of metal and has a fixed aperture type (such as a single aperture in the center or four apertures around the perimeter). The advantages of the shaping aperture 1 are its simple structure, low manufacturing cost, high damage threshold, and lack of external driving circuitry, making it particularly suitable for industrial or scientific research scenarios with a single beam mode, fixed collimation accuracy requirements, and long-term stable operation. However, for complex laser systems that require frequent beam mode switching and adaptation to multi-wavelength or multi-aperture inputs, the fixed aperture is not flexible enough.

[0039] Therefore, this application also provides a liquid crystal light modulator as an alternative implementation. A liquid crystal light modulator is an active spatial light modulation device that can control the alignment of liquid crystal molecules via electrical signals, thereby dynamically reconstructing the shape, size, and position of the light-transmitting region. Compared to the shaping aperture 1, the liquid crystal light modulator supports software programming to define aperture parameters, and can complete the switching from a single aperture to four apertures, or even any custom pattern, within milliseconds, without the need for mechanical replacement of parts. This dynamic programmable characteristic makes it particularly suitable for applications requiring multimodal beam switching, adaptive optics compensation, or online adjustment of the collimation reference.

[0040] Example 5 In this embodiment, the first reflecting mirror 2 and the second reflecting mirror 3 are adjusted together to satisfy the following relationship: , Wherein, ΔP1_x and ΔP1_y are the positional offsets of the beam at the first detection plate 4 in the x and y directions, respectively; ΔP2_x and ΔP2_y are the positional offsets of the beam at the second detection plate 5 in the x and y directions, respectively; ΔM1_x and ΔM1_y are the required adjustment amounts of the first reflector 2 in the x and y directions, respectively; ΔM2_x and ΔM2_y are the required adjustment amounts of the second reflector 3 in the x and y directions, respectively; and M is the mapping matrix corresponding to the second mapping relationship. .

[0041] Specifically, in the matrix equation above, the four-dimensional vector on the right-hand side represents the deviation between the current state of the beam and the ideal target state, i.e., the positional error observed by the system on the two axial sections; the four-dimensional vector on the left-hand side represents the actuator action required to eliminate this deviation, i.e., the angular or displacement adjustment values ​​of the two mirrors in the orthogonal dimension. It should be noted that the x-direction and y-direction in the formula are local coordinate systems established relative to the ideal propagation optical axis of the beam. The propagation direction of the optical axis is usually defined as the z-axis, and the x-axis and y-axis are perpendicular to each other and both perpendicular to the z-axis.

[0042] Furthermore, in conjunction with Examples 1 to 4, the mapping matrix This is a 4×4 system transfer function matrix, which illustrates the linear influence coefficients of minute adjustments made by the first reflector 2 and the second reflector 3 in the x and y dimensions on the position of the light spot at the first detection plate 4 and the second detection plate 5. For example, the element in the first row and first column of the matrix represents the displacement of the light spot at the first detection plate 4 in the x-direction caused by the first reflector 2 moving a unit step in the x-direction. Given four positional deviations, four optimal adjustment values ​​are solved simultaneously through matrix operations, thereby achieving synchronous correction of the beam position and direction.

[0043] In the specific solution process, after the system collects the current ΔP1_x, ΔP1_y, ΔP2_x, and ΔP2_y, the mapping matrix can be calculated. The inverse or pseudo-inverse matrix can be used to directly obtain the required adjustment vector. If the matrix If the matrix is ​​full rank and has a good condition number, an exact solution can be obtained by direct inversion. If calibration noise causes the matrix to be nearly singular, the least squares method or regularization method can be used to obtain the optimal approximate solution. This joint adjustment method based on the matrix model avoids the time loss caused by repeated trial and error and overcomes the risk of oscillation and divergence caused by multivariate coupling compared to the traditional single-variable successive approximation method. From a physical mechanism perspective, this set of equations is actually searching for the shortest path from the current deviation point to the origin in the four-dimensional state space. Therefore, it can significantly reduce the number of iterations. Typically, the beam position deviation can be converged to the micrometer level and the pointing deviation to the microradian level within 3 to 5 cycles, meeting the stringent requirements of large laser systems for efficient and high-precision collimation.

[0044] Example 6 This embodiment provides a beam collimation system based on a near-field reference for implementing the method, including: Beam shaping module, used to shape the beam into a pinhole beam; The first detection plate 4 is disposed in the transmission optical path of the light beam, and has a through hole corresponding to the pinhole light. The second detection board 5 is disposed in the optical path downstream of the first detection board 4 and serves as a blind plate. The first reflecting mirror 2 and the second reflecting mirror 3 are disposed in the optical path between the beam shaping module and the first detection plate 4, and are used to adjust the direction and position of the beam. The position detection module is used to collect the position of the light spot at the first detection plate 4 and the second detection plate 5.

[0045] Among them, the beam shaping module is set as the shaping aperture 1, which is a typical passive optical element, usually made of metal material, and has a fixed light-passing aperture.

[0046] In addition, it also includes a processor. The processor calls the corresponding program module to control the position detection module (such as an external image acquisition device) to obtain the position data of the light spot at the first detection plate 4 and the second detection plate 5, and calculates the adjustment amount of the first reflector 2 and the second reflector 3 according to the preset mapping relationship matrix, and then outputs a control signal to drive the reflector adjustment mechanism to act.

[0047] Example 7 This embodiment provides a specific application scenario to verify the actual effect of the aforementioned beam collimation method in near-field collimation of a large laser transmission system. In this scenario, the laser system has a large beam aperture, and due to thermal drift or mechanical creep after long-term operation, the initial position deviation of the beam when entering the collimation unit is significant, exceeding the aperture radius.

[0048] If the position and direction are directly corrected by adjusting the first reflecting mirror 2 and the second reflecting mirror 3 together, the beam will be severely blocked by the aperture wall when it reaches the pinhole plate due to the large initial deviation. Only a small portion of the light energy will pass through, and the light spot formed on the blind plate will be an incomplete crescent shape or an asymmetrical shape. At this time, the centroid position calculated based on the incomplete light spot contains a huge systematic error and cannot truly reflect the actual transmission axis of the beam. Solving based on this distorted feedback data will often output incorrect adjustment values, causing the beam to deviate further, or even oscillate and diverge during the iteration process, ultimately leading to collimation failure.

[0049] In contrast, the beam collimation method provided in this application effectively addresses the aforementioned challenges. At the initial collimation startup, the system detects a large offset in the first position at the first detection plate 4 and then enters the anti-blocking adjustment stage. During this stage, the system temporarily ignores the adjustment of the second reflector 3 and independently drives the first reflector 2 for rapid correction based solely on the pre-calibrated first mapping relationship. Since the first reflector 2 is located upstream of the optical path, it has high sensitivity to adjusting the beam position at the first detection plate 4, quickly adjusting the beam center to within the aperture range of the first detection plate 4. Actual measurement data shows that after one or two independent adjustments to the first reflector 2, the beam can completely pass through the first detection plate 4, eliminating the light blockage phenomenon and allowing the second detection plate 5 to once again exhibit a complete and symmetrical beam pattern.

[0050] After confirming the elimination of light obstruction, the system automatically switches to the joint adjustment stage. At this point, since the light spot signals on both detection plates are real and valid, the system, based on the mapping matrix M corresponding to the second mapping relationship and combined with the real-time position offsets at the first detection plate 4 and the second detection plate 5, accurately calculates the optimal joint adjustment amount for the first reflector 2 and the second reflector 3. In this stage, the position and pointing deviations of the beam are synchronously corrected. Experimental results show that after completing the aforementioned obstruction removal preprocessing, the system only needs to perform 3 to 5 more joint adjustment iterations to converge the position deviation of the beam at the first detection plate 4 and the second detection plate 5 to within 50 μm and the pointing deviation to within 10 μrad, satisfying the preset collimation conditions.

[0051] Through comparative verification in the above application scenarios, it is evident that this application, by decomposing the collimation process into two logically sequential stages—eliminating occlusion and achieving joint convergence—fundamentally severs the causal chain that leads to data distortion due to large deviations, thereby causing algorithm divergence. This step-by-step adjustment strategy not only ensures the stability of the collimation process across the entire deviation range but also avoids the time loss caused by repeated trial and error or manual intervention, significantly improving the operation and maintenance efficiency and automation level of the laser system.

[0052] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments, and will not be repeated here.

[0054] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0055] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0056] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A beam collimation method based on a near-field reference, characterized in that, include: A first detection plate with a limited aperture and a second detection plate without a limited aperture are set in the optical path of the beam transmission; The first position offset of the beam at the first detection plate is obtained, and the first reflector is adjusted based on the first mapping relationship between the adjustment amount of the first reflector and the beam offset at the first detection plate, so as to eliminate the light transmission blockage of the beam at the first detection plate. The second position offset of the beam at the first detection plate and the third position offset at the second detection plate are obtained; Based on the second mapping relationship between the pre-calibrated adjustment amount of the reflector and the beam offset at the detection plate, the first and second reflectors are adjusted in combination with the second and third position offsets until the position deviation of the beam at the first and second detection plates meets the preset collimation accuracy.

2. The beam collimation method based on a near-field reference according to claim 1, characterized in that, The first detection plate is a perforated plate, and the second detection plate is a blind plate. The distance between the perforated plate and the blind plate is determined based on a preset collimation accuracy.

3. The beam collimation method based on a near-field reference according to claim 2, characterized in that, The light-transmitting hole structure of the small aperture plate is either a single hole structure in the middle or a four-hole structure around the perimeter, and the aperture of the light-transmitting hole of the small aperture plate is smaller than the aperture of the light beam. When the light-transmitting aperture structure is a four-hole structure, the position of the light beam at the small aperture plate is the average value of the light spot positions at the four light-transmitting apertures.

4. The beam collimation method based on a near-field reference according to claim 1, characterized in that, The first mapping relationship and the second mapping relationship are obtained by decoupling the motion of the first reflector and the second reflector in two mutually orthogonal dimensions and then calibrating them.

5. The beam collimation method based on a near-field reference according to claim 4, characterized in that, The calibration process includes: S01. Under the initial posture, acquire the initial spot position of the beam at the first detection plate and the second detection plate; S02. Control the first reflector to move by a preset step length in the two dimensions respectively, collect the position of the first spot of the beam at the first detection plate, and after moving the first detection plate out of the transmission optical path, control the first reflector to move by a preset step length in the two dimensions respectively, collect the position of the second spot of the beam at the second detection plate. S03. Control the second reflector to move by a preset step length in the two dimensions respectively, collect the third spot position of the beam at the second detection plate, and after the first detection plate is moved back into the transmission optical path, collect the fourth spot position of the beam at the first detection plate. S04. Based on the initial spot position, the first spot position, the second spot position, the third spot position, and the fourth spot position, determine the first mapping relationship and the second mapping relationship.

6. The beam collimation method based on a near-field reference according to claim 5, characterized in that, The execution order of step S02 can be adjusted to after step S03.

7. The beam collimation method based on a near-field reference according to claim 1, characterized in that, Before the light beam enters the transmission optical path, the method further includes: The beam is shaped into a pinhole beam.

8. The beam collimation method based on a near-field reference according to claim 7, characterized in that, The step of shaping the light beam into a pinhole light includes: The light beam is shaped using an aperture or a liquid crystal light modulator.

9. The beam collimation method based on a near-field reference according to claim 1, characterized in that, The joint adjustment of the first and second reflectors satisfies the following relationship: ， Wherein, ΔP1_x and ΔP1_y are the positional offsets of the beam at the first detection plate in the x and y directions, respectively; ΔP2_x and ΔP2_y are the positional offsets of the beam at the second detection plate in the x and y directions, respectively; ΔM1_x and ΔM1_y are the required adjustment amounts of the first reflector in the x and y directions, respectively; ΔM2_x and ΔM2_y are the required adjustment amounts of the second reflector in the x and y directions, respectively; and M is the mapping matrix corresponding to the second mapping relationship. .

10. A beam collimation system based on a near-field reference, used to implement the method according to any one of claims 1-9, characterized in that, include: Beam shaping module, used to shape the beam into a pinhole beam; A first detection plate is disposed in the transmission optical path of the light beam, and has a through hole corresponding to the pinhole light. The second detection board is disposed in the optical path downstream of the first detection board and serves as a blind board; The first and second reflectors are disposed in the optical path between the beam shaping module and the first detection plate, and are used to adjust the direction and position of the beam. The position detection module is used to collect the position of the light spot at the first detection plate and the second detection plate.

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