A wavefront correction method and system based on deformable mirror response distribution reconstruction

Abstract

The application discloses a wavefront correction method and system based on a response distribution reconstruction of a deformable mirror, and belongs to the technical field of lasers. The method comprises the following steps: a spatial coordinate mapping relationship between a repetition frequency reference surface and a working surface is established; an actual measured response function is collected on the repetition frequency reference surface; a longitudinal response distribution and a transverse spatial point array distribution of each driving unit are extracted; and finally, a complete response function of the working surface is reconstructed. The application does not directly measure the response function on the working surface, but eliminates the influence of sensor noise and environmental interference on the measurement result through function fitting and spatial point array distribution reconstruction, so that the reconstructed response function can more truly reflect the intrinsic response characteristics of the deformable mirror than the directly measured response function. Under the same optical path conditions, the PV value of the wavefront correction result of the application reaches 0.3-0.4 microns, which is superior to the existing measurement method, and is suitable for the field of single laser systems, high-power laser systems and other fields that cannot obtain the response function of the deformable mirror based on the repetition frequency laser test, and greatly expands the application range of the wavefront correction of the deformable mirror.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a wavefront correction method and system based on deformable mirror response distribution reconstruction. Background Technology

[0002] Adaptive optics is a core technology for achieving high-beam-quality laser output and precise wavefront control, and it is widely used in high-energy-density physics experiments, high-power laser engineering, precision optical processing, astronomical observation, and other fields. The core objective of wavefront correction is to obtain an output beam with high surface accuracy, thereby achieving high energy concentration in the far-field focal spot. Deformable mirrors, with their advantages of large wavefront adjustment range and resistance to strong light damage, have become the most crucial wavefront correction actuators in adaptive optics systems.

[0003] The wavefront correction capability of a deformable mirror relies on a precise wavefront control algorithm, and the response function (RF) matrix of each driving unit of the deformable mirror is the core input of wavefront control. Due to the inherent cross-linking response of the driving units of the deformable mirror, the deformation of a single driving unit will have a coupling effect on the surrounding area. Only by obtaining a complete and accurate response function matrix can the driving voltage required for wavefront correction be accurately calculated, thereby achieving the expected correction effect.

[0004] In existing technologies, the conventional method for measuring the response function of deformable mirrors involves sequentially applying a rated voltage to each drive unit of the deformable mirror under high-repetition-rate (PRR) laser mode. Wavefront sensors are used to collect the wavefront changes of each drive unit before and after the voltage application, and the response function of each drive unit is then calculated, ultimately constructing a complete response function matrix. However, this method can only be implemented under high-repetition-rate (PRR) conditions. In applications such as single-emission high-power laser systems and large-aperture high-power optical paths, it suffers from insurmountable technical limitations. First, obtaining the response function is extremely costly, and may even be impossible. Single-emission high-power laser systems have extremely low emission frequencies, typically only one main emission every 3-6 hours. For an N-element deformable mirror, obtaining the response function using conventional methods requires N main emissions. For a 67-element deformable mirror, measuring the response function alone would require at least 22 working days. The time cost, equipment operating cost, and component losses are extremely high, making it impractical in engineering.

[0005] Second, the response function cannot be directly measured on the working surface. In the high-power optical path, the wavefront measurement module of the working surface is located after the high-magnification attenuation module. It can only detect effective signals when the main emission high-energy laser outputs. In the low-repetition-rate weak light mode, there is no effective optical signal input, so it is impossible to directly perform traversal measurement of the response function on the working surface.

[0006] Third, the accuracy of directly measured response functions is low, introducing additional errors. The response function measured directly by conventional methods inevitably introduces interference from wavefront sensor noise, ambient airflow disturbances, mechanical vibrations, etc., causing the response function to deviate from the intrinsic response characteristics of the deformable mirror. At the same time, the response function of the edge driving unit of the deformable mirror exceeds the effective measurement area of ​​the wavefront sensor. Existing technologies usually use zero-padding, which introduces serious calculation errors and directly reduces the accuracy of wavefront correction.

[0007] In summary, existing technologies cannot reconstruct a complete and accurate deformable mirror response function on working surfaces that are difficult to measure directly, which severely restricts the application of adaptive optics technology in core scenarios such as single-emission high-power laser systems and high-power optical paths. Summary of the Invention

[0008] The purpose of this invention is to provide a wavefront correction method and system based on deformable mirror response distribution reconstruction to solve the above-mentioned technical problems. This addresses a series of issues in the prior art, such as the inability to directly measure the response function on the working surface, high cost of obtaining the response function, low measurement accuracy, and poor wavefront correction effect. It enables efficient and high-precision reconstruction of the deformable mirror response function in a single-shot high-power laser system, significantly improving wavefront correction performance. It is particularly suitable for large-aperture single-shot high-power laser systems and high-power optical paths where the response function cannot be obtained through repetition rate laser testing.

[0009] On one hand, the present invention provides a wavefront correction method based on deformable mirror response distribution reconstruction, the method comprising: Wavefront data of localization feature points are collected on the repetition rate reference plane and the working plane respectively, and a spatial coordinate mapping relationship between the repetition rate reference plane and the working plane is established based on the collected wavefront data. The measured response function was acquired on the repetition frequency reference surface, and the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror were extracted based on the measured response function. The complete response function of the working surface is reconstructed based on spatial coordinate mapping, longitudinal response distribution, and transverse response distribution.

[0010] On the other hand, the present invention also provides a wavefront correction system based on deformable mirror response distribution reconstruction, the system comprising: The positional mapping module is used to collect wavefront data of positioning feature points on the repetition frequency reference plane and the working plane respectively, and to establish a spatial coordinate mapping relationship between the repetition frequency reference plane and the working plane based on the collected wavefront data.

[0011] The unidirectional distribution extraction module is used to collect the measured response function on the repetition frequency reference surface and extract the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror based on the measured response function. The response function reconstruction module is used to reconstruct the complete response function of the working surface based on spatial coordinate mapping relationship, longitudinal response distribution, and transverse spatial lattice distribution. The wavefront correction module is used to perform iterative correction control on the wavefront data collected from the working face based on the complete response function of the working face.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Overcoming application scenario limitations. This invention eliminates the need to measure the response functions of each driving unit of the deformable mirror across the working surface. Only one main emission is required to acquire the wavefront data of the positioning feature points, thus reconstructing the complete response function matrix of the working surface. For a 67-element deformable mirror, the number of main emissions required to acquire the response function is reduced from 67 to 1. For large laser systems with a thermal recovery time of 3-6 hours, the workload that originally took 22 working days is compressed to one day, significantly reducing time costs, equipment operating costs, and component losses. It completely solves the problem that single-emission high-power laser systems and high-power optical paths cannot obtain the response function through repetition rate laser testing, greatly expanding the application scope of deformable mirror wavefront correction technology.

[0013] 2. High fidelity of the response function, closely matching the intrinsic characteristics of the deformable mirror. This invention, based on the physical geometric arrangement of the deformable mirror and the measured response function of the repetition rate reference surface, reconstructs the longitudinal response distribution of the driving unit through Gaussian function fitting and the transverse spatial lattice distribution of the full aperture through coordinate mapping. This fundamentally eliminates the influence of wavefront sensor noise, ambient airflow, mechanical vibration, and other interferences on the response function. Simultaneously, the response function of the edge driving unit is obtained through Gaussian fitting extrapolation, avoiding the calculation errors caused by zero-padding in existing technologies. The reconstructed response function perfectly matches the intrinsic response characteristics of the deformable mirror.

[0014] 3. Significantly improved wavefront correction accuracy. Under the same optical path conditions and wavefront control algorithm, the PV value of the wavefront correction result achieved based on the response function reconstructed in this invention can reach 0.3~0.4μm, which is significantly better than the 0.6~0.7μm of the direct measurement response function method, and even better than the 0.5~0.6μm of conventional closed-loop correction. In high-power main emission scenarios, the initial wavefront PV value can be reduced from 3μm to 0.8μm, which greatly improves the energy concentration of the laser far-field focal spot and meets the core performance requirements of high-power laser systems.

[0015] 4. High versatility and adaptability to complex optical system requirements. Based on the principle of spatial coordinate mapping, this invention can realize the reconstruction and transfer of response functions between arbitrary wavefront measurement surfaces, support unified wavefront correction for multi-optical-path and multi-measurement-surface systems, and adapt to the multi-node wavefront control requirements of complex optical systems. This invention is not only applicable to large-aperture high-power laser systems, but can also be extended to various adaptive optics applications such as precision optical processing, astronomical observation, and free-space optical communication, demonstrating strong engineering practicality. Attached Figure Description

[0016] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the optical path structure of a typical high-power laser device provided in an embodiment of the present invention.

[0017] Figure 2 This is a flowchart of the wavefront correction method based on deformable mirror response distribution reconstruction provided by the present invention.

[0018] Figure 3 This is a schematic diagram of the spatial coordinate mapping between the repetition rate reference plane and the working plane in an embodiment of the present invention. The left figure is a wavefront distribution diagram of the positioning feature points on the repetition rate reference plane, and the right figure is a wavefront distribution diagram of the positioning feature points on the working plane.

[0019] Figure 4 This is a schematic diagram of the measured response function distribution of different driving units of the deformable mirror on the repetition frequency reference plane provided by the present invention.

[0020] Figure 5 This is a schematic diagram of Gaussian function fitting of the longitudinal response distribution of the deformable mirror driving unit provided by the present invention.

[0021] Figure 6 This is a schematic diagram of the reconstruction of the lateral spatial lattice distribution of the deformable mirror driving unit provided by the present invention.

[0022] Figure 7 This is a schematic diagram comparing the measured response function and the reconstructed response function provided by the present invention.

[0023] Figure 8 This is a diagram showing the offline verification results of wavefront correction provided by this invention.

[0024] Figure 9 This is a diagram showing the wavefront correction result of the main emission of the high-intensity optical path provided by the present invention.

[0025] The component names corresponding to the labels in each of the attached figures are as follows: 1 - Repetition rate light source, 2 - Main amplifier, 3 - Transmission module, 4 - Deformable mirror, 5 - Functional optical module, 6 - Beam splitter, 7 - High magnification attenuation module, 8 - Working surface wavefront measurement module, 9 - Repetition rate reference surface wavefront measurement module. Detailed Implementation

[0026] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0027] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0028] Example 1 This embodiment discloses a typical optical path structure for a high-power laser device used for wavefront correction, such as... Figure 1 As shown, it includes a repetition rate light source 1, a main amplifier 2, a transmission module 3, a deformable mirror 4, a functional optical module 5, a beam splitter 6, a high magnification attenuation module 7, a working surface wavefront measurement module 8, and a repetition rate reference surface wavefront measurement module 9.

[0029] The repetition rate light source 1 outputs repetition rate seed light and can operate in repetition rate mode. Its output energy is relatively low, around mJ~J, and its repetition frequency is 1Hz. It mainly provides a stable light source input for the actual measurement of response function and the acquisition of localization feature points.

[0030] The main amplifier 2 is used to amplify the seed light at a high gain in the main emission mode, and can output laser pulses in the range of kilojoules to tens of thousands of joules. It does not work in the repetition rate mode and is the core gain unit of the single-emission high-power laser system.

[0031] The transmission module 3 consists of a series of transmission mirrors, which are used for optical path folding and transformation to achieve stable transmission of laser beams between modules. The mirror coating is adapted to fundamental frequency light and third harmonic light.

[0032] The deformable mirror 4 is a core component for wavefront correction, used to make ultra-fast adjustments to the beam direction.

[0033] In a preferred embodiment, the deformable mirror 4 has a mirror size of 580mm. The large-diameter piezoelectric deformable mirror has a diameter of 440mm and is equipped with 67 drive units, corresponding to a wavefront adjustment range of not less than 10μm. The mirror surface is coated with a high damage threshold reflective film and can withstand high-energy laser irradiation.

[0034] The functional optical module 5 includes harmonic conversion elements such as KDP crystals and DKDP crystals, as well as a focusing lens, for laser wavelength conversion and focusing to meet the needs of target range physics experiments.

[0035] The beam splitter 6 is made of fused silica, with an incident angle of 22.5°. Its front and rear surfaces are uncoated, and the reflected light ratio is about 4%, while the transmitted light ratio is about 94%.

[0036] The high-rate attenuation module 7 has an adjustable attenuation rate and a maximum transmittance of 0.0001. It is used to attenuate high-energy lasers in the main emission mode, thereby protecting the subsequent measurement modules.

[0037] The working surface wavefront measurement module 8 is located after the high-magnification attenuation module 7 and can only be used to collect effective wavefront data when the main emission high-energy laser outputs. There is no effective signal in the repetition frequency mode.

[0038] The repetition rate reference surface wavefront measurement module 9 consists of a matched lens and a Hartmann wavefront sensor, and can be pushed into and out of the optical path offline. When pushed into the optical path, it can acquire stable and effective optical signals in low-light repetition rate mode for measuring the response function of the repetition rate reference surface and acquiring location feature points. In a preferred embodiment, the sensor sampling resolution is 64×64 pixels.

[0039] As can be seen, the optical path after beam splitting by beam splitter 6 is divided into two paths: the first branch is the repetition rate optical path to the repetition rate reference surface wavefront measurement module 9, and the repetition rate surface corresponding to the repetition rate reference surface wavefront measurement module 9 is a weak light surface. In the first branch, the response function can be measured based on the repetition rate light; the second branch is the main emission optical path of high magnification attenuation module 7 and working surface wavefront measurement module 8, and the working surface corresponding to the working surface wavefront measurement module 8 is a strong light surface.

[0040] Since the response function cannot be directly measured in the second branch, the core of the improved scheme in this embodiment of the invention is to realize open-loop control by using the response function of the weak light surface. By applying positioning feature points at specific positions on the deformable mirror 4 of the target range, positioning hole wavefronts are obtained on the weak light surface and the strong light surface respectively. Based on the spatial coordinate transformation, the spatial mapping relationship between the (weak light) repetition frequency reference surface and the (strong light) working surface is obtained, thereby establishing the relationship between the static wavefront and the strong light wavefront.

[0041] On the other hand, the reconstructed response function method predicts the response of all driving units based on the response of the partial driving units of the deformable mirror, and obtains complete distribution information that can be applied to any working surface. Therefore, this invention mainly reconstructs the complete working surface response function distribution by combining the mapping relationship between the first and second branches with the measured response data of the repetition frequency reference surface.

[0042] Example 2 This embodiment improves upon the wavefront correction method based on deformable mirror response distribution reconstruction. It can be applied to the laser device provided in the aforementioned embodiments and the adaptive optics wavefront correction system in arbitrary space. After performing response function measurements on a reference surface where repetition rate measurements can be carried out, the intrinsic response characteristics of each driving unit in the transverse and longitudinal directions are extracted. Then, by locating feature points, a spatial coordinate mapping relationship is established between the repetition rate reference surface and the working surface that cannot be directly measured, and the transverse lattice distribution of the deformable mirror on the repetition rate reference surface is accurately mapped to the working surface. The longitudinal response distribution is generated numerically at each transverse lattice point on the working surface, that is, a complete response function matrix is ​​generated. Finally, wavefront correction is carried out on the working surface based on the reconstructed response function.

[0043] Specifically, such as Figure 2 As shown, the method includes the following steps: Step S1: Collect wavefront data of the localization feature points.

[0044] The voltage of the positioning feature point is applied to the selected driving unit on the deformable mirror 4, and the wavefront data of the positioning feature point is collected and obtained on the repetition rate reference plane and the working plane respectively.

[0045] Among them, the positioning feature points are the reference for establishing spatial coordinate mapping. This is mainly achieved by applying voltage to selected driving units on deformable mirror 4, causing identifiable protrusions / depressions to form stable positioning feature points at corresponding mirror positions on deformable mirror 4. The specific implementation steps are as follows: First, select no fewer than four driving units as positioning feature points within the effective light-transmitting area of ​​the deformable mirror. The positioning feature points are distributed as irregularly and evenly as possible at the four corners of the effective light-transmitting area, thereby covering most of the wavefront measurement surface and improving the accuracy of coordinate mapping.

[0046] Secondly, the selected drive unit is loaded with a voltage for the positioning feature point. The voltage value can be selected as positive or negative according to the range of the deformable mirror to ensure that the positioning feature point can be clearly identified in the wavefront measurement surface without coupling interference from adjacent feature points, and its center position can be identified relatively accurately.

[0047] Finally, wavefront data of the localization feature points were collected at the repetition rate reference plane and the working plane, respectively. The wavefront data of the repetition rate reference plane was collected in the low repetition rate light mode, while the wavefront data of the working plane was generally collected in the single main emission mode.

[0048] Step S2: Establish the spatial coordinate mapping relationship between the repetition rate reference surface and the working surface based on the acquired wavefront data.

[0049] Based on the wavefront data of the location feature points of the collected repetition rate reference plane and working plane, the center coordinates of each feature point are extracted, the spatial transformation parameters between the two planes are calculated, and the spatial coordinate transformation matrix between the repetition rate reference plane and the working plane is established to obtain the spatial coordinate mapping relationship, thereby realizing the accurate transformation of arbitrary pixel coordinates between the two planes.

[0050] The spatial transformation includes three rigid body transformations: translation, rotation, and scaling. Its mathematical model is as follows: Let the pixel coordinates of the feature points within the repetition rate reference plane be ( , The pixel coordinates of the corresponding feature points within the working surface are ( , If the coordinates are 0, then the spatial coordinate transformation relationship is: (1) In the formula, The translation transformation matrix is... , These are the translation parameters in the X and Y directions; Let be the rotation transformation matrix. This is the rotation angle parameter between the two surfaces; is the scaling factor, representing the imaging scaling ratio between the two surfaces.

[0051] Preferably, the transformation parameters are solved using the least squares method through at least four sets of feature point coordinate pairs to establish a complete spatial coordinate mapping relationship. A schematic diagram of the spatial coordinate mapping between the repetition rate reference plane and the working plane is shown below. Figure 3 As shown.

[0052] The relationship between the repetition rate reference plane and the working plane is obtained based on spatial coordinate transformation. Then, the relationship between the static wavefront and the strong light wavefront is established. The core of this is that open-loop control needs to utilize the response function of the (weak light) repetition rate reference plane. Step S3: Collect the measured response function of the repetition rate reference surface.

[0053] The repetition rate reference plane is a wavefront measurement plane that can be used to measure the response function through repetition rate laser. Stable and effective optical signals can be obtained at this position in low repetition rate light mode without the need for a main emission process and without optical component loss.

[0054] Specifically, first, the repetition rate (RPR) light source 1 is turned on to output a stable RRP seed light, ensuring that the beam aperture, transmission optical path, and main emission conditions are consistent. Then, the rated driving voltage is sequentially applied to each driving unit of the deformable mirror 4, and wavefront data is acquired using the Hartmann wavefront sensor of the RRP reference surface wavefront measurement module 9. Finally, the wavefront difference data before and after the driving unit loading are compared, and the measured response function of each driving unit on the RRP reference surface is calculated, ultimately constructing the measured response function matrix of the RRP reference surface. The distribution of the measured response functions of a typical driving unit is shown below. Figure 4 As shown, where Figure 4 (a) is drive unit number 3; Figure 4 (b) is drive unit number 32; Figure 4 (c) is drive unit number 34; Figure 4 (d) is drive unit number 65.

[0055] Step S4: Reconstruct the longitudinal response distribution of the driving unit. Based on the measured response function on the repetition frequency reference surface, extract the one-dimensional response distribution data of the driving unit, and use a Gaussian function for fitting to obtain the fitting parameters of the longitudinal response distribution of the driving unit on the deformable mirror 4.

[0056] The longitudinal response distribution of the driving unit is an inherent physical characteristic of the deformable mirror, characterizing the radial distribution of the surface deformation generated by a single driving unit after applying voltage. In this embodiment of the invention, a Gaussian function is used to fit the one-dimensional distribution of the measured response function to reconstruct the intrinsic longitudinal response distribution of the driving unit, eliminating the influence of sensor noise and environmental interference.

[0057] The specific implementation steps are as follows. First, select 2-5 driving units located in the central region of the piezoelectric deformable mirror with complete and uninterrupted responses from the response function. Extract the one-dimensional response distribution data in the X and Y directions for each driving unit, and calculate the average one-dimensional response distribution data in the X and Y directions to eliminate the influence of measurement errors of single driving units. Then, use a Gaussian function to fit the average one-dimensional response distribution data. The Gaussian function can accurately characterize the flat-top response distribution of the piezoelectric deformable mirror driving unit, and its mathematical expression is: (2) In the formula, Radial position Deformation height at the point, In response to peak amplitude, The center position of the drive unit It is a Gaussian order.

[0058] Finally, the nonlinear least squares method is used for fitting and solving. Generally, the fitting confidence level R2 ≥ 0.95 is required. The obtained Gaussian fitting parameters characterize the longitudinal response distribution of the deformable mirror driving unit.

[0059] Further research shows that the response parameters of the actuators at different locations, such as the central region, the outermost region, and the corner boundaries, differ due to varying coupling effects from nearby actuators. Therefore, the fitting in this embodiment mainly focuses on the actuators located in the central region, and the Gaussian fitting result of the longitudinal response distribution of the actuator is as follows: Figure 5 As shown.

[0060] Step S5: Reconstruct the lateral spatial lattice distribution of the repetition rate reference surface.

[0061] The lateral spatial lattice distribution characterizes the center coordinate distribution of all driving units of the deformable mirror 4 on the wavefront measurement surface, serving as the spatial reference for reconstructing the complete response function. This embodiment of the invention combines the physical geometric arrangement of the deformable mirror driving units with the center coordinates of the measured response function to reconstruct the full-aperture lateral spatial lattice distribution, solving the problems of truncated response and unobtainable data from edge driving units.

[0062] like Figure 6 As shown, the specific implementation steps are as follows: First, the pixel coordinates of the center points of the driving units corresponding to the measured response functions on the repetition rate reference plane are extracted. Combined with the physical geometric arrangement dimensions of the driving units in deformable mirror 4, a linear mapping relationship is established between the wavefront pixel coordinates (in pixels) and the deformable mirror geometric coordinates (in mm) corresponding to the localized feature points. Second, based on the physical geometric coordinates of all driving units across the entire aperture of the deformable mirror, the center pixel coordinates (in pixels) of all driving units on the deformable mirror on the repetition rate reference plane are calculated using the aforementioned linear mapping relationship. This includes edge driving units outside the effective measurement area of ​​the wavefront sensor. Finally, the complete lateral spatial point array distribution is reconstructed.

[0063] Step S6: Completely reconstruct the distribution of the working surface response function.

[0064] Based on the spatial coordinate mapping relationship, longitudinal response distribution fitting parameters, and transverse spatial lattice distribution obtained in step S2 above, the complete reconstruction and wavefront correction of the working surface response function distribution are completed. The specific steps are as follows: Based on the spatial coordinate mapping relationship, the lateral spatial lattice distribution of all driving units on the repetition rate reference plane is mapped to the working plane, and the lateral spatial lattice position of all driving units on the working plane is calculated. The two-dimensional response function of each driving unit is generated by Gaussian fitting of the parameter values ​​based on the longitudinal response distribution at the transverse center coordinates of each driving unit on the working surface. By integrating the two-dimensional response functions of all driving units, a complete response function matrix is ​​constructed, thus obtaining the distribution of the response function on the working surface.

[0065] Step S7, wavefront correction control.

[0066] Based on the initial wavefront data collected from the working face and the response function matrix reconstructed in step S6, the wavefront iterative algorithm is used to solve for the new driving voltage required for wavefront correction. The calculated new driving voltage is applied to the deformable mirror, and a new wavefront is collected. The open-loop iterative process is repeated until the requirements are met, thereby realizing wavefront iterative correction control.

[0067] Furthermore, this invention supports response function reconstruction and unified wavefront correction for multi-faceted optical systems. Specifically, a repetition rate reference plane is selected as the reference plane for response function reconstruction. Spatial coordinate mapping relationships between the multiple working planes in the system and the reference plane are established respectively. The response function reconstructed by the reference plane is mapped to each working plane, thereby completing the response function reconstruction of each working plane and realizing unified wavefront correction for complex multi-faceted optical systems.

[0068] As can be seen, the improved embodiment of the present invention does not require direct measurement of the response function on the working surface, and is applicable to fields such as single-shot laser systems and high-power laser systems where the response function of deformable mirrors cannot be obtained based on repetition rate laser testing, thus greatly expanding the application scope of deformable mirror wavefront correction.

[0069] Example 3 This invention provides a wavefront correction system based on deformable mirror response distribution reconstruction, corresponding to any of the aforementioned method embodiments. The system consists of multiple module units for implementing the steps in the aforementioned method embodiments, and the module units cooperate with each other to complete the aforementioned wavefront correction method based on deformable mirror response distribution reconstruction.

[0070] Specifically, the system includes: The positional mapping module is used to collect wavefront data of positioning feature points on a repetition frequency reference surface and at least one working surface, and to establish a spatial coordinate mapping relationship between the repetition frequency reference surface and the working surface based on the collected wavefront data.

[0071] The unidirectional distribution extraction module is used to collect the measured response function on the repetition frequency reference surface and extract the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror based on the measured response function. The response function reconstruction module is used to reconstruct the complete response function distribution of the working surface based on spatial coordinate mapping relationship, vertical response distribution, and horizontal spatial lattice distribution. The wavefront correction module is used to perform iterative correction control on wavefront data collected from the working face based on the complete response function distribution of the working face.

[0072] Example 4 This embodiment describes the simulation verification experiment based on any of the aforementioned laser devices and response distribution reconstruction methods. This embodiment is an offline verification experiment; the main amplifier 2 is not operational, and there is no main emission process. It is used to verify the feasibility of the principle and the advantages of the correction accuracy of the method provided in this embodiment of the invention. The specific implementation steps are as follows: 1. Experimental System Setup The working surface wavefront measurement module 8 and the repetition rate reference surface wavefront measurement module 9 are configured as a switchable structure with the same optical path via a high-precision translation stage. This allows the working surface wavefront measurement module 8 to receive repetition rate optical signals in repetition rate mode, thus establishing an offline verification optical path. The repetition rate light source 1 is turned on, outputting a stable repetition rate seed light, while the main amplifier 2 remains inactive.

[0073] 2. Select four driving units on deformable mirror 4 to apply voltage to the positioning feature points. The four driving units are evenly distributed in the effective light-transmitting area of ​​the deformable mirror to ensure that the positioning feature points cover the effective measurement area of ​​the wavefront measurement surface. Switch to the repetition rate reference surface wavefront measurement module 9 to collect the wavefront data of the positioning feature points on the repetition rate reference surface, such as... Figure 3 As shown in the left figure; switch out of the repetition rate reference surface wavefront measurement module 9, switch into the working surface wavefront measurement module 8, and collect wavefront data of the positioning feature points on the working surface, such as... Figure 3 As shown in the right figure, the center pixel coordinates of four positioning feature points on the repetition rate reference surface and the working surface are extracted respectively. The translation, rotation and scaling parameters between the two surfaces are calculated, and a spatial coordinate transformation matrix is ​​established to complete the spatial coordinate mapping between the repetition rate reference surface and the working surface.

[0074] 3. Switch back to the repetition rate reference surface wavefront measurement module 9, maintain the repetition rate light source in normal operation, and sequentially apply the rated driving voltage to each of the 67 driving units of the deformable mirror 4. For each driving unit applied, acquire wavefront data once through the repetition rate reference surface wavefront measurement module 9, compare the wavefront changes before and after application, and calculate the measured response function of each driving unit on the repetition rate reference surface. The measured response function of a typical driving unit is shown below. Figure 4 As shown.

[0075] 4. From the measured response functions, three driving units (units 33, 34, and 35) located in the central region of the deformable mirror and with complete, untruncated responses were selected. One-dimensional response distribution data in the X and Y directions of each of the three driving units were extracted, and the average one-dimensional response distribution data in the X and Y directions were calculated. A Gaussian function was used to fit the average one-dimensional response distribution data. In this embodiment, the confidence level R² after fitting was 0.98, satisfying the requirement of R² ≥ 0.95, thus obtaining uniform Gaussian fitting parameters. For simplicity, the longitudinal response distribution of all driving units of the deformable mirror was characterized using this set of fitting parameters. The fitting process is as follows: Figure 5 As shown.

[0076] 5. Extract the pixel coordinates of the center point of each driving unit corresponding to the measured response function on the repetition rate reference surface. Combine the physical geometric arrangement dimensions of the 67 driving units of the deformable mirror to establish a linear mapping relationship between the wavefront pixel coordinates and the geometric coordinates of the deformable mirror. Based on the geometric coordinates of the 67 driving units of the full aperture of the deformable mirror, the lateral spatial lattice distribution of all driving units on the repetition rate reference surface is reconstructed through the above mapping relationship, including the edge driving units outside the effective measurement area of ​​the wavefront sensor. The reconstruction process is shown in Figure 6.

[0077] 6. Based on the aforementioned spatial coordinate mapping relationship, the lateral spatial lattice distribution of the 67 driving units on the repetition rate reference plane is mapped to the working surface, obtaining the lateral spatial lattice positions of all driving units on the working surface. At the lateral spatial coordinates of each driving unit on the working surface, a two-dimensional response function for each driving unit is generated based on the obtained Gaussian fitting parameter values, ultimately completing the reconstruction of the complete response function matrix of the working surface. Comparison between the measured response function and the reconstructed response function is shown below. Figure 7 As shown, the reconstructed response function is free from noise interference and has no truncation or zero-padding error at the edges, which better matches the intrinsic response characteristics of the deformable mirror.

[0078] 7. Based on the initial wavefront data acquired from the working face and the reconstructed response function matrix, a classic open-loop iterative algorithm is used for wavefront correction control. The iterative process is as follows: Figure 8 As shown, after four iterations, the wavefront PV value decreased to 0.3~0.4μm; while under the same conditions, the wavefront PV value based on the correction result of the direct measured response function could only be reduced to 0.5μm, which fully verifies the effectiveness and correction accuracy advantage of the method of the present invention.

[0079] Example 5 This embodiment describes the experimental operation for verifying the main emission application of a high-power optical path based on any of the aforementioned laser devices and methods. This embodiment is a practical engineering application verification, implemented in a real single-emission high-power laser system main emission scenario, to verify the engineering practicality of the improved method of this invention. The specific implementation steps are as follows: 1. Experimental system restored.

[0080] Using the same high-power laser optical path system as in Example 1, the working surface wavefront measurement module 8 is restored to its original optical path position, that is, after the high-magnification attenuation module 7. At this position, effective wavefront data can only be collected when the main emission high-energy laser outputs. There is no effective signal in the repetition rate weak light mode, and the response function cannot be directly measured, thus completely restoring the actual working conditions of the project.

[0081] 2. Pre-acquisition of basic parameters of the repetition frequency reference surface.

[0082] Turn on the repetition frequency light source 1, keep the main amplifier 2 in a non-operating state, and complete the actual measurement of the response function of each driving unit of the deformable mirror on the repetition frequency reference surface, Gaussian fitting of the longitudinal response distribution, and reconstruction of the transverse spatial lattice distribution according to the steps of the previous embodiment. The complete response function matrix on the repetition frequency reference surface is obtained, and the preparatory work is completed. This process does not require main emission and has no equipment loss.

[0083] 3. Establishment of spatial coordinate mapping relationship (first main launch).

[0084] a. Apply the same voltage to the four positioning feature points as in the previous embodiment onto the deformable mirror 4, perform the first main emission, and the main amplifier 2 operates to amplify the seed light with a high gain and output a high-energy laser. b. After being reflected by beam splitter 6 and attenuated by high-magnification attenuation module 7, the laser is incident on the wavefront measurement module 8 of the working surface to collect wavefront data of the positioning feature points on the working surface. c. Combine the pre-acquired wavefront data of the feature points located on the repetition rate reference surface, extract the center coordinates of the feature points, calculate the translation, rotation, and scaling parameters between the two surfaces, establish a spatial coordinate transformation matrix, and complete the spatial coordinate mapping between the repetition rate reference surface and the working surface.

[0085] 4. Complete reconstruction of the working surface response function.

[0086] Based on the spatial coordinate mapping relationship established in the previous step, the pre-acquired repetition rate reference surface driving unit lateral spatial lattice distribution is mapped to the working surface to obtain the lateral spatial lattice positions of 67 driving units on the working surface; at the lateral spatial coordinates of each driving unit on the working surface, based on the pre-acquired longitudinal response distribution Gaussian fitting parameters, the two-dimensional response function of each driving unit is numerically generated to complete the reconstruction of the complete response function matrix of the working surface.

[0087] 5. Verification of main emission wavefront correction.

[0088] a. Perform the second main emission. Deformable mirror 4 is not loaded with any voltage. The initial wavefront data of the main emission optical path is collected by the working surface wavefront measurement module 8. The initial wavefront PV value is measured to be about 3μm, as shown in Figure 9(a). b. Based on the reconstructed response function matrix and initial wavefront data, the driving voltage required for wavefront correction is calculated by the pseudo-inverse matrix, applied to deformable mirror 4, and subsequent main emission iterative correction is performed; c. After three main emission iterations of correction, the PV value of the working surface wavefront decreased to 0.8 μm, as shown in Figure 9 (b). The corresponding energy concentration of the laser far-field focal spot was greatly improved, meeting the engineering requirements of the high-power laser system.

[0089] In this embodiment, for a 67-element deformable mirror, the method of the present invention only requires one main launch to complete the response function reconstruction, while the existing conventional method requires 67 main launches. The time cost is reduced from 22 working days to 1 day, which is highly practical for engineering.

[0090] In summary, this invention addresses the engineering bottleneck of efficiently and accurately acquiring the response function of deformable mirrors in single-emission high-power laser systems. An improved method based on spatial coordinate mapping is proposed to reconstruct the response function of deformable mirrors. Through theoretical analysis, offline principle experiments, and high-power laser main emission engineering experiments, the technical feasibility and engineering application advantages of this method are systematically verified. This method establishes a spatial coordinate mapping relationship between the repetition rate reference plane and the working plane by locating feature points. The complete response function matrix reconstruction of the working plane can be completed with only one main emission, significantly reducing the time cost, equipment operating cost, and optical component loss in response function acquisition. This solves the technical problem of directly measuring the response function of the working plane in single-emission high-power laser systems.

[0091] This method uses Gaussian function fitting to reconstruct the longitudinal response distribution of the driving unit, and combines this with the physical geometric arrangement of the deformable mirror to reconstruct the lateral spatial lattice distribution. This effectively eliminates interference from sensor noise, environmental airflow disturbances, and mechanical vibrations, while also eliminating zero-padding errors caused by truncation of the edge driving unit response. This ensures the reconstructed response function accurately matches the intrinsic response characteristics of the deformable mirror, providing reliable data support for high-precision wavefront correction. Experimental results show that, under the same optical path conditions, the wavefront correction PV value reconstructed using this method can reach 0.3–0.4 μm, significantly better than the 0.6–0.7 μm of the traditional direct measurement method. In high-power laser main emission engineering scenarios, the initial wavefront PV value can be reduced from 3 μm to 0.8 μm, effectively improving wavefront correction accuracy and the energy concentration of the laser far-field focal spot, meeting the core performance requirements of major high-power laser devices.

[0092] In summary, the improved method of this invention, based on spatial coordinate mapping, can reconstruct and transfer the response function between arbitrary wavefront measurement surfaces, supporting unified wavefront correction for multi-path, multi-faceted systems. It not only meets the application requirements of large-aperture, high-power laser systems but can also be extended to adaptive optics fields such as precision optical processing, astronomical observation, and free-space optical communication, demonstrating strong engineering practicality and broad application value. Future research will focus on wavefront prediction methods for the edge regions of large-aperture deformable mirrors to further improve edge correction accuracy and optimize the unified correction algorithm for multi-faceted systems, continuously expanding the application scope of this method in complex optical systems.

[0093] The present invention has been described in detail above. However, the present invention is not limited to the specific embodiments described above, nor to the application scenarios described above. It can be applied to any laser signal application scenario, and the present invention does not limit it in this regard. Furthermore, the present invention extends to any new features or any new combinations disclosed in this specification, as well as any new steps or any new combinations of any disclosed new methods or processes.

Claims

1. A wavefront correction method based on deformable mirror response distribution reconstruction, characterized in that, The method includes: Wavefront data of localization feature points are collected on a repetition rate reference surface and at least one working surface, and a spatial coordinate mapping relationship between the repetition rate reference surface and the working surface is established based on the collected wavefront data. The measured response function was acquired on the repetition frequency reference surface, and the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror were extracted based on the measured response function. The complete response function distribution of the working surface is reconstructed based on spatial coordinate mapping, longitudinal response distribution, and transverse spatial lattice distribution.

2. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 1, characterized in that, The method further includes performing wavefront iterative correction control on the wavefront data collected from the working face after reconstructing the complete response function distribution of the working face.

3. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 1, characterized in that, The step of acquiring wavefront data of positioning feature points on a repetition rate reference plane and at least one working plane includes selecting several driving units as positioning feature points within the effective light transmission area of ​​the deformable mirror, applying positioning feature point voltage to the selected driving units, and acquiring wavefront data of the positioning feature points on the repetition rate reference plane and the working plane respectively.

4. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 3, characterized in that, Wavefront data of the repetition rate reference plane was acquired in the low-light repetition rate mode, while wavefront data of the working plane was acquired in the single main emission mode.

5. A wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 1 or 2, characterized in that, The spatial coordinate mapping relationship between the repetition rate reference surface and the working surface is established based on the acquired wavefront data. This includes extracting the center coordinates of each positioning feature point, calculating the spatial transformation parameters between the repetition rate reference surface and the working surface, and establishing the spatial coordinate transformation matrix between the repetition rate reference surface and the working surface to obtain the spatial coordinate mapping relationship.

6. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 1, characterized in that, The measured response function is acquired on the repetition rate reference plane, including controlling the repetition rate light source to output a stable repetition rate seed light, applying the rated driving voltage to each driving unit of the deformable mirror, and acquiring wavefront data through the wavefront measurement module of the repetition rate reference plane. Finally, the measured response function of each driving unit on the repetition rate reference plane is obtained by comparing the wavefront difference data before and after the rated driving voltage is applied to the driving unit.

7. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 6, characterized in that, Based on the measured response function, the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror are extracted, including, Based on the measured response function of the repetition frequency reference surface, the one-dimensional response distribution data of the driving unit is extracted and fitted to obtain the fitting parameters of the longitudinal response distribution of the driving unit on the deformable mirror. The pixel coordinates of the center point of the driving unit corresponding to the measured response function are extracted. Combined with the physical geometric arrangement size of the driving unit of the deformable mirror, a linear mapping relationship between the wavefront pixel coordinates and the geometric coordinates of the deformable mirror is established. Then, based on the physical geometric coordinates of all driving units of the full aperture of the deformable mirror and the linear mapping relationship, the center pixel coordinates of all driving units on the repetition rate reference plane are calculated.

8. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 7, characterized in that, The complete response function of the working face is reconstructed based on spatial coordinate mapping, longitudinal response distribution, and transverse response distribution, including: Based on the spatial coordinate mapping relationship, the lateral spatial lattice distribution of all driving units on the repetition rate reference plane is mapped to the working plane, and the lateral spatial lattice position of all driving units on the working plane is calculated. At the center coordinates of each driving unit on the working surface, a two-dimensional response function for each driving unit is generated based on the fitting parameter values ​​of the longitudinal response distribution. By integrating the two-dimensional response functions of all driving units, a complete response function distribution of the working surface is constructed.

9. The wavefront correction method based on deformable mirror response distribution reconstruction as described in claim 2, characterized in that, Wavefront iterative correction control is carried out on wavefront data collected from the working face, including solving the driving voltage required for wavefront correction using the wavefront iterative method based on the reconstructed response function distribution, and using the calculated driving voltage to perform wavefront iterative correction.

10. A wavefront correction system based on deformable mirror response distribution reconstruction, characterized in that, The system is used to implement the wavefront correction method based on deformable mirror response distribution reconstruction as described in any one of claims 1-9, and the system comprises: The positional relationship mapping module is used to collect wavefront data of positioning feature points on a repetition frequency reference surface and at least the working surface, and to establish a spatial coordinate mapping relationship between the repetition frequency reference surface and the working surface based on the collected wavefront data. The unidirectional distribution extraction module is used to collect the measured response function on the repetition frequency reference surface and extract the longitudinal response distribution and transverse spatial lattice distribution of each driving unit of the deformable mirror based on the measured response function. The response function reconstruction module is used to reconstruct the complete response function distribution of the working surface based on spatial coordinate mapping relationship, vertical response distribution, and horizontal spatial lattice distribution. The wavefront correction module is used to perform iterative correction control on wavefront data collected from the working face based on the complete response function distribution of the working face.

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