Optical machine wave surface repairing method and system based on wavefront modulation

Abstract

The invention provides an optical machine wavefront repairing method and system based on wavefront modulation, and relates to the technical field of wavefront repairing, and the method comprises the steps: measuring the wavefront error of an emergent light beam of an optical machine system through a wavefront sensor, calculating the wavefront modulation compensation amount when the error is in a repairable range, and carrying out the phase modulation of the wavefront of the light beam through a spatial light modulator, and generating compensation phase distribution opposite to the wavefront error, and performing iterative optimization until the residual wavefront error is lower than a threshold value required by the system. The wavefront distortion of the optical-mechanical system can be effectively compensated, the imaging quality of the system is improved, and the manufacturing difficulty and cost of the optical system are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wavefront correction, and in particular to an optical-mechanical wavefront correction method and system based on wavefront modulation. BACKGROUND

[0002] As a high-speed information transmission technology in space-to-ground and inter-satellite, the stability of the communication link of space laser communication highly depends on the optical performance of the optical-mechanical system, which needs to ensure that the laser beam maintains a high-quality wavefront in the space transmission of hundreds of kilometers. Otherwise, the signal will be attenuated, the bit error rate will be increased, and even the communication link will be interrupted due to wavefront distortion. However, in the special application scenario of space laser communication, the wavefront distortion inducement faced by the optical-mechanical system is more complex and severe. The mechanical impact during satellite launching, the extreme temperature difference and micro-vibration during on-orbit operation, and other factors will exacerbate the installation error offset and thermal deformation of the optical element. These factors make the wavefront distortion problem of the system output beam more prominent, and the real-time, adaptability and reliability requirements of wavefront correction are much higher than those in the ground scenario.

[0003] The traditional wavefront correction method of the optical-mechanical system mainly relies on high-precision optical element processing and fine adjustment assembly process. When the wavefront error is detected, the element is usually replaced, reprocessed or mechanically adjusted to improve the wavefront quality. In addition, fixed compensation sheets, adaptive optical systems and other methods are also used for wavefront correction.

[0004] The traditional mechanical adjustment and element replacement method is low in work efficiency, needs repeated disassembly and debugging, increases the system installation and adjustment time and cost, and cannot respond to the wavefront changes in the system working process in real time. Moreover, the optical element cannot be disassembled, replaced or repeatedly debugged after the satellite is on orbit, and the complex mechanism required for mechanical adjustment will increase the volume and weight of the satellite load, which is contrary to the design constraints of "lightweight and miniaturization" of the space platform, and cannot cope with the sudden wavefront distortion on orbit.

[0005] The traditional fixed compensation sheet can only correct specific static wavefront errors, and lacks flexibility and dynamic adaptability. In space laser communication, the wavefront distortion changes dynamically with the satellite attitude, orbit position and space environment, and the fixed compensation sheet lacks dynamic adaptability and cannot match the dynamic change characteristics of the wavefront in the scene. Although the existing adaptive optical system has dynamic correction capability, it is usually complex in structure, large in size and high in cost, and lacks a standardized wavefront error evaluation model and iterative optimization process for space dynamic disturbance, resulting in large fluctuation of wavefront correction accuracy during on-orbit repair and inability to stably guarantee the high-quality transmission of the space laser communication link. SUMMARY

[0006] The embodiment of the present application provides a wavefront modulation-based optical-mechanical wavefront repair method and system, and problems in the prior art can be solved.

[0007] In a first aspect, the embodiment of the present application provides a wavefront modulation-based optical-mechanical wavefront repair method, which comprises the following steps: Assembling an optical-mechanical system so that the optical-mechanical system reaches a working state in which wavefront measurement can be performed; performing wavefront measurement on an outgoing light beam of the optical-mechanical system by a wavefront sensor to obtain wavefront error distribution data; Comparing the wavefront error distribution data with a preset error threshold to determine whether the wavefront error distribution data is in a repairable range; When the wavefront error distribution data is in the repairable range, calculating a wavefront modulation compensation amount based on the wavefront error distribution data, and performing phase modulation on the wavefront of the light beam by a spatial light modulation device integrated in an optical path of the optical-mechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; Performing wavefront measurement on the modulated light beam by the wavefront sensor to obtain residual wavefront error distribution data, and taking the residual wavefront error distribution data as new wavefront error distribution data to repeatedly perform error determination and wavefront modulation compensation until the residual wavefront error distribution data is lower than a system performance requirement threshold.

[0008] Assembling an optical-mechanical system so that the optical-mechanical system reaches a working state in which wavefront measurement can be performed; performing wavefront measurement on an outgoing light beam of the optical-mechanical system by a wavefront sensor to obtain wavefront error distribution data comprises the following steps: Optically connecting a light source module and an optical emission assembly in the optical-mechanical system, and establishing optical path connection between an outgoing end of the optical emission assembly and a modulation surface of the spatial light modulation device; Setting the wavefront sensor on an outgoing optical path of the spatial light modulation device so that a detection surface of the wavefront sensor receives the outgoing light beam modulated by the spatial light modulation device; Controlling the spatial light modulation device to be in an initial modulation state, performing initial wavefront measurement on the outgoing light beam by the wavefront sensor to obtain initial wavefront distribution data, and verifying optical path connectivity of the optical-mechanical system and measurement effectiveness of the wavefront sensor according to the initial wavefront distribution data; Establishing a wavefront measurement reference of the optical-mechanical system based on the initial wavefront distribution data, taking the wavefront measurement reference as a reference reference for calculating the wavefront error distribution data, and obtaining the wavefront error distribution data.

[0009] calculating a wavefront modulation compensation amount based on the wavefront error distribution data, and modulating a phase of a wavefront of an incident light beam by a spatial light modulation device integrated in an optical path of the optical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data, comprising: spatially decomposing the wavefront error distribution data to obtain a low-order wavefront error component and a high-order wavefront error component, wherein the low-order wavefront error component represents wavefront distortion caused by overall alignment deviation of the system, and the high-order wavefront error component represents wavefront distortion caused by local defects of optical elements and environmental disturbances; calculating a low-order compensation phase distribution and a high-order compensation phase distribution corresponding to the low-order wavefront error component and the high-order wavefront error component respectively, and superimposing and synthesizing the low-order compensation phase distribution and the high-order compensation phase distribution to obtain a total compensation phase distribution; generating spatial light modulation device driving instructions according to the total compensation phase distribution and a phase modulation response characteristic of the spatial light modulation device, wherein the spatial light modulation device driving instructions include phase modulation control parameters for each pixel unit of the spatial light modulation device; sending the spatial light modulation device driving instructions to the spatial light modulation device to control each pixel unit of the spatial light modulation device to spatially modulate a wavefront of an incident light beam according to the phase modulation control parameters, so as to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data in the outgoing light beam.

[0010] controlling each pixel unit of the spatial light modulation device to spatially modulate a wavefront of an incident light beam according to the phase modulation control parameters, comprising: determining spatial coordinate positions and corresponding phase modulation amounts of each pixel unit of the spatial light modulation device according to the phase modulation control parameters in the spatial light modulation device driving instructions, and establishing a mapping relationship between the spatial coordinate positions and the phase modulation amounts of the pixel units; converting the phase modulation amounts into driving voltage signals of the corresponding pixel units according to the mapping relationship, and loading the driving voltage signals to each pixel unit of the spatial light modulation device; after the driving voltage signals are loaded, monitoring a phase response state of each pixel unit of the spatial light modulation device, and when the phase response state reaches a stable condition, confirming that the spatial light modulation device completes phase modulation loading, and generating a phase modulation ready signal; after receiving the phase modulation ready signal, controlling the light source module to output an incident light beam to the spatial light modulation device, so that the incident light beam forms an outgoing light beam carrying a wavefront compensation phase distribution after being spatially phase-modulated by each pixel unit of the spatial light modulation device.

[0011] The wavefront sensor is used to measure the wavefront of the modulated light beam to obtain residual wavefront error distribution data, including: The wavefront sensor is controlled to receive the exit light beam modulated by the spatial light modulation device and to sample the wavefront of the exit light beam to obtain modulated wavefront measurement data; The modulated wavefront measurement data is differentially operated with the wavefront measurement reference to obtain wavefront variation data; The wavefront variation data is compared and analyzed with the wavefront compensation phase distribution to extract the wavefront distortion component that is not completely offset by the wavefront compensation phase distribution, and the residual wavefront error distribution data is obtained.

[0012] In a second aspect of the embodiment, an optical-mechanical wavefront repair system based on wavefront modulation is provided, including: A first unit is configured to assemble an optical-mechanical system to make the optical-mechanical system reach a working state capable of performing wavefront measurement, and to measure the wavefront of an exit light beam of the optical-mechanical system by a wavefront sensor to obtain wavefront error distribution data; A second unit is configured to compare the wavefront error distribution data with a preset error threshold to determine whether the wavefront error distribution data is within a repairable range; A third unit is configured to calculate a wavefront modulation compensation amount based on the wavefront error distribution data when the wavefront error distribution data is within the repairable range, and to modulate the phase of the wavefront of a light beam by a spatial light modulation device integrated in the optical path of the optical-mechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; A fourth unit is configured to measure the wavefront of the modulated light beam by the wavefront sensor to obtain residual wavefront error distribution data, and to repeat the error determination and wavefront modulation compensation with the residual wavefront error distribution data as new wavefront error distribution data until the residual wavefront error distribution data is lower than a system performance requirement threshold.

[0013] In a third aspect of the embodiment, an electronic device is provided, including: A processor; A memory configured to store wavefront repair related instructions executable by the processor; The processor is configured to call the instructions stored in the memory to execute the spatial laser communication wavefront repair method as described in the preceding claims to realize real-time detection, error evaluation and dynamic correction of the wavefront distortion of the light beam in the optical-mechanical system.

[0014] In a fourth aspect, the present application provides a computer readable storage medium having computer program instructions stored thereon, wherein the computer program instructions are special program instructions for wavefront modulation-based optical system wavefront repair, and when the computer program instructions are executed by a processor, the wavefront modulation-based optical system wavefront repair method described above is implemented, and is specifically used for detecting, error evaluating and dynamically correcting the beam wavefront distortion in the optical system.

[0015] The present application has the following advantages: The wavefront modulation-based optical system wavefront repair method provided by the present application can effectively repair the wavefront error of the optical system, overcome the problem that the conventional optical system is difficult to achieve ideal optical performance during manufacturing and adjustment, and improve the wavefront quality without disassembling the optical system or reworking the optical element.

[0016] The present application integrates a spatial light modulation device into the optical system and adopts an iterative optimization strategy, thereby accurately compensating for the complex optical wavefront error and greatly improving the wavefront quality of the outgoing beam of the optical system. The method is simple to operate, has high repair efficiency, and can be applied to various types of optical systems.

[0017] The wavefront repair method of the present application can be adjusted and optimized in real time after the system is assembled, effectively reduces the manufacturing cost and development cycle of the optical system, improves the product yield, and has a significant effect on improving the overall performance and stability of the optical system, and is particularly suitable for wavefront error correction of high-precision optical systems. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a flowchart of the wavefront modulation-based optical system wavefront repair method of the present application; Figure 2 FIG. 2 is a flowchart of the wavefront error compensation spatial light modulation technology of the present application. DETAILED DESCRIPTION

[0019] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described in detail below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] The technical scheme of the present application will be described in detail below with reference to the following specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in detail in some embodiments.

[0021] Figure 1 A flowchart of a wavefront modulation based optical machine wavefront repair method according to an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the method comprises the following steps: Figure 1 Assembling an optical machine system to reach a working state in which wavefront measurement can be performed; measuring the wavefront of an outgoing light beam of the optical machine system by a wavefront sensor to obtain wavefront error distribution data; Comparing the wavefront error distribution data with a preset error threshold to determine whether the wavefront error distribution data is within a repairable range; When the wavefront error distribution data is within the repairable range, calculating a wavefront modulation compensation amount based on the wavefront error distribution data, and modulating the phase of the light beam wavefront by a spatial light modulation device integrated in the optical path of the optical machine system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; Measuring the wavefront of the modulated light beam by the wavefront sensor to obtain residual wavefront error distribution data, and taking the residual wavefront error distribution data as new wavefront error distribution data to repeat the error determination and wavefront modulation compensation until the residual wavefront error distribution data is lower than a system performance requirement threshold.

[0022] In an alternative embodiment, assembling an optical machine system to reach a working state in which wavefront measurement can be performed; measuring the wavefront of an outgoing light beam of the optical machine system by a wavefront sensor to obtain wavefront error distribution data comprises: Optically connecting a light source module and an optical emission assembly in the optical machine system, and establishing optical path connection between an outgoing end of the optical emission assembly and a modulation surface of the spatial light modulation device; Providing the wavefront sensor on the outgoing optical path of the spatial light modulation device so that a detection surface of the wavefront sensor receives the outgoing light beam modulated by the spatial light modulation device; Controlling the spatial light modulation device to be in an initial modulation state, measuring the initial wavefront of the outgoing light beam by the wavefront sensor to obtain initial wavefront distribution data, and verifying the optical path connectivity of the optical machine system and the measurement effectiveness of the wavefront sensor according to the initial wavefront distribution data; Establishing a wavefront measurement reference of the optical machine system based on the initial wavefront distribution data, taking the wavefront measurement reference as a reference reference for calculating the wavefront error distribution data, and obtaining the wavefront error distribution data.

[0023] ​When assembling the optical-mechanical system, precise optical path connection between each component of the system needs to be ensured, specifically, the light source module and the optical emission component are optically connected. The light source module can use a laser with a wavelength of 532 nm as the light source, and the output power of the collimated light beam is 100 mW. The optical emission component includes a collimating lens group and a beam expander system. The collimating lens group is composed of two plano-convex lenses with focal lengths of 25 mm and 50 mm, which is used to convert the divergent light beam output by the laser into a parallel light beam. The beam expander system is composed of two lenses with a focal length ratio of 1:5, which expands the light beam diameter from 2 mm to 10 mm to meet the effective modulation area requirements of the subsequent spatial light modulation device.

[0024] When optically connecting, the light source module and the optical emission component are precisely adjusted in six degrees of freedom using a fine adjustment platform to ensure that the optical axis alignment error is less than 50 pm and the angle deviation is less than 0.1°. By setting an optical intensity monitor at the connection point, the connection efficiency is monitored in real time. When the optical intensity transmission rate reaches more than 95%, it indicates that the optical connection is successful. After completing the connection, the connection point is fixed using ultraviolet curing glue, and the curing time is 60 seconds to ensure long-term stability.

[0025] The exit end of the optical emission component is optically connected to the modulation surface of the spatial light modulation device. The spatial light modulation device selects a liquid crystal type spatial light modulator with a resolution of 1920x1080 pixels, a pixel size of 6.4 pm, and a modulation area of 12.5 mm x 7.1 mm. When optically connecting, the center of the exit light beam is aligned with the center of the modulator, with a deviation controlled within ±0.5 mm; at the same time, the incident angle is ensured to be within ±5° of the modulator's optimal working angle, which is usually perpendicular incidence or small-angle incidence (<10°).

[0026] To verify the quality of the optical connection, a uniform gray value (such as gray value 128) pattern can be loaded on the spatial light modulator to observe the uniformity and integrity of the exit light spot. When the light spot covers more than 90% of the modulation area and the intensity distribution is uniform (intensity variation <±10%), it indicates that the optical connection is successfully established.

[0027] A wavefront sensor is placed in the exit light path of the spatial light modulation device, so that the detection surface of the wavefront sensor can receive the exit light beam modulated by the spatial light modulator. The wavefront sensor uses a Shack-Hartmann type wavefront sensor with a resolution of 640x480 pixels and a pixel size of 5.6 pm, and the focal length of the microlens array is 5 mm with a sampling point number of 32x32. The wavefront sensor is placed 150 mm behind the exit surface of the spatial light modulator to ensure that the received light beam diameter matches the effective detection area of the sensor (about 9.6 mm x 7.2 mm).

[0028] The sensor is installed with a five-degree-of-freedom precision adjusting frame, including three-dimensional translation and pitch and yaw angle adjustment, to ensure that the sensor detection surface is perpendicular to the incident light beam, with an angle deviation of less than 0.5°. The light spot position is monitored through a real-time image feedback system, and when the coincidence degree of the light spot center and the sensor center reaches more than 95%, the precise positioning of the wavefront sensor is completed.

[0029] The spatial light modulation device is controlled to be in an initial modulation state, i.e., a full-zero phase pattern (corresponding to a gray value of 0) is loaded, and an initial wavefront measurement is performed on the outgoing light beam by the wavefront sensor. The measurement acquisition frequency is set to 30 Hz, and the average value is obtained by accumulating 100 frames to improve the signal-to-noise ratio. The initial wavefront distribution data obtained includes 32x32 sampling points of wavefront phase values, and the data represents the optical path difference in microns.

[0030] The criteria for verifying the light path connectivity and the effectiveness of the wavefront sensor measurement are: the uniformity of the light intensity distribution is greater than 85% (i.e., the ratio of the maximum light intensity to the minimum light intensity is less than 1.2); the light spot centroid position stability is better than ±2 pixels; the wavefront RMS (root mean square) value stability is better than λ / 20 (about 0.027 μm @ 532 nm); and the system noise level is less than λ / 50 (about 0.011 μm @ 532 nm). When the above conditions are met, it is confirmed that the system light path is connected normally and the wavefront measurement is effective.

[0031] Based on the initial wavefront distribution data, a wavefront measurement reference of the optical-mechanical system is established, and the 32x32 wavefront phase distribution matrix in the initial state is recorded as a reference matrix. This matrix includes the optical aberrations of the system itself, such as spherical aberration (typical value about 0.15λ), coma (typical value about 0.08λ), and astigmatism (typical value about 0.12λ). The subsequent wavefront error distribution data is calculated by the difference between the current measurement value and the reference matrix, so as to exclude the influence of the system inherent aberration and only reflect the modulation effect introduced by the spatial light modulator.

[0032] In actual application, when the spatial light modulator loads different phase patterns (such as tilted wavefront, defocused wavefront, or complex wavefront), the phase distribution collected by the wavefront sensor is subtracted from the reference matrix, and the difference obtained is the wavefront error distribution data. For example, when a linear phase slope within a 2π phase range is loaded, the average deviation of the measured wavefront error distribution should be controlled within λ / 10, and the peak-to-valley deviation should be controlled within λ / 8, to ensure that the phase modulation accuracy of the spatial light modulator meets the requirements.

[0033] In an alternative embodiment, a wavefront modulation compensation amount is calculated based on the wavefront error distribution data, and a spatial light modulation device integrated in the optical-mechanical system light path is used to modulate the phase of the light beam wavefront to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data. The wavefront error distribution data is subjected to spatial frequency domain decomposition to obtain a low-order wavefront error component and a high-order wavefront error component, wherein the low-order wavefront error component represents wavefront distortion caused by overall system alignment deviation, and the high-order wavefront error component represents wavefront distortion caused by local defects of optical elements and environmental disturbances. A low-order compensation phase distribution and a high-order compensation phase distribution corresponding to the low-order wavefront error component and the high-order wavefront error component are respectively calculated, and the low-order compensation phase distribution and the high-order compensation phase distribution are superimposed to obtain a total compensation phase distribution. Based on the total compensation phase distribution and the phase modulation response characteristics of the spatial light modulation device, spatial light modulation device driving instructions are generated, which include phase modulation control parameters for each pixel unit of the spatial light modulation device. The spatial light modulation device driving instructions are sent to the spatial light modulation device to control each pixel unit of the spatial light modulation device to perform spatial phase modulation on the wavefront of an incident light beam according to the phase modulation control parameters, so as to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data in the outgoing light beam.

[0034] As shown in Figure 2 The method comprises: After the wavefront error distribution data is obtained, a spatial frequency domain decomposition technique is used to process it, and a two-dimensional discrete wavelet transform is used to perform multi-scale decomposition on the wavefront error data, so as to express the wavefront error as a linear combination of different scale coefficients. Assuming that the wavefront error data matrix has a 512x512 pixel resolution, a Daubechies wavelet basis function is selected to perform 5-level decomposition, so as to obtain a low-frequency approximation component and different scale detail components. The low-frequency approximation component corresponds to a low-order wavefront error, and mainly represents overall system alignment deviation; the high-frequency detail component corresponds to a high-order wavefront error, and mainly represents local defects of optical elements and environmental disturbances. In an actual case, the measured peak-to-valley value of the wavefront error is 2.8λ (λ is the working wavelength), and after decomposition, the low-order component contributes about 1.6λ, and the high-order component contributes about 1.2λ.

[0035] The Zernike polynomial fitting method is used to process the low-order wavefront error component, map the low-order wavefront error to a unit circle, and then use the first 15 Zernike polynomial coefficients to perform fitting, so as to obtain a coefficient set. In an actual system, it is found through fitting calculation that the main contributions come from about 0.85λ of astigmatism (Z5, Z6) and about 0.55λ of coma (Z7, Z8), and the rest of the coefficients are small. Based on these coefficients, a low-order compensation phase distribution for offsetting the low-order wavefront error is calculated, and the phase value is converted into a modulator control unit.

[0036] The direct compensation method is used for the high-order wavefront error component, and the high-order wavefront error distribution map is reconstructed by inverse transforming the high-frequency coefficients after wavelet transform. In order to improve the compensation effect, the smoothing processing is introduced to avoid the phase mutation between pixels, and the 5*5 Gaussian filter kernel is used for filtering the high-order error map, and the standard deviation of the filter is set to 1.2 pixels. Through testing, this processing can make the high-frequency compensation effect improve about 12%, and at the same time reduce the pixel load difference of the modulator.

[0037] After the separate calculation of the low-order and high-order compensation phase distributions is completed, the phase distribution superposition is carried out, the phase values of corresponding pixel points on the same spatial resolution grid are added, and the total compensation phase distribution is obtained. Considering the 2π periodicity problem caused by phase superposition, the phase unfolding and folding processing is implemented to ensure that the final phase distribution is within the modulation range of the spatial light modulator.

[0038] According to the phase modulation response characteristics of the spatial light modulator, the total compensation phase distribution is converted into device driving instructions. For liquid crystal type spatial light modulators, considering the nonlinear phase modulation characteristics, the look-up table method is used for compensation. The actual device used has a 0-2π phase modulation range, and the corresponding gray value is 0-255. Through the phase response curve calibrated in advance, the mapping relationship between the phase value and the gray value is established. For example, under the working wavelength of λ=1064nm, the phase value 0 corresponds to the gray value 0, the phase value π corresponds to the gray value 135, and the phase value 2π corresponds to the gray value 255. According to this mapping relationship, the total compensation phase distribution is converted into a 512*512 gray image matrix, which is used as the driving instruction of the spatial light modulator.

[0039] The driving instruction is transmitted to the spatial light modulator control unit through the data interface, and the DVI data interface is used to continuously transmit the gray image at a refresh rate of 60Hz. After the control unit receives the image, it is distributed to each pixel driving circuit. Each pixel unit adjusts the arrangement of liquid crystal molecules according to the received gray value to realize corresponding phase modulation. The spatial light modulator is placed at the conjugate plane position in the optical path to ensure that the phase modulation and the wavefront error have accurate spatial correspondence. After the incident light beam passes through the modulator, the wavefront obtains a phase distribution opposite to the original wavefront error distribution, realizing active compensation of wavefront distortion.

[0040] In actual application cases, after the wavefront error of 2.8λ peak-to-valley value is compensated by this method, the residual wavefront error is reduced to 0.32λ, and the compensation efficiency is 88.6%. The system Strehl ratio is improved from 0.42 to 0.91, and the far-field focal spot size is reduced by 2.8 times, effectively verifying the performance of the wavefront compensation method.

[0041] The above implementation modes can be adjusted in parameters, such as decomposition levels, filtering parameters, phase mapping relationships, etc., according to actual system requirements, to adapt to different accuracy requirements and optical system characteristics. The entire compensation process can realize closed-loop control, dynamically adjusts the compensation strategy according to the residual wavefront error after compensation, and further improves the system performance.

[0042] In an alternative embodiment, controlling each pixel unit of the spatial light modulation device to perform spatial phase modulation on the wavefront of the incident light beam according to the phase modulation control parameter comprises: According to the phase modulation control parameter in the spatial light modulation device driving instruction, the spatial coordinate position of each pixel unit of the spatial light modulation device and the corresponding phase modulation amount are determined, and a mapping relationship between the spatial coordinate of the pixel unit and the phase modulation amount is established; According to the mapping relationship, the phase modulation amount is converted into a driving voltage signal of the corresponding pixel unit, and the driving voltage signal is loaded to each pixel unit of the spatial light modulation device; After the driving voltage signal is loaded, the phase response state of each pixel unit of the spatial light modulation device is monitored, and when the phase response state reaches a stable condition, it is confirmed that the spatial light modulation device completes the phase modulation loading, and a phase modulation ready signal is generated; After receiving the phase modulation ready signal, the light source module is controlled to output an incident light beam to the spatial light modulation device, so that the incident light beam is spatially phase modulated by each pixel unit of the spatial light modulation device to form an outgoing light beam carrying a wavefront compensation phase distribution.

[0043] The spatial light modulation device includes a two-dimensional pixel array, and each pixel unit can independently adjust the phase of light. In practical applications, the device can be a liquid crystal type spatial light modulator, a micro-electromechanical system reflective type spatial light modulator, or other types of phase modulation devices. The spatial light modulation device used in this embodiment has a pixel resolution of 1920x1080, a pixel size of 8 microns x 8 microns, and a phase modulation range of 0-2π.

[0044] The spatial light modulation device is controlled to perform wavefront modulation. According to the phase modulation control parameter in the driving instruction of the spatial light modulation device, the spatial coordinate position of each pixel unit of the spatial light modulation device and the corresponding phase modulation amount are determined, and a mapping relationship between the spatial coordinate of the pixel unit and the phase modulation amount is established. Specifically, the processor reads the phase distribution data contained in the driving instruction. The data can be a two-dimensional array, indicating the phase value to be applied to each pixel position. For example, for a pixel unit with a coordinate position of (x=500, y=600), the instruction specifies that the phase modulation amount is 1.2π. The processor will traverse the entire pixel array and assign a corresponding phase value to each pixel position to form a complete phase mapping table. In a specific embodiment, the processor constructs a 1920x1080 two-dimensional array, where each element stores the phase value of the corresponding pixel position, with a value range of 0 to 2π and an accuracy of 0.01π.

[0045] According to the established mapping relationship, the phase modulation amount is converted into a driving voltage signal of the corresponding pixel unit, and the driving voltage signal is loaded to each pixel unit of the spatial light modulation device. The spatial light modulation device usually has a nonlinear phase-voltage response relationship, so it is necessary to map the phase value to the corresponding driving voltage through table lookup or function conversion. In this embodiment, the phase-voltage relationship of the liquid crystal spatial light modulator used has been obtained through calibration and stored in a preset lookup table. The lookup table contains 256 discrete voltage levels corresponding to a phase modulation range of 0 to 2π. For example, when a phase modulation of 1.5π is required, the corresponding driving voltage obtained by table lookup is 3.6 volts. The processor converts all the phase values in the entire phase mapping table into corresponding voltage values, and then applies these voltage signals to each pixel unit of the spatial light modulation device through the driving circuit. In actual implementation, the driving circuit adopts a row-column scanning method, and the driving voltage is loaded in groups of 256 pixels per row. The entire loading process takes about 15 milliseconds.

[0046] After the driving voltage signal loading is completed, the phase response state of each pixel unit of the spatial light modulation device is monitored, and when the phase response state reaches a stable condition, it is confirmed that the spatial light modulation device completes the phase modulation loading, and a phase modulation ready signal is generated. Due to the need for a certain time for the turning of the liquid crystal molecules, there is a response delay between the pixel unit receiving the driving voltage and stabilizing at the target phase state. In this embodiment, the phase response state is monitored in two ways: one is based on a time threshold, according to the specification parameters of the liquid crystal spatial light modulator, the response time is 25 milliseconds, and the system waits for 30 milliseconds after the driving voltage loading is completed to ensure that all pixel units reach a stable state; the other is through optical detection, an auxiliary light source and a photodetector are used to monitor the intensity change of the reflected light, and when the intensity change rate is less than a preset threshold of 0.5% / ms, it is determined that the stable state is reached. When the system confirms that the phase response state has stabilized, the controller generates a high-level phase modulation ready signal and transmits it to the light source control module.

[0047] After receiving the phase modulation ready signal, the light source module outputs an incident light beam to the spatial light modulation device, so that the incident light beam forms an outgoing light beam carrying a wavefront compensation phase distribution after being spatially phase modulated by each pixel unit of the spatial light modulation device. The light source module includes a laser diode with a wavelength of 1064 nanometers and an output power of 100 milliwatts. When the light source control module receives the phase modulation ready signal, it activates the laser diode to generate a collimated light beam with a diameter of 8 millimeters, which is incident on the spatial light modulation device. When the incident light beam passes through the pixel array, each pixel unit delays the light wave according to the loaded phase modulation amount, thereby changing the wavefront shape of the entire light beam. For example, if the spherical aberration in the optical path is to be compensated, a phase pattern exhibiting a radial fourth power distribution can be loaded; if focusing of the light beam is to be achieved, a quadratic phase distribution (similar to the function of a convex lens) is loaded. The modulated outgoing light beam carries the preset wavefront phase distribution and can be used for subsequent optical processing or imaging. In a specific application example, the system loads a spiral phase pattern (the phase varies linearly along the angle from 0 to 2π) to make the outgoing light beam carry orbital angular momentum, successfully converting a normal Gaussian light beam into a vortex light beam.

[0048] Through the above detailed steps, the spatial light modulation device can accurately modulate the wavefront of the light beam according to the preset parameters, realize complex light field control functions, and provide key wavefront correction and light field shaping capabilities for advanced optical systems.

[0049] In an alternative embodiment, the wavefront measurement of the modulated light beam by the wavefront sensor includes: The wavefront sensor is controlled to receive the outgoing light beam modulated by the spatial light modulation device and to sample the wavefront of the outgoing light beam to obtain modulated wavefront measurement data. The modulated wavefront measurement data is compared with the wavefront measurement reference to obtain the wavefront change data; By comparing and analyzing the wavefront variation data with the wavefront compensation phase distribution, the wavefront distortion component that was not completely offset by the wavefront compensation phase distribution is extracted to obtain the residual wavefront error distribution data.

[0050] The spatial light modulator receives the incident light beam to be processed and modulates it according to a preset wavefront compensation phase distribution, outputting a modulated outgoing light beam. This wavefront compensation phase distribution is a phase compensation pattern generated based on the system's initial optical aberration measurement data, used to compensate for inherent optical distortions in the system. A wavefront sensor is located behind the spatial light modulator in the system's optical path and is used to receive the modulated outgoing light beam. This wavefront sensor can be a Shaker-Hartmann wavefront sensor, which includes a microlens array and a photodetector, used for high-precision sampling of the wavefront state of the incident light beam.

[0051] When controlling the wavefront sensor to receive the emitted light beam modulated by the spatial light modulator, a precise optical path design ensures that the modulated beam is completely projected onto the photosensitive surface of the wavefront sensor. Specifically, a mirror array can be used to guide the emitted beam to the wavefront sensor, and a beam collimator ensures that the beam size matches the effective receiving area of ​​the wavefront sensor. After receiving the beam, the wavefront sensor performs wavefront sampling on the emitted beam to acquire modulated wavefront measurement data.

[0052] During sampling, a microlens array divides the incident wavefront into multiple sub-beams and focuses them onto a photodetector, forming a spot array. The magnitude and direction of the displacement of each spot from its reference position reflect the local tilt of the wavefront. For example, a Shaker-Hartmann sensor containing 32×32 sub-beams will form 1024 spots. The photodetector captures the position data of these spots, and the system records the lateral and longitudinal offsets of each spot relative to its ideal position, such as (Δx1, Δy1), (Δx2, Δy2), etc. These offset data constitute the modulated wavefront measurement data.

[0053] The modulated wavefront measurement data is differentially analyzed with a wavefront measurement reference to obtain wavefront variation data. The wavefront measurement reference is either reference wavefront data acquired under ideal optical system conditions or predefined ideal planar wavefront data. During the differential analysis, the system subtracts the corresponding reference point's data from the wavefront data of each actual sampling point to calculate the wavefront deviation value for each sampling point. For example, for the i-th sampling point, if the actual measured spot position offset is (Δxi, Δyi), and the reference position offset is (Δxi...)... ref ,Δyi refIf ), then the wavefront change at that point is (Δxi - Δxi). ref , Δyi-Δyi ref By performing this differential calculation on all sampling points, the system obtains a complete set of wavefront variation data, which reflects the actual changes in the modulated beam wavefront relative to the ideal state.

[0054] When comparing wavefront variation data with wavefront-compensated phase distribution, the wavefront variation data is converted to the same representation format as the wavefront-compensated phase distribution, typically a phase value distribution or optical path difference distribution. For a 32×32 sampling grid system, this means generating a wavefront variation distribution map containing 1024 data points. The system then performs a point-to-point comparison of this wavefront variation distribution map with the initially applied wavefront-compensated phase distribution. Ideally, if the wavefront-compensated phase distribution completely cancels out the system's wavefront distortion, the wavefront variation should be close to zero. In practice, due to various factors such as the nonlinear response of the spatial light modulator, pixel gap effects, and system vibration, wavefront compensation usually cannot achieve perfect results.

[0055] When extracting wavefront distortion components that are not completely offset by the wavefront compensation phase distribution, the system analyzes the portion of the wavefront variation data that deviates from zero. Specifically, the system can set a threshold, such as 1 / 20 of the wavelength (approximately 31.5 nm, assuming a light source with a wavelength of 633 nm). When the wavefront variation in a certain region exceeds this threshold, the system identifies it as a wavefront distortion component that has not been fully compensated. For example, if an optical path difference of 42 nm is detected at sampling point (15, 20), exceeding the set threshold, this point is marked as having residual wavefront error. The system performs the same processing on all sampling points, ultimately obtaining complete residual wavefront error distribution data. This data typically includes the position coordinates of each sampling point and the corresponding residual wavefront error value, such as a residual error of 42 nm at point (15, 20) and 38 nm at point (16, 21), etc.

[0056] In practical applications, to improve measurement accuracy, the sampling frequency of the wavefront sensor can be set to above 60Hz to reduce the impact of environmental vibrations on the measurement results. Simultaneously, averaging of multiple frames of data can be performed, such as continuously acquiring 100 frames and calculating the average value, to further improve the signal-to-noise ratio. The accuracy of residual wavefront error distribution data can typically reach the order of 1 / 100th of the wavelength, approximately 6.33 nanometers (for a 633-nanometer wavelength light source). This high-precision data provides an accurate foundation for subsequent wavefront optimization.

[0057] A second aspect of the present invention provides an optomechanical wavefront restoration system based on wavefront modulation, comprising: The first unit is used to assemble the optomechanical system, enabling it to reach a working state capable of performing wavefront measurements; and to perform wavefront measurements on the emitted beam of the optomechanical system using a wavefront sensor to obtain wavefront error distribution data. The second unit is used to compare the wavefront error distribution data with a preset error threshold to determine whether the wavefront error distribution data is within a repairable range. The third unit is used to calculate the wavefront modulation compensation amount based on the wavefront error distribution data when the wavefront error distribution data is within the repairable range, and to perform phase modulation on the wavefront of the beam through a spatial light modulation device integrated in the optical path of the optomechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; The fourth unit is used to perform wavefront measurement on the modulated beam using the wavefront sensor, obtain residual wavefront error distribution data, and use the residual wavefront error distribution data as new wavefront error distribution data to repeatedly perform error determination and wavefront modulation compensation until the residual wavefront error distribution data is lower than the system performance requirement threshold.

[0058] A third aspect of the present invention provides an electronic device, comprising: processor; A memory for storing wavefront repair-related instructions executable by the processor; The processor is configured to call instructions stored in the memory to execute the space laser communication wavefront repair method described above, thereby realizing real-time detection, error assessment, and dynamic correction of beam wavefront distortion in the optomechanical system.

[0059] A fourth aspect of the present invention provides a computer-readable storage medium storing computer program instructions thereon, characterized in that the computer program instructions are dedicated program instructions for space laser communication wavefront repair, and when the computer program instructions are executed by a processor, they implement the aforementioned space laser communication wavefront repair method, specifically used for detecting, evaluating, and dynamically correcting beam wavefront distortion in an optomechanical system.

[0060] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for repairing the optomechanical wavefront based on wavefront modulation, characterized in that, include: The optomechanical system is assembled to achieve a working state capable of performing wavefront measurements; wavefront measurement is performed on the emitted beam of the optomechanical system using a wavefront sensor to obtain wavefront error distribution data; The wavefront error distribution data is compared with a preset error threshold to determine whether the wavefront error distribution data is within a repairable range. When the wavefront error distribution data is within the repairable range, the wavefront modulation compensation amount is calculated based on the wavefront error distribution data, and the wavefront of the beam is phase-modulated by a spatial light modulation device integrated in the optical path of the optomechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; The wavefront sensor is used to measure the modulated beam to obtain residual wavefront error distribution data. The residual wavefront error distribution data is then used as new wavefront error distribution data. Error determination and wavefront modulation compensation are repeated until the residual wavefront error distribution data is lower than the system performance requirement threshold.

2. The method according to claim 1, characterized in that, Assemble the optomechanical system to bring it into a working state capable of performing wavefront measurements; perform wavefront measurements on the emitted beam of the optomechanical system using a wavefront sensor to obtain wavefront error distribution data, including: The light source module in the optomechanical system is optically connected to the optical emission component, and the output end of the optical emission component is optically connected to the modulation surface of the spatial light modulation device. The wavefront sensor is arranged in the output optical path of the spatial light modulator, so that the detection surface of the wavefront sensor receives the output light beam modulated by the spatial light modulator; The spatial light modulation device is controlled to be in an initial modulation state. The wavefront sensor is used to perform initial wavefront measurement on the emitted beam to obtain initial wavefront distribution data. The optical path connectivity of the optomechanical system and the measurement effectiveness of the wavefront sensor are verified based on the initial wavefront distribution data. Based on the initial wavefront distribution data, a wavefront measurement reference for the optomechanical system is established, and the wavefront measurement reference is used as a reference for calculating the wavefront error distribution data to obtain the wavefront error distribution data.

3. The method according to claim 1, characterized in that, The wavefront modulation compensation amount is calculated based on the wavefront error distribution data, and the wavefront of the beam is phase-modulated by a spatial light modulator integrated in the optical path of the optomechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data, including: The wavefront error distribution data is spatially and frequency-domain decomposed to obtain low-order and high-order wavefront error components. The low-order wavefront error components characterize the wavefront distortion caused by the overall system assembly and adjustment deviation, while the high-order wavefront error components characterize the wavefront distortion caused by local defects in optical elements and environmental disturbances. For the low-order wavefront error component and the high-order wavefront error component, the corresponding low-order compensation phase distribution and high-order compensation phase distribution are calculated respectively, and the low-order compensation phase distribution and the high-order compensation phase distribution are superimposed and synthesized to obtain the total compensation phase distribution; Based on the total compensated phase distribution and the phase modulation response characteristics of the spatial light modulator, a spatial light modulator driving command is generated, wherein the spatial light modulator driving command includes phase modulation control parameters for each pixel unit of the spatial light modulator; The driving command for the spatial light modulator is sent to the spatial light modulator to control each pixel unit of the spatial light modulator to perform spatial phase modulation on the wavefront of the incident beam according to the phase modulation control parameters, so as to generate a wavefront compensation phase distribution in the outgoing beam that is opposite to the wavefront error distribution data.

4. The method according to claim 3, characterized in that, Controlling each pixel unit of the spatial light modulation device to perform spatial phase modulation on the wavefront of the incident light beam according to the phase modulation control parameters includes: Based on the phase modulation control parameters in the driving command of the spatial light modulator, the spatial coordinate position of each pixel unit of the spatial light modulator and the corresponding phase modulation amount are determined, and a mapping relationship between the spatial coordinates of the pixel unit and the phase modulation amount is established; According to the mapping relationship, the phase modulation amount is converted into a driving voltage signal for the corresponding pixel unit, and the driving voltage signal is applied to each pixel unit of the spatial light modulation device; After the driving voltage signal is loaded, the phase response state of each pixel unit of the spatial light modulator is monitored. When the phase response state reaches a stable condition, it is confirmed that the spatial light modulator has completed phase modulation loading and a phase modulation ready signal is generated. Upon receiving the phase modulation ready signal, the light source module is controlled to output the incident beam to the spatial light modulator, so that the incident beam is spatially phase modulated by each pixel unit of the spatial light modulator to form an outgoing beam carrying a wavefront compensated phase distribution.

5. The method according to claim 1, characterized in that, The wavefront sensor is used to measure the wavefront of the modulated beam to obtain residual wavefront error distribution data, including: The wavefront sensor is controlled to receive the emitted light beam modulated by the spatial light modulator, and the emitted light beam is sampled on the wavefront to obtain modulated wavefront measurement data; The modulated wavefront measurement data is compared with the wavefront measurement reference to obtain the wavefront change data; By comparing and analyzing the wavefront variation data with the wavefront compensation phase distribution, the wavefront distortion component that was not completely offset by the wavefront compensation phase distribution is extracted to obtain the residual wavefront error distribution data.

6. An optomechanical wavefront restoration system based on wavefront modulation, used to implement the method as described in any one of claims 1-5, characterized in that, include: The first unit is used to assemble the optomechanical system, enabling it to reach a working state capable of performing wavefront measurements; and to perform wavefront measurements on the emitted beam of the optomechanical system using a wavefront sensor to obtain wavefront error distribution data. The second unit is used to compare the wavefront error distribution data with a preset error threshold to determine whether the wavefront error distribution data is within a repairable range. The third unit is used to calculate the wavefront modulation compensation amount based on the wavefront error distribution data when the wavefront error distribution data is within the repairable range, and to perform phase modulation on the wavefront of the beam through a spatial light modulation device integrated in the optical path of the optomechanical system to generate a wavefront compensation phase distribution opposite to the wavefront error distribution data; The fourth unit is used to perform wavefront measurement on the modulated beam using the wavefront sensor, obtain residual wavefront error distribution data, and use the residual wavefront error distribution data as new wavefront error distribution data to repeatedly perform error determination and wavefront modulation compensation until the residual wavefront error distribution data is lower than the system performance requirement threshold.

7. An electronic device, characterized in that, include: processor; A memory for storing wavefront repair-related instructions executable by the processor; The processor is configured to call instructions stored in the memory to execute the space laser communication wavefront repair method according to any one of claims 1 to 5, thereby realizing real-time detection, error assessment and dynamic correction of beam wavefront distortion in the optical engine.

8. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, The computer program instructions are dedicated program instructions for space laser communication wavefront repair, and when the computer program instructions are executed by the processor, they implement the space laser communication wavefront repair method according to any one of claims 1 to 5, specifically used for detecting, evaluating, and dynamically correcting beam wavefront distortion in the optomechanical system.

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