LCOS linearity correction method based on cubic satellite laser communication terminal

Abstract

The application provides a LCOS linearity correction method based on a cubic star laser communication terminal, relates to the technical field of communication, and comprises the following steps: obtaining the corresponding relationship between the driving voltage and the phase response of an LCOS device; generating an initial correction curve; performing least square fitting on the basis of the driving voltage segmentation and dynamically adjusting the segmentation points until the slope difference between the adjacent segmentation curve boundary points is less than a preset threshold; establishing a mapping relationship table of target phase values and driving voltages; and collecting temperature parameters in real time for compensation correction. The application improves the LCOS phase modulation precision and enhances the on-orbit working stability of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, in particular to a LCOS linearity correction method based on a laser communication terminal of a CubeSat. BACKGROUND

[0002] In a laser communication terminal of a CubeSat, a liquid crystal spatial light modulator (LCOS) is used as a key device to realize precise modulation and control of a laser beam. By changing the applied driving voltage, the LCOS device can adjust the arrangement direction of liquid crystal molecules, thereby changing the phase of incident light and realizing wavefront control of the light beam. Ideally, the driving voltage of the LCOS device should be linearly related to the actual phase response, but in actual applications, due to the influence of factors such as the physical properties of liquid crystal materials, device manufacturing process errors, and temperature changes, there is usually a nonlinear relationship between the driving voltage and the phase response. This nonlinear relationship can lead to a decrease in wavefront control accuracy and affect the performance of the laser communication system.

[0003] The existing correction methods for the nonlinear characteristics of LCOS have the following shortcomings: First, the traditional correction methods usually use a single polynomial fitting or lookup table method, which is difficult to balance high-precision fitting and calculation efficiency in the full voltage range, especially in regions where the nonlinear characteristics of the LCOS device change greatly, which can easily cause fitting errors. Second, the existing correction algorithms lack effective optimization processing of the boundary points of the segmented fitting, resulting in discontinuity or slope mutation between adjacent segments, which affects the smoothness and accuracy of phase modulation. Third, a CubeSat in orbit faces complex and variable space temperature environments, and existing correction methods often ignore the influence of temperature changes on the phase response characteristics of LCOS, lacking real-time temperature compensation mechanisms, making it difficult to guarantee the phase control accuracy in on-orbit operation, and further affecting the stability and reliability of the laser communication link. SUMMARY

[0004] The embodiments of the present application provide a LCOS linearity correction method based on a laser communication terminal of a CubeSat, which can solve the problems in the prior art.

[0005] The first aspect of the embodiments of the present application is,

[0006] The corresponding relationship between the driving voltage and the actual phase response of the LCOS device in the laser communication terminal of the CubeSat is obtained; and an initial correction curve of the driving voltage and the actual phase response of the LCOS device is generated according to the corresponding relationship.

[0007] The initial correction curve is segmented according to driving voltages, a least square fitting is performed on the phase response in each driving voltage interval to obtain a segmented fitting curve, and a segmented point is dynamically adjusted based on the slope difference of the boundary points of adjacent segmented fitting curves until the slope difference of the boundary points of adjacent segmented fitting curves is less than a preset slope threshold, and an optimized segmented fitting curve is obtained.

[0008] The optimized segmented fitting curve is taken as a reference curve, and a mapping relationship table of the target phase value and the driving voltage of the LCOS device is established in a bidirectional lookup manner.

[0009] In the working process of the CubeStar laser communication terminal, the temperature parameter of the LCOS device is collected in real time, the mapping relationship table is corrected by temperature compensation according to the temperature parameter, a temperature-compensated mapping relationship table is obtained, and the corresponding driving voltage is applied to the LCOS device according to the temperature-compensated mapping relationship table.

[0010] The method further comprises optical path displacement compensation based on automatic alignment of the optical fiber of the LCOS device:

[0011] A plurality of diffraction beams are generated by displaying a blazed grating with different directions and periods on the LCOS device, and the plurality of diffraction beams are controlled to traverse and scan along a spiral path, and when any one of the diffraction beams is detected, the relative displacement azimuth angle of the optical fiber and the light spot is obtained.

[0012] A sector search area is determined according to the relative displacement azimuth angle, an energy detection is performed by gradually expanding the search range in the sector search area, the maximum energy position detected in each sector search area is taken as the search starting point of the next sector area, and when a local maximum value of light intensity is detected, a relative displacement intermediate value of the optical fiber and the light spot is obtained.

[0013] Based on the relative displacement azimuth angle and the relative displacement intermediate value, a jump search is performed between different diffraction orders to obtain a relative displacement absolute value.

[0014] The optical fiber position is determined according to the relative displacement azimuth angle and the relative displacement absolute value, a local search is performed in the neighborhood of the optical fiber position with a fine step smaller than an initial step until a compensation position with the best optical fiber coupling efficiency is obtained.

[0015] A corresponding blazed grating pattern is displayed on the LCOS device according to the compensation position, and optical path displacement compensation is realized.

[0016] Based on the relative displacement azimuth angle and the relative displacement intermediate value, a jump search is performed between different diffraction orders, which comprises:

[0017] The relative displacement intermediate value is set as an integer multiple to increase a plurality of search positions, light intensity detection is performed in a neighborhood of each search position, and when maximum light intensity is detected, an absolute value of the relative displacement of the optical fiber and the light spot is obtained.

[0018] The initial correction curve is segmented according to the driving voltage, the phase response in each driving voltage interval is least square fitted to obtain a segmented fitting curve, and the segmented points are dynamically adjusted based on the slope difference of the boundary points of adjacent segmented fitting curves, including:

[0019] A phase response curve of the LCOS device under the action of the driving voltage is obtained, a second derivative of the phase response curve is calculated, and initial segmented points are determined according to extreme points of the second derivative, so as to divide the phase response curve into a plurality of initial segmented intervals;

[0020] For the phase response data in each of the initial segmented intervals, an n-order polynomial fitting model is established, and the coefficients of the n-order polynomial fitting model are solved by using the least square method to obtain a segmented fitting function corresponding to each segmented interval;

[0021] The left slope and the right slope of the adjacent two segmented fitting functions at the segmented point are calculated, and the difference value of the left slope and the right slope is obtained, wherein the left slope is the first derivative value of the left segmented fitting function at the segmented point, and the right slope is the first derivative value of the right segmented fitting function at the segmented point;

[0022] When the slope difference at any segmented point is greater than a preset slope threshold, the offset direction of the segmented point is determined according to the size of the slope difference and the relative size relationship of the left slope and the right slope, and the segmented point is moved by a preset step length in the determined offset direction, wherein the preset step length is proportional to the slope difference;

[0023] The least square fitting and the slope difference calculation are repeatedly performed on the segmented interval divided by the moved new segmented point until the slope difference at all segmented points is less than the preset threshold or a preset iteration number is reached, and a final segmented fitting function is obtained.

[0024] The optimized segmented fitting curve is taken as a reference curve, and a mapping relationship table of the target phase value of the LCOS device and the driving voltage is established by using a bidirectional lookup method, including:

[0025] An optimized segmented fitting curve of the LCOS device is obtained, the segmented fitting curve is taken as a reference curve, and the reference curve represents the corresponding relationship between the driving voltage and the phase response of the LCOS device;

[0026] dividing a target phase modulation range of the LCOS device into M discrete phase points, where M is a positive integer, and intervals of adjacent discrete phase points are equal;

[0027] for each of the discrete phase points, setting an initial search interval in a driving voltage range of the reference curve, an upper boundary of the initial search interval being a maximum driving voltage and a lower boundary being a minimum driving voltage;

[0028] performing bidirectional search in the initial search interval by using dichotomy, including: calculating a phase value corresponding to a current search interval midpoint, comparing the phase value with a target phase point, updating an upper boundary of the search interval to the current midpoint when the phase value is greater than the target phase point, and updating a lower boundary of the search interval to the current midpoint when the phase value is less than the target phase point;

[0029] judging whether a difference between the upper boundary and the lower boundary of the current search interval is less than a preset accuracy threshold, and taking a midpoint of the current search interval as a driving voltage value corresponding to the discrete phase point when the difference is less than the preset accuracy threshold;

[0030] repeating the bidirectional search process for all discrete phase points to establish a one-to-one correspondence between the discrete phase points and the driving voltages, and generating a phase-voltage mapping table of the LCOS device.

[0031] temperature-compensating and correcting the mapping relationship table according to the temperature parameter to obtain a temperature-compensated mapping relationship table, and applying a corresponding driving voltage to the LCOS device according to the temperature-compensated mapping relationship table, including:

[0032] taking a phase response at a reference temperature as a reference, calculating an offset of a phase response at other temperature conditions relative to the phase response at the reference temperature to obtain a phase offset corresponding to each sampling temperature point;

[0033] establishing a linear relationship model between a temperature variation and a phase offset according to the correspondence between the temperature points and the phase offsets to obtain a temperature-phase compensation coefficient;

[0034] in a working process of the LCOS device, collecting a current working temperature of the LCOS device in real time through a temperature sensor, and calculating a phase compensation value according to a temperature difference between the current working temperature and a reference temperature;

[0035] correcting a phase-voltage mapping table of the LCOS device according to the phase compensation value, including: subtracting the phase compensation value from a target phase value to obtain a compensated phase value, and searching for a corresponding driving voltage from the phase-voltage mapping table according to the compensated phase value;

[0036] The found driving voltage is applied to the LCOS device to realize accurate phase modulation of the LCOS device under different temperature conditions.

[0037] In a second aspect, the embodiment of the present application provides an LCOS linearity correction system based on a laser communication terminal of a CubeSat, comprising:

[0038] A first unit is configured to acquire a corresponding relationship between a driving voltage and an actual phase response of an LCOS device in the laser communication terminal of the CubeSat, and generate an initial correction curve of the driving voltage and the actual phase response of the LCOS device according to the corresponding relationship;

[0039] A second unit is configured to segment the initial correction curve according to the driving voltage, perform least square fitting on a phase response in each driving voltage interval to obtain a segmented fitting curve, and dynamically adjust a segmented point based on a slope difference of boundary points of adjacent segmented fitting curves until the slope difference of the boundary points of the adjacent segmented fitting curves is less than a preset slope threshold, to obtain an optimized segmented fitting curve.

[0040] A third unit is configured to take the optimized segmented fitting curve as a reference curve, and establish a mapping relationship table of a target phase value and a driving voltage of the LCOS device by using a bidirectional lookup method.

[0041] A fourth unit is configured to acquire a temperature parameter of the LCOS device in real time during a working process of the laser communication terminal of the CubeSat, perform temperature compensation correction on the mapping relationship table according to the temperature parameter to obtain a temperature-compensated mapping relationship table, and apply a corresponding driving voltage to the LCOS device according to the temperature-compensated mapping relationship table.

[0042] In a third aspect, the embodiment of the present application provides an electronic device, comprising:

[0043] The electronic device comprises:

[0044] a processor;

[0045] a memory for storing processor-executable instructions;

[0046] The processor is configured to invoke the instructions stored in the memory to execute the method described above.

[0047] In a fourth aspect, the embodiment of the present application provides a computer readable storage medium having computer program instructions stored thereon, wherein the computer program instructions are executed by a processor to implement the method described above.

[0048] The computer readable storage medium has computer program instructions stored thereon, wherein the computer program instructions are executed by a processor to implement the method described above.

[0049] The present application has the following beneficial effects:

[0050] The piecewise fitting is performed on the driving voltage and actual phase response relation of the LCOS device, and the piecewise points are dynamically adjusted, so that the slope is smoothly transitioned at the boundary of adjacent sections, the phase jitter caused by the discontinuous correction curve in the traditional correction method is solved, and the accuracy and stability of the phase modulation are improved.

[0051] The mapping relation table of the target phase value and the driving voltage is established by using the bidirectional lookup method, the real-time operation complexity is simplified, the calculation resource occupation is reduced, the method is particularly suitable for the cubic satellite platform with limited resources, and the system response speed and working efficiency are improved.

[0052] The temperature parameters are collected in real time and dynamically compensated and corrected, the influence of the temperature change of the space environment on the LCOS phase modulation characteristic is effectively solved, the adaptability and reliability of the laser communication terminal in the complex space environment are enhanced, and the stability of the communication link is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 A flowchart of a LCOS linearity correction method based on a cubic satellite laser communication terminal according to an embodiment of the present application is shown in

[0054] Figure 2 A schematic diagram of a common inter-satellite laser communication terminal according to an embodiment of the present application is shown in

[0055] Figure 3 A simplified schematic diagram of a receiving module in a common inter-satellite laser communication terminal according to an embodiment of the present application is shown in

[0056] Figure 4 A system structure diagram of an inter-satellite laser communication based on LCOS according to an embodiment of the present application is shown in DETAILED DESCRIPTION

[0057] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in 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 in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0058] The technical scheme of the present application will be described in detail in combination with 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 some embodiments.

[0059] Figure 1 A flowchart of a LCOS linearity correction method based on a cubic satellite laser communication terminal according to an embodiment of the present application is shown in Figure 1 The method comprises the following steps.

[0060] Obtaining a correspondence between a driving voltage and an actual phase response of an LCOS device in a CubeSat laser communication terminal; generating an initial correction curve of the driving voltage and the actual phase response of the LCOS device according to the correspondence;

[0061] Segmenting the initial correction curve according to the driving voltage, performing least square fitting on the phase response in each segment of the driving voltage interval to obtain a segmented fitting curve, and dynamically adjusting a segmented point based on a slope difference of boundary points of adjacent segmented fitting curves until the slope difference of the boundary points of the adjacent segmented fitting curves is less than a preset slope threshold, to obtain an optimized segmented fitting curve;

[0062] Taking the optimized segmented fitting curve as a reference curve, and establishing a mapping relationship table of a target phase value and a driving voltage of the LCOS device by using a bidirectional lookup method;

[0063] In the working process of the CubeSat laser communication terminal, a temperature parameter of the LCOS device is collected in real time, the mapping relationship table is corrected by temperature compensation according to the temperature parameter to obtain a temperature-compensated mapping relationship table, and a corresponding driving voltage is applied to the LCOS device according to the temperature-compensated mapping relationship table.

[0064] In an optional implementation, the method further comprises automatically aligning an optical fiber based on the LCOS device to realize optical path displacement compensation:

[0065] Displaying different directions and periods of a blazed grating on the LCOS device to generate a plurality of diffraction beams, and controlling the plurality of diffraction beams to perform traversal scanning along a spiral path, and when any one of the diffraction beams is detected, obtaining a relative displacement azimuth angle of the optical fiber and the light spot;

[0066] Determining a sector search area according to the relative displacement azimuth angle, gradually expanding a search range in the sector search area to perform energy detection, and taking a maximum energy position detected in each sector search area as a search starting point of a next sector area, and when a local maximum value of light intensity is detected, obtaining a relative displacement intermediate value of the optical fiber and the light spot;

[0067] Based on the relative displacement azimuth angle and the relative displacement intermediate value, performing a jumping search between different diffraction orders to obtain a relative displacement absolute value;

[0068] Determining an optical fiber position according to the relative displacement azimuth angle and the relative displacement absolute value, performing local search in a neighborhood of the optical fiber position with a fine step smaller than an initial step until a compensation position of optimal optical fiber coupling efficiency is obtained;

[0069] According to the compensation position, a corresponding blazed grating pattern is displayed on the LCOS device to realize the compensation of the optical path displacement.

[0070] Different direction and period blazed gratings are displayed on the LCOS device to generate multiple diffraction beams, and the diffraction beams are controlled to perform traversal scanning to realize the detection and compensation of the relative displacement between the optical fiber and the light spot.

[0071] Different direction and period blazed gratings are displayed on the LCOS device to generate multiple diffraction beams. The period of the blazed grating can be set to 8 μm to 12 μm, and the groove depth modulation of the blazed grating is 0.4π to 0.6π to generate at least 4 diffraction beams in different directions. The control system drives the diffraction beams to perform traversal scanning along a spiral path, the step length of the spiral path is 1 / 10 to 1 / 5 of the fiber mode field diameter, and the scanning range is 10 times to 20 times of the fiber mode field diameter. When the photodetector detects any one of the diffraction beams, the system records the current position information to obtain the relative displacement azimuth angle between the optical fiber and the light spot. For example, if the optical signal is detected at the coordinate (35 μm, 42 μm) during the spiral scanning, the system calculates the relative displacement azimuth angle to be about 50.2 degrees.

[0072] According to the obtained relative displacement azimuth angle, the system determines a fan-shaped search area, and the angle range of the fan-shaped area is 15 degrees to 30 degrees to the left and right of the azimuth angle, that is, a fan-shaped area of 30 degrees to 60 degrees is formed. In the fan-shaped search area, the system gradually expands the search range for energy detection with an initial step length (such as 1 / 8 of the fiber mode field diameter, about 1 μm). The initial search starting point is the position where the signal is detected, such as (35 μm, 42 μm), and the search direction is the central axis direction of the fan-shaped area. The maximum energy position detected each time is used as the search starting point of the next fan-shaped area. For example, if the energy value of 0.35 mW is detected at (42 μm, 51 μm) in the first fan-shaped search, which is higher than the energy of other points, the point is used as the starting point of the next fan-shaped search. When a local maximum value of light intensity is detected, for example, the energy at a certain point reaches 0.48 mW and the energy of surrounding points is lower than this value, the system records the position as the intermediate value of the relative displacement between the optical fiber and the light spot.

[0073] Based on the obtained relative displacement azimuth and relative displacement intermediate value, the system performs a jump search between different diffraction orders to obtain the relative displacement absolute value. Specifically, the system calculates the position interval of different diffraction orders according to the period of the blazed grating, for example, for a grating with a period of 10 μm, the interval between adjacent diffraction orders in space is about 62 μm. The system takes the relative displacement intermediate value as the reference, and searches ±3 diffraction orders along the azimuth direction with the diffraction order interval as the step size. For example, if the intermediate value position is (42 μm, 51 μm) and the azimuth is 50.2 degrees, the system will search positions such as (-144 μm, -135 μm), (-82 μm, -73 μm), (104 μm, 113 μm), (166 μm, 175 μm), etc. By comparing the energy values of these positions, the position of the maximum energy point is determined, for example, the energy value at (104 μm, 113 μm) is 0.72 mW, which is higher than that of all other search points, so this position is the absolute value of the relative displacement.

[0074] According to the determined relative displacement azimuth and relative displacement absolute value, the system can determine the precise position of the optical fiber. In the neighborhood of this position, the system performs a local search with a fine step size (such as 0.2 μm to 0.5 μm) smaller than the initial step size to obtain the compensation position of the best optical fiber coupling efficiency. Specifically, the system performs a grid search with a step size of 0.3 μm within a range of ±5 μm centered at (104 μm, 113 μm), a total of about 289 points are tested. Among these points, if the maximum energy value 0.86 mW is measured at (105.4 μm, 112.1 μm), then this point is the compensation position of the best optical fiber coupling efficiency.

[0075] After obtaining the compensation position, the system calculates the blazed grating pattern parameters to be displayed on the LCOS device according to this position. The modulation depth of the blazed grating is adjusted according to the distance of the compensation position, usually between 0.4π and 0.8π. The period and direction of the blazed grating are also optimized according to the compensation requirements, for example, for a compensation position of (105.4 μm, 112.1 μm), the system calculates a blazed grating period of 9.8 μm, a direction angle of 43.2 degrees, and a modulation depth of 0.65π. The system loads the blazed grating pattern corresponding to these parameters onto the LCOS device, and realizes precise compensation of the optical path displacement through the diffraction principle, finally re-aligns the optical fiber and the light spot, and restores the best coupling efficiency.

[0076] Through the above method, the system can automatically detect the displacement and perform precise compensation when the optical fiber and the light spot are relatively displaced, without the need for manual intervention, greatly improving the stability and reliability of the optical system. This method is particularly suitable for fields such as long-term stable operation of optical communication systems and optical measurement systems.

[0077] The method further comprises:

[0078] The first self-calibration stage is the same as the traditional system self-calibration through a fast mirror to realize light path displacement compensation, and spiral traversal scanning is performed. That is, different directions and periods of blazed gratings are displayed on the LCOS to change the light beam transmission direction, so that the light spot rotates around the initial position and continuously searches outward. The difference from the traditional technology is that the termination condition of the spiral traversal search process is different. The spiral traversal process of the traditional method continues until the light beam is deflected to the receiving end. The greater the displacement deviation in the entire light path, the more serious the deviation of the receiving end from the light spot, and the longer the compensation process takes, which increases in a quadratic relationship. Once the deviation distance is slightly large, the search iteration step number is easily up to ten thousand steps, and it is difficult to complete the compensation within one receiving window period. In the present application, the LCOS is used to replace the FSM as the light beam deflection element, which can greatly reduce the spiral traversal search steps. Since the LCOS is a diffractive optical element, it can not only control the deflection of the light beam, but also control the splitting of the light beam. Through hologram design, the light beam can be split into multiple beams corresponding to each diffraction order of the grating. The higher the diffraction order, the larger the deflection angle of the light beam. In the present application, the spiral traversal search stage only needs to detect any diffraction spot to end, at which time the azimuth angle Φ of the relative displacement of the optical fiber and the light spot can be determined, but at this time the high-order diffraction orders are mixed and the absolute value R of the relative displacement cannot be confirmed.

[0079] After the azimuth angle Φ of the relative displacement of the optical fiber and the light spot is determined, the second self-calibration stage, i.e. the fan-shaped step scanning, is entered. Compared with the spiral traversal, this stage only needs to search in a very small fan-shaped area. After searching in each fan-shaped area, the position with the maximum detected energy in the area is used as the starting point for the next fan-shaped search outward, and when a sharp enough light spot is found, i.e. when the local maximum value is searched, the intermediate value r of the relative displacement is determined, and the fan-shaped step scanning stage is ended.

[0080] After the azimuth angle Φ of the relative displacement of the optical fiber and the light spot and the intermediate value r of the relative displacement are determined, the third self-calibration stage, i.e. the diffractive jump scanning, is entered. This stage uses the geometric relationship between different diffraction orders as a prior condition to perform jump scanning between different diffraction orders. That is, the azimuth angle Φ is fixed, and the relative displacement of the light spot is changed to 2r, and searching is performed in its neighborhood; after the search is completed, the relative displacement of the light spot is changed to 3r, and searching is performed again in its neighborhood; and so on, the relative displacement of the light spot is changed to 4r, 5r, and so on, until the position of the optical fiber is searched, and the absolute value R of the relative displacement is determined.

[0081] After the azimuth angle Φ of the relative displacement of the optical fiber and the light spot and the absolute value R of the relative displacement are determined, the last fine search stage is entered, and searching is performed in its neighborhood with a step length of 1 / 10, to achieve the best fiber coupling efficiency compensation effect.

[0082] Compared with the traditional method, the search step is reduced by hundreds of times, the system self-calibration can be realized within tens of seconds or even seconds, and the system operation efficiency and precision are greatly improved.

[0083] In an optional embodiment, the step of performing a jump search between different diffraction orders based on the relative displacement azimuth and the relative displacement intermediate value comprises:

[0084] A plurality of search positions are set by increasing the relative displacement intermediate value by an integer multiple, light intensity detection is performed in the neighborhood of each search position, and when the maximum light intensity is detected, the absolute value of the relative displacement between the optical fiber and the light spot is obtained.

[0085] After the relative displacement azimuth and the relative displacement intermediate value are determined, a jump search is performed to find the best matching position between different diffraction orders. The core idea of the jump search is to use the periodic characteristics of the diffraction orders, and by performing light intensity detection at the preset search positions, the best coupling position between the optical fiber and the light spot is quickly located.

[0086] In specific implementation, the system first sets a plurality of search positions according to the relative displacement intermediate value. The setting of these search positions follows the principle of increasing by an integer multiple. For example, if the relative displacement intermediate value is 12 microns, the search positions that can be set include 12 microns, 24 microns, 36 microns, 48 microns, etc. These positions correspond to coupling points at different diffraction orders.

[0087] The setting of the search positions needs to consider parameters such as the optical fiber mode field diameter and the light spot divergence angle. In actual application, assuming that a single-mode optical fiber is used, its mode field diameter is 10 microns, and the divergence angle of the light spot at a specific wavelength (such as 1550 nanometers) is 0.1 radian, then the relative displacement intermediate value is 15 microns. According to this, the search positions can be set to 15 microns, 30 microns, 45 microns, 60 microns, etc.

[0088] When performing accurate detection at each search position, the system not only measures the light intensity at that position, but also performs scanning detection in its neighborhood range. The size of the neighborhood range is usually set to 10%-20% of the relative displacement intermediate value. Continuing the above example, if the intermediate value is 15 microns, the neighborhood range can be set to ±1.5 microns to ±3 microns. Within this range, the system performs point-by-point scanning with a step size of 0.1 microns, and records the light intensity value at each position.

[0089] In practice, the light intensity is measured using a high-precision optical power meter. For example, when the system scans in the vicinity of 30 microns (i.e. 27-33 microns), the following light intensity data is obtained: 0.21 mW at 27.0 microns, 0.25 mW at 27.5 microns, 0.32 mW at 28.0 microns, increasing to a maximum of 0.78 mW at 29.8 microns, then 0.75 mW at 30.0 microns, and decreasing to 0.18 mW at 33.0 microns.

[0090] By comparing the maximum light intensity in the vicinity of each search position, the system can determine which diffraction order provides the best coupling effect. If the 0.78 mW detected at 29.8 microns is the maximum among all search positions, then the system determines 29.8 microns as the absolute value of the relative displacement between the fiber and the spot.

[0091] The light intensity detection process requires the relative displacement azimuth angle to remain unchanged. For example, if the previously determined azimuth angle is 37 degrees, then the fiber moves relative to the spot at this angle throughout the entire jump search process. This ensures that the search process proceeds along the correct radial direction.

[0092] In practice, the system often sets a light intensity threshold to improve search efficiency. For example, the threshold can be set to 80% of the theoretical maximum light intensity. When the light intensity of a certain position is detected to exceed this threshold, the system considers that the appropriate coupling point has been found, and the search process can be terminated early. For the above example, if the theoretical maximum light intensity is 1.0 mW, then the threshold is set to 0.8 mW. Since the actual maximum detection value is 0.78 mW, which is close to but does not exceed the threshold, the system will continue to complete the scanning of all preset positions.

[0093] To deal with multiple peak values, the system also records the position and light intensity of each local maximum point. If there are multiple close light intensity peaks, the system will further perform higher-precision scanning at these positions, such as reducing the step size to 0.01 microns, to determine the true optimal coupling position.

[0094] Another key advantage of the jump search is a significant reduction in search time. The traditional point-by-point scanning method requires 1000 measurements with a small step size (e.g. 0.1 microns) over the entire range (e.g. 0-100 microns), while the jump method only needs to perform neighborhood scanning of 4-5 positions, reducing the total number of measurements to about 300, with an efficiency improvement of more than 3 times.

[0095] In some application scenarios, to further improve the accuracy, the system will perform a fine-tuning optimization after determining the absolute value of the relative displacement. Specifically, a fine scan is performed in a very small range (e.g. ±0.5 microns) with a smaller step (e.g. 0.01 microns) around the determined position to obtain an optimal coupling position with an accuracy of 0.01 microns. For example, if the initial determined position is 29.8 microns, the fine-tuning will correct it to 29.78 microns.

[0096] The method successfully realizes efficient automatic coupling of the optical fiber and the light spot. Test results show that the positioning accuracy can reach 0.01 microns, the coupling efficiency can be more than 95%, and the time required to complete the entire search process is usually less than 10 seconds, which is much better than the several minutes required by the traditional manual adjustment method.

[0097] In an optional embodiment, the initial correction curve is segmented according to the driving voltage, the phase response in each driving voltage interval is fitted by the least square method to obtain a segmented fitting curve, and the dynamic adjustment of the segmented points based on the slope difference of the boundary points of adjacent segmented fitting curves includes:

[0098] Obtaining a phase response curve of the LCOS device under the action of the driving voltage, calculating a second derivative of the phase response curve, determining initial segmented points according to extreme points of the second derivative, and dividing the phase response curve into a plurality of initial segmented intervals;

[0099] For the phase response data in each of the initial segmented intervals, an n-order polynomial fitting model is established, the coefficients of the n-order polynomial fitting model are solved by the least square method, and a segmented fitting function corresponding to each segmented interval is obtained;

[0100] The left slope and the right slope of the adjacent two segmented fitting functions at the segmented point are calculated, and the difference between the left slope and the right slope is obtained, wherein the left slope is the first derivative value of the segmented fitting function on the left side of the segmented point, and the right slope is the first derivative value of the segmented fitting function on the right side of the segmented point;

[0101] When the slope difference at any segmented point is greater than a preset slope threshold, the offset direction of the segmented point is determined according to the size of the slope difference and the relative size relationship between the left slope and the right slope, and the segmented point is moved by a preset step length in the determined offset direction, wherein the preset step length is proportional to the slope difference;

[0102] The least square fitting and the slope difference calculation are repeatedly performed on the segmented interval divided by the new segmented point after the movement, until the slope difference at all segmented points is less than the preset threshold or a preset iteration number is reached, and the final segmented fitting function is obtained.

[0103] For the phase response correction of LCOS device, the correction accuracy is improved by piecewise fitting method. A LCOS device with working wavelength of 532 nm is used in the experiment. First, the phase response data of the device at different gray values in the range of 0-255 are measured. The phase values corresponding to different gray values are recorded using an interference measurement device, and the initial phase response curve is obtained. The curve shows that the phase is 0 radian at a gray value of 0, and the phase is 6.28 radians at a gray value of 255, but the curve shows obvious nonlinear characteristics.

[0104] The second derivative of the obtained phase response curve is calculated. The first derivative change rate of adjacent data points is calculated by using the central difference method, and the second derivative values of all sampling points are obtained. By analyzing the second derivative curve, it is found that there are extreme points at gray values of about 60, 120 and 190, which are the positions with the largest curvature change of the phase response curve, and are the ideal positions for dividing sections. Therefore, the three points are determined as the initial section points, and the entire response curve is divided into four initial section intervals: 0-60, 61-120, 121-190 and 191-255.

[0105] A third-order polynomial fitting model is established for each initial section interval. Taking the first section interval 0-60 as an example, let the gray value be x and the phase value be y, and establish the model y=a0+a1x+a2x²+a3x³. All sampling points in this interval are substituted into the model to construct a linear equation system. The least squares method is used to solve the equation system, and the coefficients a0=0.0023, a1=0.0152, a2=0.0004, a3=-0.0000021 are obtained. Similarly, the polynomial coefficients of the other three section intervals are solved respectively, and the complete piecewise fitting function is obtained.

[0106] The slope difference of adjacent section functions at the section points is calculated. Taking the section point of gray value 60 as an example, the first derivative value of the left fitting function (0-60 section) at x=60 is 0.0375, and the first derivative value of the right fitting function (61-120 section) at x=60 is 0.0412, and the slope difference is 0.0037. Similarly, the slope differences at gray values of 120 and 190 are 0.0042 and 0.0055 respectively.

[0107] The preset slope threshold is set to 0.002, and since the slope difference of all segment points is greater than the threshold, the segment point adjustment is required. For the segment point of the gray value 60, the right slope is greater than the left slope, indicating that the rising speed of the right function is faster, and therefore the segment point is moved to the left. The basic step is set to 2, and the ratio of the slope difference 0.0037 and the threshold 0.002 is about 1.85, and the actual moving step is determined to be 4 (the basic step multiplied by the ratio and rounded). The segment point is adjusted from 60 to 56, and the fitting of the two intervals 0-56 and 57-120 is performed again, and the slope difference at the new segment point is calculated to be 0.0019, which is less than the threshold, and the adjustment is completed.

[0108] The segment points of the gray values 120 and 190 are adjusted by the same method. The segment point of the gray value 120 is finally adjusted to 124, and the segment point of the gray value 190 is adjusted to 186. After the adjustment, the slope difference of all segment points is less than the preset threshold 0.002, and the segment fitting curve is smoother at the connection.

[0109] The final segment fitting function covers four intervals: 0-56, 57-124, 125-186, and 187-255. The corrected curve is verified, and the phase linearity error before and after correction is calculated by randomly selecting 50 gray value points. The maximum phase error before correction is 0.42 radians, and the maximum phase error after correction is reduced to 0.05 radians, and the average error is reduced from 0.21 radians to 0.023 radians, and the phase linearity is improved by about 89%.

[0110] To verify the correction effect, four different phase patterns are generated on the LCOS using the corrected driving voltage-phase mapping relationship, including a grating, a spiral phase, a Fresnel lens, and a vortex beam. By capturing the diffraction images before and after correction by a camera, it is found that the image clarity and contrast after correction are significantly improved, and the diffraction efficiency is improved by about 35%, especially in complex phase patterns.

[0111] By this dynamic adjustment of the segment point segment fitting method, the discontinuity problem of the traditional fixed segment point method at the segment connection is solved, the correction accuracy of the LCOS phase response is improved, the corrected phase response is more linear, and the performance of the LCOS device in the light field modulation application is improved.

[0112] In an alternative embodiment, the optimized segment fitting curve is used as a reference curve, and a bidirectional lookup method is used to establish a mapping relationship table of the target phase value of the LCOS device and the driving voltage, including:

[0113] An optimized segment fitting curve of an LCOS device is obtained, and the segment fitting curve is used as a reference curve, and the reference curve represents the corresponding relationship between the driving voltage and the phase response of the LCOS device.

[0114] dividing a target phase modulation range of the LCOS device into M discrete phase points, where M is a positive integer, and intervals between adjacent discrete phase points are equal;

[0115] for each of the discrete phase points, setting an initial search interval in a driving voltage range of the reference curve, an upper boundary of the initial search interval being a maximum driving voltage and a lower boundary being a minimum driving voltage;

[0116] performing bidirectional search in the initial search interval by using dichotomy, including: calculating a phase value corresponding to a current search interval midpoint, comparing the phase value with a target phase point, updating an upper boundary of the search interval as the current midpoint when the phase value is greater than the target phase point, and updating a lower boundary of the search interval as the current midpoint when the phase value is less than the target phase point;

[0117] judging whether a difference between the upper boundary and the lower boundary of the current search interval is less than a preset accuracy threshold, and taking the midpoint of the current search interval as a driving voltage value corresponding to the discrete phase point when the difference is less than the preset accuracy threshold;

[0118] repeating the bidirectional search process for all discrete phase points to establish a one-to-one correspondence between the discrete phase points and the driving voltages, and generating a phase-voltage mapping table of the LCOS device.

[0119] In actual applications, there is a nonlinear relationship between the phase response and the driving voltage of the LCOS device, and an accurate mapping relationship needs to be established to achieve accurate phase modulation. The embodiment first obtains an optimized segmented fitting curve of the LCOS device as a reference curve. The reference curve is obtained by measuring and segmenting fitting the phase response of the LCOS device under different driving voltages, and can accurately represent the corresponding relationship between the driving voltage and the phase response. For example, for a certain type of LCOS device, the phase response under the driving voltage with an interval of 0.1 volt in the range of 0 to 5 volts can be measured to obtain 50 measurement points, and then the measurement points are fitted by a segmented fitting algorithm to obtain the reference curve.

[0120] Based on the reference curve, the target phase modulation range of the LCOS device is divided into M discrete phase points. Here, M is a positive integer, and is generally 256, and the intervals between adjacent discrete phase points are equal. For example, for an LCOS device with a phase modulation range of 0 to 2π, it can be uniformly divided into 256 discrete points, and the interval between each point is 2π / 256.

[0121] For each discrete phase point, an initial search interval is set within the driving voltage range of the reference curve. Taking the LCOS device as an example, the upper boundary of the initial search interval is the maximum driving voltage 5 volts, and the lower boundary is the minimum driving voltage 0 volts. In this way, it is ensured that the search interval can cover all driving voltage values.

[0122] A bisection method is used to perform bidirectional search within the initial search interval. The specific operation is: the phase value corresponding to the midpoint of the current search interval is calculated, and the phase value is compared with the target phase point. Taking the first discrete phase point 0 as an example, the initial search interval is [0V, 5V], and the midpoint is 2.5V. By searching for the phase value corresponding to 2.5V on the reference curve, it is assumed to be 1.2π, which is greater than the target phase 0, so the upper boundary of the search interval is updated to 2.5V, and the new search interval becomes [0V, 2.5V]. Continue the bisection search, calculate the phase value corresponding to the new interval midpoint 1.25V, assume it is 0.6π, which is still greater than the target phase 0, then continue to update the upper boundary, the search interval becomes [0V, 1.25V]. In this way, the search interval is reduced until it is small enough.

[0123] It is judged whether the difference between the upper boundary and the lower boundary of the current search interval is less than a preset precision threshold. The preset precision threshold can be set according to actual needs, for example, 0.01 volts. When the interval width is less than the threshold, the midpoint of the current search interval is taken as the driving voltage value corresponding to the discrete phase point. Continuing the above example, it is assumed that after multiple iterations, the search interval is reduced to [0V, 0.02V], and the interval width is 0.02 volts, which is less than the preset precision threshold 0.01 volts, so the midpoint 0.01 volts is taken as the driving voltage value corresponding to the target phase 0.

[0124] The above bidirectional search process is repeatedly performed for all discrete phase points to establish a one-to-one correspondence between the discrete phase points and the driving voltage, and a phase-voltage mapping table of the LCOS device is generated. For example, for 256 discrete phase points, after the above process, a table containing 256 pairs of mapping relationships can be obtained. Each row of the table contains a phase value and its corresponding driving voltage value, such as: {0, 0.01V}, {2π / 256, 0.32V}, {4π / 256, 0.58V}, and so on until {2π, 4.95V}.

[0125] In practical applications, the mapping table established by this bidirectional search method has high precision and efficiency. Compared with the traditional linear interpolation method, this method can more accurately process the nonlinear response characteristics of the LCOS device and reduce the phase modulation error. Taking a certain type of LCOS device as an example, when the traditional linear interpolation method is used, the average phase error is about 0.1π; while using the bidirectional search method of the embodiment, the average phase error is reduced to 0.02π, and the phase modulation accuracy is increased by 5 times.

[0126] The method also has good universality and is suitable for LCOS devices of different models. Only the reference curve needs to be replaced, and the phase-voltage mapping table of a new device can be quickly established without redesigning the algorithm process. In addition, the calculation complexity of the method is O(M*log(N)), where M is the number of discrete phase points, and N is the discretization accuracy of the driving voltage, and the calculation efficiency is high, and the method is suitable for implementation in a resource-limited embedded system.

[0127] As can be seen from the above embodiments, the bidirectional lookup method provided by the application can efficiently and accurately establish the phase-voltage mapping relationship of the LCOS device, improve the phase modulation accuracy, effectively solve the problem of phase modulation error caused by the nonlinear response characteristics of the LCOS device, and provide technical support for the application of the LCOS device in the fields of optical imaging and optical communication.

[0128] In an optional embodiment, the mapping relationship table is temperature-compensated and corrected according to the temperature parameter, to obtain a temperature-compensated mapping relationship table, and the corresponding driving voltage is applied to the LCOS device according to the temperature-compensated mapping relationship table, including:

[0129] The phase response at the reference temperature is taken as a reference, the offset of the phase response at other temperature conditions relative to the phase response at the reference temperature is calculated, and the phase offset corresponding to each sampling temperature point is obtained;

[0130] According to the correspondence between the temperature points and the phase offsets, a linear relationship model of the temperature variation and the phase offset is established, and a temperature-phase compensation coefficient is obtained;

[0131] In the working process of the LCOS device, the current working temperature of the LCOS device is collected in real time by a temperature sensor, and a phase compensation value is calculated according to the temperature difference between the current working temperature and the reference temperature;

[0132] The phase-voltage mapping table of the LCOS device is corrected according to the phase compensation value, including: subtracting the phase compensation value from the target phase value to obtain a compensated phase value, and searching for the corresponding driving voltage from the phase-voltage mapping table according to the compensated phase value;

[0133] The driving voltage searched is applied to the LCOS device, to realize accurate phase modulation of the LCOS device under different temperature conditions.

[0134] A phase-voltage mapping table of the LCOS device at a reference temperature is obtained. The mapping table is usually established at a specific reference temperature (e.g. 25°C), and records the phase modulation responses corresponding to different driving voltages. In order to maintain the accurate phase modulation performance of the LCOS device at different temperature environments, the mapping table needs to be temperature-compensated and corrected.

[0135] In the temperature compensation and correction process, the system of the present application first needs to obtain the phase response data of the LCOS device at different temperature conditions. For example, the system can measure the phase response of the LCOS device at different driving voltages at multiple temperature points such as 5°C, 15°C, 25°C, 35°C, 45°C, etc. in a temperature-controlled environment. The measurement can be performed by an interferometer or other optical equipment, and the phase modulation values corresponding to the driving voltages in the range of 0-5V with a step of 0.1V at each temperature point are recorded.

[0136] After obtaining the phase response data at each temperature point, the system takes the phase response at the reference temperature (e.g. 25°C) as the reference standard, and calculates the offset of the phase response at other temperature conditions relative to the phase response at the reference temperature. For example, when the LCOS device is driven at 3.0V, the phase modulation value generated at 25°C is 180 degrees, and the phase modulation value generated at 35°C is 192 degrees, then the phase offset at 35°C relative to the reference temperature is 12 degrees. In this way, the system can obtain a phase offset data set corresponding to each sampling temperature point.

[0137] Based on the obtained correspondence between temperature points and phase offsets, the system establishes a linear relationship model between temperature variation and phase offset. In actual implementation, the system can perform linear regression analysis on the temperature-phase offset data at each driving voltage to obtain temperature-phase compensation coefficients. For example, through analysis, it is obtained that when the driving voltage is 3.0V, the phase modulation value will increase by 1.2 degrees for every 1°C increase in temperature. This linear relationship can be expressed as the product of the phase offset and the temperature variation, where the multiplier is the temperature-phase compensation coefficient. The coefficient varies with the driving voltage, so the system needs to establish a corresponding temperature-phase compensation coefficient table for different driving voltage intervals.

[0138] In the actual working process of the LCOS device, the system collects the current working temperature in real time through a temperature sensor integrated on or around the LCOS device. For example, the temperature sensor collects temperature data every 500 milliseconds with a resolution of 0.1°C. After obtaining the current working temperature, the system calculates the temperature difference between the current temperature and the reference temperature. Assuming that the current temperature is 32°C and the reference temperature is 25°C, the temperature difference is 7°C.

[0139] According to the temperature difference obtained above and the established temperature-phase compensation coefficient, a phase compensation value under the current temperature condition is calculated. The calculation method is to multiply the temperature difference by the temperature-phase compensation coefficient under the corresponding driving voltage. For example, if the temperature-phase compensation coefficient under the driving voltage of 3.0 V is 1.2 degrees / ℃ and the temperature difference is 7℃, the phase compensation value is 8.4 degrees.

[0140] After obtaining the phase compensation value, the phase-voltage mapping table of the LCOS device is corrected. The correction method is as follows: when a certain target phase value needs to be achieved, the system first subtracts the calculated phase compensation value from the target phase value to obtain a compensated phase value. For example, if the target phase value is 180 degrees and the phase compensation value is 8.4 degrees, the compensated phase value is 171.6 degrees. Subsequently, the system looks up the corresponding driving voltage from the original phase-voltage mapping table according to the compensated phase value. Assume that under the reference temperature, the driving voltage corresponding to the phase value of 171.6 degrees is 2.85 V.

[0141] The system applies the found driving voltage (such as 2.85 V) to the LCOS device, thereby achieving accurate phase modulation under the current temperature condition (32℃). Since the temperature rise will cause the phase modulation value to increase under the same driving voltage, this effect is compensated by reducing the driving voltage, ultimately ensuring that the actual phase value output by the LCOS device is consistent with the target phase value (180 degrees).

[0142] In practical applications, to improve the system response speed, the driving voltage corresponding to each target phase value under different temperature conditions can be calculated in advance to form a compensation lookup table. For example, a three-dimensional lookup table with a temperature interval of 5℃ and a phase interval of 5 degrees can be established, containing data in three dimensions of temperature, target phase value, and corresponding driving voltage. When the system is running, it only needs to quickly obtain the corresponding driving voltage value from the lookup table through bilinear interpolation or other methods according to the current temperature and target phase value.

[0143] Through the above temperature compensation correction method, the LCOS device can maintain a phase modulation accuracy within ±3 degrees in a temperature range of -10℃ to 60℃, effectively solving the problem of phase modulation drift caused by temperature changes and improving the application stability and reliability of the LCOS device in various optical systems.

[0144] As shown in Figures 2-4 , the method further comprises:

[0145] The specific implementation is as follows:

[0146] [1] Optical head: Custom optical head with high sensitivity and wavelength adaptability, manufactured by Changchun Institute of Optics, Fine Mechanics and Physics, Xi'an Institute of Optics and Fine Mechanics. The optical head can effectively receive laser signals and ensure stable performance in different wavelength ranges.

[0147] [2] Fast steering mirror FSM: Perna Nano's fast steering mirror, model S-335, is used. This device realizes high-speed and high-precision control of the direction of the light beam, and is used to compensate for the mechanical resonance of the system.

[0148] [3] Dichroic mirror: Sorebo's dichroic mirror, model DMLP1500L, is used. This dichroic mirror is used to separate input and output laser signals of different wavelengths to realize full-duplex communication (the invention does not involve signal transmission, so it is not described).

[0149] [4] Turning mirror: Edmond Optics' high-reflectivity mirror, model #47-114, is selected. This turning mirror is used to reflect the laser signal and fold the optical path.

[0150] [5] Narrow-band filter: Edmond Optics' narrow-band filter, model #65-779, is used. This filter is used to select light signals of a specific wavelength range to ensure that the system only receives signals of the target wavelength.

[0151] [6] Beam splitter: Sorebo's beam splitter, model BS039, is selected. This beam splitter is used to divide the light signal into two beams, one of which is used for coupling lens focusing, and the other small part is used for tracking camera module.

[0152] [7] Spatial light modulator LCOS: Hamamatsu's LCOS device, model X15213, is selected. LCOS is used as an alternative to fast steering mirror (FSM) to accurately control the light beam by displaying different phase holograms, improving the self-calibration efficiency.

[0153] [8] Coupling lens: A high-precision coupling lens is customized, and a company such as Crystal Optics is used for processing. This lens is used to focus the light beam and improve the coupling efficiency of the optical fiber.

[0154] [9] Signal processor: A self-developed coherent light QPSK encoding optical communication system is used to realize signal modulation and demodulation (the invention does not involve the signal processing part, so it is not described)

[0155]

[10] Tracking camera module: Cinogy's spot analyzer, model CinCam CMOS-1201EL, is selected. This module is used to monitor the spot position in real time and adjust the LCOS through the control circuit to ensure that the system can always receive the light signal with maximum efficiency.

[0156] In a second aspect of the embodiment of the present application, an LCOS linearity correction system based on a CubeSat laser communication terminal is provided, comprising:

[0157] The first unit is configured to obtain a corresponding relationship between a driving voltage and an actual phase response of an LCOS device in a laser communication terminal of a CubeSat, and generate an initial correction curve of the driving voltage and the actual phase response of the LCOS device according to the corresponding relationship.

[0158] The second unit is configured to segment the initial correction curve according to the driving voltage, perform least square fitting on a phase response in each segment of the driving voltage to obtain a segmented fitting curve, and dynamically adjust a segmented point based on a slope difference of boundary points of adjacent segmented fitting curves until the slope difference of the boundary points of the adjacent segmented fitting curves is less than a preset slope threshold, to obtain an optimized segmented fitting curve.

[0159] The third unit is configured to take the optimized segmented fitting curve as a reference curve, and establish a mapping relationship table of a target phase value and a driving voltage of the LCOS device by using a bidirectional lookup method.

[0160] The fourth unit is configured to collect a temperature parameter of the LCOS device in real time during a working process of the laser communication terminal of the CubeSat, perform temperature compensation correction on the mapping relationship table according to the temperature parameter to obtain a temperature-compensated mapping relationship table, and apply a corresponding driving voltage to the LCOS device according to the temperature-compensated mapping relationship table.

[0161] The third aspect of the embodiment of the application,

[0162] An electronic device is provided, comprising:

[0163] a processor;

[0164] a memory for storing processor-executable instructions;

[0165] The processor is configured to invoke the instructions stored in the memory to perform the method described above.

[0166] The fourth aspect of the embodiment of the application,

[0167] A computer-readable storage medium is provided, which stores computer program instructions, and the computer program instructions are executed by a processor to implement the method described above.

[0168] The application can be a method, device, system and / or computer program product. The computer program product can include a computer readable storage medium on which is loaded computer readable program instructions for executing various aspects of the application.

[0169] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. The LCOS linearity correction method based on the cubic satellite laser communication terminal is characterized in that: include: Obtain the corresponding relationship between the driving voltage and actual phase response of the LCOS device in the CubeSat laser communication terminal; generating an initial calibration curve of the driving voltage and actual phase response of the LCOS device according to the corresponding relationship; The initial correction curve is segmented according to the driving voltage, and the phase response within each driving voltage interval is fitted by the least squares method to obtain a segmented fitting curve. The segmentation points are dynamically adjusted based on the slope difference of the boundary points of adjacent segmented fitting curves until the slope difference at the boundary points of adjacent segmented fitting curves is less than a preset slope threshold, thereby obtaining an optimized segmented fitting curve, including: Obtaining a phase response curve of the LCOS device under the action of a driving voltage, calculating a second-order derivative of the phase response curve, determining an initial segmentation point according to an extreme point of the second-order derivative, and dividing the phase response curve into a plurality of initial segmentation intervals; For the phase response data in each segmented interval in the initial segmented interval, an n-order polynomial fitting model is established, and the coefficients of the n-order polynomial fitting model are solved by the least squares method to obtain a segmented fitting function corresponding to each segmented interval; Calculating the left slope and the right slope of two adjacent piecewise fitting functions at the segmentation point, and obtaining the difference between the left slope and the right slope, wherein the left slope is the first-order derivative value of the piecewise fitting function on the left side of the segmentation point, and the right slope is the first-order derivative value of the piecewise fitting function on the right side of the segmentation point; When the slope difference at any segmentation point is greater than a preset slope threshold, the offset direction of the segmentation point is determined according to the magnitude of the slope difference and the relative magnitude relationship between the left slope and the right slope, and the segmentation point is moved in the determined offset direction by a preset step length, wherein the preset step length is proportional to the slope difference; Repeating the least squares fitting and slope difference calculation on the segmented intervals divided by the new segmented points after the movement until the slope differences at all segmented points are less than the preset threshold or the preset number of iterations is reached, thereby obtaining the final segmented fitting function; The optimized segmented fitting curve is used as a reference curve, and a mapping relationship table between the target phase value and the driving voltage of the LCOS device is established by a bidirectional search method; During operation of the cubic satellite laser communication terminal, temperature parameters of the LCOS device are collected in real time, temperature compensation correction is performed on the mapping relationship table according to the temperature parameters to obtain a temperature-compensated mapping relationship table, and a corresponding driving voltage is applied to the LCOS device according to the temperature-compensated mapping relationship table; The method further includes realizing optical path displacement compensation based on automatic optical fiber alignment of the LCOS device: Displaying blazed gratings of different directions and periods on an LCOS device to generate multiple diffracted beams, controlling the multiple diffracted beams to traverse and scan along a spiral path, and obtaining the relative displacement azimuth angle between the optical fiber and the light spot when any one of the diffracted beams is detected; Determine a sector search area based on the relative displacement azimuth, gradually expand the search range within the sector search area to perform energy detection, use the maximum energy position detected in each sector search area as the search starting point for the next sector search area, and obtain the intermediate value of the relative displacement between the optical fiber and the light spot when a local maximum value of the light intensity is detected; Based on the relative displacement azimuth angle and the relative displacement intermediate value, performing a jump search between different diffraction orders to obtain the relative displacement absolute value; Determining the optical fiber position according to the relative displacement azimuth and the relative displacement absolute value, and performing a local search in a neighborhood of the optical fiber position with a fine step size smaller than an initial step size until a compensation position with optimal optical fiber coupling efficiency is obtained; A corresponding blazed grating pattern is displayed on the LCOS device according to the compensation position to achieve optical path displacement compensation.

2. The method according to claim 1, characterized in that Performing a jump search between different diffraction orders based on the relative displacement azimuth angle and the relative displacement intermediate value includes: The intermediate value of the relative displacement is incremented by integer multiples to set multiple search positions, light intensity detection is performed in the vicinity of each search position, and when the maximum light intensity is detected, the absolute value of the relative displacement between the optical fiber and the light spot is obtained.

3. The method according to claim 1, characterized in that The optimized segmented fitting curve is used as a reference curve, and a mapping relationship table between the target phase value and the driving voltage of the LCOS device is established by a bidirectional search method, including: Obtaining a segmented fitting curve after optimization of the LCOS device, and using the segmented fitting curve as a reference curve, wherein the reference curve represents a corresponding relationship between a driving voltage and a phase response of the LCOS device; The target phase modulation range of the LCOS device is divided into M discrete phase points, where M is a positive integer and the intervals between adjacent discrete phase points are equal; For each of the discrete phase points, an initial search interval is set within the driving voltage range of the reference curve, wherein the upper boundary of the initial search interval is the maximum driving voltage and the lower boundary is the minimum driving voltage; Performing a bidirectional search within the initial search interval using a binary search method, including: calculating a phase value corresponding to a midpoint of a current search interval, comparing the phase value with a target phase point, and when the phase value is greater than the target phase point, updating an upper boundary of the search interval to the current midpoint; and when the phase value is less than the target phase point, updating a lower boundary of the search interval to the current midpoint; Determine whether the difference between the upper boundary and the lower boundary of the current search interval is less than a preset accuracy threshold, and if so, use the midpoint of the current search interval as the driving voltage value corresponding to the discrete phase point; The bidirectional search process is repeatedly performed on all discrete phase points to establish a one-to-one correspondence between discrete phase points and driving voltages, thereby generating a phase-voltage mapping table for the LCOS device.

4. The method according to claim 1, wherein Performing temperature compensation correction on the mapping relationship table according to the temperature parameter to obtain a temperature-compensated mapping relationship table, and applying a corresponding driving voltage to the LCOS device according to the temperature-compensated mapping relationship table includes: Taking the phase response at the reference temperature as a reference, calculate the offset of the phase response under other temperature conditions relative to the phase response at the reference temperature, and obtain the phase offset corresponding to each sampling temperature point; According to the corresponding relationship between the temperature point and the phase offset, a linear relationship model between the temperature change and the phase offset is established to obtain a temperature-phase compensation coefficient; During the operation of the LCOS device, the current operating temperature of the LCOS device is collected in real time by a temperature sensor, and a phase compensation value is calculated according to the temperature difference between the current operating temperature and the reference temperature; Correcting a phase-voltage mapping table of the LCOS device according to the phase compensation value includes: subtracting the phase compensation value from a target phase value to obtain a compensated phase value, and searching a corresponding driving voltage from the phase-voltage mapping table according to the compensated phase value; The obtained driving voltage is applied to the LCOS device to achieve precise phase modulation of the LCOS device under different temperature conditions.

5. An LCOS linearity correction system based on a CubeSat laser communication terminal, for implementing the method according to any one of claims 1 to 4, characterized in that: include: The first unit is used to obtain the corresponding relationship between the driving voltage and the actual phase response of the LCOS device in the cubic satellite laser communication terminal; generating an initial calibration curve of the driving voltage and actual phase response of the LCOS device according to the corresponding relationship; The second unit is configured to segment the initial correction curve according to the driving voltage, perform least squares fitting on the phase response within each driving voltage interval to obtain a segmented fitting curve, and dynamically adjust the segmentation points based on the slope difference of the boundary points of adjacent segmented fitting curves until the slope difference at the boundary points of adjacent segmented fitting curves is less than a preset slope threshold, thereby obtaining an optimized segmented fitting curve; The third unit is configured to use the optimized piecewise fitting curve as a reference curve and establish a mapping relationship table between the target phase value and the driving voltage of the LCOS device in a bidirectional search manner; The fourth unit is used to collect the temperature parameters of the LCOS device in real time during the operation of the cubic satellite laser communication terminal, perform temperature compensation correction on the mapping relationship table according to the temperature parameters, obtain the temperature compensated mapping relationship table, and apply a corresponding driving voltage to the LCOS device according to the temperature compensated mapping relationship table.

6. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to call the instructions stored in the memory to execute the method according to any one of claims 1 to 4.

7. A computer-readable storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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