Deformable mirror control method and device based on voltage iteration prediction

Abstract

The invention discloses a deformable mirror control method and device based on voltage iterative prediction, and belongs to the field of wavefront processing control, and the method comprises the steps: completing the subaperture segmentation of distorted wavefront, and obtaining the wavefront slope of a subaperture containing noise; performing model parameter identification on the wavefront slope of the sub-aperture based on the AR model of the sub-aperture slope, obtaining the optimal prediction slope at the n moment, and obtaining the prediction voltage un at the n moment; and taking a result obtained by iteratively subtracting the predicted voltage un at the n moment and the control voltage us-1 applied at the n-1 moment as an error control signal ue, inputting the error control signal ue into a controller for processing to obtain a control voltage us at the n moment, amplifying the control voltage us by a high-voltage amplifier, and then applying the control voltage us to the correction deformable mirror. The high-order high-frequency aberration can be effectively corrected, the change of the control voltage of the deformable mirror is smoother, the voltage overshoot caused by directly applying the prediction voltage is eliminated, and the stability of a control system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of wavefront processing control, and in particular relates to a method and device for controlling a deformable mirror based on voltage iteration prediction. Background Art

[0002] Due to external interference such as high-frequency narrowband disturbances introduced by mechanical devices and platform vibration, high-order high-frequency aberrations will be introduced into the light beam during propagation. The control method based on adaptive optics has the ability to predict phase. The predicted voltage calculated by the method based on linear quadratic Gaussian control is amplified by a high-voltage amplifier and applied to the deformable mirror to achieve the correction of wavefront aberrations. However, this method directly applies the predicted voltage to the deformable mirror, which will cause overshoot of the initial voltage. Summary of the invention

[0003] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0004] A deformable mirror control method based on voltage iterative prediction, comprising:

[0005] Step 1: The distorted wavefront is segmented into sub-apertures by a microlens array of a wavefront sensor to obtain the wavefront slope of the sub-aperture containing noise;

[0006] Step 2: Based on the established AR model of the sub-aperture slope, the model parameters of the wavefront slope of the sub-aperture are identified to obtain The optimal prediction slope at the moment, and according to The optimal prediction slope at the moment Predicted voltage at time ;

[0007] Step 3: Predicted voltage at time and -1 The control voltage applied at time The result of iterative subtraction is used as the error control signal , the error control signal The input controller is processed and the Control voltage at the moment ;Will Control voltage at the moment After being amplified by a high-voltage amplifier, it is applied to the correction deformable mirror.

[0008] A deformable mirror control device based on voltage iteration prediction, comprising:

[0009] The wavefront slope acquisition module completes the sub-aperture segmentation of the distorted wavefront through the microlens array of the wavefront sensor to obtain the wavefront slope of the sub-aperture containing noise;

[0010] The predicted voltage acquisition module performs model parameter identification on the wavefront slope of the subaperture based on the established AR model of the subaperture slope to obtain The optimal prediction slope at the moment, and according to The optimal prediction slope at the moment Predicted voltage at time ;

[0011] Control voltage acquisition module, Predicted voltage at time and -1 The control voltage applied at time The result of iterative subtraction is used as the error control signal , the error control signal The input controller is processed and the Control voltage at the moment ;Will Control voltage at the moment After being amplified by a high-voltage amplifier, it is applied to the correction deformable mirror.

[0012] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for controlling a deformable mirror based on voltage iteration prediction are implemented.

[0013] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the deformable mirror control method based on voltage iteration prediction.

[0014] A deformable mirror control system based on voltage iteration prediction comprises: a parallel light source generating device, a deformable mirror for simulating the generation of aberrations, a wavefront sensor, a wavefront processor, a high-voltage amplifier and a corrective deformable mirror; the parallel light source generating device generates parallel light, transmits the parallel light to the deformable mirror for simulating the generation of aberrations, uses the deformable mirror for simulating the generation of aberrations to simulate the generation of distorted wavefronts under different optical conditions, divides the sub-apertures of the distorted wavefronts by a microlens array of the wavefront sensor, and the wavefront sensor obtains the wavefront slope of the sub-aperture containing noise; the wavefront processor executes the steps of the deformable mirror control method based on voltage iteration prediction, and the high-voltage amplifier drives the corrective deformable mirror to generate a corresponding surface shape.

[0015] The present invention has the following beneficial effects:

[0016] The deformable mirror control method based on voltage iteration prediction provided by the present invention uses the Kalman filtering method to predict the slope information of the sub-aperture and obtain the predicted voltage The Kalman filter method is used to predict the slope of the sub-aperture, which can directly analyze and process the slope information containing high-order high-frequency aberrations, reduce the matrix dimension, avoid the problem of large amount of calculation, enhance the real-time processing capability of the system, and improve the correction capability of high-order high-frequency aberrations; the present invention will Predicted voltage at time and Control voltage applied at all times The subtraction result is used as the error control signal , the error control signal Through the processing of the controller, we get Control voltage applied at all times , control voltage The change is smoother; compared with directly applying the predicted voltage to the deformable mirror The present invention can eliminate voltage overshoot and improve the stability of the adaptive optical system. The deformable mirror control method based on voltage iteration prediction proposed in this paper realizes the effective correction of high-order high-frequency aberrations, and at the same time makes the change of the control voltage of the deformable mirror smoother, eliminates the voltage overshoot caused by directly applying the predicted voltage, and improves the stability of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of a deformable mirror control method based on voltage iteration prediction;

[0018] Figure 2 It is a schematic diagram of a deformable mirror control system based on voltage iteration prediction, wherein 1-a parallel light source generating device, 2-a deformable mirror for simulating aberration, 3-a deformable mirror for correction, 4-a wavefront sensor, 5-a wavefront processor, 6-a high voltage amplifier;

[0019] Figure 3 For deformable mirror Predicted voltage at time Schematic diagram of

[0020] Figure 4 For deformable mirror Control voltage at the moment Schematic diagram of

[0021] Figure 5 Root mean square (RMS) value of the residual wave front before and after correction using the deformable mirror control method based on voltage iteration prediction. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] In order to effectively correct high-order high-frequency aberrations and eliminate the voltage overshoot caused by directly applying the prediction voltage, e.g. Figure 1 As shown, the present invention proposes a deformable mirror control method based on voltage iteration prediction, comprising:

[0024] Step 1: The distorted wavefront is segmented into sub-apertures by a microlens array, and the wavefront sensor obtains the wavefront slope of the sub-aperture containing noise;

[0025] Step 2: Based on the established AR model of the sub-aperture slope, the model parameters of the wavefront slope of the sub-aperture are identified to obtain The optimal prediction slope at the moment, and according to The optimal prediction slope at the moment Predicted voltage at time ;

[0026] Step 3: Add the Predicted voltage at time and -1 The control voltage applied at time The result of iterative subtraction is used as the error control signal , the error control signal The input controller is processed and the Control voltage at the moment ;Will Control voltage at the moment After being amplified by a high-voltage amplifier, it is applied to the correction deformable mirror to achieve correction of high-order and high-frequency aberrations.

[0027] Among them, in step 2, according to the predicted slope, Predicted voltage at time The method may be a linear quadratic Gaussian control method (LQG) or other methods capable of calculating the voltage based on the slope.

[0028] Wherein, in step 3, the controller setting may be an integral controller, or may be other controllers for achieving initial voltage smoothing.

[0029] Figure 2 This is a schematic diagram of a deformable mirror control system based on voltage iteration prediction. The working process of the system is as follows:

[0030] Step 1: A parallel light source generating device 1 generates parallel light, and transmits the parallel light to a deformable mirror 2 for simulating the generation of aberrations. The deformable mirror 2 for simulating the generation of aberrations (a 64-unit deformable mirror) is used to simulate the generation of distorted wavefronts under different optical conditions. The sub-aperture of the distorted wavefront is divided into 8 images through the microlens array of the wavefront sensor. 8 spot array, wavefront sensor 4 obtains the wavefront slope of the sub-aperture containing noise ; for The moment The wavefront slope of each sub-aperture.

[0031] Step 2: Assume that the wavefront slope of the subaperture for a short time is The change over time is a random and stable process. The AR model (Formula 1) of the subaperture slope (AR model is an autoregressive model) is used to predict the wavefront slope as:

[0032] (1)

[0033] in, For the The AR model of the subaperture slope Order coefficient, The value range is 1 to , is the order of the AR model of the subaperture slope, is the wavefront slope of the ith subaperture at time nq, for The fitting error of the AR model of the subaperture slope at time t;

[0034] The power spectral density of formula (1) It can be expressed as:

[0035] (2)

[0036] Formula 2 is the power spectrum density calculation formula of the AR model (Formula 1) of the subaperture slope. is the variance of the fitting error of the AR model of the subaperture slope, is the normalized frequency, is an imaginary unit, is the absolute value operation, Indicates Sub-aperture;

[0037] Then, the least squares fitting method was used to Perform model parameter identification to obtain the parameters of the AR model of the subaperture slope , and ;

[0038] According to equations (3)-(5), the linear quadratic Gaussian control method (LQG) is performed to obtain Predicted voltage at time , that is, using the Kalman filter to predict the center of mass offset, the optimal estimate is obtained Predicted voltage at time , Predicted voltage at time like Figure 3 As shown;

[0039] (3)

[0040] (4)

[0041] (5)

[0042] (6)

[0043] (7)

[0044] (8)

[0045] In formula (3), for Always The best estimate of for Always The best prediction of is the asymptotic gain matrix of the Kalman filter, For the The centroid offset of each sub-aperture, is the response matrix of the wavefront sensor 4, is the response function of the deformable mirror, for Control voltage at the moment;

[0046] In formula (4), for Always The optimal prediction of for The optimal predicted slope at time , for The moment The wavefront slope of each sub-aperture, P is the mapping relationship matrix, A is the coefficient matrix, is the state vector of the wavefront slope, t is the time delay (time period) of adaptive optics;

[0047] In formula (7), is n-1 time pair The best estimate of for The moment The wavefront slope of the sub-aperture, is the n-m+1 time pair The best estimate of is the first The wavefront slope of each sub-aperture.

[0048] The above formula is obtained by formula (4): The optimal predicted slope at time ; Obtained by formula (5) Predicted voltage at time .

[0049] The process of model identification and slope prediction to obtain predicted voltage in step 2 above is implemented by the wavefront processor 5 , which is developed and manufactured based on the Linux + Xenomai architecture.

[0050] Step 3: Predicted voltage at time and Control voltage applied at all times The result of iterative subtraction is used as the error control signal , the expression is:

[0051] (9)

[0052] The control model is established by using an integral controller, as shown in equation (10), and then the error control signal As the reference input of the integral controller, we can get Figure 4 shown Control voltage at the moment :

[0053] (10)

[0054] in, is the proportional control coefficient, set to 0.99; is the integral control coefficient, set to 0.4;

[0055] The above step 2 is also implemented by the wavefront processor 5. Control voltage at the moment The curve is smooth and there is no transient impact. Control voltage at the moment The signals are sent to the high-voltage amplifier 6, and the high-voltage amplifier 6 drives the correction deformable mirror 3 of 64 units to generate a corresponding surface shape, thereby realizing effective correction of the high-order and high-frequency aberrations of the system.

[0056] from Figure 4 It can be seen that compared with Figure 3 , Figure 4 Eliminates direct application Predicted voltage at time The initial voltage overshoot caused by Control voltage at the moment The change is smoother, and the present invention can improve the stability of the control system and increase the service life of the deformable mirror (correction deformable mirror 3).

[0057] Figure 5 The root mean square (RMS) value of the residual wavefront before and after correction using the deformable mirror control method based on voltage iteration prediction, where the first 500 frames are the RMS values ​​of the residual wavefront before correction, and the last 500 frames are the RMS values ​​of the residual wavefront after correction. The experimental results show that the method of the present invention suppresses the wavefront aberration by more than 86.7%, realizes the effective correction of high-order high-frequency aberrations, and verifies the effectiveness of the deformable mirror control method based on voltage iteration prediction.

[0058] The deformable mirror control method based on voltage iteration prediction of the present invention includes segmenting the sub-aperture of the wavefront slope, counting the slope information of the sub-aperture, establishing a wavefront aberration model, obtaining model parameters according to the spectrum identification of the power spectral density curve of the aberration of the actual system, using Kalman filtering to obtain the predicted slope and predicted voltage, subtracting the predicted voltage at the current moment from the control voltage applied at the previous moment as an error control signal, obtaining the control voltage at the current moment after processing the error control signal through a controller, and finally sending the control voltage signal to a high-voltage amplifier, so as to achieve effective correction of high-order and high-frequency aberrations, while making the change of the control voltage of the deformable mirror smoother, improving the stability of the control system, and having strong real-time performance.

[0059] It should be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and interpreted scripting language JavaScript, etc.

[0060] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0061] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0062] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0063] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A deformable mirror control method based on voltage iteration prediction, characterized in that: include: Step 1: The distorted wavefront is segmented into sub-apertures by a microlens array of a wavefront sensor to obtain the wavefront slope of the sub-aperture containing noise; Step 2: Based on the established AR model of the subaperture slope, the model parameters of the wavefront slope of the subaperture are identified to obtain the optimal predicted slope at time n, and the predicted voltage at time n is obtained according to the optimal predicted slope at time n. ; Step 3: The predicted voltage at time n and the control voltage applied at time n-1 The result of iterative subtraction is used as the error control signal , the error control signal The input controller is processed to obtain the control voltage at time n ; Set the control voltage at time n After being amplified by a high-voltage amplifier, it is applied to the correction deformable mirror.

2. The deformable mirror control method based on voltage iteration prediction according to claim 1, characterized in that: Step 1 includes: a parallel light source generating device generates parallel light, transmits the parallel light to a deformable mirror for simulating the generation of aberrations, uses the deformable mirror for simulating the generation of aberrations to simulate the generation of distorted wavefronts under different optical conditions, divides the sub-apertures of the distorted wavefronts through a microlens array of a wavefront sensor, and obtains the wavefront slope of the sub-aperture containing noise.

3. The deformable mirror control method based on voltage iteration prediction according to claim 1, characterized in that: In step 2, obtain the predicted voltage at time n The method is the linear quadratic Gaussian control method or other methods that can calculate the voltage based on the slope.

4. The deformable mirror control method based on voltage iteration prediction according to claim 1, characterized in that: In step 2, the AR model of the subaperture slope is: （1） in, is the wavefront slope of the ith subaperture at time n, is the qth order coefficient of the AR model of the ith subaperture slope, q ranges from 1 to m, m is the order of the AR model of the subaperture slope, is the wavefront slope of the ith subaperture at time nq, is the fitting error of the AR model of the subaperture slope at time n.

5. The method for controlling a deformable mirror based on voltage iteration prediction according to claim 4, characterized in that: In step 2, the power spectral density of the AR model of the subaperture slope is for: （2） in, is the variance of the fitting error of the AR model of the subaperture slope, f is the normalized frequency, j is the imaginary unit, is the absolute value operation, i represents the i-th subaperture; The least squares fitting method was used to Perform model parameter identification to obtain the AR model parameters m, and ; According to equations (3)-(5), the Kalman filter is used to predict the center of mass offset, and the predicted voltage at time n is obtained through optimal estimation. ; （3） （4） （5） （6） （7） （8） In formula (3), For n time The best estimate of is n-1 time pair The best prediction of is the asymptotic gain matrix of the Kalman filter, is the centroid offset of the ith subaperture, D is the response matrix of the wavefront sensor, N is the response function of the deformable mirror, is the control voltage at time nt; In formula (4), is the optimal predicted slope at time n, is the wavefront slope of the ith subaperture at time n+t, P is the mapping relationship matrix, A is the coefficient matrix, is the state vector of the wavefront slope, t is the time delay (time period) of adaptive optics; In formula (7), is n-1 time pair The best estimate of is the wavefront slope of the ith subaperture at time n-1, is the n-m+1 time pair The best estimate of is the wavefront slope of the ith subaperture at time n-m+1; The optimal prediction slope at the time n is obtained by formula (4): ; Obtain the predicted voltage at time n through equation (5) .

6. The deformable mirror control method based on voltage iteration prediction according to claim 1, characterized in that: In step 3, the controller is set to be an integral controller or other controller that realizes initial voltage smoothing.

7. The deformable mirror control method based on voltage iteration prediction according to claim 1, characterized in that: In step 3, the predicted voltage at time n is and Control voltage applied at all times The result of iterative subtraction is used as the error control signal : （9） The controller is used to establish the control model, as shown in formula (10), and then the error control signal As the reference input of the controller, the control voltage at time n is obtained : （10） Among them, a is the proportional control coefficient and b is the integral control coefficient.

8. A deformable mirror control device based on voltage iteration prediction, characterized in that: include: The wavefront slope acquisition module completes the sub-aperture segmentation of the distorted wavefront through the microlens array of the wavefront sensor to obtain the wavefront slope of the sub-aperture containing noise; The predicted voltage acquisition module performs model parameter identification on the wavefront slope of the subaperture based on the established AR model of the subaperture slope, obtains the optimal predicted slope at time n, and obtains the predicted voltage at time n according to the optimal predicted slope at time n. ; Control voltage acquisition module, the predicted voltage at time n and the control voltage applied at time n-1 The result of iterative subtraction is used as the error control signal , the error control signal The input controller is processed to obtain the control voltage at time n ; Set the control voltage at time n After being amplified by a high-voltage amplifier, it is applied to the correction deformable mirror.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the deformable mirror control method based on voltage iteration prediction as described in any one of claims 1 to 7 are implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for controlling a deformable mirror based on voltage iteration prediction as described in any one of claims 1 to 7 are implemented.

11. A deformable mirror control system based on voltage iteration prediction, characterized in that: include: A parallel light source generating device, a deformable mirror for simulating the generation of aberrations, a wavefront sensor, a wavefront processor, a high-voltage amplifier and a corrective deformable mirror; the parallel light source generating device generates parallel light, transmits the parallel light to the deformable mirror for simulating the generation of aberrations, uses the deformable mirror for simulating the generation of aberrations to simulate the generation of distorted wavefronts under different optical conditions, divides the sub-apertures of the distorted wavefront through the microlens array of the wavefront sensor, and the wavefront sensor obtains the wavefront slope of the sub-aperture containing noise; the wavefront processor executes the steps of the deformable mirror control method based on voltage iteration prediction as described in any one of claims 1 to 7, and the high-voltage amplifier drives the corrective deformable mirror to generate a corresponding surface shape.

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