A control method and device for multi-beamlet low-order aberration correction

Abstract

The application discloses a control method and device for multi-beam low-order aberration correction, and belongs to the technical field of wavefront correction. The method comprises the following steps: collecting wavefront slopes of a to-be-corrected wavefront in X and Y directions in a spot array image by using a Hartmann wavefront sensor; defining a sub-beam corresponding sub-aperture screening matrix and a sub-beam closed loop selection matrix; dividing the array beam according to the sub-beam closed loop selection matrix and the sub-beam corresponding sub-aperture screening matrix, and performing partition processing on the detected wavefront slopes; calculating aberration correction voltages of the sub-beams needing to be closed according to a wavefront recovery algorithm; obtaining the control voltages of the sub-beams in the first iteration by PI control, obtaining system control voltages according to the sub-beam closed loop selection matrix, and realizing parallel closed loop control of the sub-beams. The application can realize independent or collaborative control of a single sub-mirror or multiple sub-mirrors by using only one multiplication operation, reduces the calculation amount of system operation, and improves the correction rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of wavefront correction, and in particular relates to a control method and device for correcting multi-beamlet low-order aberrations. Background Art

[0002] Adaptive optics systems transmit wavefront distortion signals measured in real time by wavefront sensors to a wavefront processor, which generates control voltages for the deformable mirrors to effectively compensate for the wavefront distortion signals. Due to its real-time effectiveness and stable performance, this wavefront distortion compensation method is widely used in fields such as high-resolution imaging observation and high-concentration energy transmission.

[0003] Arraying the light beams emitted by multiple low-power lasers is also one of the effective ways to achieve high-power laser output. This method can effectively solve the problems of poor beam quality in traditional high-energy laser systems. The existing array beam distortion wavefront correction adopts a mode in which multiple adaptive optical systems work in parallel. The system structure of this method is very large and the cost is high. At the same time, it has high requirements for the spatial alignment of the wavefront corrector and the wavefront sensor. The assembly requirements of the system are strict. In terms of system function, it can only achieve individual correction control of each sub-beam, and cannot achieve coordinated control of different sub-beams. The correction rate is low. Therefore, there is an urgent need for a control method with high correction rate and low cost to achieve coordinated control of multiple sub-beams and effectively improve the beam quality. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A control method for correcting multi-beamlet low-order aberrations, comprising:

[0006] Step 1: Use the Hartmann wavefront sensor to collect the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and ;

[0007] Step 2: Define the sub-aperture screening matrix corresponding to the beamlet and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing;

[0008] Step 3: Obtain the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage ;

[0009] Step 4: Get the sub-bundle through PI control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

[0010] A control device for correcting multi-beamlet low-order aberrations, comprising:

[0011] The wavefront slope acquisition module uses the Hartmann wavefront sensor to acquire the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and ;

[0012] Partition module, defines the sub-beam corresponding to the sub-aperture screening matrix and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing;

[0013] The correction module calculates the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage ;

[0014] Control module, obtains sub-bundles through PI control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

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

[0016] (1) The present invention sets a screening matrix to realize the division of the area affected by the aberration of different sub-beams. When the parameters of the Hartmann wavefront sensor remain unchanged, when the sub-beams are controlled differently, the dimension of the control matrix does not change, and the area control of the sub-beams at different positions can be realized, which has the advantages of flexibility and simplicity.

[0017] (2) The present invention introduces an integrated deformable mirror, which can realize the correction of the array beam using only one set of adaptive optical systems, thus avoiding the problem of strict assembly requirements of multiple sets of adaptive optical systems.

[0018] (3) The present invention sets up independent correction control for a single beamlet. Through the beamlet closed-loop selection matrix, it can realize independent or coordinated control of a single or multiple mirrors with only one multiplication operation, thereby enhancing the adaptability of the system, effectively reducing the amount of calculation of the system operation, and improving the correction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of a control method for multi-beamlet low-order aberration correction according to the present invention;

[0020] Figure 2 Schematic diagram of a control experimental device for an integrated multi-beamlet deformable mirror according to the present invention;

[0021] Figure 3 The corresponding arrangement diagrams of the integrated deformable mirror and Hartmann wavefront sensor subapertures and the arrangement diagram of a single sub-mirror driver used in the present invention; (a) is the corresponding arrangement diagram of the integrated deformable mirror and Hartmann wavefront sensor subapertures, and (b) is the arrangement diagram of a single sub-mirror driver;

[0022] Figure 4 The image of the light beam array collected by the Hartmann wavefront sensor of the present invention;

[0023] Figure 5 Schematic diagram of the voltage and wavefront slope changes after the intermediate sub-beam is individually closed-looped according to the present invention; wherein, (a) is a schematic diagram of the wavefront slope value change, and (b) is a schematic diagram of the voltage value change. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate 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 may be combined with each other as long as they do not conflict with each other.

[0025] The present invention provides a control method for correcting low-order aberrations of multiple beamlets. The method first sets a beamlet-corresponding subaperture screening matrix based on the wavefront slope information collected by the Hartmann wavefront sensor, divides the beamlets into regions, and then sets a beamlet closed-loop selection matrix to independently correct and control each beamlet. By changing the beamlet-corresponding elements in the beamlet closed-loop selection matrix, independent and coordinated control of each beamlet can be achieved. Setting the beamlet-corresponding subaperture screening matrix can effectively reduce the spatial alignment requirements for the wavefront corrector and the wavefront sensor. The setting of the beamlet closed-loop selection matrix simplifies the control process, can improve the correction rate of the system, achieve independent and coordinated control of the array beams, and at the same time achieve flexible and expanded applications of such wavefront correctors. Figure 1 As shown, the present invention includes:

[0026] Step 1: Use the Hartmann wavefront sensor to collect the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and .

[0027] Step 2: Define the sub-aperture screening matrix corresponding to the beamlet and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing, including:

[0028] Step 2.1, define the sub-aperture screening matrix corresponding to the beamlet As the total screening matrix, the total screening matrix is ​​composed of the sub-aperture screening matrices corresponding to each beamlet The composition is expressed as:

[0029] ;

[0030] in, is the screening threshold, the value depends on the actual system, and the beamlet corresponds to the sub-aperture screening matrix for dimensional matrix, and are the number of rows and columns of subapertures, is the number of beamlets, for dimensional matrix, For sub-bundle The corresponding Rank The effective subaperture screening value is expressed as:

[0031] ;

[0032] in, is the number of rows and columns of pixels in a single sub-aperture, Represents a sub-bundle The corresponding sub-aperture Rank The numerical model of the column pixel position is expressed as:

[0033] ;

[0034] Step 2.2, define the beamlet closed-loop selection matrix for dimensional matrix, when selecting a sub-bundle When the loop is closed, the beamlet closed loop selection matrix Middle Row Column 1 element ,otherwise ;

[0035] Step 2.3, select the matrix based on the beamlet closed loop and the sub-aperture screening matrix corresponding to the beamlet The incident array beam wavefront slope is divided into regions, and the detected wavefront slope data is processed in partitions to obtain the wavefront slopes of the sub-beams that need to be closed in the X and Y directions. and They are:

[0036] ;

[0037] in, and are the wavefront slopes of the wavefront to be corrected in the X and Y directions, respectively.

[0038] Step 3: Obtain the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage for:

[0039] ;

[0040] in, Represents a sub-bundle The corresponding response matrix The generalized inverse matrix of To sort by effective sub-aperture number neutron beam A vector composed of the wavefront slopes in the X and Y directions of the corresponding effective sub-aperture arranged alternately.

[0041] Wherein, the wavefront restoration algorithm includes a pattern method or a direct slope method.

[0042] Step 4: Get the sub-bundle through PI (proportional-integral) control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

[0043] Step 4.1, calculate the sub-bundle In the The control voltage of the iteration :

[0044] ;

[0045] in, is the proportional control coefficient, is the integral control coefficient, is the number of iterations, For sub-bundle In the The aberration correction control voltage of the iteration, For sub-bundle In the The aberration correction calculation voltage of the iteration;

[0046] Step 4.2, calculate the system control voltage :

[0047] ;

[0048] in, for dimensional matrix, is the total number of actuators for the system’s deformable mirrors, The values ​​of the sub-bundles are The control voltage at .

[0049] The technical solution of the present invention is described below with reference to embodiments.

[0050] The control experimental device of the integrated multi-beamlet deformable mirror used in this embodiment is as follows: Figure 2 As shown, the laser wavelength emitted by the laser is 635nm, the number of sub-apertures of the Hartmann wavefront sensor is 40×40, the number of sampling points of a single sub-aperture of the Hartmann camera (set inside the Hartmann wavefront sensor) is 16×16 pixels, and the wavefront corrector is a 7×1 distributed multi-beam integrated deformable mirror, with a total of 7 sub-mirrors.

[0051] Figure 3 The corresponding arrangement diagram of the integrated deformable mirror and Hartmann wavefront sensor sub-aperture used in the present invention and the arrangement diagram of a single sub-mirror driver are shown in the figure. Figure 3 As shown in (a), the integrated deformable mirror consists of 7 sub-mirrors. The number of effective drivers for a single sub-mirror is 9, and the drivers are arranged in a ring. The arrangement diagram of the driver for a single sub-mirror is shown in Figure 3 As shown in (b), the integrated deformable mirror can correct the 3rd, 4th, and 5th order Zernike aberrations.

[0052] This embodiment specifically includes the following steps:

[0053] Step 1: Use the Hartmann wavefront sensor to collect the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and , the beam array image collected using the Hartmann wavefront sensor is as follows Figure 4 shown.

[0054] Step 2: Define the sub-aperture screening matrix corresponding to the beamlet and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing, including:

[0055] Step 2.1, define the sub-aperture screening matrix corresponding to the beamlet The sub-aperture screening matrix corresponding to each beamlet (Dimensions 40×40) Composition:

[0056] ;

[0057] Each sub-bundle The corresponding subaperture screening matrix Expressed as:

[0058] ;

[0059] in, For sub-bundle The corresponding Rank The effective subaperture screening value is expressed as:

[0060] ;

[0061] in, Represents a sub-bundle The corresponding sub-aperture Rank The numerical model of the column pixel position is expressed as:

[0062] ;

[0063] Step 2.2, define the beamlet closed-loop selection matrix for dimensional matrix, when selecting a sub-bundle When the loop is closed, the beamlet closed-loop selection matrix Middle Row Column 1 element ,otherwise ;

[0064] Step 2.3: Define the wavefront slopes of the beamlets that need to be closed in the X and Y directions. and for:

[0065]

[0066] ;

[0067] in, and They are respectively the wavefront slopes of the wavefront to be corrected in the X and Y directions of this embodiment, and their dimensions are both 40×40.

[0068] Step 3: Obtain the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage :

[0069] ;

[0070] in, Represents a sub-bundle The corresponding response matrix The generalized inverse matrix of To sort by sub-aperture number neutron beam The vector composed of the wavefront slopes in the X and Y directions of the corresponding 52 effective sub-apertures arranged alternately.

[0071] Step 4: Get the sub-bundle through PI control Control voltage , only select sub-beam 4 for loop closure, according to the sub-beam loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams. Specifically including:

[0072] Step 4.1, calculate the control voltage of beamlet 4 :

[0073] ;

[0074] in, For the The control voltage corresponding to the iterative sub-beam 4 is, For the The calculated voltage corresponding to the iterative sub-beam 4 is obtained by setting the voltage in step 3 It is calculated to be equal to 4.

[0075] Step 4.2, calculate the system control voltage , so that the deformable mirror makes each independent control area match the spatial arrangement of each beamlet in the array beam, and the system control voltage The calculation formula is:

[0076] ;

[0077] Since only beamlet 4 is selected for closed loop, the final control voltage , Figure 5 The figure shows the change of wavefront slope and voltage value when only the middle beamlet 4 is closed. Figure 5 Schematic diagram of the voltage and wavefront slope changes after the intermediate beamlet is closed separately in the present invention; wherein, Figure 5 (a) is a schematic diagram of the change of wavefront slope value. Figure 5 (b) is a schematic diagram of voltage value change. Figure 5 The multiple (364 in total) different lines in (a) represent the wavefront slope values ​​of the subapertures at different positions. The figure shows the wavefront slope values ​​of 364 subapertures in total (a single beamlet has 52 subapertures, a total of 7 beamlets, a total of 52×7=364 subapertures). Figure 5 (a) shows the overall convergence trend of the wavefront slope value: after the wavefront slope value converges, it is mainly between -2 and 2.

[0078] The present invention further discloses a control device for correcting multi-beamlet low-order aberrations, comprising:

[0079] The wavefront slope acquisition module uses the Hartmann wavefront sensor to acquire the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and ;

[0080] Partition module, defines the sub-beam corresponding to the sub-aperture screening matrix and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing;

[0081] The correction module calculates the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage ;

[0082] Control module, obtains sub-bundles through PI control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

[0083] The present invention adopts a deformable mirror with independent correction of different regions. The deformable mirror enables each independently controlled region to match the spatial arrangement of each sub-beam in the array beam. At the same time, each region has the ability to correct the distortion of the incident wavefront, which can solve the problem of wavefront correction of the array beam at low cost and high efficiency.

[0084] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, 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 drives, CD-ROMs, optical storage devices, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention may be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0085] 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 flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 flowcharts and / or block diagrams. 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.

[0086] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work 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 The function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0088] 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.

[0089] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

[0090] The above descriptions are merely embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied to other related system fields, are also included in the scope of protection of the present invention.

[0091] The contents not described in detail in the specification of the present invention belong to the prior art known to those skilled in the art.

Claims

1. A control method for multi-beamlet low-order aberration correction, characterized in that: include: Step 1: Use the Hartmann wavefront sensor to collect the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and ; Step 2: Define the sub-aperture screening matrix corresponding to the beamlet and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing; Step 3: Obtain the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage ; Step 4: Get the sub-bundle through PI control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

2. The control method for multi-beamlet low-order aberration correction according to claim 1, characterized in that: Step 2 includes: Step 2.1, define the sub-aperture screening matrix corresponding to the beamlet As the total screening matrix, the total screening matrix is ​​composed of the sub-aperture screening matrices corresponding to each beamlet The composition is expressed as: ； in, is the screening threshold, the value depends on the actual system, and the beamlet corresponds to the sub-aperture screening matrix for dimensional matrix, and are the number of rows and columns of subapertures, is the number of beamlets, for dimensional matrix, For sub-bundle The corresponding Rank Column effective sub-aperture screening value; Step 2.2, define the beamlet closed-loop selection matrix for dimensional matrix, when selecting a sub-bundle When the loop is closed, the beamlet closed loop selection matrix Middle Row Column 1 element ,otherwise ; Step 2.3, select the matrix based on the beamlet closed loop and the sub-aperture screening matrix corresponding to the beamlet The incident array beam wavefront slope is divided into regions, and the detected wavefront slope data is processed in partitions to obtain the wavefront slopes of the sub-beams that need to be closed in the X and Y directions. and They are: ； in, and are the wavefront slopes of the wavefront to be corrected in the X and Y directions, respectively.

3. The control method for multi-beamlet low-order aberration correction according to claim 2, characterized in that: In step 2.1, for: ； in, is the number of rows and columns of pixels in a single sub-aperture, Represents a sub-bundle The corresponding sub-aperture Rank Numerical model for column pixel positions: 。 4. The control method for multi-beamlet low-order aberration correction according to claim 1, characterized in that: In step 3, the wavefront restoration algorithm is a pattern method.

5. The control method for multi-beamlet low-order aberration correction according to claim 1, characterized in that: In step 3, the wavefront restoration algorithm is the direct slope method.

6. The control method for multi-beamlet low-order aberration correction according to claim 1, characterized in that: In step 3, the sub-beams that need to be closed are obtained according to the wavefront restoration algorithm Aberration correction calculation voltage for: ； in, Represents a sub-bundle The corresponding response matrix The generalized inverse matrix of To sort by sub-aperture number neutron beam A vector composed of the wavefront slopes in the X and Y directions of the corresponding effective sub-aperture arranged alternately.

7. The control method for multi-beamlet low-order aberration correction according to claim 1, characterized in that: Step 4 includes: Step 4.1, calculate the sub-bundle In the The control voltage of the iteration ; Step 4.2, calculate the system control voltage .

8. The control method for multi-beamlet low-order aberration correction according to claim 7, characterized in that: In step 4.1, the sub-bundle In the The control voltage of the iteration for: ； in, is the proportional control coefficient, is the integral control coefficient, is the number of iterations, For sub-bundle In the The aberration correction control voltage of the iteration, For sub-bundle In the The aberration correction voltage is calculated for the iteration.

9. The control method for multi-beamlet low-order aberration correction according to claim 7, characterized in that: In step 4.2, the system control voltage for: ； in, for dimensional matrix, is the total number of actuators for the system’s deformable mirrors, The values ​​of the sub-bundles are The control voltage at .

10. A control device for multi-beamlet low-order aberration correction, characterized in that: include: The wavefront slope acquisition module uses the Hartmann wavefront sensor to acquire the wavefront slopes of the wavefront to be corrected in the X and Y directions in the spot array image. and ; Partition module, defines the sub-beam corresponding to the sub-aperture screening matrix and the beamlet closed-loop selection matrix , according to the beamlet closed-loop selection matrix and the sub-aperture screening matrix corresponding to the beamlet The array beam is divided into regions and the detected wavefront slope is and Perform partition processing; The correction module calculates the sub-beams that need to be closed according to the wavefront restoration algorithm Aberration correction calculation voltage ; Control module, obtains sub-bundles through PI control In the The control voltage of the iteration , according to the beamlet closed-loop selection matrix Get the system control voltage , realizing parallel closed-loop control of sub-beams.

Images