A method for processing pulsed ion beams based on controllable time-varying characteristics

Abstract

This invention belongs to the field of ion beam ultra-precision machining technology, specifically involving a pulsed ion beam machining method based on controllable time-varying parameters. The method includes the following steps: establishing an ion beam removal function model based on the ion beam's dwell time and beam diameter; obtaining the workpiece's surface profile to be machined and determining all machining points on that surface profile; iteratively calculating the ion beam removal function model for each machining point using a genetic algorithm to obtain the optimal dwell time and optimal beam diameter for each machining point; controlling the optimal dwell time and optimal beam diameter for each machining point, and sequentially machining all machining points. This invention, by considering the mutual influence between machining points and iteratively utilizing the results, can derive a more ideal surface profile. The ion beam removal function model, combined with the genetic algorithm calculation, yields well-optimized results, shortening the actual machining time and improving surface profile accuracy and machining efficiency.

Description

Technical Field

[0001] This invention belongs to the field of ion beam ultra-precision machining technology, specifically involving a pulsed ion beam machining method based on controllable time-varying pulses. Background Art

[0002] Ion beam polishing, as a non-contact polishing tool, removes material by sputtering it onto the surface of the component, achieving ultra-high precision surfaces. The ion beam shaping and removal function is approximately Gaussian, and its excellent shaping ability enables controllable removal of surface errors in optical materials. Its highly deterministic shaping characteristics theoretically give it nanometer-precision processing capabilities, meeting the precision requirements of optical components.

[0003] In traditional ion beam processing, the beam diameter is fixed and the ion incident energy is unchangeable. In a single iteration, only a portion of the frequency error can be removed, resulting in slow surface convergence and low processing efficiency. During the reshaping process, the removal function beam diameter is often changed by adjusting the aperture to meet the requirements of different steepness errors, and the stability of the removal function must be maintained throughout the processing. Traditional ion beam processing uses a large beam diameter for iterative processing to remove low-frequency errors, after which the aperture needs to be replaced to change the ion beam diameter for high-frequency error removal. This method not only requires a long preparation time, but increasing the aperture and decreasing the beam diameter also reduces the output ion density, thus reducing the removal efficiency. The smaller the aperture, the more pronounced this effect. Currently, the removal of mid-to-high frequency errors typically employs the aforementioned method of changing the aperture size. Each aperture replacement requires disrupting the ion beam vacuum environment and re-preparing for processing, which is time-consuming. Moreover, when removing high-frequency errors, a small aperture significantly reduces the removal efficiency, extending the processing cycle and increasing the dynamic performance requirements of the machine tool.

[0004] With the continuous development of optical systems, Chinese patent application "CN112428026B - Ion beam processing method with pulse control and adjustable beam diameter based on surface error frequency band" proposes a processing method that extracts an ion beam for processing at a fixed time and with a fixed beam diameter. However, this method can only remove a portion of low-frequency errors in a single iteration, making it difficult to effectively converge the surface shape of the component. After multiple iterations of processing, even after removing low-frequency errors, the surface shape convergence rate remains low. It is necessary to replace the aperture with a smaller beam diameter to reduce the beam diameter and change the high-frequency removal function to remove high-frequency errors. The complete processing cycle is calculated in months. When there are many high-frequency errors on the surface shape, this results in excessive dwell time being wasted on high-frequency errors, greatly reducing processing efficiency.

[0005] Therefore, current ion beam processing equipment has the following shortcomings: (1) It has low efficiency in removing high-frequency errors in surface shape, which makes it difficult to meet the production needs of optical components; (2) The dynamic performance of the machine tool cannot meet the actual processing needs. When facing high-steep errors, the fixed removal function has high requirements for the acceleration of the machine tool's motion axis; (3) Changing the beam diameter by replacing the aperture results in a long processing preparation time and makes it impossible to achieve real-time dynamic adjustment of the beam diameter, making it difficult to achieve the requirements of high-efficiency and high-precision ion beam shaping.

[0006] Therefore, proposing a pulsed ion beam processing method based on controllable time-varying pulses has become a key technical problem that urgently needs to be solved by researchers in this field. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a pulsed ion beam processing method based on controllable time-varying process that improves processing efficiency, shortens processing time, and improves processing accuracy.

[0008] This invention provides a pulsed ion beam processing method based on controllable time-varying pulses, comprising the following steps:

[0009] S1, an ion beam removal function model is established based on the residence time and beam diameter of the ion beam;

[0010] S2, obtain the surface profile of the workpiece to be machined, and determine all the points to be machined on the surface profile;

[0011] S3, the ion beam removal function model of each processing point is iteratively calculated using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point;

[0012] S4 controls the optimal residence time and optimal beam diameter of the ion beam at each processing point, and processes all processing points sequentially.

[0013] Furthermore, the ion beam removal function model is as follows:

[0014] ;

[0015] In the formula, σ represents the beam diameter during removal, t represents the dwell time, (x, y) represents the processing point, a and b represent the influence around the processing point, 0.01 represents the dwell time coefficient, and e represents the base of the natural logarithm.

[0016] Furthermore, S3 includes:

[0017] S31, assign an initial dwell time and an initial beam diameter to all points on the surface to be processed, and input the initial dwell time and beam diameter into the ion beam removal function model to calculate and obtain the pre-processed surface;

[0018] S32, assign a corrected dwell time and a corrected beam diameter to all points to be processed on the pre-processed surface, and input the corrected dwell time and the corrected beam diameter into the ion beam removal function model to calculate the iteratively processed surface;

[0019] S33. Repeat step S32 until the processed surface shape after iteration meets the required surface shape requirements and the optimal residence time and optimal beam diameter of the ion beam are obtained.

[0020] Furthermore, S2 also includes:

[0021] When determining all the points to be processed on the surface to be processed, determine the upper and lower boundaries of each point to be processed;

[0022] In S3, the initial residence time and initial beam diameter of the ion beam and the corrected residence time and corrected beam diameter of the ion beam are determined within the upper and lower bounds of the point to be processed.

[0023] Furthermore, S2 also includes expanding the surface to be processed to eliminate edge effects.

[0024] Furthermore, all processing points are arranged in a grid pattern.

[0025] Furthermore, the beam diameter of the ion beam is adjusted by installing an electromagnetic lens device for beam diameter adjustment outside the ion source.

[0026] The present invention also provides a pulsed ion beam processing apparatus based on controllable time-varying pulses, the apparatus comprising:

[0027] The ion beam removal function model module is used to establish an ion beam removal function model based on the residence time and beam diameter of the ion beam.

[0028] The workpiece surface acquisition module is used to obtain the surface profile of the workpiece to be processed and to determine all the processing points of the surface profile to be processed.

[0029] The solution module is used to iteratively calculate the ion beam removal function model for each processing point using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point.

[0030] The processing module is used to control the optimal residence time and optimal beam diameter of the ion beam at each processing point, and to process all processing points sequentially.

[0031] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described pulsed ion beam processing method based on controllable time-varying pulses.

[0032] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described pulsed ion beam processing method based on controllable time-varying pulses.

[0033] The beneficial effects of this invention are:

[0034] 1. By comprehensively considering the mutual influence between the processing points and iteratively utilizing the results, this invention can obtain a more ideal surface shape. The ion beam removal function model combined with the calculation of the genetic algorithm yields optimized results, shortens the actual shaping time, and improves the surface shape accuracy and processing efficiency.

[0035] 2. This invention enables controllable time-varying removal function processing of optical elements, greatly improving the ion beam shaping capability and laying the foundation for nanometer-precision shaping of optical elements.

[0036] 3. This invention can improve and enhance traditional processing methods, thereby shortening processing time while ensuring processing accuracy, thus improving processing efficiency and bringing better processing quality and performance. Attached Figure Description

[0037] Figure 1 This is a flowchart of the pulsed ion beam processing method based on controllable time-varying parameters of the present invention;

[0038] Figure 2 This is a schematic diagram of the pulsed ion beam processing equipment of the present invention.

[0039] Figure 3 This is a schematic diagram illustrating the beam diameter variation during processing according to the present invention;

[0040] Figure 4 This is a schematic diagram illustrating the residence time variables during processing according to the present invention;

[0041] Figure 5 This is a schematic diagram of the surface shape before processing;

[0042] Figure 6 This is a schematic diagram of the processed surface.

[0043] Figure 7 A simplified diagram showing the machining accuracy of the finished product;

[0044] Legend: Appendix Figure 3 - Appendix Figure 7 In this image, different shades of gray represent different levels of height; the darker the gray, the lower the height. Detailed Implementation

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] The technical solutions of the various embodiments of the present invention can be combined with each other, but only if they can be implemented by those skilled in the art. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0047] Ion beam shaping capability refers to its ability to correct mid-to-high frequency errors during the shaping process. Currently, it is generally believed that the smaller the spot size of the removal function, the stronger the shaping capability. The shaping capability of an ion beam is quantitatively expressed using material removal efficiency. :

[0048] ;

[0049] In the formula, d is the diameter of the removal function. The wavelength represents the error space.

[0050] Extensive experiments have shown that when the removal efficiency is less than 0.1%, it is difficult to have effective reshaping capabilities.

[0051] From this, we can obtain the relationship between the error spatial wavelength and the effective removal rate of the material:

[0052] ;

[0053] Based on this, the range of error spatial wavelengths that can be effectively removed under different removal function diameters can be obtained using this formula. Depending on the specific circumstances, we can adjust the diameter of the removal function to control the corresponding wavelength, thereby controlling the effective material removal rate. By utilizing the different effective material removal rates, we can achieve controllable time-varying of the removal function, thus greatly improving processing efficiency.

[0054] Based on this, as attached Figure 1 - Appendix Figure 7 As shown, the present invention provides a pulsed ion beam processing method based on controllable time-varying pulses, comprising the following steps:

[0055] S1. An ion beam removal function model is established based on the residence time and beam diameter of the ion beam, where residence time and beam diameter are bivariate. The ion beam removal function model is as follows:

[0056] ;

[0057] In the formula, σ represents the beam diameter during removal, t represents the dwell time, (x, y) represents the processing point, a and b represent the influence around the processing point, 0.01 represents the dwell time coefficient, and e represents the base of the natural logarithm.

[0058] This ion beam removal function model uses a Gaussian function as the removal function model. By changing the time coefficient according to the equipment and determining the residence time and beam diameter, the surface shape is refined by changing two variables. Compared with traditional processes, our two variables are the optimal solutions selected through continuous iteration, and the influence of edge effects is fully considered in the calculation process. The optimal dual variables are determined by using the extension method to calculate the processing conditions of the processing point and surrounding points, thereby greatly reducing the influence of edge effects while ensuring processing accuracy.

[0059] Due to the characteristics of the removal function, the removal amount at a single processing point is affected not only by the theoretical removal amount of the removal function processed at its current position, but also by the processing depth of the removal functions at neighboring points at that point. The degree of influence is related to the processing beam diameter. To reduce computational complexity, we ignore the influence of neighboring points more than 3σ away from the processing point, considering only the processing influence of nearby points. We then make processing judgments for each point, thus deriving the actual removal amount. In other words, this ion beam removal function model takes into account the influence around the processing point, eliminating mutual influence between processing points and improving processing accuracy.

[0060] S2, obtain the surface shape of the workpiece to be processed, and determine all the processing points of the surface shape to be processed. It is preferred that all processing points be processed in a grid pattern. Specifically, the surface of the workpiece to be processed can be scanned by a scanning device to obtain the surface shape of the workpiece to be processed.

[0061] S3, the ion beam removal function model of each processing point is iteratively calculated using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point. In this step, the optimal residence time and optimal beam diameter of the ion beam at each processing point are generally different. After obtaining the residence time and beam diameter results, the surface shape result is obtained by using a simulation processing method and compared with the previously obtained results. The optimal residence time and optimal beam diameter are determined for processing by continuously comparing the results or adjusting the initial values.

[0062] S4 controls the optimal residence time and optimal beam diameter of the ion beam at each processing point, and processes all processing points sequentially.

[0063] The pulsed ion beam processing method based on controllable time-varying characteristics provided by this invention has the following advantages:

[0064] 1. By comprehensively considering the mutual influence between the processing points and iteratively utilizing the results, this invention can obtain a more ideal surface shape. The ion beam removal function model combined with the calculation of the genetic algorithm yields optimized results, shortens the actual shaping time, and improves the surface shape accuracy and processing efficiency.

[0065] 2. This invention enables controllable time-varying removal function processing of optical elements, greatly improving the ion beam shaping capability and laying the foundation for nanometer-precision shaping of optical elements.

[0066] 3. This invention can improve and enhance traditional processing methods, thereby shortening processing time while ensuring processing accuracy, thus improving processing efficiency and bringing better processing quality and performance.

[0067] 4. This invention can significantly reduce the impact of processing one point on other points around it during processing, thereby weakening the edge effect and improving the shaping capability of the ion beam.

[0068] By using a genetic algorithm, the minimum value of the fitness function and the values ​​of the variables can be obtained. After the population is initialized, the genetic algorithm evaluates each individual according to the predetermined objective function and gives the corresponding fitness value. Based on the fitness value, the individuals are selected, crossovered, and mutated to iterate and improve the performance and solution quality of the algorithm in order to obtain the optimal solution.

[0069] In this invention, according to simulation requirements, the accuracy of the machining profile can be equivalent to the variance between the machined height and the expected height at each machining point. Based on this understanding, we can establish a fitness function to represent the difference between the machined height and the actual expected height. The fitness function is:

[0070] ;

[0071] In the formula, Y is the fitness function, h is the initial height, q is the amount of material removed, and eh represents the desired height;

[0072] This allows us to represent the actual shaping error at each point, facilitating subsequent calculations.

[0073] Based on this, S3 includes:

[0074] S31, assign an initial dwell time and an initial beam diameter to all points on the surface to be processed, and input the initial dwell time and beam diameter into the ion beam removal function model to calculate and obtain the pre-processed surface;

[0075] S32, assign a corrected dwell time and a corrected beam diameter to all points to be processed on the pre-processed surface, wherein the corrected dwell time and the corrected beam diameter are the fitness values ​​in the genetic algorithm, and input the corrected dwell time and the corrected beam diameter into the ion beam removal function model to calculate the processed surface after iteration;

[0076] S33, repeat step S32 until the processed surface shape after iteration meets the required processing surface shape. This involves selecting, crossing over, and mutating individuals based on fitness values ​​and iterating. When the fitness function meets the requirements and reaches the threshold, the optimal residence time and optimal beam diameter of the ion beam are obtained. In obtaining the optimal solution, the results of the previous calculation are saved and called in the next processing. After obtaining the new result, it is compared with the previous processed surface shape. As the number of calculations increases, the surface shape accuracy will not improve indefinitely. It is necessary to find the optimal adjustment direction by continuously comparing the results or adjusting the initial values ​​to improve the surface shape accuracy.

[0077] In one embodiment, S2 further includes:

[0078] When determining all the points to be processed on the surface to be processed, determine the upper and lower boundaries of each point to be processed;

[0079] In S3, the initial dwell time and initial beam diameter of the ion beam and the corrected dwell time and corrected beam diameter of the ion beam are determined within the upper and lower bounds of the points to be processed. That is, when an initial dwell time and initial beam diameter are given to all points to be processed on the surface to be processed in S31, the height of the processed points after processing is within the range of the upper and lower bounds when the ion beam with the initial dwell time and initial beam diameter is used to process the points to be processed. In S32, a corrected dwell time and corrected beam diameter are given to all points to be processed on the pre-processed surface, and the height of the processed points after processing is within the range of the upper and lower bounds when the ion beam with the corrected dwell time and corrected beam diameter is used to process the points to be processed.

[0080] By defining upper and lower bounds and limiting the processing of ion beams during the simulation process to these bounds, a large amount of useless calculations can be eliminated, greatly reducing the computational load.

[0081] Considering the potential edge effect during ion beam processing, in one embodiment, step S2 further includes expanding the surface to be processed and using an expansion method to eliminate the edge effect, i.e., assuming there are still processing points outside the edge that affect the process, and reducing the edge effect through calculation.

[0082] In one embodiment, the beam diameter of the ion beam is adjusted by adding a beam diameter-adjusting electromagnetic lens device outside the ion source. By changing the distribution of the electric and magnetic fields inside the lens, different beam diameters are adjusted, thereby eliminating errors in different frequency bands and achieving sub-nanometer precision shaping of optical components. This technology changes the ion emission trajectory and the beam diameter of the ion beam removal function through the electromagnetic lens, eliminating the need for repeated aperture replacements, significantly reducing preparation time, while maintaining beam current density and increasing removal efficiency, thus achieving efficient and high-precision shaping of optical components. In this embodiment, this pulsed ion beam processing method based on controllable time-varying characteristics does not require aperture replacement every time the beam diameter is changed, thereby maintaining the ion beam vacuum environment, maximizing machine tool performance, and protecting the machine tool.

[0083] According to the appendix Figure 3 and attached Figure 4 It is evident that by adding the dwell time variable to the original beam diameter control model, we can significantly improve shaping accuracy and optimize processing efficiency. In this extended algorithm, the beam diameter and dwell time variables are matched and adjusted to achieve optimal processing results. This method of effectively matching beam diameter and dwell time not only improves processing efficiency by 19% but also reduces total time by 30%. The time reduction also significantly improves shaping accuracy, resulting in better processing quality and performance.

[0084] According to the appendix Figure 4 and attached Figure 5 The simulation results show that variations in beam diameter and dwell time significantly impact the shaping effect. Further extended analysis reveals that these data indicate that appropriately adjusting the beam diameter and dwell time during the shaping process can achieve more refined and efficient shaping results. A larger beam diameter generally accelerates the shaping process, while a smaller beam diameter improves shaping accuracy. Adjusting different dwell times further enhances shaping accuracy and surface finish. (See attached...) Figure 4 and attached Figure 5 It can be seen that the large undulations that existed before processing gradually became smoother after shaping, and the precision was continuously improved.

[0085] According to the appendix Figure 6 Simulation results show that by introducing a time variable into the beam diameter control model and performing matching adjustments, the shaping accuracy is significantly improved, allowing the machining error to be controlled within an extremely high level of less than 5 nanometers. This precise control means a substantial increase in the stability and accuracy of the machining process, laying a solid foundation for achieving higher-quality machining results.

[0086] In summary, the pulsed ion beam processing method based on controllable time-varying parameters of this invention achieves maximum improvement in processing efficiency and shaping accuracy. A spot test method is used for arbitrary surface shapes, analyzing each scanned point to obtain the optimal combination of removal functions. During processing, shaping is achieved through bivariate variations in beam diameter and residence time. Experimental verification shows a 19% increase in efficiency, a 30% reduction in processing time, and a machining accuracy improved to 5nm, ensuring higher quality results. In the future, controllable time-varying ion beam processing methods will play an even more important role in ultra-precision machining.

[0087] The present invention also provides a pulsed ion beam processing apparatus based on controllable time-varying pulses, the apparatus comprising:

[0088] The ion beam removal function model module is used to establish an ion beam removal function model based on the residence time and beam diameter of the ion beam.

[0089] The workpiece surface acquisition module is used to obtain the surface profile of the workpiece to be processed and to determine all the processing points of the surface profile to be processed.

[0090] The solution module is used to iteratively calculate the ion beam removal function model for each processing point using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point.

[0091] The processing module is used to control the optimal residence time and optimal beam diameter of the ion beam at each processing point, and to process all processing points sequentially.

[0092] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described pulsed ion beam processing method based on controllable time-varying pulses.

[0093] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the above-described pulsed ion beam processing method based on controllable time-varying pulses.

[0094] The above description is merely an embodiment and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solutions of the present invention without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A pulsed ion beam processing method based on controllable time-varying pulses, characterized in that, Includes the following steps: S1, an ion beam removal function model is established based on the residence time and beam diameter of the ion beam; S2, obtain the surface profile of the workpiece to be machined, and determine all the points to be machined on the surface profile; S3, the ion beam removal function model of each processing point is iteratively calculated using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point; S4 controls the optimal residence time and optimal beam diameter of the ion beam at each processing point, and processes all processing points sequentially. The ion beam removal function model is as follows: In the formula, σ represents the beam diameter during removal, t represents the dwell time, (x, y) represents the processing point, a and b represent the influence around the processing point, 0.01 represents the dwell time coefficient, and e represents the base of the natural logarithm. S3 includes: S31, assign an initial dwell time and an initial beam diameter to all points on the surface to be processed, and input the initial dwell time and beam diameter into the ion beam removal function model to calculate and obtain the pre-processed surface; S32, assign a corrected dwell time and a corrected beam diameter to all points to be processed on the pre-processed surface, and input the corrected dwell time and the corrected beam diameter into the ion beam removal function model to calculate the iteratively processed surface; S33. Repeat step S32 until the processed surface shape after iteration meets the required surface shape requirements and the optimal residence time and optimal beam diameter of the ion beam are obtained.

2. The pulsed ion beam processing method based on controllable time-varying as described in claim 1, characterized in that, S2 further includes: When determining all the points to be processed on the surface to be processed, determine the upper and lower boundaries of each point to be processed; In S3, the initial residence time and initial beam diameter of the ion beam and the corrected residence time and corrected beam diameter of the ion beam are determined within the upper and lower bounds of the point to be processed.

3. The pulsed ion beam processing method based on controllable time-varying as described in claim 1 or 2, characterized in that, S2 further includes expanding the surface to be processed to eliminate edge effects.

4. The pulsed ion beam processing method based on controllable time-varying as described in claim 1 or 2, characterized in that, All processing points are arranged in a grid pattern.

5. The pulsed ion beam processing method based on controllable time-varying as described in claim 1 or 2, characterized in that, The beam diameter is adjusted by installing an electromagnetic lens device for beam diameter adjustment outside the ion source.

6. A pulsed ion beam processing apparatus based on a controllable time-varying pulsed ion beam processing method as described in any one of claims 1-5, characterized in that, The device includes: The ion beam removal function model module is used to establish an ion beam removal function model based on the residence time and beam diameter of the ion beam. The workpiece surface acquisition module is used to obtain the surface profile of the workpiece to be processed and to determine all the processing points of the surface profile to be processed. The solution module is used to iteratively calculate the ion beam removal function model for each processing point using a genetic algorithm to obtain the optimal residence time and optimal beam diameter of the ion beam at each processing point. The processing module is used to control the optimal residence time and optimal beam diameter of the ion beam at each processing point, and to process all processing points sequentially.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the pulsed ion beam processing method based on any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the pulsed ion beam processing method based on any one of claims 1 to 5.

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