Method for ion beam processing of visible light aluminum mirror based on improved trimming strategy

Abstract

This invention discloses an ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy, comprising the following steps: 1) correcting the surface shape error of the aluminum mirror using a single-point diamond turning process; 2) correcting the surface shape error of the aluminum mirror corrected by the single-point diamond turning process using a magnetorheological process; 3) obtaining the surface shape error matrix R of the aluminum mirror corrected by the magnetorheological process. mrf and the amount of material removed r during magnetorheological processing m Based on the amount of material removed r m Calculate the contamination layer removal residence time matrix T in the residence time matrix of ion beam processing. c According to the surface error matrix R mrf Calculate the matrix removal residence time matrix T in the residence time matrix of ion beam processing. s The aluminum reflector, after being corrected using magnetorheological technology, is processed using an ion beam process using the aforementioned residence time matrix. This invention improves the ion beam shaping strategy to further enhance surface accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to optical processing technology, and in particular to a visible light aluminum mirror ion beam processing method based on an improved modification strategy. BACKGROUND

[0002] Due to the characteristics of light weight, high reflectivity and good processability, aluminum alloy has broad application prospects in the field of aerospace loads. With the application of complex curved surfaces in optical systems, optical systems can have better performance and more compact design structure. While bringing advantages, the machining of complex curved aluminum mirrors has become a key factor limiting performance improvement. The most commonly used machining method for complex curved aluminum mirrors is single-point diamond machining, which can simultaneously obtain high precision surface shape and nanometer-level surface roughness. However, due to the principle of maternal processing, the machining surface shape precision is limited by the precision of the machine tool itself. Moreover, due to the inherent machining defects, the aluminum mirror surface will have inherent turning knife marks. Therefore, the precision of the aluminum mirror machined by single-point diamond turning can only meet the application of infrared waveband. In order to realize the application of visible light or even ultraviolet light, a higher precision machining method is needed. Magnetorheological process is a common surface shape improvement process, which belongs to evolutionary processing and is not limited by the precision of the machine tool. The magnetorheological process has successfully machined a free-form surface aluminum mirror that can be applied to the visible light waveband. However, the magnetorheological machining process produces an inherent surface contamination layer, causing serious surface quality deterioration. Common methods to improve surface quality such as chemical mechanical polishing can improve surface quality, but will cause deterioration of surface shape precision, so it is difficult to achieve breakthrough in final machining precision.

[0003] Ion beam technology has the characteristics of non-contact, good stability, low processing pollution, and has great application prospects in the field of aluminum mirror machining. Ion beam technology has been proven to have effective contamination layer removal effect, which can greatly improve surface quality and reflectivity. Currently, ion beam technology is mainly used for surface cleaning, and the uniform scanning removal machining strategy is adopted, which is expected to remove contamination while maintaining the surface shape distribution and surface shape precision after magnetorheological machining, so the machining precision of magnetorheological machining still limits the final machining precision of aluminum mirror.

[0004] Ion beam processing is considered the optical processing method with the highest precision, and it holds promise for further improving the processing accuracy of aluminum mirrors. During ion beam sputtering, the composition of the contaminant layer is dynamically changing, and this composition significantly determines the removal efficiency of the ion beam sputtering. Therefore, it is difficult to accurately predict the material removal efficiency of the ion beam during processing. Furthermore, since the characteristics of the contaminant layer are closely related to the magnetorheological processing time, and the residence time at different points on the surface often varies greatly during common magnetorheological shaping processes, the surface contaminant layer is unevenly distributed, which also poses a significant challenge to high-precision ion beam shaping. Summary of the Invention

[0005] The technical problem to be solved by this invention is: In view of the technical problems existing in the prior art, this invention provides an ion beam processing method for visible light aluminum reflectors based on an improved shaping strategy. By combining the results of magnetorheological processing and the prediction of processing amount, the state of the contamination layer is determined. By combining the improvement of the ion beam shaping strategy, the surface shape accuracy is further improved in the process of removing the surface contamination layer.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] An ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy includes the following steps:

[0008] 1) The aluminum reflector is corrected for surface shape error using a single-point diamond turning process;

[0009] 2) The surface shape error of the aluminum reflector after correction by single-point diamond turning is corrected by magnetorheological process;

[0010] 3) Obtain the surface shape error matrix R of the aluminum mirror after correction using magnetorheological technology. mrf and the amount of material removed r during magnetorheological processing m Based on the amount of material removed r m Calculate the contamination layer removal residence time matrix T in the residence time matrix of ion beam processing. c According to the surface error matrix R mrf Calculate the matrix removal residence time matrix T in the residence time matrix of ion beam processing. s The aluminum reflector, after being corrected by magnetorheological process, is processed using ion beam technology using the residence time matrix.

[0011] Furthermore, in step 3, based on the amount of material removed r m Calculate the contamination layer removal residence time matrix T in the residence time matrix of ion beam processing. c Specifically, it includes:

[0012] 3.1a) preset the material removal amount r m multiply the preset contamination layer generation parameter k to obtain the contamination layer depth distribution matrix R c ;

[0013] 3.1b) adjust the process parameters of ion beam polishing, set the ion energy, working current and processing distance, and according to the above process parameters, the ion beam removal function is made for the aluminum alloy mirror surface processed by the magnetorheological process, to obtain the removal function matrix set {r ibf};

[0014] 3.1c) according to the contamination layer depth distribution matrix R c , combined with the removal function matrix set {r ibf}, the removal intensity matrix R is generated, and the contamination layer removal residence time matrix T c is calculated according to the removal intensity matrix R and the removal function matrix set {r ibf}.

[0015] Preferably, the preset contamination layer generation parameter k in step 3.1a is 0.6.

[0016] Further, after step 1, it further includes: obtaining the removal function matrix r of the aluminum mirror corrected by the single-point diamond turning process as the substrate removal function through experimental test; and step 3 calculates the substrate removal residence time matrix T s in the ion beam processing residence time matrix according to the surface error matrix R mrf . Specifically includes:

[0017] 3.2a) subtract the contamination layer depth distribution matrix R c from the surface error matrix R mrf to obtain the substrate material removal matrix R s ;

[0018] 3.2b) calculate the substrate removal residence time matrix T s according to the substrate material removal matrix R s and the removal function matrix r.

[0019] Further, the residence time matrix is the sum of the contamination layer removal residence time matrix T c and the substrate removal residence time matrix T s .

[0020] Further, step 3 utilizes the residence time matrix to process the aluminum mirror corrected by the magnetorheological process by the ion beam process, which includes:

[0021] 3.3a) according to the residence time matrix and the removal function matrix set {r ibfThe minimum running speed v of the ion beam processing tool is calculated;

[0022] 3.3b) introducing an integer n as a processing adjustment factor, if the minimum running speed v is greater than or equal to the preset processing speed, the processing adjustment factor n is 1; if the minimum running speed v is less than the preset processing speed, the size of the processing adjustment factor n is adjusted so that the product of the minimum running speed v and the processing adjustment factor n is greater than or equal to the preset processing speed;

[0023] 3.3c) dividing the residence time matrix by the processing adjustment factor n to obtain a new residence time matrix, according to the new residence time matrix, the surface of the aluminum mirror after the magnetorheological process is processed n times by the ion beam process according to the minimum running speed v.

[0024] Preferably, in step 3.3c, the time interval between single iterations when the ion beam process is performed n times is a preset specified time length.

[0025] Further, the end condition of step 1 of correcting the surface error of the aluminum mirror by the single-point diamond turning process is that the surface error correction is better than the first preset threshold value in RMS value.

[0026] Further, the end condition of step 2 of correcting the surface error of the aluminum mirror after the single-point diamond turning process by the magnetorheological process is that the surface error correction is better than the second preset threshold value in RMS value, and the second preset threshold value is smaller than the first preset threshold value.

[0027] Preferably, the first preset threshold value is 100 nm, and the second preset threshold value is 50 nm.

[0028] Compared with the prior art, the advantages of the present application are:

[0029] The present application optimizes and improves the ion beam process processing strategy based on the prediction of the magnetorheological processing state. When the aluminum mirror is processed by the ion beam process, the removal function and the material removal amount are compensated, so that the material removal is more controllable, the high-precision shaping of the material removal layer composed of the pollution layer and the substrate layer is realized, the surface shape precision is controlled and improved while the pollution layer is removed, and the processing certainty and the final processing precision are improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flowchart of the embodiment of the present application. DETAILED DESCRIPTION

[0031] The present application is further described below in conjunction with the drawings and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0032] Based on the ion sputtering effect, ion beam technology can effectively remove the contamination layer from the surface of aluminum mirrors after magnetorheological processing. However, currently, ion beam technology is only used as a surface cleaning process, often employing a uniform scanning method to achieve uniform removal of surface materials. Due to the dynamic changes in contaminant content during sputtering, the ion beam removal efficiency is difficult to estimate, and currently, only surface shape accuracy can be maintained, making further improvement in accuracy difficult.

[0033] This embodiment proposes an ion beam processing method for visible light aluminum reflectors based on an improved shaping strategy. By controlling the ion beam shaping strategy, high-precision shaping of the material removal layer, consisting of a contamination layer and a collective layer, is achieved. This method simultaneously removes the contamination layer and controls and improves surface shape accuracy, thereby enhancing processing certainty and final processing precision. Figure 1 As shown, it includes the following steps:

[0034] 1) The aluminum reflector is corrected for surface shape error using a single-point diamond turning process;

[0035] 2) The surface shape error of the aluminum reflector after correction by single-point diamond turning is corrected by magnetorheological process;

[0036] 3) Obtain the surface shape error matrix R of the aluminum mirror after correction using magnetorheological technology. mrf and the amount of material removed r during magnetorheological processing m Based on the amount of material removed r m Calculate the contamination layer removal residence time matrix T in the residence time matrix of ion beam processing. c According to the surface error matrix R mrf The residence time matrix for ion beam processing is calculated, and the aluminum mirror, after being corrected by magnetorheological process, is processed by ion beam process using the residence time matrix.

[0037] Through the above steps, in this embodiment, when processing an aluminum mirror using ion beam technology, the surface shape error matrix R of the aluminum mirror after magnetorheological processing is determined. mrf and the amount of material removed r during magnetorheological processing m Calculate the contamination layer removal residence time matrix T in the residence time matrix. c and matrix removal residence time matrix T s The removal function and material removal amount are compensated to make the material removal more controllable, and to achieve high-precision shaping of the material removal layer composed of the contamination layer and the substrate layer. While removing the contamination layer, the surface shape accuracy is controlled and improved, thereby improving the processing certainty and final processing accuracy.

[0038] The following provides a detailed explanation of each step.

[0039] The step 1 of the embodiment first detects the surface error of the aluminum mirror to be processed, corrects the surface error by using the single-point diamond turning process until the end condition is reached, and obtains the surface error R of the turned mirror spdt As shown in Figure 1 The end condition of the surface error correction of the aluminum mirror by using the single-point diamond turning process in step 1 is that the surface error correction reaches the RMS value better than the first preset threshold 100 nm.

[0040] The step 2 of the embodiment first selects the magnetorheological processing parameters such as magnetic field strength, polishing wheel speed, processing gap, polishing fluid flow rate, and polishing fluid viscosity, obtains the corresponding removal function matrix r mrf ; then takes the surface error R spdt as the removal amount matrix, calculates the residence time matrix M mrf of the magnetorheological shaping according to the removal function matrix r mrf and the removal amount matrix R spdt , corrects the surface error of the aluminum mirror corrected by using the single-point diamond turning process by using the magnetorheological process according to the removal function matrix r mrf and the residence time matrix M mrf until the end condition is reached, and obtains the corresponding surface error matrix R mrf As shown in Figure 1 The end condition of the surface error correction of the aluminum mirror corrected by using the single-point diamond turning process by using the magnetorheological process in step 2 is that the surface error correction reaches the RMS value better than the second preset threshold 50 nm; finally, the material removal amount r m in the magnetorheological processing process is calculated according to the removal function matrix r mrf and the residence time matrix M mrf , and the specific calculation process of the forward convolution method is not improved in the scheme and will not be described here.

[0041] Specifically, in step 2 of the embodiment, when the magnetorheological processing parameters such as magnetic field strength, polishing wheel speed, processing gap, polishing fluid flow rate, and polishing fluid viscosity are selected, the magnetic field strength is set to 300 mT-400 mT, the polishing wheel speed is set to 200 rpm-220 rpm, the processing gap is set to 0.1 mm-0.25 mm, the polishing fluid flow rate is set to 100 L / h-150 L / h, and the polishing fluid viscosity is set to 0.35 Pa·s-0.55 Pa·s.

[0042] In step 3 of the embodiment, the pollution layer removal residence time matrix T c in the residence time matrix of the ion beam processing is calculated according to the material removal amount r m Specifically, the following steps are included:

[0043] 3.1a) define the contamination layer generation parameter k, and the material removal amount r m Multiply the contamination layer generation parameter k to obtain the contamination layer depth distribution matrix R c , that is, R c = k·r m ;

[0044] 3.1b) adjust the process parameters of ion beam polishing, set the ion energy, working current and processing distance, and according to the above process parameters, the ion beam removal function is made for the aluminum alloy mirror surface processed by the magnetorheological process, to obtain the removal function matrix set {r ibf}, in this embodiment, the energy of the ion beam is set to 800eV, the working distance is 40mm, the working gas is argon, and the ion beam removal function is made for the aluminum mirror surface corrected by the magnetorheological process with 0s-180s as an interval and 10s as a step. The uniform scanning method is used and the scanning speed is 50mm / min. In addition, the removal function matrix r of the aluminum mirror corrected by the single-point diamond turning process is obtained by experimental test as the substrate removal function;

[0045] 3.1c) using the linear equation method, first, according to the contamination layer depth distribution matrix R c , combined with the removal function matrix set {r ibf}, the removal intensity matrix R is generated, and the mathematical relationship between the contamination layer depth distribution matrix R c and the removal intensity matrix R is: R*T c = R c ;

[0046] Then, according to the removal intensity matrix R and the removal function matrix set {r ibf}, the contamination layer removal residence time matrix T c and the corresponding machining surface shape accuracy are calculated;

[0047] This scheme does not involve the improvement of the specific calculation process of the linear equation method, and the specific calculation process is not described here.

[0048] In step 3.1a of this embodiment, the contamination layer generation parameter k is preferably 0.6.

[0049] In step 3 of this embodiment, the substrate removal residence time matrix T s in the ion beam machining residence time matrix is calculated according to the surface shape error matrix R mrf , which specifically includes the following steps:

[0050] 3.2a) subtract the contamination layer depth distribution matrix R c from the surface shape error matrix R mrf to obtain the substrate material removal matrix Rs , i.e. R s = R mrf - R c ;

[0051] 3.2b) Calculate the substrate removal residence time matrix T s and the removal function matrix r, using the pulse iteration method, according to the substrate material removal matrix R s and the corresponding machining surface shape accuracy. This scheme does not involve the improvement of the specific calculation process of the pulse iteration method, and the specific calculation process is not described here.

[0052] The residence time matrix in this embodiment is the pollution layer removal residence time matrix T c and the substrate removal residence time matrix T s , i.e. T = T c + T s . Step 3 utilizes the residence time matrix to perform ion beam process on the aluminum mirror modified by the magneto-rheological process, including:

[0053] 3.3a) Calculate the minimum running speed v of the ion beam machining tool according to the residence time matrix T and the removal function matrix set {r ibf}, using the forward convolution method. This scheme does not involve the improvement of the specific calculation process of the forward convolution method, and the specific calculation process is not described here;

[0054] 3.3b) Introduce an integer n (n >= 1 and is an integer) as a machining adjustment factor. If the minimum running speed v is greater than or equal to the preset machining speed, take the machining adjustment factor n as 1; if the minimum running speed v is less than the preset machining speed, adjust the size of the machining adjustment factor n, so that the product of the minimum running speed v and the machining adjustment factor n is greater than or equal to the preset machining speed;

[0055] In this embodiment, the preset machining speed is 100 mm / min. If v >= 100 mm / min, then n = 1; if v < 100 mm / min, then adjust n so that v*n >= 100 / min;

[0056] 3.3c) Divide the residence time matrix by the machining adjustment factor n to obtain a new residence time matrix, i.e. T new = T / n. According to the new residence time matrix T new , and according to the minimum running speed v, the surface of the aluminum mirror modified by the magneto-rheological process is iteratively machined n times by the ion beam process. When the ion beam process is iteratively machined n times, the time interval between single iterations is a preset specified time length. In this embodiment, the specified time length is 1 hour.

[0057] After n times of iteration processing by the ion beam process, the processing of the aluminum mirror is completed. The method of the embodiment optimizes the ion beam process processing strategy based on the prediction of the magnetorheological processing state, establishes the high-precision ion beam shaping method suitable for the aluminum mirror with the magnetorheological pollution layer based on the understanding of the characteristics of the pollution layer and the modeling work of the dynamic removal function, and can realize the manufacturing and processing of the aluminum mirror with visible light level precision, significantly improves the manufacturing precision, further shapes the aluminum mirror surface shape precision on the premise of removing the surface pollution, and further improves the surface shape precision.

[0058] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Therefore, any simple modification, equivalent change and modification of the above embodiment made without departing from the technical solution of the present application and according to the technical essence of the present application shall fall within the protection scope of the technical solution of the present application.

Claims

1. A visible light aluminum mirror ion beam processing method based on an improved shaping strategy, characterized in that, Includes the following steps: 1) A single-point diamond turning process was used to correct the surface shape error of the aluminum reflector; for the aluminum reflector corrected by the single-point diamond turning process, the removal function matrix was obtained through experimental testing. r As a matrix removal function; 2) The surface shape error of the aluminum reflector after correction by single-point diamond turning is corrected by magnetorheological process; 3) Obtain the surface shape error matrix of the aluminum mirror after correction using magnetorheological technology. R mrf and the amount of material removed during magnetorheological processing r m Based on the amount of material removed r m Calculate the residence time matrix of ion beam processing T The residence time matrix for contaminant removal in the middle T c According to the surface error matrix R mrf Calculate the residence time matrix of ion beam processing T Matrix removal residence time matrix T s Using the dwell time matrix T The aluminum mirror, modified using magnetorheological technology, is processed using ion beam technology, and the residence time matrix is... T Residence time matrix for removing contaminant layer T c Matrix removal residence time matrix T s sum; Based on material removal volume r m Calculate the residence time matrix of ion beam processing T The residence time matrix for contaminant removal in the middle T c Specifically, it includes: 3.1a) Material removal amount r m With preset contamination layer generation parameters k Multiplying them yields the contamination layer depth distribution matrix. R c ; 3.1b) Adjust the process parameters of ion beam polishing, set the ion energy, working current, and processing distance. Based on the above process parameters, fabricate the ion beam removal function for the surface of the aluminum alloy mirror processed by magnetorheological process, and obtain the set of removal function matrices { r ibf }; 3.1c) Based on the contamination layer depth distribution matrix R c Combined with the set of removal function matrices { r ibf }, generate the intensity removal matrix R According to the intensity matrix removal R and the set of removal function matrices { r ibf Calculate the residence time matrix for contamination layer removal. T c ; Based on the surface error matrix R mrf Calculate the residence time matrix of ion beam processing T Matrix removal residence time matrix T s Specifically, it includes: 3.2a) The surface shape error matrix R mrf Subtract the depth distribution matrix of the contamination layer R c The matrix material removal matrix is ​​obtained. R s ; 3.2b) Based on the matrix material removal matrix R s and removal function matrix r Calculate the matrix removal residence time matrix T s ; Using the dwell time matrix T The aluminum reflector, after being modified by magnetorheological process, is processed using ion beam technology, specifically including: 3.3a) Based on the residence time matrix T and the set of removal function matrices { r ibf The minimum operating speed of the ion beam processing tool was calculated. v ; 3.3b) Introducing Integers n As a processing adjustment factor, if the minimum operating speed v If the processing speed is greater than or equal to the preset processing speed, then the processing adjustment factor is applied. n =1; if the minimum running speed is 1 v If the processing speed is less than the preset processing speed, adjust the processing adjustment factor. n The size of the value makes the minimum running speed v With processing adjustment factor n The product is greater than or equal to the preset processing speed; 3.3c) The residence time matrix T Divided by processing adjustment factor n Obtain the new residence time matrix T new According to the new residence time matrix T new According to the minimum running speed v The surface of the aluminum mirror, after being modified by magnetorheological process, is then subjected to ion beam processing. n Subsequent iterations of processing.

2. The ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy according to claim 1, characterized in that, The preset contamination layer generation parameters in step 3.1a k The value is 0.

6.

3. The ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy according to claim 1, characterized in that, Step 3.3c uses ion beam technology. n During each iteration, the time interval between iterations is a preset specified duration.

4. The ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy according to claim 1, characterized in that, The termination condition for step 1, which uses a single-point diamond turning process to correct the surface shape error of the aluminum reflector, is that the surface shape error is corrected to an RMS value that is better than the first preset threshold.

5. The ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy according to claim 4, characterized in that, In step 2, the termination condition for correcting the surface shape error of the aluminum reflector after correction by single-point diamond turning is that the surface shape error is corrected to an RMS value that is better than a second preset threshold, and the second preset threshold is smaller than the first preset threshold.

6. The ion beam processing method for visible light aluminum mirrors based on an improved shaping strategy according to claim 5, characterized in that, The first preset threshold is 100nm, and the second preset threshold is 50nm.

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