CN119673731A - Stacked Magnetic Lenses - Google Patents
Stacked Magnetic Lenses Download PDFInfo
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- CN119673731A CN119673731A CN202510148878.8A CN202510148878A CN119673731A CN 119673731 A CN119673731 A CN 119673731A CN 202510148878 A CN202510148878 A CN 202510148878A CN 119673731 A CN119673731 A CN 119673731A
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Abstract
本发明提供了一种堆叠式磁透镜，包括：环形永磁体组，环形永磁体组包括沿中轴同轴依次设置的多个环形永磁体，多个环形永磁体用于产生基础可调磁场，基础可调磁场作用于向环形永磁体组的内环区域射入的粒子束；多个环形永磁体中的至少一个环形永磁体能相对于其他环形永磁体在中轴的延伸方向上进行相对位移，以调节基础可调磁场的磁场分布和大小。
The present invention provides a stacked magnetic lens, comprising: an annular permanent magnet group, the annular permanent magnet group comprising a plurality of annular permanent magnets coaxially arranged in sequence along a central axis, the plurality of annular permanent magnets being used to generate a basic adjustable magnetic field, the basic adjustable magnetic field acting on a particle beam injected into an inner ring region of the annular permanent magnet group; at least one of the plurality of annular permanent magnets being able to perform relative displacement relative to the other annular permanent magnets in the extension direction of the central axis, so as to adjust the magnetic field distribution and size of the basic adjustable magnetic field.
Description
Technical Field
The invention relates to the technical field of magnetic lenses, in particular to a stacked magnetic lens.
Background
The permanent magnet magnetic lens is widely applied to various precise instruments such as electron microscopes, electron beam processing equipment, particle accelerators and the like. In electron optical devices, conventional lens systems mostly use electromagnetic lenses to perform electron beam operation, which limits the trend of miniaturization of the lens systems, and also introduces a series of problems about thermal management problems and narrow application range of the lens systems.
Disclosure of Invention
In view of the above, the present invention provides a stacked magnetic lens.
According to a first aspect of the invention, a stacked magnetic lens is provided, comprising an annular permanent magnet group, wherein the annular permanent magnet group comprises a plurality of annular permanent magnets which are coaxially and sequentially arranged along a central axis, the annular permanent magnets are used for generating a basic adjustable magnetic field, the basic adjustable magnetic field acts on a particle beam injected into an inner ring area of the annular permanent magnet group, and at least one annular permanent magnet in the annular permanent magnets can relatively displace relative to other annular permanent magnets in the extending direction of the central axis so as to adjust the magnetic field distribution and the size of the basic adjustable magnetic field.
According to an embodiment of the present invention, an outer diameter of an i-th annular permanent magnet of the plurality of annular permanent magnets is smaller than an inner diameter of an i+k-th annular permanent magnet of the plurality of annular permanent magnets, so that the i-th annular permanent magnet is relatively displaced with respect to the i+k-th annular permanent magnet in an inner annular region of the i+k-th annular permanent magnet, i being a positive integer, k=1, 2.
According to an embodiment of the invention, each annular permanent magnet comprises an inner side surface close to the central axis and an outer side surface remote from the central axis, the inner side surface and the outer side surface of each annular permanent magnet being opposite in polarity to each other.
According to an embodiment of the present invention, the outer side surface of the i-th annular permanent magnet of the plurality of annular permanent magnets and the inner side surface of the i+1th annular permanent magnet of the plurality of annular permanent magnets are opposite in magnetic polarity to each other, i being a positive integer.
According to an embodiment of the invention, the plurality of ring-shaped permanent magnets comprises stacked ring-shaped permanent magnets, the stacked ring-shaped permanent magnets comprising at least two ring-shaped permanent magnets stacked in a direction in which the central axis extends, the at least two ring-shaped permanent magnets having an inner diameter identical to each other and an outer diameter identical to each other, wherein adjacent ring-shaped permanent magnets of the at least two ring-shaped permanent magnets are in contact based on magnetic forces applied to each other by the adjacent ring-shaped permanent magnets.
According to an embodiment of the present invention, an outer diameter of a j-th set of stacked annular permanent magnets of the plurality of annular permanent magnets is smaller than an inner diameter of a j+p-th set of stacked annular permanent magnets of the plurality of annular permanent magnets, so that the j-th set of stacked annular permanent magnets is relatively displaced with respect to the j+p-th set of stacked annular permanent magnets in an inner ring region of the j+p-th set of stacked annular permanent magnets, j being a positive integer, p=1, 2.
According to the embodiment of the invention, the outer side surface of the ith annular permanent magnet in the plurality of annular permanent magnets and the inner side surface of the (i+1) th annular permanent magnet in the plurality of annular permanent magnets are the same in magnetic pole, i is a positive integer, the plurality of annular permanent magnets comprise superposed annular permanent magnets, the superposed annular permanent magnets comprise at least two annular permanent magnets superposed in the extending direction of a central shaft, the at least two annular permanent magnets are the same in inner diameter and the same in outer diameter, and adjacent annular permanent magnets in the at least two annular permanent magnets are contacted based on external acting force except magnetic force of the adjacent annular permanent magnets.
According to an embodiment of the present invention, the ring-shaped permanent magnet group is plural, and the plural ring-shaped permanent magnet groups are arranged in an array in a predetermined pattern in the same plane so as to receive the particle beam corresponding to the predetermined pattern, the particle beam corresponding to the predetermined pattern being emitted by the multiple electron sources, or the particle beam emitted by the single electron source being split in the predetermined pattern by the beam splitter.
According to an embodiment of the invention, the predetermined pattern comprises a symmetrical pattern.
According to the embodiment of the invention, the magnetic lens further comprises an electromagnetic coil, a group of electromagnetic coils is wound around one annular permanent magnet along the outer side surface of the annular permanent magnet, wherein the electromagnetic coil is used for generating an additional adjustable magnetic field, a superimposed magnetic field formed by the basic adjustable magnetic field and the additional adjustable magnetic field acts on the particle beam entering the inner ring area of the annular permanent magnet group, and the magnetic field strength of the additional adjustable magnetic field changes along with the change of the current size and the direction of the input electromagnetic coil.
According to the embodiment of the invention, the plurality of annular permanent magnets in the annular permanent magnet group are sleeved in sequence along the same axis, so that the basic adjustable magnetic fields formed by superposition of the magnetic fields of the plurality of annular permanent magnets are distributed along the radial direction of the central axis, the stray field of the magnetic lens is reduced, and the precision and the stability of the magnetic lens are improved. On the basis, by controlling the relative displacement between at least one of the plurality of annular permanent magnets and other annular permanent magnet groups in the extending direction of the central axis, the magnetic field distribution and the magnetic field extremum of the basic adjustable magnetic field can be flexibly adjusted from the mechanical level, and an electromagnetic coil is not required to be used for adjusting the magnetic field distribution and the magnetic field extremum of the magnetic lens, so that the adjustment is the mechanical adjustment of a passive system, and the thermal management problem is not required to be considered.
Drawings
The foregoing and other objects, features and advantages of the invention will be apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:
fig. 1A schematically illustrates a schematic diagram of a stacked magnetic lens according to an embodiment of the invention.
Fig. 1B schematically illustrates a second schematic diagram of a stacked magnetic lens according to an embodiment of the invention.
Fig. 1C schematically illustrates a schematic diagram three of a stacked magnetic lens according to an embodiment of the invention.
Fig. 2 schematically shows a schematic view of one magnetization direction of a ring-shaped permanent magnet according to an embodiment of the invention.
Fig. 3 schematically shows a schematic structural view of stacked ring permanent magnets according to an embodiment of the present invention.
Fig. 4 schematically shows a schematic structural view of two sets of stacked ring-shaped permanent magnets according to an embodiment of the present invention.
Fig. 5 schematically shows a schematic superposition of ring-shaped permanent magnets according to an embodiment of the invention.
Fig. 6 schematically shows a stacked schematic of ring permanent magnets according to another embodiment of the invention.
Fig. 7 schematically shows a schematic view of a magnetic lens with an electromagnetic coil and a ring-shaped permanent magnet according to an embodiment of the invention.
Fig. 8A schematically shows a schematic view of an array of ring-shaped permanent magnet sets according to an embodiment of the invention.
Fig. 8B schematically shows a schematic view of an array of ring-shaped permanent magnet sets according to another embodiment of the invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a convention should be interpreted in accordance with the meaning of one of skill in the art having generally understood the convention (e.g., "a system having at least one of A, B and C" would include, but not be limited to, systems having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
The invention provides a stacked magnetic lens, which can reduce stray field of the magnetic lens and adjust magnetic field distribution and magnetic field extremum of the magnetic lens without using an electromagnetic coil.
Fig. 1A schematically illustrates a schematic diagram of a stacked magnetic lens according to an embodiment of the invention.
Fig. 1B schematically illustrates a second schematic diagram of a stacked magnetic lens according to an embodiment of the invention.
Fig. 1C schematically illustrates a schematic diagram three of a stacked magnetic lens according to an embodiment of the invention.
As shown in fig. 1A, 1B, and 1C, the stacked magnetic lens of this embodiment includes an annular permanent magnet group. The annular permanent magnet group comprises a plurality of permanent magnet groups which are coaxially and sequentially arranged along a central axis AX annular permanent magnet 110_1. 110_q, q is a positive integer greater than 1. The material of the ring permanent magnet may include, but is not limited to, neodymium iron boron (NdFeB), samarium cobalt (SmCo), and the like. A plurality of ring permanent magnets 110_1. In the first direction X and with the first direction X the intersecting second directions Y (which may be perpendicular to each other, for example) are nested sequentially from inside to outside. The ring-shaped permanent magnet 110_1 is located in the inner ring area of the ring-shaped permanent magnet 110_2, the ring-shaped permanent magnet 110_2 is located in the inner ring area of the ring-shaped permanent magnet 110_3, and so on, and will not be described herein. It will be appreciated that the ring-shaped permanent magnet itself is of annular configuration, with an annular effective aperture area inside the ring-shaped permanent magnet that allows the particle beam to pass through, i.e. an area corresponding to the inner ring of the ring-shaped permanent magnet.
A plurality of ring permanent magnets 110_1. 110_q is used to generate a basic tunable magnetic field. The base adjustable magnetic field may be a magnetic field formed by superposition of respective magnetic fields of the plurality of ring-shaped permanent magnets 110_1. The basic adjustable magnetic field acts on the particle beam entering the inner ring area IS of the ring-shaped permanent magnet group, so that the particle beam can be deflected. For example, the inner ring area IS of the ring-shaped permanent magnet group may correspond to the effective aperture area of the ring-shaped permanent magnet 110_1 located at the innermost layer of the ring-shaped permanent magnet group.
Because the axial magnetization magnetic ring design can generate a larger residual magnetic field, the magnetization direction of the annular permanent magnet group in the invention is designed to be unfolded along the radial direction of the annular permanent magnet. Radial radiation magnetization of the annular permanent magnet can improve magnetic field uniformity. In designing a magnetic lens, systematic aberrations will be minimized by optimizing the magnetic field distribution. In order to improve the uniformity of the magnetic field, the radial magnetized annular permanent magnet is easier to complete complex magnetic field segmentation and superposition configuration.
At least one ring-shaped permanent magnet of the plurality of ring-shaped permanent magnets 110_1..the ring-shaped permanent magnets 110_q is capable of being relatively displaced in the extending direction of the central axis AX with respect to the other ring-shaped permanent magnets to adjust the magnetic field distribution and the magnitude of the basic adjustable magnetic field. For example, the number of the cells to be processed, at least one of the plurality of ring-shaped permanent magnets 110_1. I.e. in a third direction Z (which may be, for example, mutually perpendicular) where the first direction X and the second direction Y intersect. For example, at least one of the ring-shaped permanent magnets 110_1..the ring-shaped permanent magnets 110_q may be relatively displaced in a third direction with respect to the other ring-shaped permanent magnets within the same group, such that the relative position between the plurality of ring-shaped permanent magnets is changed, such that the magnetic field distribution and the magnetic field extremum of the basic adjustable magnetic field may be changed, such that the force of the basic adjustable magnetic field on the particle beam is changed, such that the deflection direction and the deflection angle of the particle beam are changed.
According to the embodiment of the invention, the plurality of annular permanent magnets 110_1, 110_q in the annular permanent magnet group are sleeved in sequence along the same axis, so that basic adjustable magnetic fields formed by superposition of respective magnetic fields of the plurality of annular permanent magnets 110_1, 110_q are distributed along the central axis AX in the radial direction, stray fields of the magnetic lens are reduced, and the precision and stability of the magnetic lens are improved. On this basis, by controlling the relative displacement between at least one of the plurality of ring-shaped permanent magnets 110_1..the other ring-shaped permanent magnet groups in the extending direction of the central axis AX, the magnetic field distribution and the magnetic field extremum of the basic adjustable magnetic field can be flexibly adjusted from the mechanical level, without using electromagnetic coils to adjust the magnetic field distribution and the magnetic field extremum of the magnetic lens, the volume of the magnetic lens is reduced, and since this adjustment is a mechanical adjustment of the passive system, thermal management problems do not need to be considered.
According to an embodiment of the present invention, the movable area of the ring-shaped permanent magnet located at the inner layer is determined based on the inner ring area of the ring-shaped permanent magnet located at the periphery of the ring-shaped permanent magnet. For example, the number of the cells to be processed, the outer diameter of the i-th annular permanent magnet in the plurality of annular permanent magnets 110_1. The plurality of ring-shaped permanent magnets 110_1. So that the i-th annular permanent magnet is displaced relative to the i-th annular permanent magnet in the inner annular region of the i+k-th annular permanent magnet, i being a positive integer, k=1, 2. i+k is less than or equal to Q. Q in the present invention represents the number.
As will be appreciated, since each ring-shaped permanent magnet has a width in the third direction Z, the inner ring region of each ring-shaped permanent magnet may be an inner cavity enclosed by the ring-shaped structure of the ring-shaped permanent magnet. The (i+k) th ring permanent magnet may be the (Q) th ring permanent magnet 110_q or a permanent magnet located between the (i) th ring permanent magnet and the (Q) th ring permanent magnet 110_q. Taking the ring-shaped permanent magnet 110_1 and the ring-shaped permanent magnet 110_q as an example, the ring-shaped permanent magnet 110_1 is displaced in the third direction Z only in the ring-shaped area of the ring-shaped permanent magnet 110_q. In the case of an inner annular permanent magnet exceeding the outer annular permanent magnet in the third direction Z, the basic adjustable magnetic field diverges from a position close to the third direction Z to a direction away from the third direction Z, so that the stray field is enhanced. Therefore, the inner annular permanent magnet is limited to move in the inner annular area of the outer annular permanent magnet, stray fields can be effectively restrained, and the annular permanent magnet group is convenient to package.
According to an embodiment of the invention, each annular permanent magnet comprises an inner side surface close to the central axis AX and an outer side surface remote from the central axis AX, the inner side surface and the outer side surface of each annular permanent magnet being opposite in polarity to each other. Taking the Q-th ring-shaped permanent magnet 110_q as an example, the inner side surface if1_q of the Q-th ring-shaped permanent magnet 110_q may be N-pole, the outer side surface if2_q may be S-pole, or the inner side surface if1_q of the Q-th ring-shaped permanent magnet 110_q may be S-pole, and the outer side surface if2_q may be N-pole.
In accordance with an embodiment of the present invention, the plurality of ring-shaped permanent magnets 110_1..an i-th ring-shaped permanent magnet 110_1..of the 110_q..110_q.) and the plurality of ring-shaped permanent magnets. The inner side surfaces of the i+1 th ring-shaped permanent magnet in the number 110_q are opposite in magnetic pole to each other, i is a positive integer.
For example, the outer side surface of the i-th annular permanent magnet may be an S-pole, the inner side surface of the i+1-th annular permanent magnet may be an N-pole, and the i-th annular permanent magnet and the i+1-th annular permanent magnet may be attracted to each other based on a magnetic force applied to each other, thereby maintaining a relatively stationary state. On this basis, by applying opposite forces to the i-th annular permanent magnet and the i+1-th annular permanent magnet in the third direction Z, the i-th annular permanent magnet and the i+1-th annular permanent magnet can be displaced relative to each other, thereby adjusting the basic adjustable magnetic field. For example, the opposite force may be applied to the i-th annular permanent magnet and the i+1th annular permanent magnet in the third direction Z by a preset device, which is not limited by the present invention.
For example, a plurality of ring permanent magnets 110_1.. the stacked ring-shaped permanent magnets include at least two ring-shaped permanent magnets stacked in a direction in which the central axis AX extends, the at least two ring-shaped permanent magnets having the same inner diameter and the same outer diameter as each other. Adjacent ones of the at least two annular permanent magnets are in contact based on magnetic forces applied to each other by the adjacent annular permanent magnets.
Fig. 2 schematically shows one direction of magnetization of a ring-shaped permanent magnet according to an embodiment of the present invention, it being understood that in the present invention the direction of magnetization may also be opposite to the direction shown in fig. 2. Fig. 3 schematically shows a schematic structure of stacked ring-shaped permanent magnets according to an embodiment of the present invention, the magnetizing directions of which are opposite to each other in fig. 3.
Fig. 4 schematically shows a schematic structural view of two sets of stacked ring-shaped permanent magnets according to an embodiment of the present invention. As shown in fig. 4, the set of stacked ring-shaped permanent magnets located at the inner layer may include two stacked ring-shaped permanent magnets, and the set of stacked ring-shaped permanent magnets located at the outer layer may include two stacked ring-shaped permanent magnets. It should be understood that in the present invention, the stacked ring-shaped permanent magnets are not limited to two ring-shaped permanent magnets, but may be three, four, five, or the like, and the present invention is not limited thereto.
Fig. 5 schematically shows a schematic superposition of ring-shaped permanent magnets according to an embodiment of the invention. It is to be noted that in fig. 5, N and S each represent a magnetic pole.
In fig. 5a stacked double layer annular permanent magnet (a) is shown. The magnetizing directions of the first layer annular permanent magnet and the second layer annular permanent magnet in the double-layer annular permanent magnet (a) are opposite, so that the effect of alternately radiating and magnetizing can be achieved. The structural design is favorable for enhancing the uniformity of the magnetic field and improving the magnetic field distribution to a certain extent, and is suitable for application scenes with special requirements on the magnetizing direction.
Also shown in fig. 5 are four stacked layers of annular permanent magnets (b). The magnetizing directions of the annular permanent magnets of two adjacent layers in the four layers of annular permanent magnets (b) are opposite. By increasing the number of stacked layers, the magnetic field density can be enhanced, and the magnetic field interference can be effectively reduced by the design of multi-layer alternate magnetization, so that the performance stability of the magnetic ring is improved.
Also shown in fig. 5 are six stacked layers of annular permanent magnets (c). The magnetizing directions of the annular permanent magnets of two adjacent layers in the six layers of annular permanent magnets (c) are opposite, so that complex magnetic field distribution can be formed. The six-layer stacked structure can provide a strong and uniform magnetic field, is suitable for high-precision and high-power equipment, and has important application in the field requiring high magnetic field stability.
It should be noted that the above is only an example, and the stacked ring permanent magnets may have other stacked structures, such as 3,5, 7, 8, or 9.
In accordance with an embodiment of the present invention, the outer diameter of the j-th stacked ring permanent magnet in the plurality of ring permanent magnets 110_1. A plurality of annular permanent magnets 110_1. So that the j-th set of stacked annular permanent magnets is relatively displaced with respect to the j+p-th set of stacked annular permanent magnets in the inner annular region of the j+p-th set of stacked annular permanent magnets, j being a positive integer, p=1, 2. j+p is less than Q.
For example, the extent of the inner ring region of the stacked annular permanent magnets may be determined based on the area of the inner ring region of each of the stacked annular permanent magnets in the first direction X and the second direction Y and the width in the third direction Z, i.e., the extent of the inner ring region of the stacked annular permanent magnets may be an inner cavity surrounded by the annular structures of the stacked annular permanent magnets together. In case the stacked annular permanent magnets of the inner layer exceed the stacked annular permanent magnets of the outer layer in the third direction Z, the basic adjustable magnetic field diverges from a position close to the third direction Z in a direction away from the third direction Z, so that the stray field is enhanced. Therefore, the inner annular permanent magnet is limited to move in the inner annular area of the outer annular permanent magnet, stray fields can be effectively restrained, and the annular permanent magnet group is convenient to package.
According to an embodiment of the present invention, the outer side surface of the i-th annular permanent magnet 110_1 of the plurality of annular permanent magnets 110_1. The plurality of ring permanent magnets 110_1. The stacked ring-shaped permanent magnets include at least two ring-shaped permanent magnets stacked in the extending direction of the center axis AX, the at least two ring-shaped permanent magnets having the same inner diameter and the same outer diameter as each other. Adjacent ones of the at least two annular permanent magnets are in contact based on an external force other than the magnetic force of the adjacent annular permanent magnets. For example, the technical defects of the annular permanent magnet in annular manufacturing, such as difficulty in manufacturing an annular structure with high aspect ratio, can be overcome by gluing and other fixing means.
Fig. 6 schematically shows a stacked schematic of ring permanent magnets according to another embodiment of the invention. Note that in fig. 6, N and S each represent a magnetic pole.
In fig. 6 a stacked double layer annular permanent magnet (a) is shown. The magnetizing directions of the first layer annular permanent magnet and the second layer annular permanent magnet in the double-layer annular permanent magnet (a) are the same. The structural design is also beneficial to enhancing the uniformity of the magnetic field, improves the magnetic field distribution to a certain extent, and is suitable for application scenes with special requirements on the magnetizing direction.
Also shown in fig. 6 are four stacked layers of annular permanent magnets (b). The magnetizing directions of the annular permanent magnets in the four layers of annular permanent magnets (b) are the same. By increasing the number of stacked layers, the magnetic field density can be enhanced, and the magnetic field interference can be effectively reduced by the design of multi-layer magnetization, so that the performance stability of the magnetic ring is improved.
Also shown in fig. 6 are six layers of annular permanent magnets (c) stacked. The magnetizing directions of the annular permanent magnets in the six layers of annular permanent magnets (c) are the same, so that complex magnetic field distribution can be formed. The six-layer stacked structure can provide a strong and uniform magnetic field, is suitable for high-precision and high-power equipment, and has important application in the field requiring high magnetic field stability.
It should be noted that the above is only an example, and the stacked ring permanent magnets may have other stacked structures, such as 3,5, 7, 8, or 9.
According to an embodiment of the present invention, the magnetic lens further includes a set of electromagnetic coils wound around one ring-shaped permanent magnet along an outer side surface of the one ring-shaped permanent magnet. Fig. 7 schematically shows a schematic view of a magnetic lens with an electromagnetic coil and a ring-shaped permanent magnet according to an embodiment of the invention. As shown in fig. 7, the magnetic lens may include an annular permanent magnet 701 located at an outermost layer and an annular permanent magnet 702 located at an inner layer. The electromagnetic coil 703 may be wound around the ring-shaped permanent magnet 701 positioned at the outermost layer, and the magnetic conductive magnetic circuit 704 may magnetically conduct the magnetic fields generated by the ring-shaped permanent magnet 701, the ring-shaped permanent magnet 702, and the electromagnetic coil 703. The electromagnetic coil is used for generating an additional adjustable magnetic field, a superimposed magnetic field formed by the basic adjustable magnetic field and the additional adjustable magnetic field acts on the particle beam injected into the inner ring area of the annular permanent magnet group, and the magnetic field strength of the additional adjustable magnetic field changes along with the change of the current size and the direction input into the electromagnetic coil. For example, the electromagnetic coil may be wound around the outer side surface of the ring-shaped permanent magnet in a clockwise or counterclockwise direction. After the electromagnetic coil is electrified, the additional adjustable magnetic field can strengthen the basic adjustable magnetic field or weaken the basic adjustable magnetic field.
In an embodiment of the invention, the permanent magnet and the electromagnetic adjusting coil together form a closed magnetic circuit, the permanent magnet being arranged between the grinder assemblies made of a high magnetic permeability material. The total magnetic flux of the composite structure is adjusted through the electromagnetic coil, so that the intensity and the direction of the magnetic field in the lens system are finely adjusted, the focal length is adjusted, and the magnetic field intensity and the direction deviation are compensated in operation.
Based on the first mechanical adjusting means of the stacked annular permanent magnet, the electromagnetic adjusting means is used as the second electromagnetic adjusting means, so that the magnetic field configuration which is controllable and adjustable can be created according to different working condition requirements, the modularized control and adjustability of the magnetic lens system are improved, and the applicability of the magnetic lens structure in particle beam equipment is improved. In addition, the composite magnetic lens structure formed by the annular permanent magnet group is small in geometric dimension, and is beneficial to popularization and application in multi-beam equipment.
Based on this, the present invention provides a lens array of a three-lens system or a multi-beam device that can be used in a ubiquitous charged particle beam device, while ensuring mechanical and electromagnetic adjustability. For example, the ring-shaped permanent magnet groups are plural, and the plural ring-shaped permanent magnet groups are arranged in an array in a predetermined pattern in the same plane so as to receive the particle beams corresponding to the predetermined pattern, the particle beams corresponding to the predetermined pattern being emitted by the multiple electron sources, or the particle beams emitted by the single electron sources being split in the predetermined pattern by the beam splitter. For example, the predetermined pattern includes a symmetrical pattern. Fig. 8A schematically shows a schematic view of an array of ring-shaped permanent magnet sets according to an embodiment of the invention. Fig. 8B schematically shows a schematic view of an array of ring-shaped permanent magnet sets according to another embodiment of the invention. For example, the array may be arranged in a rectangular shape as shown in fig. 8A, or in a circular array as shown in fig. 8B. In a rectangular array, each cell can be individually tuned to achieve different directional magnetic field focusing and tuning functions. The array is suitable for applications requiring a uniform magnetic field distribution over a large space, such as magnetic field generation in Magnetic Resonance Imaging (MRI) devices. In a circular array, the circular array is formed by a plurality of cells arranged in a circular trajectory to form a uniform circular magnetic field distribution. Each unit can be electromagnetically adjusted as required to control the intensity, shape and focusing effect of the overall magnetic field of the array. Circular arrays are suitable for applications requiring precisely concentrated magnetic fields, such as particle accelerators or specific experimental scenarios. By different array layouts (e.g. rectangular or circular arrays) the magnetic fields of the cells interact to form a specific overall magnetic field distribution. Based on the effect of the array on magnetic field control and optimization, the array has flexibility and high efficiency of magnetic field adjustment in practical application.
Based on this, the present invention provides a dual tunable permanent magnet lens structure that integrates stacked radiation-charged annular permanent magnets and electromagnetic coils to achieve higher magnetic field configuration flexibility and adaptability. The system can assist in lens system design of the particle beam apparatus, also helps to design miniaturized lens arrays in the multi-beam apparatus, can be adapted to multi-beam particle beam apparatus arrays, and provides electron beam focusing assemblies for the multi-beam particle beam apparatus.
In design principle, the design scheme of the magnetic lens of the invention allows the composite permanent magnet lens to be designed in the same tunable way by using permanent magnets of different types and different processes, so as to meet the adaptability to different magnetic field configurations and application environments. In another aspect of the invention, a method of designing a magnetic lens is also provided.
Step 1, firstly, selecting the permanent magnet material. A combination of manufacturing process, magnetization direction, and operating temperature range, etc. is required. For example, depending on the performance requirements of the selected material, suitable manufacturing processes such as hot press molding, sinter molding, bond molding, additive manufacturing, and the like are determined. Different processes affect the magnetic properties, dimensional accuracy and consistency of the permanent magnets. For example, a ring-shaped permanent magnet can be prepared by a hot pressing process or an additive manufacturing process to meet the requirement of higher magnetic energy product and stability. Also, the magnetization direction can be chosen to suit the application, the choice of magnetization direction affecting the final magnetic field distribution and its stability. In addition, the permanent magnet material with the adaptive working temperature range can be selected according to the actual use environment, so that the material is ensured not to demagnetize or lose magnetic force under the extreme environment. Typical permanent magnet materials such as neodymium iron boron (NdFeB), samarium cobalt (SmCo), etc. should be selected appropriately according to the required magnetic strength, stability and working environment.
And 2, determining the geometric dimension and the stacking mode. After the permanent magnet materials are selected, the geometry of the ring permanent magnet and its stacking method need to be determined next. The method comprises the following specific steps:
And determining the geometric dimensions, namely firstly determining the external diameter, the internal diameter, the height and other dimensional parameters of each annular permanent magnet according to design requirements. The accuracy of the dimensions directly affects the distribution and application of the final magnetic field, and therefore, the dimensions need to be controlled strictly according to the design requirements.
Design of the stacking means in a multilayer stacking structure, the stacking means are critical for the strength and uniformity of the magnetic field. The stacking in the same direction or the stacking in the opposite direction can be selected according to application requirements. The reasonable selection of the stacking mode is helpful for optimizing the distribution of the whole magnetic field and reducing the phenomenon of uneven magnetic field or magnetic leakage.
The implementation of this step requires detailed engineering calculations and simulation analysis to ensure that the chosen geometry and stacking scheme can meet the performance criteria of magnetic field strength, uniformity, etc.
And 3, optimizing structural parameters. And further optimizing the structural parameters of the magnet according to the requirements and the use environments of the actual working conditions. The specific optimization content comprises the following steps:
the shape optimization of the magnetic circuit, namely, the shape of the magnetic circuit is properly adjusted, such as changing the edge shape, surface treatment, chamfering and the like, so that the magnetic conductivity of the magnetic circuit is improved;
and the matching of the annular permanent magnet with the magnetic circuit and the lens shell structure is that the relative positions of each component and other additional equipment are determined, and the coupling effect of the magnetic field is optimized. The interaction forces between the stacked rings are taken into account, avoiding too strong mutual repulsion or attraction forces.
And 4, determining the tunability. To ensure that the system can flexibly adjust the magnetic field strength and direction, a certain tunable mechanism needs to be designed. The tuning mechanism may be implemented in several ways:
and the stacking mode and the relative position of the lantern ring are adjusted, namely the adjustment of the magnetic field intensity is realized by changing the stacking sequence or the relative position of a plurality of annular permanent magnets. For example, the ratio of co-stacking and counter-stacking is changed. Meanwhile, the adjusting range and the accuracy of the magnetic field can be optimized by fine-adjusting the positions of the magnetic rings of all layers. This fine tuning may be accomplished by high precision mechanical means or magnetic field sensor feedback mechanisms.
Current regulation of the peripheral electromagnetic coil assembly the peripheral electromagnetic coil can further adjust the strength and distribution of the magnetic field by varying the magnitude of the current. Through accurate control current, can realize the dynamic adjustment to composite construction magnetic field, satisfy the demand under the different operating conditions.
And 5, determining the relative positions of the plurality of annular permanent magnets. The relative positions of the plurality of ring-shaped permanent magnets are determined. For this purpose, the following operations are performed:
Numerical calculation based on Finite Element Analysis (FEA) or other numerical simulation methods, calculating the effect of the relative positions of different pluralities of ring permanent magnets on the magnetic field distribution. Through simulation analysis, the relative positions of the magnetic ring and the lantern ring are optimized to achieve preset magnetic field strength and uniformity.
And (3) establishing an experimental test scheme, namely designing an experimental verification scheme according to a numerical calculation result, and testing the actual distribution condition of the magnetic field through the combination of the actual annular permanent magnets. And the positions of the plurality of annular permanent magnets are adjusted through experimental feedback so as to further optimize the design scheme.
In the experimental process, a flexible lens system test platform needs to be built, and a precise magnetic field measuring instrument (such as a Hall probe, a magnetic field probe and the like) is used for monitoring the magnetic field intensity and distribution in real time.
The above steps are basic embodiments of the present technology, covering all aspects from material selection, geometry design, determination of stacking style, to magnetic field tunability and stack position optimization. Through accurate design and experimental verification, the embodiment can effectively realize the strength, uniformity and regulation function of the target magnetic field, and meet specific application requirements.
The following is an example of a possible design:
A double-stacked annular permanent magnet is combined with an electromagnetic coil to form a composite permanent magnet lens as a first-stage lens structure of a three-lens system, the composite permanent magnet lens is called a first condenser, the composite lens with the same configuration is adopted as a second condenser at different Z-axis positions, and a magnetic lens with electromagnetic adjustment capability is adopted as an objective lens of the whole system to be arranged at the tail end of the system so as to optimize an optical path and reduce comprehensive aberration of the whole system.
The radiation magnetization annular permanent magnet with relatively small stray magnetic field is preferentially adopted, and the theoretical design of the composite permanent magnet lens assembly is realized according to ampere loop law by combining the magnetic circuit design of edge chamfering.
And calculating the electron optical parameters of the designed three-lens system, and respectively assembling the three lens assemblies in a mechanically adjustable frame under the condition of given electron sources and observation devices, so as to build an experimental test environment of the three-lens system.
And optimizing an electron optical system by utilizing the composite permanent magnet lens. The system comprises a three-stage lens structure, wherein the three-stage lens structure comprises two condensing lenses (respectively used as a first condensing lens and a second condensing lens) formed by combining a composite double-stacked annular permanent magnet and an electromagnetic coil, and a magnetic lens with electromagnetic adjusting capability is used as an objective lens. By precisely designing the position and adjustment mechanism of each lens assembly, the system aims to reduce optical distortion and improve the adjustment accuracy of the optical path.
And 1, selecting the design of permanent magnet materials and electromagnetic coils. First, to ensure stability and efficiency of the system, a suitable permanent magnet material and electromagnetic coil configuration is selected.
The permanent magnet material is selected by preferably selecting a radiation magnetized annular permanent magnet (such as neodymium iron boron or samarium cobalt material) with relatively small stray magnetic fields. The material has higher magnetic energy product and lower temperature coefficient, and can ensure stable magnetic field output.
Electromagnetic coil design the electromagnetic coil is used in combination with annular permanent magnet, the electromagnetic coil can be selected as copper coil winding with circular or rectangular cross section, so as to adjust the intensity and distribution of magnetic field by adjusting current. The design of the electromagnetic coil allows for the coordination of the current adjustability with the permanent magnets, and the heat dissipation problem is negligible here, since the electromagnetic coil according to the invention is used only as an adjustable auxiliary adjusting magnetic field and not as a basic magnetic field generating unit.
And 2, designing a composite permanent magnet lens. The composite permanent magnet lens is formed by combining a double-stacked annular permanent magnet and an electromagnetic coil, and the specific design steps are as follows:
The stacking mode adopts a double-stacking annular permanent magnet structure, the magnetic rings are stacked in the same direction or in opposite directions, and the stacking mode is optimized according to the calculation result so as to realize optimal magnetic field distribution. The stacking approach requires precise ring-to-ring spacing design depending on the needs of the electron optical system.
And an electromagnetic adjusting mechanism, which combines the current adjusting capability of the electromagnetic coil to realize the dynamic adjustment of the magnetic field intensity of the compound lens. On the basis of a primary magnetic field formed by stacking annular permanent magnets, the performance of a composite permanent magnet lens result is accurately controlled by adjusting coil current, an electron light path is optimized, and optical distortion is reduced.
Magnetic circuit design, namely adopting magnetic circuit design with edge chamfer, and reducing the influence of magnetic leakage and nonuniform magnetic field by accurately designing the shape of the magnetic circuit and the chamfer of the edge by utilizing ampere loop law.
And 3, designing a three-lens system. The three-lens system is composed of three lens components, namely a first condenser lens, a second condenser lens and an objective lens.
The first condensing lens (first lens component) is designed by adopting a composite permanent magnet lens and is arranged at the initial position of the system. The lens is combined with an electromagnetic coil through a double-stacked annular permanent magnet, focuses an electron beam and controls the beam direction.
The second condenser lens (second lens component) is designed to be identical to the first condenser lens but is arranged on the Z axis of the system in a different position, so that the focusing effect of the electron beam is further optimized. By adjusting the relative position of the second condenser lens, the optical path of the entire optical system can be effectively calibrated.
Objective lens (third lens component), the objective lens is used as key lens of whole system, and adopts magnetic lens design with electromagnetic regulation capability. The objective lens adjusts the final beam focus by an electromagnetic adjustment mechanism and reduces the aberrations introduced by the two-stage condenser lens.
And 4, calculating and adjusting the electron optical parameters. After the design of the three-lens system is completed, the calculation of the electron-optical parameters is required to ensure the light path precision and the focusing effect of the whole system. The calculation content comprises:
And simulating optical performance by using optical design software to simulate the designed three-lens system and calculating key parameters such as focusing capacity, beam current distribution, aberration and the like of the system.
And (3) parameter optimization, namely adjusting the geometric dimension, stacking mode and current setting of the electromagnetic coil of each lens assembly according to the simulation result, and optimizing the electron optical performance of the system. And through repeated iterative computation and simulation, the accuracy and stability of the optical path are ensured.
And 5, mechanical assembly and debugging. In order to verify the feasibility of theoretical design, an experimental platform of the three-lens system is built and is debugged. The method comprises the following specific steps:
Mechanical frame design the mechanical frame is made according to the design of the lens system, ensuring that the position of each lens assembly can be accurately adjusted. The frame should have good stability to avoid vibrations and displacements affecting system performance.
And assembling the lens assembly, namely sequentially assembling the designed first condenser lens, the designed second condenser lens and the designed objective lens in the mechanically adjustable frame. Each lens assembly can be independently adjusted to precisely adjust the optical path.
And (3) experimental test, namely building an electron source and an observation window to perform system test, and testing focusing precision and electron optical parameters of the system. And adjusting the current of the electromagnetic coil, the relative positions of the stacked annular permanent magnets and the number and stacking mode of the stacked magnets, so as to further optimize the system performance.
And 6, performance verification and optimization. And verifying whether the performance of the three-lens system meets the design requirement according to the experimental test result. If a performance deviation is found, fine adjustments to the design parameters are required:
and (3) evaluating the optical distortion, the light beam focusing effect and the light path stability of the system, and determining whether the design target is realized.
And the adjustment scheme is optimized, namely the adjustment range of the electromagnetic coil, the stacking distance and the stacking angle of the annular permanent magnets are optimized according to the test result, and the light path adjustment precision is further improved.
Through implementation of the steps, the application of the composite permanent magnet lens in a three-lens system is realized, the focusing precision of an optical path is effectively optimized, and the optical distortion is reduced. The combination of the permanent magnet material and the electromagnetic adjusting mechanism provides a flexible and accurate optical adjusting scheme, and is suitable for the design and application of a high-precision electron optical system.
Those skilled in the art will appreciate that the features recited in the various embodiments of the invention can be combined and/or combined in a variety of ways, even if such combinations or combinations are not explicitly recited in the present invention. In particular, the features recited in the various embodiments of the invention can be combined and/or combined in various ways without departing from the spirit and teachings of the invention. All such combinations and/or combinations fall within the scope of the invention.
The embodiments of the present invention are described above. These examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the invention, and such alternatives and modifications are intended to fall within the scope of the invention.
Claims (10)
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD291223A7 (en) * | 1976-06-21 | 1991-06-27 | Thomas Demuth | METHOD AND DEVICE FOR ADJUSTING LENSES |
| DE3687840D1 (en) * | 1985-08-14 | 1993-04-01 | Philips Patentverwaltung | OPTICAL SCANNER UNIT. |
| US5763971A (en) * | 1995-03-16 | 1998-06-09 | Koyo Seiko Co., Ltd. | Superconducting bearing device |
| US20030011451A1 (en) * | 2000-08-22 | 2003-01-16 | Ehud Katznelson | Permanent magnet assemblies for use in medical applications |
| CN1590979A (en) * | 2003-04-24 | 2005-03-09 | Fei公司 | Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens |
| US20110012018A1 (en) * | 2009-07-16 | 2011-01-20 | Bryan Barnard | Magnetic Lens, Method for Focusing Charged Particles and Charged Particle Energy Analyzer |
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- 2025-02-11 CN CN202510148878.8A patent/CN119673731B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD291223A7 (en) * | 1976-06-21 | 1991-06-27 | Thomas Demuth | METHOD AND DEVICE FOR ADJUSTING LENSES |
| DE3687840D1 (en) * | 1985-08-14 | 1993-04-01 | Philips Patentverwaltung | OPTICAL SCANNER UNIT. |
| US5763971A (en) * | 1995-03-16 | 1998-06-09 | Koyo Seiko Co., Ltd. | Superconducting bearing device |
| US20030011451A1 (en) * | 2000-08-22 | 2003-01-16 | Ehud Katznelson | Permanent magnet assemblies for use in medical applications |
| CN1590979A (en) * | 2003-04-24 | 2005-03-09 | Fei公司 | Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens |
| US20110012018A1 (en) * | 2009-07-16 | 2011-01-20 | Bryan Barnard | Magnetic Lens, Method for Focusing Charged Particles and Charged Particle Energy Analyzer |
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| CN119673731B (en) | 2025-05-06 |
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