Pole shoe assembly applied to electron microscope and use method of electron microscope

Abstract

The invention discloses a pole shoe assembly applied to an electron microscope and a use method of the electron microscope, the pole shoe assembly applied to the electron microscope comprises a first pole shoe and a second pole shoe, the first pole shoe is used for focusing an electron beam and is provided with a first channel; the second pole shoe is used for further focusing the electron beam and is provided with a second channel, the electron beam can sequentially pass through the first channel and the second channel to be focused, the distance between the first pole shoe and the second pole shoe is smaller than 4 mm, and the aperture of the first channel and the aperture of the second channel are smaller than 2 mm. An electron beam obtains sample information through the focusing effect of the first pole shoe and the second pole shoe, the focused electron beam finally forms a sample image, compared with a traditional cryoelectron microscope, the distance between the first pole shoe and the second pole shoe is reduced, the magnetic field intensity between the first pole shoe and the second pole shoe is improved, and the detection accuracy is improved. Meanwhile, the apertures of the first channel and the second channel are reduced, so that the magnetic field intensity between the first pole shoe and the second pole shoe is further improved, and the imaging quality of the cryoelectron microscope is ensured.

Description

Technical Field

[0001] This application relates to the field of electron microscopy technology, and in particular to a pole shoe assembly for use in an electron microscope and a method for using the electron microscope. Background Technology

[0002] In cryo-electron microscopy, the pole piece system is the core component of the objective lens, consisting of two pole pieces forming an electromagnetic lens system. A strong magnetic field can be generated between the pole pieces, and the movement of the electron beam is controlled within this magnetic field using the Lorentz force.

[0003] Traditional cryo-electron microscopy requires large cold shielding structures at the pole pieces. Because these structures occupy significant space, they reduce the magnetic field strength between the pole pieces, resulting in lower imaging resolution and hindering subsequent observation. Furthermore, to observe larger sample areas, traditional cryo-electron microscopy necessitates larger electron beam channels, which increases the pole piece spacing, further reducing the magnetic field strength and gradient between the pole pieces, ultimately leading to lower imaging resolution.

[0004] In related technologies, the narrow pole piece space of transmission electron microscopes can be adapted to improve the accuracy by improving the sample carrier or chip technology. However, if applied to cryo-electron microscopes, it is still impossible to solve the problems of low magnetic field strength between pole pieces and low imaging resolution caused by the large volume of the cold shielding structure.

[0005] In addition, to improve the resolution of electron microscopes, optimization algorithms and multi-lens focusing are usually used, but the implementation of these methods is very complicated. Summary of the Invention

[0006] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a pole piece assembly for an electron microscope that can improve the magnetic field strength between the pole pieces by reducing the distance between the first and second pole pieces and by reducing the aperture of the first and second channels, thereby ensuring imaging quality.

[0007] This application also proposes a method for using an electron microscope.

[0008] According to a first aspect embodiment of this application, a pole piece assembly for an electron microscope includes a first pole piece and a second pole piece. The first pole piece is used to focus an electron beam and has a first channel. The second pole piece is used to further focus the electron beam and has a second channel. The electron beam can be focused by passing through the first channel and the second channel in sequence. The distance between the first pole piece and the second pole piece is less than 4 mm, and the aperture of both the first channel and the second channel is less than 2 mm.

[0009] The pole piece assembly for electron microscopes according to the embodiments of this application has at least the following beneficial effects: the electron beam acquires sample information through the focusing effect of the first pole piece and the second pole piece, and the electron beam focused by the first pole piece and the second pole piece finally forms an image of the sample. Compared with the traditional cryo-electron microscope, the distance between the first pole piece and the second pole piece is reduced, which is beneficial to improving the magnetic field strength between the first pole piece and the second pole piece. At the same time, the aperture of the first channel and the second channel is reduced, which is further beneficial to improving the magnetic field strength between the first pole piece and the second pole piece, thereby ensuring the imaging quality of the cryo-electron microscope.

[0010] According to some embodiments of this application, the pole piece assembly for use in an electron microscope further includes a cold shielding structure located between the first pole piece and the second pole piece, wherein the cold shielding structure is fitted with a sample carrier mesh, and the electron beam is focused onto the sample on the carrier mesh through the first pole piece.

[0011] According to some embodiments of this application, the cold shielding structure includes a heat sink and a mounting portion for mounting the carrier net, wherein the heat sink is connected to opposite sides of the mounting portion.

[0012] According to some embodiments of this application, when the electron microscope is in operation, the temperature of the heat sink is lower than the temperature of the carrier mesh.

[0013] According to some embodiments of this application, the temperature of the heat sink is 1-10°C lower than the temperature of the carrier mesh.

[0014] According to some embodiments of this application, the thickness of the mounting portion is less than the thickness of the heat sink portion, and the first pole shoe and the second pole shoe extend into the space between the respective heat sink portions.

[0015] According to some embodiments of this application, the thickness of the mounting portion on which the carrier net is installed is 0.85mm-2mm.

[0016] According to some embodiments of this application, the carrier mesh is provided with a slit region for carrying the sample, and the width of the slit region is 1μm-10μm.

[0017] According to some embodiments of this application, the cold shielding structure drives the sample within the slit region to the position where the electron beam is focused by unidirectional movement.

[0018] According to some embodiments of this application, the extension direction of the slit region is the same as the movement direction of the cold shielding structure.

[0019] According to some embodiments of this application, the first pole piece and the second pole piece are distributed vertically to define the first channel and the second channel as vertically corresponding.

[0020] According to some embodiments of this application, the first pole shoe is provided with a through first hole, the inner wall of the first hole defining the first channel.

[0021] According to some embodiments of this application, the radial dimension of the first pole piece gradually decreases in the direction approaching the second pole piece.

[0022] According to some embodiments of this application, the second pole shoe is provided with a through second hole, the inner wall of the second hole defining the second channel.

[0023] According to some embodiments of this application, the radial dimension of the second pole shoe gradually decreases in the direction close to the first pole shoe.

[0024] According to some embodiments of this application, the pole piece assembly applied to an electron microscope further includes a coil, which generates a magnetic field between the first pole piece and the second pole piece by energizing the coil.

[0025] The method of using an electron microscope according to a second aspect embodiment of this application includes:

[0026] A magnetic field is formed between the first pole shoe and the second pole shoe;

[0027] The electron beam is focused through the first pole shoe and the second pole shoe;

[0028] A carrier net supporting the sample is installed on a cold shielding structure;

[0029] The cold shielding structure passes through the gap between the first pole shoe and the second pole shoe.

[0030] The method of using the pole piece assembly for an electron microscope according to the embodiments of this application has at least the following beneficial effects: The pole piece assembly for an electron microscope according to the first aspect embodiment of this application includes a first pole piece and a second pole piece. The electron beam acquires sample information through the focusing effect of the first pole piece and the second pole piece. The focused electron beam finally forms an image of the sample. Compared with the traditional cryo-electron microscope, the distance between the first pole piece and the second pole piece is reduced, which is beneficial to improving the magnetic field strength between the first pole piece and the second pole piece. At the same time, the aperture of the first channel and the second channel is reduced, which is further beneficial to improving the magnetic field strength between the first pole piece and the second pole piece, thereby ensuring the imaging quality of the cryo-electron microscope.

[0031] According to some embodiments of this application, a magnetic field is formed between the first pole shoe and the second pole shoe, including:

[0032] When the coil is energized, the magnetic field is generated through the coil.

[0033] According to some embodiments of this application, the electron beam is focused through the first pole shoe and the second pole shoe, and further includes:

[0034] The electron beam propagates from the first channel of the first pole piece to the second channel of the second pole piece.

[0035] According to some embodiments of this application, the installation of the carrier net bearing the sample on the cold shielding structure includes:

[0036] The carrier mesh has a slit area, and the sample is added to the slit area.

[0037] According to some embodiments of this application, the installation of the carrier net bearing the sample on the cold shielding structure further includes:

[0038] The carrier net is installed on the mounting part of the cold shielding structure.

[0039] According to some embodiments of this application, the installation of the carrier net bearing the sample on the cold shielding structure further includes:

[0040] The heat sink of the cold shielding structure reduces its temperature through heat transfer, making the temperature of the heat sink of the cold shielding structure lower than the temperature of the carrier network.

[0041] According to some embodiments of this application, the cold shielding structure passes through the gap between the first pole shoe and the second pole shoe, and includes:

[0042] The cold shielding structure moves along the extension direction of the slit region.

[0043] According to some embodiments of this application, the cold shielding structure passes through the gap between the first pole shoe and the second pole shoe, and further includes:

[0044] The cold shielding structure is moved to focus the electron beam at different locations within the slit region.

[0045] According to some embodiments of this application, the cold shielding structure passes through the gap between the first pole shoe and the second pole shoe, and further includes:

[0046] An electron beam focused by the second pole shoe forms an image at different locations within the slit region.

[0047] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0048] The present application will be further illustrated below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments illustrated in the following drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application.

[0049] Figure 1 This is a cross-sectional view of the pole shoe assembly in a traditional cryo-electron microscope.

[0050] Figure 2 This is a cross-sectional view of the pole shoe assembly of an electron microscope according to an embodiment of this application;

[0051] Figure 3 This application describes the pole shoe assembly used in an electron microscope. Figure 2 A magnified view of part A in the middle.

[0052] Figure label:

[0053] First pole shoe 100; First channel 101;

[0054] Second pole shoe 200; Second channel 201;

[0055] Cold shielding structure 300; mounting part 301; heat sink part 302; carrier net 303. Detailed Implementation

[0056] The embodiments of this application are described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0057] In the description of this application, it should be understood that the terms "center", "middle", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0058] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0059] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0060] In the description of this application, the use of terms such as "one embodiment," "some embodiments," "an example," "some instances," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] In cryo-electron microscopy, the pole piece system is the core component of the objective lens, consisting of two pole pieces forming an electromagnetic lens system. Its working principle involves generating a strong axisymmetric magnetic field between the pole pieces by energizing a coil, and using the Lorentz force (F = e(v × B)) to control the movement of the electron beam. When a high-energy electron beam (typically in the range of 60-300 keV) passes through the magnetic field between the pole pieces, the electrons undergo helical motion under the influence of the magnetic field, achieving a focusing effect similar to that of an optical lens. The magnetic field strength can be controlled by precisely adjusting the coil current, thus achieving precise focusing of the electron beam. To obtain optimal spatial resolution, the pole piece system needs to operate under strictly controlled environmental conditions, including ultra-high vacuum, low temperature, and low humidity (15% RH or lower). Furthermore, the design of multi-pole pole piece systems can correct for aberrations such as spherical aberration and chromatic aberration, ultimately achieving atomic-level resolution. This precise electron beam control mechanism makes cryo-electron microscopy an important tool for studying the structure of biological macromolecules.

[0062] like Figure 1 As shown, current cryo-electron microscopy has certain limitations, mainly including the following four points: First, the sample needs to be moved in multiple directions; second, the cold shielding structure 300 in cryo-electron microscopy occupies a large space between the pole pieces; third, cryo-electron microscopy requires a large observation range (about 3 mm), which requires a large pole piece aperture; fourth, due to the limitation of the cold shielding structure 300, cryo-electron microscopy requires a large pole piece spacing, which affects the imaging quality.

[0063] In principle, the electron beam moves towards the sample because the pole pieces provide a magnetic field. The stronger the magnetic field, the faster the electron beam travels, the shorter the wavelength, and the higher the achievable imaging resolution. There are two ways to increase the magnetic field strength: first, by improving the aperture and gap of the pole pieces; second, by increasing the current intensity. However, increasing the current generates more heat, which needs to be dissipated using water cooling. Water cooling can cause structural vibrations, affecting subsequent imaging results. Therefore, improving the aperture and gap is the preferred method to increase the magnetic field strength.

[0064] Refer to the following magnetic reluctance formula:

[0065] R m = l / μS;

[0066] Among them, R m Let be the magnetic reluctance, l be the magnetic path length, μ be the permeability, and S be the cross-sectional area of ​​the magnetic path. In the upper and lower pole pieces of a cryo-electron microscope, reducing the aperture and the spacing is equivalent to shortening the equivalent length of the magnetic path. Therefore, reducing the aperture and the spacing reduces the magnetic reluctance, as shown in the following Ohm's law formula for magnetic paths:

[0067] Φ=F m / R m ;

[0068] Where Φ is the magnetic flux, F m For magnetomotive force, when the magnetic reluctance R m When the magnetomotive force F decreases, at the same magnetomotive force F m As the magnetic flux Φ increases, refer to the following formula:

[0069] B = μH;

[0070] Φ = BS;

[0071] Where B is the magnetic flux density, an increase in magnetic flux Φ means an increase in the magnetic field.

[0072] It is understandable that the larger the aperture and spacing of the pole pieces, the weaker the magnetic field strength between the upper and lower pole pieces of the electron microscope, which is not conducive to improving the resolution of electron microscope imaging; while the smaller the aperture and spacing of the pole pieces, the stronger the magnetic field strength between the upper and lower pole pieces of the electron microscope, which can improve the resolution of electron microscope imaging.

[0073] like Figure 1 As shown, the existing cryo-electron microscope's cold shielding structure 300 is a metal box. The cold shielding structure 300 of the metal box needs to be cooled separately to adsorb water molecules in the electron microscope and prevent water molecules from condensing on the sample. However, the current cold shielding structure 300 needs to have a certain volume, which will hinder the reduction of the distance between the upper and lower pole shoes.

[0074] In addition, the area of ​​the existing sample-bearing grid 303 is relatively large, requiring a large field of view. The field of view is determined by the size of the spot formed by the electron beam on the sample, which in turn is determined by the aperture of the pole pieces. To ensure comprehensive observation of the sample, current cryo-electron microscopes require large apertures for both the upper and lower pole pieces to guarantee the field of view.

[0075] The objective of this application is to improve the magnetic field strength between pole pieces and ensure the imaging quality of cryo-electron microscopy by structurally designing the pole piece assembly to reduce the aperture and spacing of the pole pieces. Simultaneously, the grid 303 used in this application carries the sample in a narrow slit region. The electron beam focused by the pole pieces in this application can form a spot in the slit region, and the width of the slit region corresponds to the size of the spot. Even with a small aperture and spacing of the pole pieces, it is possible to ensure that the spot covers a sufficient amount of sample. It is understood that when the grid 303 moves unidirectionally along the length of the slit region, comprehensive observation of the sample can be achieved.

[0076] Therefore, such as Figure 2 As shown, this application improves the magnetic field strength between pole pieces by optimizing sample movement, rearranging the cold shielding structure 300, and optimizing the observation area, thereby ensuring the imaging quality of cryo-electron microscopy.

[0077] In terms of optimizing sample movement, this application restricts sample movement to a single direction, thereby simplifying the mechanical structure of the cryo-electron microscope.

[0078] Regarding the relocation of the cold shielding structure 300, the larger parts of the cold shielding structure 300 are moved to free up space between the pole pieces, making it easier to shorten the pole piece spacing. This reduces the pole piece spacing and increases the magnetic field strength between the pole pieces, thus ensuring the imaging quality of the system.

[0079] In terms of optimizing the observation area, the observation area is reduced from the traditional approximately 3mm to 1μm-10μm to facilitate the reduction of the pole piece aperture, thereby increasing the magnetic field strength between the pole pieces and ensuring the imaging quality of the system.

[0080] Therefore, the pole piece assembly of this application achieves structural optimization, with a significantly shortened pole piece spacing, a greatly reduced pole piece aperture, and a more compact system structure. The structural improvements enhance the performance of cryo-electron microscopes using the pole piece assembly of this application, specifically in terms of improved electron optical performance, improved imaging quality, and enhanced system stability. The pole piece assembly of this application also achieves space utilization optimization, resulting in a more rational spatial layout, reduced mechanical interference, and optimized temperature control methods.

[0081] like Figure 2As shown, this application provides a pole piece assembly for an electron microscope, comprising a first pole piece 100 and a second pole piece 200. The first pole piece 100 is used to focus an electron beam, and the second pole piece 200 further focuses the electron beam. It is understood that the sample is located between the first pole piece 100 and the second pole piece 200. The electron beam focused by the first pole piece 100 reaches the sample, thereby acquiring the sample's features. The electron beam carrying the sample's features is further focused by the second pole piece 200, ultimately forming an image of the sample.

[0082] Furthermore, the first pole piece 100 is provided with a first channel 101, and the second pole piece 200 is provided with a second channel 201, and the electron beam formed by the first pole piece 100 can propagate from the first channel 101 to the second channel 201.

[0083] The primary function of cryo-electron microscopy is to image frozen samples using an electron beam. The electron beam originates from the electron gun, travels through the space between the pole pieces to reach the sample, and then passes through a series of electromagnetic lenses for imaging. The presence of the first channel 101 and the second channel 201 provides a path for the electron beam, ensuring that it accurately reaches the sample's location, thereby achieving image formation.

[0084] In the electron optics system of cryo-electron microscopy, the pole piece plays a role in generating a magnetic field to focus the electron beam. The arrangement of the first channel 101 and the second channel 201 helps to precisely control the distribution and intensity of the magnetic field, enabling the electron beam to achieve better focusing as it passes through the channel.

[0085] Specifically, the distance between the first pole piece 100 and the second pole piece 200 is less than 4 mm, which is smaller than the distance between pole pieces in a conventional cryo-electron microscope. Simultaneously, the aperture of the first channel 101 and the second channel 201 is less than 2 mm, which is smaller than the aperture of pole pieces in a conventional cryo-electron microscope. This application improves the magnetic field strength between the pole pieces by reducing the distance and aperture of the pole pieces, thereby ensuring the imaging quality of the cryo-electron microscope.

[0086] like Figure 3 As shown, in some examples, the pole piece assembly used in the electron microscope also includes a cold shielding structure 300 located between the first pole piece 100 and the second pole piece 200. Specifically, the first pole piece 100 is the upper pole piece in the cryo-electron microscope, and the second pole piece 200 is the lower pole piece. Therefore, the first pole piece 100 is located at the top of the cold shielding structure 300, and the second pole piece 200 is located at the bottom of the cold shielding structure 300.

[0087] In this cryo-electron microscope, the cold shielding structure 300 is equipped with a sample carrier 303. The sample carrier 303 is used to support the sample. When the sample carrier 303 is installed in the cold shielding structure 300, the sample carrier 303 and the cold shielding structure 300 form a whole. During sample observation, the cold shielding structure 300 and the sample-carrying sample carrier 303 move together. During the movement, the cold shielding structure 300 continuously conducts cold to the sample carrier 303, ensuring the freezing effect of the sample during movement. In contrast, in traditional cryo-electron microscopy, the sample carrier 303 and the cold shielding structure 300 are two independent structures. When the sample carrier 303 reaches the cold shielding structure 300, it can freeze the sample. However, during sample observation, the sample carrier 303 will detach from the cold shielding structure 300 through movement. At this time, the freezing effect of the sample is difficult to guarantee, resulting in a deterioration in the sample imaging effect.

[0088] It is understandable that the electron beam passes through the first channel 101 of the first pole piece 100 and is focused on the carrier mesh 303, thereby interacting with the sample to obtain the sample's feature information. After the electron beam interacts with the sample, the electron beam passes through the carrier mesh 303 and the cold shielding structure 300, thereby propagating to the second channel 201 of the second pole piece 200. After being further focused by the second pole piece 200, an image of the sample is formed.

[0089] like Figure 3 As shown, in some examples, the cold shielding structure 300 includes a mounting part 301 and a heat sink part 302. The mounting part 301 is used to mount the carrier mesh 303, and the heat sink part 302 is used to absorb water molecules in the electron microscope tube to prevent water molecules from contaminating the sample.

[0090] Specifically, when the electron microscope is in operation, the cooling energy of the external structure is conducted to the heat sink 302 via heat transfer, and then from the heat sink 302 to the grid 303. It is understood that the heat sink 302 has a lower temperature than the grid 303, ensuring that water molecules in the microscope tube are preferentially absorbed by the heat sink 302. After the heat sink 302 absorbs the water molecules in the microscope tube, the first electrode 100 focuses the electron beam, which acquires information about the sample, and the second electrode 200 receives the electron beam carrying this information.

[0091] Furthermore, since the mounting part 301 is used to mount the carrier mesh 303, and the carrier mesh 303 needs to be positioned between the first pole piece 100 and the second pole piece 200, the mounting part 301 is also positioned between the first pole piece 100 and the second pole piece 200. The heat sink 302 functions by relying on its own low temperature and has no specific positional requirement. Therefore, in this application, the heat sink 302 is connected to opposite sides of the mounting part 301. That is, the space in the Y-axis direction is used to house the heat sink 302, preventing the thicker heat sink 302 from occupying the space between the first pole piece 100 and the second pole piece 200. This facilitates reducing the distance between the first pole piece 100 and the second pole piece 200, thereby increasing the magnetic field strength between the first pole piece 100 and the second pole piece 200 and ensuring the imaging quality of the electron microscope.

[0092] In some examples, the thickness of the mounting portion 301 is less than the thickness of the heat sink portion 302. The main function of the mounting portion 301 is to support the carrier mesh 303, and there are no specific requirements for its volume. Since the mounting portion 301 is located between the first pole piece 100 and the second pole piece 200, reducing the thickness of the mounting portion 301 helps to reduce the distance between the first pole piece 100 and the second pole piece 200, thereby increasing the magnetic field strength between the first pole piece 100 and the second pole piece 200. Therefore, while ensuring the supporting strength of the mounting portion 301 for the carrier mesh 303, it is necessary to minimize the thickness of the mounting portion 301.

[0093] Meanwhile, since the thickness of the mounting part 301 is less than the thickness of the heat sink part 302, the mounting part 301 and the heat sink parts 302 located on opposite sides of the mounting part 301 will form a groove-shaped recessed structure. There is a certain space between the two heat sink parts 302, and the pole shoe can extend into the space between the two heat sink parts 302, thereby further reducing the distance between the first pole shoe 100 and the second pole shoe 200.

[0094] Specifically, the cold shielding structure 300 has the aforementioned groove structure on the side facing the first pole piece 100, and the cold shielding structure 300 also has the aforementioned groove structure on the side facing the second pole piece 200, ensuring that both the first pole piece 100 and the second pole piece 200 can extend into the space between the two heat sinks 302, greatly reducing the distance between the first pole piece 100 and the second pole piece 200.

[0095] In some examples, the carrier mesh 303 is mounted after the cold shielding structure 300, and the common thickness of the carrier mesh 303 and the mounting portion 301 is 0.85mm-2mm, which is much smaller than the thickness of the cold shielding structure 300 in conventional cryo-electron microscopy. It is understandable that, since the carrier mesh 303 and the mounting portion 301 are located between the first pole piece 100 and the second pole piece 200, reducing the common thickness of the carrier mesh 303 and the mounting portion 301 helps to reduce the distance between the first pole piece 100 and the second pole piece 200.

[0096] In some examples, the carrier mesh 303 has a slit region for holding the sample. The slit region is narrow, so that the electron microscope does not need a large field of view to cover the width of the slit region.

[0097] Furthermore, the field of view of the electron microscope corresponds to the focusing spot size of the electron beam in the slit region. It can be understood that the spot size is positively correlated with the aperture sizes of the first channel 101 and the second channel 201. That is, the larger the aperture of the first channel 101 and the second channel 201, the larger the spot size; and the smaller the aperture of the first channel 101 and the second channel 201, the smaller the spot size. Therefore, a narrower slit region does not require a larger spot size, making it easier to reduce the aperture of the first channel 101 and the second channel 201, thereby increasing the magnetic field strength between the first pole piece 100 and the second pole piece 200. This design maximizes the magnetic field strength while ensuring observational effectiveness.

[0098] Meanwhile, since the electron microscope's field of view can cover the width of the slit region, the entire sample within the slit region can be observed simply by moving the grid 303 and the cold shielding structure 300 in a single direction (X-axis direction), eliminating the need for them to move in multiple directions. Therefore, the grid 303 and the cold shielding structure 300 do not need to move in the Y-axis direction, and the space in the Y-axis direction can be used to install the heat sink 302. Even if the distance between the first pole piece 100 and the second pole piece 200 is small, collisions between the heat sink 302 and the pole piece can be avoided during the movement of the cold shielding structure 300.

[0099] Specifically, the width of the slit region is 1μm-10μm, which is much smaller than the width of the sample region on the traditional cryo-electron microscope grid 303, making it easier for the spot formed by the electron beam to cover the width of the slit region.

[0100] In some examples, the cold shielding structure 300 drives the sample within the slit region to the spot position of the electron beam focusing by unidirectional movement, without requiring the cold shielding structure 300 to move in multiple directions.

[0101] Specifically, since the slit region is quite long, the spot formed by the electron beam focusing cannot completely cover the length of the slit region. The cold shielding structure 300 needs to move the carrier mesh 303 together in the X-axis direction to ensure that the samples in the slit region arrive at the spot position in the X-axis direction in sequence, thus ensuring the comprehensiveness of the observation.

[0102] As the cold shielding structure 300 moves, the light spot focuses on a certain position within the slit region, forming a sample image at that position. After the image at the current position is captured, the cold shielding structure 300 continues to move, and the light spot refocuses on another adjacent position within the slit region, forming another sample image. This process continues until all sample images within the slit region are acquired, thus ensuring the comprehensiveness of the observation.

[0103] It is understandable that the extension direction of the slit region is the same as the movement direction of the cold shielding structure 300, that is, the movement direction of the cold shielding structure 300 is the length direction of the slit region.

[0104] In some examples, the first pole piece 100 and the second pole piece 200 are arranged vertically, with the first pole piece 100 located on top of the second pole piece 200. Therefore, the first channel 101 and the second channel 201 are also vertically aligned, ensuring that the electron beam derived from the first channel 101 can propagate into the second channel 201, facilitating the formation of an image of the sample after focusing by the second pole piece 200.

[0105] In some examples, the first pole piece 100 has a through hole that is approximately vertical. Correspondingly, the second pole piece 200 has a through hole that is also approximately vertical.

[0106] It is understandable that the internal space of the first hole defines the first channel 101, and the internal space of the second hole also defines the second channel 201. The first hole and the second hole correspond vertically to ensure the propagation of the electron beam between the first pole piece 100 and the second pole piece 200.

[0107] In some examples, the distance between the first pole piece 100 and the second pole piece 200 is the distance between the position of the first aperture focusing the electron beam and the position of the second aperture receiving the electron beam. To reduce the distance between the first pole piece 100 and the second pole piece 200, it is necessary to reduce the distance from the position of the first aperture focusing the electron beam to the position of the second aperture receiving the electron beam, regardless of other positions of the first pole piece 100 and the second pole piece 200. Therefore, the specific shapes of the first pole piece 100 and the second pole piece 200 can be set according to actual conditions to ensure a stable and safe distance between the pole piece and the heat sink 302, avoiding collisions between the pole piece and the heat sink 302.

[0108] Specifically, the radial dimension of the first pole piece 100 gradually decreases in the direction close to the second pole piece 200, that is, the first pole piece 100 is formed into a cone shape; at the same time, the radial dimension of the second pole piece 200 also gradually decreases in the direction close to the first pole piece 100, that is, the second pole piece 200 is also formed into a cone shape.

[0109] In some examples, the pole piece assembly used in electron microscopes also includes coils that ensure a magnetic field exists between the first pole piece 100 and the second pole piece 200.

[0110] Specifically, the coil generates a magnetic field between the first pole piece 100 and the second pole piece 200 by energizing it. In some examples, the first pole piece 100 and the second pole piece 200 adopt an asymmetrical design. By optimizing their respective conical structural parameters, the magnetic field strength between the pole pieces is ensured while providing more room for the cold shielding structure 300 to move, thereby achieving a balance between high-resolution imaging and sample cooling.

[0111] Based on the above-described pole piece assembly used in electron microscopes, various embodiments of the method of using the electron microscope of this application are presented below.

[0112] The electron microscope includes the aforementioned pole piece assembly, and its use may include, but is not limited to, the following steps:

[0113] A magnetic field is formed between the first pole piece 100 and the second pole piece 200;

[0114] The electron beam is focused through the first pole piece 100 and the second pole piece 200;

[0115] A carrier net 303 carrying the sample is installed on the cold shielding structure 300;

[0116] The cold shielding structure 300 passes through the gap between the first pole shoe 100 and the second pole shoe 200.

[0117] In some examples, the first pole piece 100 and the second pole piece 200 need to be manufactured with small apertures. Since the first and second holes form the first channel 101 and the second channel 201 respectively, a smaller aperture means that the spot size of the electron beam focusing is also smaller.

[0118] It is worth noting that the apertures of the first and second holes also need to correspond to the width of the slit area of ​​the carrier mesh 303. Specifically, the apertures of the first and second holes are set to 1mm-2mm.

[0119] Meanwhile, during the installation of the first pole shoe 100 and the second pole shoe 200, it is necessary to ensure that the first pole shoe 100 and the second pole shoe 200 have a small gap.

[0120] The smaller aperture and spacing of the first pole piece 100 and the second pole piece 200 facilitate the formation of a larger magnetic field strength between them, thereby ensuring image quality. Specifically, the spacing between the first pole piece 100 and the second pole piece 200 is 2mm-4mm.

[0121] As the coil is energized, a magnetic field is formed between the first pole piece 100 and the second pole piece 200. Under the influence of the magnetic field, the electron beam is focused by passing through the first pole piece 100 and the second pole piece 200 in sequence. The electron beam focused by the second pole piece 200 finally forms an image of the sample.

[0122] Furthermore, a carrier net 303 is installed on the cold shielding structure 300, and the carrier net 303 carries the sample. The electron beam can form a light spot on the carrier net 303, thereby capturing the sample image at the position of the light spot.

[0123] As the cold shielding structure 300 moves, the electron beam will scan the sample on the grid 303, ensuring comprehensive observation.

[0124] In addition, forming a magnetic field between the first pole piece 100 and the second pole piece 200 includes, but is not limited to, the following steps:

[0125] When the coil is energized, the magnetic field is generated through the coil.

[0126] In some examples, because the first pole piece 100 and the second pole piece 200 are symmetrical in shape, the energized coil can form a symmetrical magnetic field between the first pole piece 100 and the second pole piece 200, which facilitates better propagation of the electron beam.

[0127] In addition, the electron beam is focused through the first pole piece 100 and the second pole piece 200, including but not limited to the following steps:

[0128] The electron beam propagates from the first channel 101 of the first pole piece 100 to the second channel 201 of the second pole piece 200.

[0129] In some examples, the first pole piece 100 forms an electron beam, which propagates through the carrier grid 303 to the second pole piece 200, where an image of the sample is formed.

[0130] Specifically, the first channel 101 formed by the first aperture and the second channel 201 formed by the second aperture form the propagation path of the electron beam.

[0131] Additionally, the installation of the sample-bearing net 303 on the cold shielding structure 300 includes, but is not limited to, the following steps:

[0132] The carrier net 303 has a slit area, on which the sample is carried.

[0133] In some examples, the slit region is narrow, which can cover the width of the slit region even when the field of view of the electron microscope is small. In addition, with the movement of the cold shielding structure 300 and the carrier net 303, it can ensure that the sample in the slit region can be observed in a comprehensive manner.

[0134] Meanwhile, the smaller field of view of the electron microscope means that the apertures of the first and second apertures are smaller, which helps to increase the magnetic field strength between the first pole piece 100 and the second pole piece 200, thus ensuring the imaging quality of the electron microscope.

[0135] Additionally, the installation of the sample-bearing net 303 on the cold shielding structure 300 includes, but is not limited to, the following steps:

[0136] The carrier net 303 is installed on the mounting part 301 of the cold shielding structure 300.

[0137] In some examples, the carrier mesh 303 is mounted on the mounting part 301. The mounting part 301, which has a smaller thickness, is located between the first pole piece 100 and the second pole piece 200. This makes it easier to reduce the distance between the first pole piece 100 and the second pole piece 200, thereby further improving the magnetic field strength between the first pole piece 100 and the second pole piece 200 and ensuring the imaging quality of the electron microscope.

[0138] Additionally, the installation of the sample-bearing net 303 on the cold shielding structure 300 includes, but is not limited to, the following steps:

[0139] The heat sink 302 of the cold shielding structure 300 reduces the temperature through heat transfer, so that the temperature of the heat sink 302 of the cold shielding structure 300 is lower than the temperature of the carrier mesh 303.

[0140] In some examples, the heat sink 302 reduces its temperature through heat transfer from the external structure, while the mesh 303 reduces its temperature through heat transfer with the heat sink 302, making the temperature of the heat sink 302 lower than that of the mesh 303. Water molecules in the microscope tube tend to be adsorbed on the lower-temperature heat sink 302, thus avoiding water molecule contamination of the sample. The temperature of the heat sink 302 is 1-10°C lower than that of the mesh 303.

[0141] Additionally, the cold shielding structure 300 passes through the gap between the first pole shoe 100 and the second pole shoe 200, including but not limited to the following steps:

[0142] The cold shielding structure 300 moves in the direction of extension of the slit region.

[0143] In some examples, since the focused spot of the electron beam can cover the width of the slit region, in order to ensure the comprehensiveness of the observation, the cold shielding structure 300 moves in the extension direction of the slit region, that is, the cold shielding structure 300 moves in the length direction of the slit region.

[0144] Additionally, the cold shielding structure 300 passes through the gap between the first pole shoe 100 and the second pole shoe 200, including but not limited to the following steps:

[0145] The cold shielding structure 300 moves to focus the electron beam onto different positions of the sample within the slit region.

[0146] Additionally, the cold shielding structure 300 passes through the gap between the first pole shoe 100 and the second pole shoe 200, including but not limited to the following steps:

[0147] Images are obtained at different locations within the slit area through the focusing effect of the second pole shoe 200.

[0148] In some examples, as the cold shielding structure 300 moves, the electron beam will continuously focus on different positions in the slit region, thereby causing the electron microscope to continuously form sample images at different positions in the slit region. After the electron beam scans the slit region, the staff can analyze and compare the several images formed by the electron microscope to ensure the comprehensiveness of the observation.

[0149] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A pole shoe assembly for use in an electron microscope, characterized in that, include: A first pole piece (100) is used to focus the electron beam, and the first pole piece (100) is provided with a first channel (101); The second pole piece (200) is used to further focus the electron beam. The second pole piece (200) is provided with a second channel (201). The electron beam can be focused by passing through the first channel (101) and the second channel (201) in sequence. The distance between the first pole piece (100) and the second pole piece (200) is less than 4 mm, and the aperture of the first channel (101) and the second channel (201) is less than 2 mm.

2. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The pole piece assembly for use in an electron microscope further includes a cold shielding structure (300) located between the first pole piece (100) and the second pole piece (200), wherein the cold shielding structure (300) is equipped with a sample carrier mesh (303), and the electron beam is focused on the sample on the carrier mesh (303) through the first pole piece (100).

3. The pole shoe assembly for use in an electron microscope according to claim 2, characterized in that, The cold shielding structure (300) includes a heat sink (302) and a mounting part (301) for mounting the carrier net (303), wherein the heat sink (302) is connected to opposite sides of the mounting part (301).

4. The pole shoe assembly for use in an electron microscope according to claim 3, characterized in that, When the electron microscope is in operation, the temperature of the heat sink (302) is lower than the temperature of the carrier mesh (303).

5. The pole shoe assembly for use in an electron microscope according to claim 4, characterized in that, The temperature of the heat sink (302) is 1-10°C lower than the temperature of the carrier net (303).

6. The pole shoe assembly for use in an electron microscope according to claim 3, characterized in that, The thickness of the mounting portion (301) is less than the thickness of the heat sink portion (302), and the first pole shoe (100) and the second pole shoe (200) extend into the space between each of the heat sink portions (302).

7. The pole shoe assembly for an electron microscope according to claim 6, characterized in that, The thickness of the mounting part (301) on which the carrier net (303) is installed is 0.85mm-2mm.

8. The pole shoe assembly for use in an electron microscope according to claim 2, characterized in that, The carrier mesh (303) has a slit area for carrying the sample, and the width of the slit area is 1μm-10μm.

9. The pole shoe assembly for use in an electron microscope according to claim 8, characterized in that, The cold shielding structure (300) drives the sample in the slit region to the electron beam focusing position by unidirectional movement.

10. The pole shoe assembly for an electron microscope according to claim 9, characterized in that, The extension direction of the slit region is the same as the movement direction of the cold shielding structure (300).

11. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The first pole piece (100) and the second pole piece (200) are distributed vertically to define the first channel (101) and the second channel (201) as vertically corresponding.

12. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The first pole shoe (100) has a through hole, and the inner wall of the first hole defines the first channel (101).

13. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The radial dimension of the first pole piece (100) gradually decreases in the direction approaching the second pole piece (200).

14. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The second pole shoe (200) is provided with a through second hole, the inner wall of which defines the second channel (201).

15. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The radial dimension of the second pole piece (200) gradually decreases in the direction close to the first pole piece (100).

16. The pole shoe assembly for an electron microscope according to claim 1, characterized in that, The pole piece assembly for use in an electron microscope also includes a coil that generates a magnetic field between the first pole piece (100) and the second pole piece (200) by energizing the coil.

17. A method of using an electron microscope, wherein the electron microscope comprises a pole shoe assembly according to any one of claims 1-16 forming a magnetic field between the first pole shoe (100) and the second pole shoe (200); The electron beam is focused through the first pole piece (100) and the second pole piece (200); A carrier net (303) bearing the sample is installed on the cold shielding structure (300); The cold shielding structure (300) passes through the gap between the first pole piece (100) and the second pole piece (200).

18. The method of using an electron microscope according to claim 17, characterized in that, A magnetic field is formed between the first pole piece (100) and the second pole piece (200), including: When the coil is energized, the magnetic field is generated through the coil.

19. The method of using an electron microscope according to claim 17, characterized in that, The electron beam is focused through the first pole piece (100) and the second pole piece (200), and further includes: The electron beam propagates from the first channel (101) of the first pole piece (100) to the second channel (201) of the second pole piece (200).

20. The method of using an electron microscope according to claim 17, characterized in that, The installation of the sample-bearing net (303) on the cold shielding structure (300) includes: The carrier mesh (303) has a slit area, and the sample is added to the slit area.

21. The method of using an electron microscope according to claim 17, characterized in that, The method of mounting a sample-bearing net (303) on the cold shielding structure (300) further includes: The carrier net (303) is installed on the mounting part (301) of the cold shielding structure (300).

22. The method of using an electron microscope according to claim 21, characterized in that, The method of mounting a sample-bearing net (303) on the cold shielding structure (300) further includes: The heat sink (302) of the cold shielding structure (300) reduces the temperature through heat transfer, so that the temperature of the heat sink (302) of the cold shielding structure (300) is lower than the temperature of the carrier mesh (303).

23. The method of using an electron microscope according to claim 20, characterized in that, The cold shielding structure (300) passes through the gap between the first pole shoe (100) and the second pole shoe (200), and includes: The cold shielding structure (300) moves in the direction of extension of the slit region.

24. The method of using an electron microscope according to claim 20, characterized in that, The cold shielding structure (300) passes through the gap between the first pole shoe (100) and the second pole shoe (200), and further includes: The cold shielding structure (300) moves to focus the electron beam at different locations within the slit region.

25. The method of using an electron microscope according to claim 20, characterized in that, The cold shielding structure (300) passes through the gap between the first pole shoe (100) and the second pole shoe (200), and further includes: Images are obtained at different locations within the slit region by the focusing effect of the second pole shoe (200).

Images