A field-free environment sample rod for a transmission electron microscope

Abstract

The present application relates to the technical field of transmission electron microscopy, and particularly relates to a magnetic field-free environment sample rod for a transmission electron microscope, which comprises a sample rod body, a rod head, a magnetic shielding device, a sample carrying device and a sample displacement driving device, the rod head is fixed to the sample rod body, the magnetic shielding device and the sample carrying device are installed on the rod head, the magnetic shielding device comprises a high-permeability screen, a magnetic flux accommodation cavity is formed in the center of the high-permeability screen, the sample carrying device comprises a sample probe assembly, the sample probe assembly extends to the magnetic flux accommodation cavity, the sample displacement driving device is installed in the sample rod body and is connected to drive the sample carrying device. A magnetic field-free environment is constructed in the magnetic flux accommodation cavity through the high-permeability screen, the structure is compact, the cost is controllable, the device can be directly adapted to conventional transmission electron microscopes on the market, has good universality and economy, the magnetic shielding device and the rod head are detachably installed, different specifications of the magnetic shielding assembly can be replaced, and the practicality and flexibility of the device are improved.

Description

Technical Field

[0001] This invention relates to the field of transmission electron microscopy, and more particularly to a sample holder for a magnetic field-free environment for transmission electron microscopy. Background Technology

[0002] Transmission electron microscopy (TEM), a key tool in materials science and nanotechnology research, uses a high-voltage accelerated electron beam to penetrate a sample and focuses and images it using a short-focal-length, strongly magnetized electromagnetic lens, achieving atomic-scale resolution. To achieve effective focusing of the electron beam, conventional TEM objectives typically require a strong magnetic field of 2–3 Tesla between the pole pieces, with the sample completely immersed in this environment during observation. However, for magnetic materials, superconducting materials, and alloys containing magnetic elements (such as Fe, Co, and Ni), this design suffers from severe interference with the intrinsic physical states of the sample. This can lead to the destruction of magnetic domain structures, alteration of spin texture, and loss of superconductivity, resulting in severely distorted observations. Furthermore, magnetized samples may even adhere to the pole pieces, compromising the safety of the TEM. Therefore, in characterizing the intrinsic microstructure of these sensitive materials, providing a magnetic field-free environment inside the TEM is a critical technical challenge that needs to be addressed.

[0003] Currently, to address the interference of strong magnetic fields on sensitive sample observations in transmission electron microscopy (TEM), the field primarily employs two technical solutions. First, the Lorentz mode, which involves closing or significantly reducing the objective lens magnetic field and using a long-focal-length, weakly excited Lorentz lens system for imaging. While this approach can reduce the magnetic field in the sample region to some extent, the drastic drop in focusing power due to the closed objective lens results in spatial resolution typically only reaching the nanometer level, failing to meet the demands of high-resolution characterization. Users are forced to make trade-offs between a magnetic-free environment and high-resolution imaging. Second, dedicated magnetic-free objective systems, such as the JEM-Z200MF electron microscope developed by NEC Corporation, employ a double-lens design located above and below the sample to cancel out the magnetic fields at the sample plane. Although this approach achieves high-resolution magnetic-free imaging, it requires a complete reconstruction of the electron microscope objective system, making the equipment extremely expensive. Furthermore, the modified system makes it difficult to assemble the objective aperture, severely impacting the contrast effects of classic modes such as bright-field, dark-field, and diffraction contrast imaging. Furthermore, both of the above solutions attempt to modify the electron microscope itself, which cannot be directly adapted to existing conventional transmission electron microscopes, resulting in poor universality and limited application. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention proposes a magnetic field-free sample holder for transmission electron microscopy, which is compatible with conventional transmission electron microscopes and can effectively shield the strong magnetic field of the objective lens without introducing additional magnetic interference while maintaining high-resolution imaging capabilities.

[0005] A sample holder for a transmission electron microscope in a magnetic field-free environment according to an embodiment of the present invention includes a sample holder body, a holder head, a magnetic shielding device, a sample mounting device, and a sample displacement driving device. The sample holder body has a hollow cavity formed inside. The holder head is fixed to one end of the sample holder body. The magnetic shielding device is detachably mounted on the holder head and includes a high-permeability magnetic screen with a magnetic flux absorption cavity formed at its center. The sample mounting device is movably disposed on the holder head and includes a sample probe assembly for carrying the sample. The front end of the sample probe assembly extends into the magnetic flux absorption cavity. The sample displacement driving device is installed in the hollow cavity of the sample holder body and is drivenly connected to the sample mounting device to drive the front end of the sample probe assembly to move within the magnetic flux absorption cavity.

[0006] According to one embodiment of the present invention, the rod head includes a frame body connected to the end of the sample rod body. The frame body is provided with a mounting part, and the mounting part forms a magnetic screen mounting groove. The high-permeability magnetic screen is installed in the magnetic screen mounting groove, and a through part is formed in the magnetic screen mounting groove. A limiting groove communicating with the through part is formed on the frame body. The sample probe assembly is movably disposed in the limiting groove, and the front end of the sample probe assembly passes through the through part and extends to the magnetic flux absorption cavity of the high-permeability magnetic screen.

[0007] According to one embodiment of the present invention, the magnetic shielding device further includes a magnetic screen fixing member, which fits and covers the axial end face of the high-permeability magnetic screen and is embedded in the mounting portion of the frame body. The magnetic screen fixing member is fastened to the mounting portion of the frame body through a first connector to fix the high-permeability magnetic screen in the magnetic screen mounting groove.

[0008] According to one embodiment of the present invention, the magnetic screen fixing member has a central hole, the size of which is smaller than the size of the high-permeability magnetic screen.

[0009] According to one embodiment of the present invention, the sample mounting device further includes a connecting seat and a probe connecting fastener. The connecting seat is made of antimagnetic material and is a sleeve structure. One end of the connecting seat is detachably connected to the sample displacement driving device. The end of the connecting seat away from the sample displacement driving device is provided with a shaped connecting groove for connecting the sample probe assembly. The probe connecting fastener fits and covers the shaped connecting groove of the connecting seat. The probe connecting fastener is fastened to the connecting seat through a second connecting member to fix one end of the sample probe assembly to the shaped connecting groove of the connecting seat.

[0010] According to one embodiment of the present invention, the sample probe assembly includes a fixed base, a transition member, and a sample probe. One end of the fixed base has an irregularly shaped connecting portion, which is fixedly engaged with an irregularly shaped connecting groove of the connecting base. The transition member is connected to the end of the fixed base away from the connecting base and is movably disposed within the limiting groove of the rod head. The sample probe is connected to the end of the transition member away from the fixed base and passes through the through portion of the rod head and extends to the flux absorption cavity of the high-permeability magnetic screen.

[0011] According to one embodiment of the present invention, the sample displacement driving device includes a first displacement driver, an axial transmission rod, and a second displacement driver. The first displacement driver is disposed in the hollow cavity of the sample rod body and arranged along the axial direction of the sample rod body. The first displacement driver is used to output a displacement variable along the axial direction of the sample rod body. The axial transmission rod is connected to the output end of the first displacement driver. The second displacement driver is connected to the end of the axial transmission rod away from the first displacement driver. The second displacement driver is connected to the sample mounting device and is used to output a displacement variable along the radial direction of the sample rod body.

[0012] According to one embodiment of the present invention, the sample displacement driving device further includes a double-layer dynamic sealing ring and a probe interface. The double-layer dynamic sealing ring is disposed between the axial transmission rod and the inner wall of the sample rod body for vacuum sealing and buffering mechanical vibration. The probe interface is formed as a sleeve structure, with one end of the probe interface connected to the second displacement driver and the other end connected to the sample mounting device.

[0013] According to one embodiment of the present invention, the sample rod body is made of an antimagnetic alloy, and the sample rod body is provided with a second displacement driver electrical interface and a first displacement driver electrical interface. The second displacement driver electrical interface is electrically connected to the second displacement driver, and the first displacement driver electrical interface is electrically connected to the first displacement driver, for connecting an external driving power supply.

[0014] According to one embodiment of the present invention, the second displacement actuator is a piezoelectric ceramic tube, the outer wall of which is formed with four quadrant electrodes. The electrical interface of the second displacement actuator is electrically connected to the four quadrant electrodes of the piezoelectric ceramic tube through a control circuit, and is used to apply a voltage combination to the four quadrant electrodes based on an external signal, so that the piezoelectric ceramic tube deforms and expands radially along the sample rod.

[0015] The first displacement actuator is a cylindrical piezoelectric actuator, which has two opposing electrodes. The electrical interface of the first displacement actuator is electrically connected to the two electrodes of the cylindrical piezoelectric actuator through a control circuit, and is used to apply a voltage to one of the electrodes based on an external signal, so as to cause the cylindrical piezoelectric actuator to produce axial extension and retraction.

[0016] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: A magnetic shielding device is constructed using a high-permeability magnetic screen. Utilizing its high permeability, the magnetic field lines generated by the objective lens are actively guided and converged, allowing them to travel along the annular wall of the high-permeability magnetic screen, where they are diverted and trapped. This prevents the magnetic field lines from entering the central flux absorption cavity, creating a stable, uniform, magnetic field-free or extremely low-magnetic-field environment within the cavity. The sample, carried at the front end of the sample probe assembly, is precisely located in this magnetic field-free environment, thus avoiding interference from external strong magnetic fields. Simultaneously, the operator can drive the sample displacement drive device via an external control system, enabling three-dimensional movement of the sample probe assembly within the flux absorption cavity for high-resolution observation of different regions of the sample. The sample holder of this transmission electron microscope is completely independent of the main electron microscope and does not require any modification to the objective system or closure of the objective. Therefore, it can fully retain the original high-resolution imaging capability of the electron microscope. A non-magnetic environment is locally constructed at the front end of the sample holder by a high-permeability magnetic screen, rather than changing the magnetic field distribution of the entire electron microscope. It has a compact structure, controllable cost, and can be directly adapted to conventional transmission electron microscopes on the market, with good versatility and economy.

[0017] Additional aspects and advantages of the invention 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 the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention and are not considered as limitations on this application. Moreover, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0019] Figure 1 This is a schematic external structural diagram of the sample holder for a transmission electron microscope in a magnetic field-free environment provided by the present invention.

[0020] Figure 2 This is a schematic internal structure diagram of the sample holder for a transmission electron microscope in a magnetic field-free environment provided by the present invention.

[0021] Figure 3This is a schematic front view of the sample holder head for a transmission electron microscope in a magnetic field-free environment, provided by the present invention.

[0022] Figure 4 This is a schematic back view of the sample holder head for a transmission electron microscope in a magnetic field-free environment, provided by the present invention.

[0023] Figure 5 This is a schematic exploded view of the sample rod head portion of the non-magnetic environment sample rod for transmission electron microscopy provided by the present invention.

[0024] Figure 6 This is one of the schematic diagrams showing the combined structure of the magnetic shielding device and the sample mounting device provided by the present invention.

[0025] Figure 7 This is the second schematic diagram of the combined structure of the magnetic shielding device and the sample mounting device provided by the present invention.

[0026] Figure label: 1. Sample rod body; 2. Rod head; 3. Magnetic shielding device; 4. Sample mounting device; 5. Sample displacement driving device; 11. Electrical interface of the second displacement driver; 12. Electrical interface of the first displacement driver; 21. Frame; 22. Mounting part; 23. Magnetic shield mounting slot; 24. Through part; 25. Limiting slot; 31. High-permeability magnetic screen; 32. Magnetic flux absorption cavity; 33. Magnetic screen fixing component; 34. First connecting component; 41. Sample probe assembly; 42. Connector; 43. Probe connection fastener; 44. Second connector; 411. Fixture; 412. Transition component; 413. Sample probe; 51. First displacement actuator; 52. Axial transmission rod; 53. Second displacement actuator; 54. Double-layer dynamic sealing ring; 55. Probe interface. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in 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 the present invention, and should not be construed as limiting the present invention.

[0028] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0029] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0030] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 invention based on the specific circumstances.

[0032] The following is combined with Figures 1 to 7 The present invention describes a magnetic field-free environment sample holder for transmission electron microscopy and a transmission electron microscope.

[0033] This invention proposes a magnetic field-free sample holder for transmission electron microscopy (TEM), which is compatible with conventional TEMs and can effectively shield the strong magnetic field of the objective lens without sacrificing high-resolution imaging capabilities and without introducing additional magnetic interference. In one embodiment of this invention, combined with... Figure 1 and Figure 2As shown, the sample rod for a transmission electron microscope in a magnetic field-free environment includes a sample rod body 1, a rod head 2, a magnetic shielding device 3, a sample mounting device 4, and a sample displacement driving device 5. The sample rod body 1 has a hollow cavity inside. The rod head 2 is fixed to one end of the sample rod body 1. The magnetic shielding device 3 is detachably installed on the rod head 2 and includes a high-permeability magnetic screen 31 with a magnetic flux absorption cavity 32 at its center. The sample mounting device 4 is movably disposed on the rod head 2 and includes a sample probe assembly 41 for carrying the sample. The front end of the sample probe assembly 41 extends into the magnetic flux absorption cavity 32. The sample displacement driving device 5 is installed in the hollow cavity of the sample rod body 1 and is drivenly connected to the sample mounting device 4 to drive the front end of the sample probe assembly 41 to move within the magnetic flux absorption cavity 32.

[0034] It is understood that the transmission electron microscope sample rod of this embodiment has an overall rod-shaped structure, mainly including a sample rod body 1, a rod head 2, a magnetic shielding device 3, a sample mounting device 4, and a sample displacement driving device 5. The sample rod body 1 has a hollow cavity inside to accommodate the sample displacement driving device 5 and related control circuitry. The rod head 2 is fixedly connected to one end of the sample rod body 1, serving as an integrated carrier for the front-end functional components. The magnetic shielding device 3 is detachably installed at the front end of the rod head 2. The core component of the magnetic shielding device 3 is a high-permeability magnetic screen 31, which is made of a magnetic material with high permeability and high saturation magnetization (such as permalloy). A hollow magnetic flux absorption cavity 32 is formed in its central region. The sample mounting device 4 is movably disposed inside the rod head 2. The sample mounting device 4 includes a sample probe assembly 41 for directly carrying the sample to be tested, and the front end of the sample probe assembly 41 extends into the magnetic flux absorption cavity 32 of the high-permeability magnetic screen 31. The sample displacement driving device 5 is installed in the hollow cavity of the sample rod body 1 and forms a driving connection with the sample mounting device 4. It is used to drive the front end of the sample probe assembly 41 to move in the magnetic flux absorption cavity 32 under the action of external control signals.

[0035] After the sample rod of this embodiment is inserted into the sample port of a conventional transmission electron microscope, the strong magnetic field (approximately 2-3T) generated by the electron microscope objective pole shoe acts on the front end of the sample rod. At this time, the magnetic shielding device 3, composed of a high-permeability magnetic screen 31, actively guides and converges the magnetic field lines generated by the objective lens, causing them to travel along the annular wall of the high-permeability magnetic screen 31, thereby being diverted and trapped, preventing the magnetic field lines from entering the central magnetic flux absorption cavity 32. Therefore, a stable and uniform magnetic field-free or extremely low magnetic field environment is formed inside the magnetic flux absorption cavity 32. The sample carried on the front end of the sample probe assembly 41 is located precisely in this magnetic field-free environment, thus being protected from interference from external strong magnetic fields. At the same time, the operator can drive the sample displacement drive device 5 through an external control system to move the sample probe assembly 41 in three dimensions within the magnetic flux absorption cavity 32, so as to perform high-resolution observation of different areas of the sample.

[0036] It is important to understand that the sample holder of this transmission electron microscope in this embodiment is completely independent of the main electron microscope unit. No modification to the objective system or disabling of the objectives is required, thus preserving the original high-resolution imaging capability of the electron microscope. This embodiment creates a localized non-magnetic environment at the front end of the sample holder using a high-permeability magnetic shield 31, rather than altering the overall magnetic field distribution of the electron microscope. This results in a compact structure, controllable cost, and direct compatibility with commercially available conventional transmission electron microscopes, offering excellent versatility and economy. Furthermore, the magnetic shielding device 3 and the holder head 2 are detachably installed, facilitating the replacement of different specifications of magnetic shielding components according to different electron microscope models or observation requirements, further enhancing the practicality and flexibility of the device.

[0037] In one embodiment of the present invention, see Figure 5 As shown, the rod head 2 includes a frame body 21 connected to the end of the sample rod body 1. The frame body 21 is provided with a mounting part 22, and the mounting part 22 forms a magnetic screen mounting groove 23. A high-permeability magnetic screen 31 is installed in the magnetic screen mounting groove 23. A through part 24 is formed in the magnetic screen mounting groove 23. A limiting groove 25 communicating with the through part 24 is formed on the frame body 21. The sample probe assembly 41 is movably disposed in the limiting groove 25. The front end of the sample probe assembly 41 passes through the through part 24 and extends to the magnetic flux absorption cavity 32 of the high-permeability magnetic screen 31.

[0038] It is understood that this embodiment specifically defines the rod head 2 and its mating structure with the magnetic shielding device 3 and the sample probe assembly 41. See also Figure 5As shown, the rod head 2 includes a frame body 21, which is fixedly connected to the end of the sample rod body 1. A mounting portion 22 is provided on the frame body 21, forming a precisely shaped magnetic screen mounting groove 23 for accommodating and positioning the high-permeability magnetic screen 31. A through portion 24 is further formed inside the magnetic screen mounting groove 23, serving as a connecting channel between the mounting portion 22 and the internal area of ​​the frame body 21. Simultaneously, a limiting groove 25 is formed on the frame body 21, which communicates with the through portion 24. The sample probe assembly 41 is movably disposed within the limiting groove 25, and the front end of the sample probe assembly 41 passes through the through portion 24, precisely extending into the magnetic flux absorption cavity 32 at the center of the high-permeability magnetic screen 31.

[0039] In the specific implementation process, the high-permeability magnetic screen 31 is first embedded into the magnetic screen mounting groove 23 of the frame 21, and the radial and axial positioning of the high-permeability magnetic screen 31 is initially achieved by utilizing the geometric constraints of the mounting groove. Then, the pre-assembled sample probe assembly 41 is inserted into the limiting groove 25 from the rear of the frame 21. The limiting groove 25 is larger than the outer diameter of the sample probe assembly 41, providing a guide channel for axial movement and reserved space for radial movement. Guided by the limiting groove 25, the front end of the sample probe assembly 41 smoothly passes through the through-hole 24 and finally enters the magnetic flux absorption cavity 32 at the center of the high-permeability magnetic screen 31, ensuring that the probe tip is located at the center of the non-magnetic region. In this structure, the sample probe assembly 41 is both constrained by the limiting groove 25 to maintain motion stability and can be precisely displaced along the limiting groove 25 under the drive of the sample displacement driving device 5.

[0040] It is important to understand that, through the aforementioned structure, the embedded fit between the magnetic shield mounting slot 23 and the high-permeability magnetic screen 31 in this embodiment ensures high-precision coaxial positioning between the magnetic shielding device 3 and the rod head 2. This facilitates the alignment of the magnetic flux absorption cavity 32 with the optical axis of the electron microscope objective, thereby avoiding magnetic field distortion caused by structural eccentricity and ensuring the stability of high-resolution imaging. The continuous channel design of the limiting slot 25 and the through-hole 24 provides full guidance and protection for the slender sample probe assembly 41, preventing it from colliding or getting stuck with the rod head 2 or the high-permeability magnetic screen 31 during movement, thus improving the safety of sample mounting and displacement. In this embodiment, the mounting reference of the magnetic shielding device 3 and the motion guidance reference of the sample probe are integrated on the same frame 21, which simplifies the assembly process, reduces accumulated assembly errors, and makes the entire front-end module structure compact, highly reliable, and easy to operate within the limited pole shoe space.

[0041] In one embodiment of the present invention, combined with Figure 3 , Figure 4 and Figure 5As shown, the magnetic shielding device 3 also includes a magnetic screen fixing member 33, which fits and covers the axial end face of the high-permeability magnetic screen 31 and is embedded in the mounting part 22 of the frame body 21. The magnetic screen fixing member 33 is fastened to the mounting part 22 of the frame body 21 through the first connector 34 to fix the high-permeability magnetic screen 31 in the magnetic screen mounting groove 23.

[0042] It is understood that, in addition to the high-permeability magnetic screen 31, the magnetic shielding device 3 of this embodiment further includes a magnetic screen fixing member 33 and a first connecting member 34. After the high-permeability magnetic screen 31 is embedded in the magnetic screen mounting groove 23 of the frame body 21, its axial end face (i.e., the side facing the electron microscope objective) is exposed. The magnetic screen fixing member 33 is configured to fit and cover the axial end face of the high-permeability magnetic screen 31, and the outer dimensions of the magnetic screen fixing member 33 match the mounting portion 22 of the frame body 21, so that the magnetic screen fixing member 33 can be precisely fitted into the mounting portion 22. The first connecting member 34 (e.g., a non-magnetic screw) passes through the preset mounting hole on the magnetic screen fixing member 33 and forms a threaded fastening connection with the mounting portion 22 of the frame body 21, thereby firmly pressing and fixing the magnetic screen fixing member 33 onto the mounting portion 22. In this fixed state, the high-permeability magnetic screen 31 is clamped and locked from both ends of the axial direction by the magnetic screen fixing member 33 and the bottom wall of the magnetic screen mounting groove 23, so as to achieve complete fixation of the high-permeability magnetic screen 31 on the rod head 2.

[0043] In the specific implementation process, the operator first accurately places the high-permeability magnetic screen 31 into the magnetic screen mounting slot 23 of the frame 21, ensuring that it fits snugly against the bottom of the slot 23. Then, the magnetic screen fixing member 33 is aligned with the mounting position of the mounting part 22, ensuring its back surface is flat against the axial end face of the high-permeability magnetic screen 31. Next, the first connecting member 34 (such as a screw) is passed through the through holes on the magnetic screen fixing member 33 one by one and screwed into the corresponding threaded holes on the frame 21, tightening evenly in a diagonal sequence to apply uniform axial pressure to the end face of the high-permeability magnetic screen 31. After tightening, the outer surface of the magnetic screen fixing member 33 is basically flush with the outer edge of the mounting part 22 of the frame 21, forming a flat, unified appearance surface that is both aesthetically pleasing and avoids interference when inserting the electron microscope pole piece.

[0044] It should be understood that, in this embodiment, the magnetic screen fixing component 33, in conjunction with the first connecting component 34, can reliably fix the high-permeability magnetic screen 31 axially, preventing it from loosening, shifting, or falling off during long-term use or under mechanical vibration, thus ensuring the long-term stability and repeatability of the magnetic shielding effect. The magnetic screen fixing component 33 is embedded in the mounting part 22, and its outer surface is flush with the frame body 21. This embedded design reduces the radial dimension of the front end of the rod head 2, ensuring that the sample rod can be smoothly inserted into the narrow space between the pole shoes of the transmission electron microscope (usually only a few millimeters of gap). This embodiment adopts a detachable cover plate and connecting component structure, making the replacement or maintenance of the high-permeability magnetic screen 31 simple and easy. The high-permeability magnetic screen 31 can be removed simply by removing the first connecting component 34 and the magnetic screen fixing component 33, without having to replace the entire rod head 2, reducing maintenance costs and downtime.

[0045] Furthermore, the magnetic shielding fixture 33 has a central hole, the size of which is smaller than the size of the high-permeability magnetic shielding 31. It is understandable that in some specific examples, the magnetic shielding fixture 33 has undergone further optimized design. Combined with... Figure 3 , Figure 4 and Figure 5 As shown, the magnetic shield fixing member 33 is not a complete solid plate, but rather has a central hole in its central area. The size of this central hole is designed to be smaller than the size of the high-permeability magnetic shield 31. Specifically, when the magnetic shield fixing member 33 is fitted and covers the axial end face of the high-permeability magnetic shield 31, since the diameter of the central hole is smaller than the outer diameter of the high-permeability magnetic shield 31 (and also smaller than the area defined by its inner diameter), the magnetic shield fixing member 33 only covers the outer annular area of ​​the axial end face of the high-permeability magnetic shield 31, while the central part of the high-permeability magnetic shield 31 (including the opening end of the magnetic flux absorption cavity 32) is exposed to the external environment through the central hole.

[0046] In the specific implementation process, firstly, based on the outer diameter of the selected high-permeability magnetic screen 31, the diameter of the central hole of the magnetic screen fixing component 33 is determined. Typically, the diameter of the central hole is set to be smaller than the outer diameter of the high-permeability magnetic screen 31, but greater than or equal to the inner diameter of the high-permeability magnetic screen 31 (i.e., the diameter of the flux absorption cavity 32). The machined magnetic screen fixing component 33 is aligned with the axial end face of the high-permeability magnetic screen 31, ensuring that the central hole is coaxially aligned with the central region of the high-permeability magnetic screen 31. Then, the magnetic screen fixing component 33 is fastened to the mounting portion 22 of the frame body 21 via the first connecting component 34. After fastening, the inner wall of the high-permeability magnetic screen 31 and its internal flux absorption cavity 32 can be seen through the central hole of the magnetic screen fixing component 33. The electron beam of the electron microscope passes axially through this central hole and is incident unobstructed onto the sample located within the flux absorption cavity 32.

[0047] It is important to understand that in the structure of the magnetic shielding fixture 33 in this example, the fixture 33 only presses down on the outer annular area of ​​the high-permeability magnetic shield 31, leaving most of the surface area of ​​the high-permeability magnetic shield 31 (including its inner wall and part of its end face) exposed. This allows the high-permeability magnetic shield 31 to fully contact the magnetic field generated by the objective lens, exerting its ability to guide and converge magnetic field lines, and avoiding weakening the magnetic shielding effect due to the large area coverage of the cover plate. The presence of the central hole provides an unobstructed channel for the electron beam, ensuring that the electron beam can pass through the magnetic shielding fixture 33 without obstruction and be incident on the sample. At the same time, the signal electrons emitted from the sample can also be successfully received by the detector without affecting the imaging optical path of the transmission electron microscope. This example simultaneously achieves a balance between fixing function and functionality. The outer edge being pressed down ensures the installation firmness of the high-permeability magnetic shield 31, while the central opening ensures magnetic shielding effectiveness and imaging light transmission, achieving a balance between structural stability and physical functionality.

[0048] The magnetic shielding fixture 33 in the above embodiments and examples, see also Figures 3 to 5 As shown, the magnetic screen fixing component 33 adopts the structure of a magnetic screen cover plate. It should be understood that the magnetic screen fixing component 33 can be in the form of a magnetic screen cover plate, or it can be fixed in the form of a triangular claw, a buckle, etc., as long as it can fix the high-conductivity magnetic screen 31 in the magnetic screen mounting groove 23 of the frame body 21. The specific external structure of the magnetic screen fixing component 33 is not limited here.

[0049] In one embodiment of the present invention, combined with Figure 4 and Figure 5 As shown, the sample mounting device 4 also includes a connecting seat 42 and a probe connecting fastener 43. The connecting seat 42 is made of an antimagnetic material (such as non-magnetic stainless steel) and is made into a sleeve structure. One end of the connecting seat 42 is detachably connected to the sample displacement driving device 5. The end of the connecting seat 42 away from the sample displacement driving device 5 is provided with a shaped connecting groove, which is used to connect the sample probe assembly 41. The probe connecting fastener 43 fits and covers the shaped connecting groove of the connecting seat 42. The probe connecting fastener 43 can be a cover plate or other fixing structure. The probe connecting fastener 43 is fastened to the connecting seat 42 through a second connecting member 44 to fix one end of the sample probe assembly 41 to the shaped connecting groove of the connecting seat 42.

[0050] It is understood that this embodiment specifically defines the intermediate transition structure in the sample mounting device 4 used to connect the sample probe assembly 41 and the sample displacement driving device 5. Combined with... Figure 6 and Figure 7As shown, the sample mounting device 4, in addition to the sample probe assembly 41, also includes a connecting seat 42 and a probe connecting fastener 43. The connecting seat 42 is made of non-magnetic stainless steel and is a cylindrical sleeve structure. One end of it forms a detachable connection (such as a threaded connection or plug-in connection) with the sample displacement driving device 5 (specifically, the probe interface 55 or the second displacement driver 53). The other end face of the connecting seat 42, away from the sample displacement driving device 5, has a shaped connecting groove (e.g., a D-shaped groove, a rectangular groove, or a polygonal groove). This shaped connecting groove is used to accommodate and position the tail end of the sample probe assembly 41. The shape of the probe connecting fastener 43 matches the opening contour of the shaped connecting groove and fits snugly over the shaped connecting groove of the connecting seat 42. A second connecting member 44 (e.g., a non-magnetic screw) passes through the mounting hole on the probe connecting fastener 43 and forms a threaded fastening connection with the connecting seat 42, thereby reliably pressing and fixing the tail end of the sample probe assembly 41 within the shaped connecting groove.

[0051] In the specific implementation process, the operator first securely connects one end of the connector 42 to the output end (such as the probe interface 55) of the sample displacement drive device 5. Then, the tail of the sample probe assembly 41 is placed into the irregular connecting groove on the end face of the connector 42 at a preset orientation angle. Because the irregular connecting groove has a non-circular cross-sectional profile, the corresponding irregular connecting part of the tail of the sample probe assembly 41 can only be embedded in the groove at a single correct angle, thereby achieving automatic circumferential positioning. Next, the probe connecting fastener 43 is placed over the tail of the sample probe assembly 41, making it fit against the end face of the connector 42. Finally, the second connector 44 is passed through the screw hole of the probe connecting fastener 43 and screwed into the corresponding threaded hole on the connector 42, and tightened evenly to complete the fixing of the sample probe assembly 41. When it is necessary to replace the sample probe assembly 41, simply loosen the second connector 44 and remove the probe connecting fastener 43 to remove the sample probe assembly 41 from the irregular connecting groove, achieving quick replacement.

[0052] It is important to understand that in the structure of the sample mounting device 4 in this embodiment, the connecting seat 42 serves as an intermediate transition component, enabling modular connection between the sample displacement driving device 5 and the sample probe assembly 41. This allows for independent assembly and disassembly, improving the convenience of assembly and maintenance. The cooperation between the irregularly shaped connecting groove and the irregularly shaped connecting part at the tail of the sample probe assembly 41 serves a dual purpose of circumferential anti-rotation and precise positioning, ensuring that the front end of the sample probe 413 has a defined angular orientation after assembly, preventing rotational displacement during use, thereby guaranteeing the transmission accuracy and repeatability of the displacement drive. The clamping and fixing structure formed by the probe connecting fastener 43 and the second connecting element 44 adopts a surface contact clamping method, increasing the clamping area and friction, making the fixation more secure and reliable, while avoiding stress concentration that could lead to deformation or damage to the sample probe assembly 41. The sample mounting device 4 in this embodiment can achieve a high-precision, high-reliability, and easily replaceable modular connection, providing structural protection for the safe mounting of samples and precise displacement drive.

[0053] In one embodiment of the present invention, see Figure 5 As shown, the sample probe assembly 41 includes a fixed base 411, a transition member 412, and a sample probe 413. One end of the fixed base 411 has an irregularly shaped connecting part, which is fixed in place with the irregularly shaped connecting groove of the connecting base 42. The transition member 412 is connected to the end of the fixed base 411 away from the connecting base 42, and the transition member 412 is movably disposed in the limiting groove 25 of the rod head 2. The sample probe 413 is connected to the end of the transition member 412 away from the fixed base 411, and the sample probe 413 passes through the through portion 24 of the rod head 2 and extends to the flux absorption cavity 32 of the high permeability magnetic screen 31.

[0054] Understandably, in combination Figure 6 and Figure 7As shown, the sample probe assembly 41 in this embodiment is formed by sequentially connecting a fixing base 411, a transition piece 412, and a sample probe 413. One end of the fixed base 411 has an irregularly shaped connecting part (such as a D-shaped, rectangular, or polygonal boss). The shape of this irregularly shaped connecting part matches the irregularly shaped connecting groove on the end face of the connecting base 42, which is used to achieve anti-rotation positioning and fixed connection with the connecting base 42. The transition piece 412 is connected to the other end of the fixed base 411 away from the connecting base 42. The outer diameter of the transition piece 412 is designed to form a sliding fit with the limiting groove 25 of the rod head 2, so that the transition piece 412 can be movably set in the limiting groove 25. The sample probe 413 is connected to the end of the transition piece 412 away from the fixed base 411. The sample probe 413 is a slender rod, and its outer diameter is smaller than the aperture of the through part 24 of the rod head 2. The sample probe 413 passes through the through part 24 and extends further forward, finally entering the magnetic flux absorption cavity 32 in the center of the high-permeability magnetic screen 31. Its tip is used to carry the sample to be observed. The sample is mounted in the form of the sample probe 413, which is convenient for compatibility with focused ion beam (FOC) Beam (FIB) and quick replacement improve experimental efficiency.

[0055] In the specific implementation process, firstly, the irregularly shaped connecting part of the fixing seat 411 is inserted into the irregularly shaped connecting groove of the connecting seat 42 at a preset angle, ensuring that the two fit tightly and cannot rotate relative to each other. Then, the fixing seat 411 is pressed and fixed by the probe connecting fixing part 43 and the second connecting part 44. At this time, the fixing seat 411, the transition part 412 and the sample probe 413 are a rigid whole, and its rear end is firmly locked on the connecting seat 42. Next, the front end of the entire sample probe assembly 41 (i.e., the sample probe 413) is driven by the sample displacement driving device 5, passing through the limiting groove 25 of the rod head 2, and the sample probe 413 is moved to the through part 24. After the tip of the sample probe 413 accurately passes through the through part 24, it is stably stopped at the predetermined position in the magnetic flux absorption cavity 32, waiting for sample loading and electron microscopy observation. During this process, the inner wall of the limiting groove 25 forms a sliding limiting space, providing reserved space for the triaxial displacement of the sample probe assembly 41.

[0056] It should be understood that in the sample probe assembly 41 structure of this embodiment, the irregularly shaped connecting part at the end of the fixing seat 411 cooperates with the irregularly shaped connecting groove of the connecting seat 42 to achieve reliable circumferential anti-rotation and quick assembly / disassembly, ensuring the repeatability of the angular orientation of the sample probe 413 tip. This embodiment integrates the irregularly shaped connecting function (fixing seat 411), guiding function (transition piece 412), and sample carrying function (sample probe 413) into three independent components, which also achieves functional decoupling. When the sample probe 413 needs to be replaced due to wear or contamination, only this component needs to be replaced, without replacing the entire fixing seat 411 and transition piece 412, reducing usage costs and maintenance difficulty.

[0057] In one embodiment of the present invention, see Figure 2 As shown, the sample displacement driving device 5 includes a first displacement driver 51, an axial transmission rod 52, and a second displacement driver 53. The first displacement driver 51 is disposed in the hollow cavity of the sample rod body 1 and arranged along the axial direction of the sample rod body 1. The first displacement driver 51 is used to output the displacement variable along the axial direction of the sample rod body 1. The axial transmission rod 52 is connected to the output end of the first displacement driver 51. The second displacement driver 53 is connected to the end of the axial transmission rod 52 away from the first displacement driver 51. The second displacement driver 53 is connected to the sample mounting device 4 and is used to output the displacement variable along the radial direction of the sample rod body 1.

[0058] Understandably, see Figure 2 As shown, the sample displacement driving device 5 includes a first displacement actuator 51, an axial transmission rod 52, and a second displacement actuator 53. The first displacement actuator 51 is disposed within the hollow cavity of the sample rod body 1 and is arranged along the axial direction (i.e., the X-axis direction) of the sample rod body 1. Under the action of an external driving voltage, the first displacement actuator 51 can generate an axial displacement output, thereby outputting a precise displacement variable along the axial direction of the sample rod body 1. One end of the axial transmission rod 52 is rigidly connected to the output end of the first displacement actuator 51, and the other end is connected to the second displacement actuator 53. The second displacement actuator 53 can generate bending or expansion deformation along the radial direction (i.e., any direction within the YZ plane) of the sample rod body 1. The end of the second displacement actuator 53 away from the axial transmission rod 52 is drivenly connected to the sample mounting device 4 (specifically, the connecting seat 42), thereby outputting radial displacement to the sample probe assembly 41.

[0059] It is important to understand that in this embodiment, the first displacement actuator 51 and the second displacement actuator 53 are arranged in series along the axial direction, enabling three-dimensional driving capability in both the X-axis (axial) and YZ plane (radial) directions. The overall structure is compact, completely housed within the hollow cavity of the sample rod body 1, without adding any external dimensions, ensuring that the sample rod can be smoothly inserted into the electrode shoe gap of the electron microscope. The axial transmission rod 52, acting as a rigid connector, transmits the axial displacement of the first displacement actuator 51 to the front end without loss or hysteresis, ensuring the accuracy and response speed of the X-axis displacement. The second displacement actuator 53 achieves precise movement in two degrees of freedom in the YZ plane with a single component, simplifying the structure, reducing the number of parts, and lowering assembly difficulty and failure rate. The entire driving system is based on the inverse piezoelectric effect of piezoelectric ceramics, far exceeding the accuracy of conventional stepper motors or screw drives, meeting the stringent requirements of sample positioning in atomic-scale high-resolution imaging.

[0060] In one embodiment of the invention, see again Figure 2As shown, the sample displacement driving device 5 also includes a double-layer dynamic sealing ring 54 and a probe interface 55. The double-layer dynamic sealing ring 54 is disposed between the axial transmission rod 52 and the inner wall of the sample rod body 1, and is used for vacuum sealing and buffering mechanical vibration. The probe interface 55 is formed into a cylindrical sleeve structure. One end of the probe interface 55 is connected to the second displacement driver 53, and the other end is connected to the sample mounting device 4.

[0061] It is understood that this embodiment further integrates sealing and connection functional components into the sample displacement driving device 5. See again Figure 2 As shown, the sample displacement driving device 5 also includes a double-layer dynamic sealing ring 54 and a probe interface 55. The double-layer dynamic sealing ring 54 is disposed between the axial transmission rod 52 and the inner wall of the sample rod body 1. The double-layer dynamic sealing ring 54 is composed of two independent elastic sealing rings (e.g., made of fluororubber or silicone rubber) arranged parallel to each other along the axial direction. The outer ring of each sealing ring forms an interference fit with the inner wall of the sample rod body 1, and the inner ring forms a tight fit with the outer wall of the axial transmission rod 52. The probe interface 55 is formed as a cylindrical sleeve structure. One end of it is fixedly connected to the end of the second displacement driver 53 away from the axial transmission rod 52 (e.g., interference fit or threaded connection), and the other end is detachably connected to the sample mounting device 4 (specifically, the connecting seat 42).

[0062] In the specific implementation process, the double-layer dynamic sealing ring 54 is first fitted onto the outer wall of the axial transmission rod 52, ensuring that the two sealing rings maintain a preset distance in the axial direction. Then, the axial transmission rod 52 equipped with the double-layer dynamic sealing ring 54 is inserted into the hollow cavity of the sample rod body 1, so that the outer ring of the double-layer dynamic sealing ring 54 is in close contact with the inner wall of the rod. When the sample displacement driving device 5 operates, the mechanical vibrations generated by the first displacement actuator 51 and the second displacement actuator 53 are transmitted along the axial transmission rod 52. At this time, the elastic material properties of the double-layer dynamic sealing ring 54 enable it to absorb and buffer this vibration energy, reducing the vibration amplitude transmitted to the sample mounting device 4 and the sample probe 413. Simultaneously, the double-layer dynamic sealing ring 54 forms two independent sealing barriers between the inner wall of the rod and the axial transmission rod 52, preventing outside air from entering the vacuum chamber of the electron microscope tube along the gap between the axial transmission rod 52 and the inner wall of the rod. The probe interface 55 serves as a mechanical adapter between the drive unit and the execution unit. One end of it is firmly connected to the output end of the second displacement driver 53, and the other end is detachably connected to the connector 42 of the sample mounting device 4 via a thread or plug-in method, thereby achieving stable transmission of displacement driving force.

[0063] It is important to understand that the double-layer dynamic sealing ring 54 adopts a double-sealing structure with two parallel rings. Even if one sealing ring ages or wears due to long-term use, the other sealing ring can still maintain the vacuum sealing function, improving the reliability and redundancy of the seal and ensuring a stable high-vacuum environment for the electron microscope tube over a long period of time. The elastic sealing ring, while achieving the sealing function, also has a vibration buffering function. It can isolate the inherent mechanical vibration generated by the second displacement actuator 53 and the first displacement actuator 51 during operation, preventing vibration from being transmitted to the tip of the sample probe 413, which would cause image blurring or position drift, thereby improving the stability and clarity of high-resolution imaging. The probe interface 55, as a modular adapter component, can realize a standardized detachable connection between the second displacement actuator 53 and the sample mounting device 4, making it possible to independently disassemble, replace, or maintain the sample mounting device 4 without disassembling the second displacement actuator 53 or the axial drive rod 52, greatly simplifying maintenance operations.

[0064] In some specific examples, the sample rod body 1 is made of an antimagnetic alloy. The sample rod body 1 is equipped with a second displacement actuator electrical interface 11 and a first displacement actuator electrical interface 12 for connecting an external driving power supply. The first displacement actuator 51 can be a cylindrical piezoelectric actuator with two opposing electrodes. The first displacement actuator electrical interface 12 is electrically connected to the two electrodes of the cylindrical piezoelectric actuator via a control circuit, used to apply a voltage to one of the electrodes based on an external signal, causing the cylindrical piezoelectric actuator to extend or retract axially. The second displacement actuator 53 can be a piezoelectric ceramic tube with four quadrant electrodes formed on its outer wall. The second displacement actuator electrical interface 11 is electrically connected to the four quadrant electrodes of the piezoelectric ceramic tube via a control circuit, used to apply a voltage combination to the four quadrant electrodes based on an external signal, causing the piezoelectric ceramic tube to deform or extend radially along the sample rod body 1.

[0065] It is understood that the sample rod 1 in this embodiment is made of an antimagnetic alloy (such as titanium alloy or oxygen-free copper), and its end is provided with a second displacement driver electrical interface 11 and a first displacement driver electrical interface 12. These two interfaces are used to connect to independent external driving power supplies. The outer wall of the second displacement driver 53 is evenly divided circumferentially to form four independent quadrant electrodes (corresponding to the Y+, Y-, Z+, and Z- directions, respectively). The second displacement driver electrical interface 11 is electrically connected to the four quadrant electrodes of the second displacement driver 53 through an internally integrated control circuit (including a signal amplification module and a voltage regulation module). The first displacement driver 51 has two opposing electrodes (positive and negative), and the first displacement driver electrical interface 12 is electrically connected to the two electrodes of the first displacement driver 51 through the control circuit.

[0066] In the specific driving process, when it is necessary to drive the sample to move along the X-axis (i.e., the axial direction of the sample rod), the external control system sends a driving signal to the control circuit of the first displacement driver 51 through the electrical interface 12 of the first displacement driver. The control circuit amplifies the signal and converts it into a driving voltage, which is applied between the two electrodes of the first displacement driver 51. Under the inverse piezoelectric effect, the first displacement driver 51 elongates or shortens along the axial direction, thereby achieving precise displacement output in the X-axis. The displacement in the X-axis output by the first displacement driver 51 is transmitted to the second displacement driver 53 through the rigid axial transmission rod 52, which in turn drives the sample mounting device 4 and the sample probe assembly 41 connected to the second displacement driver 53 to move synchronously along the X-axis.

[0067] When it is necessary to drive the sample to move along the Y-axis or Z-axis (i.e., the radial direction of the sample rod), the external control system sends a control command containing voltage amplitude and polarity combination to the control circuit of the second displacement driver 53 through the electrical interface 11 of the second displacement driver. The control circuit then applies a specific voltage combination to the four quadrant electrodes of the second displacement driver 53 accordingly. For example, when a positive voltage is applied to the Y+ quadrant electrode and a negative voltage is applied to the Y- quadrant electrode, the second displacement driver 53 will bend along the positive Y-axis. Similarly, by adjusting the voltage combination of the Z+ and Z- quadrant electrodes, radial bending in the Z-direction can be achieved. By precisely controlling the voltage amplitude and polarity combination of each electrode, the end of the second displacement driver 53 can achieve precise displacement in any direction within the YZ plane, and drive the tip of the sample probe assembly 41 to perform two-dimensional scanning or positioning within the flux absorption cavity 32.

[0068] It is important to understand that the sample rod 1 in this example is made of an antimagnetic alloy to prevent the rod itself from being magnetized in the strong magnetic field of the electron microscope, thus eliminating the possibility of introducing additional magnetic interference and ensuring the purity of the non-magnetic environment within the flux absorption cavity 32. The four-quadrant electrode design of the second displacement actuator 53 allows a single piezoelectric element to achieve precise motion control of two degrees of freedom in the YZ plane, eliminating the need for two independent radial drive mechanisms, resulting in a compact structure and flexible control. The first displacement actuator 51 and the second displacement actuator 53 are powered and controlled by independent electrical interfaces, achieving decoupled control of X-axis displacement and YZ plane radial displacement. They can be driven independently or collaboratively without interference, facilitating the realization of complex three-dimensional scanning trajectories. Based on the inverse piezoelectric effect driving method of piezoelectric ceramics, this example exhibits high displacement accuracy, fast response speed, and no electromagnetic interference, making it particularly suitable for long-term stable operation in the strong magnetic field and vacuum environments of a transmission electron microscope.

[0069] The magnetic field-free environment sample holder for transmission electron microscopy (TEM) proposed in this invention is adaptable to conventional TEMs. A magnetic field-free environment is achieved in the TEM sample area through a magnetic shield integrated at the front end of the sample holder. In some specific examples, the existing objective system, electron gun, imaging system, and vacuum system remain unchanged in their conventional configurations within the TEM system, requiring no hardware modifications. The magnetic field-free environment sample holder for TEM is used as an accessory and inserted into the microscope tube via the microscope's built-in sample holder interface. The magnetic shielding device 3 at the front end of the sample holder is located in the gap between the upper and lower pole shoes of the objective lens. The tip of the sample probe 413 extends precisely into the flux absorption cavity 32 at the center of the high-permeability magnetic shield 31. The magnetic field-sensitive sample to be observed (such as magnetic materials, superconducting materials, or alloys containing magnetic elements) is pre-loaded onto the tip of the sample probe 413 and positioned together with the sample probe 413 in the central region of the flux absorption cavity 32. The high-energy electron beam emitted by the electron gun of the electron microscope propagates along the axis of the microscope tube, passes through the central hole of the magnetic screen fixing member 33, and enters the sample in the magnetic flux absorption cavity 32. The emitted electron beam carrying the sample structural information is then received and magnified by the imaging system below.

[0070] In the specific implementation process, the operator first loads the prepared sample onto the tip of the sample probe 413, and then inserts the assembled sample rod into the sample rod interface of the transmission electron microscope (TEM). The sample rod is coarsely adjusted using the TEM's goniometer stage displacement system to ensure axial alignment between the magnetic shielding device 3 and the objective pole shoes. After starting the TEM, a strong magnetic field of 2-3T is generated between the objective pole shoes. At this time, a stable non-magnetic environment is formed inside the flux absorption cavity 32 due to the guidance and convergence of the magnetic field lines from the high-permeability magnetic screen 31. The operator sends a drive signal to the sample displacement drive device 5 through the external control system, driving the sample probe 413 to perform three-dimensional precise displacement in the X-axis and YZ planes within the flux absorption cavity 32 to locate the target observation area. Subsequently, the TEM performs high-resolution imaging of the sample in a conventional high-resolution imaging mode (without needing to activate the Lorentz mode or turn off the objective), obtaining clear images of the sample's intrinsic microstructure in real time.

[0071] This embodiment integrates the aforementioned magnetic field-free environment sample holder into a conventional transmission electron microscope (TEM). Without any hardware modifications to the TEM main unit, a magnetic field-free environment for the sample region can be achieved within a conventional TEM. This solves the problem of existing technologies requiring expensive dedicated magnetic field-free TEMs or sacrificing resolution (Lorentz mode), lowering the technical threshold and economic cost of magnetic field-free high-resolution characterization. Because the objective lens remains in normal excitation mode, the original high-resolution imaging capability of the TEM is fully preserved. Users can obtain the same information resolution as in conventional high-resolution mode in a magnetic field-free environment, achieving a balance between magnetic field-free operation and high resolution. The TEM of this embodiment can be used for the intrinsic structure characterization of magnetic and superconducting materials sensitive to magnetic fields. When needed, the magnetic field-free sample holder can be removed and replaced with a conventional sample holder for high-resolution observation of non-sensitive materials. It offers multiple uses, with advantages such as low cost, strong adaptability, comprehensive functionality, and high imaging quality.

[0072] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A sample holder for a magnetic field-free environment used in transmission electron microscopy, characterized in that, include: The sample rod body (1) has a hollow cavity inside; The rod head (2) is fixed to one end of the sample rod body (1); A magnetic shielding device (3) is detachably installed on the rod head (2). The magnetic shielding device (3) includes a high-permeability magnetic screen (31). A magnetic flux absorption cavity (32) is formed in the center of the high-permeability magnetic screen (31). The high-permeability magnetic screen (31) is used to guide the magnetic field lines generated by the objective lens of the transmission electron microscope to be transmitted along the annular wall of the high-permeability magnetic screen (31) so as to form a magnetic field-free environment in the magnetic flux absorption cavity (32). The sample mounting device (4) is movably mounted on the rod head (2). The sample mounting device (4) includes a sample probe assembly (41) for carrying the sample. The front end of the sample probe assembly (41) extends into the magnetic flux absorption cavity (32). The sample displacement driving device (5) is installed in the hollow cavity of the sample rod body (1). The sample displacement driving device (5) is driven to be connected to the sample mounting device (4) and is used to drive the front end of the sample probe assembly (41) to move in the magnetic flux absorption cavity (32).

2. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 1, characterized in that, The rod head (2) includes a frame body (21) connected to the end of the sample rod body (1). The frame body (21) is provided with a mounting part (22). The mounting part (22) forms a magnetic screen mounting groove (23). The high-permeability magnetic screen (31) is installed in the magnetic screen mounting groove (23). A through part (24) is formed in the magnetic screen mounting groove (23). A limiting groove (25) communicating with the through part (24) is formed on the frame body (21). The sample probe assembly (41) is movably disposed in the limiting groove (25). The front end of the sample probe assembly (41) passes through the through part (24) and extends to the magnetic flux absorption cavity (32) of the high-permeability magnetic screen (31).

3. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 2, characterized in that, The magnetic shielding device (3) further includes a magnetic screen fixing component (33), which fits and covers the axial end face of the high-permeability magnetic screen (31) and is embedded in the mounting part (22) of the frame body (21). The magnetic screen fixing component (33) is fastened to the mounting part (22) of the frame body (21) through a first connector (34) to fix the high-permeability magnetic screen (31) in the magnetic screen mounting groove (23).

4. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 3, characterized in that, The magnetic screen fixing member (33) has a central hole, the size of which is smaller than the size of the high-permeability magnetic screen (31).

5. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 2, characterized in that, The sample mounting device (4) further includes: The connecting seat (42) is made of antimagnetic material and is a sleeve structure. One end of the connecting seat (42) is detachably connected to the sample displacement driving device (5). The end of the connecting seat (42) away from the sample displacement driving device (5) is provided with an irregular connecting groove, which is used to connect the sample probe assembly (41). The probe connection fastener (43) fits and covers the irregular connection groove of the connector (42). The probe connection fastener (43) is fastened to the connector (42) through the second connector (44) to fix one end of the sample probe assembly (41) to the irregular connection groove of the connector (42).

6. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 5, characterized in that, The sample probe assembly (41) includes: A fixed base (411) has an irregularly shaped connecting part at one end, which is fixed in conjunction with the irregularly shaped connecting groove of the connecting base (42). A transition piece (412) is connected to the end of the fixed base (411) away from the connecting base (42), and the transition piece (412) is movably disposed in the limiting groove (25) of the rod head (2); The sample probe (413) is connected to the end of the transition piece (412) away from the fixed base (411). The sample probe (413) passes through the through portion (24) of the rod head (2) and extends to the flux absorption cavity (32) of the high-permeability magnetic screen (31).

7. The sample holder for a transmission electron microscope in a magnetic field-free environment according to any one of claims 1 to 6, characterized in that, The sample displacement driving device (5) includes: The first displacement actuator (51) is disposed in the hollow cavity of the sample rod body (1) and arranged along the axial direction of the sample rod body (1). The first displacement actuator (51) is used to output the displacement variable along the axial direction of the sample rod body (1). An axial transmission rod (52) is connected to the output end of the first displacement driver (51); The second displacement actuator (53) is connected to the end of the axial transmission rod (52) away from the first displacement actuator (51). The second displacement actuator (53) is connected to the sample mounting device (4) and is used to output the displacement variable along the radial direction of the sample rod body (1).

8. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 7, characterized in that, The sample displacement driving device (5) further includes: A double-layer dynamic sealing ring (54) is disposed between the inner wall of the axial transmission rod (52) and the sample rod body (1) for vacuum sealing and buffering mechanical vibration; The probe interface (55) is formed as a sleeve structure. One end of the probe interface (55) is connected to the second displacement driver (53), and the other end is connected to the sample mounting device (4).

9. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 7, characterized in that, The sample rod body (1) is made of antimagnetic alloy. The sample rod body (1) is provided with a second displacement driver electrical interface (11) and a first displacement driver electrical interface (12). The second displacement driver electrical interface (11) is electrically connected to the second displacement driver (53), and the first displacement driver electrical interface (12) is electrically connected to the first displacement driver (51) for external driving power supply.

10. The sample holder for a transmission electron microscope in a magnetic field-free environment according to claim 9, characterized in that, The second displacement actuator (53) is a piezoelectric ceramic tube. The outer wall of the piezoelectric ceramic tube is formed into four quadrant electrodes. The electrical interface (11) of the second displacement actuator is electrically connected to the four quadrant electrodes of the piezoelectric ceramic tube through the control circuit. It is used to apply a voltage combination to the four quadrant electrodes based on the output signal so that the piezoelectric ceramic tube deforms and stretches radially along the sample rod body (1). The first displacement actuator (51) is a cylindrical piezoelectric actuator, which has two opposing electrodes. The electrical interface (12) of the first displacement actuator is electrically connected to the two electrodes of the cylindrical piezoelectric actuator through a control circuit, and is used to apply a voltage to one of the electrodes based on an external signal so that the cylindrical piezoelectric actuator can generate axial extension and retraction.

Images