X-ray tube

Abstract

The invention relates to an X-ray tube. An X-ray tube includes a tube body, an electron source, and an anode target. A vacuum cavity is formed in the tube body, the electron source comprises an optical fiber and an electron emission layer, the light emitting end of the optical fiber is located in the vacuum cavity, the electron emission layer is arranged at the light emitting end of the optical fiber and at least comprises an electron excitation layer, and the electron excitation layer is arranged on a light emitting path of laser emitted by the optical fiber. Therefore, the electron excitation layer can emit electrons under the excitation of the laser. The anode target is arranged in the vacuum chamber, the anode target and the light emitting end of the optical fiber are oppositely arranged in a spaced mode, and the anode target is used for receiving electrons emitted by the electron excitation layer so as to emit X-rays. Wherein the tube body is provided with an output window facing the anode target, and the output window is configured to be capable of guiding the X-rays to be emitted out of the vacuum chamber. The electron source of the X-ray tube can be utilized to realize cold emission of electrons, and the heat accumulation problem of the anode target can be obviously improved.

Description

Technical Field

[0001] This application relates to the technical field of X-ray tubes, and particularly to X-ray tubes. Background Art

[0002] An X-ray tube is a vacuum electronic device that uses high-speed electrons to strike a metal target surface to generate X-rays. Traditional X-ray tubes generally include a filament (as the cathode) for emitting electrons and a target material (as the anode) for receiving electron bombardment. Both the cathode and the anode are sealed in a high-vacuum glass or ceramic housing. However, in traditional X-ray tubes, the working temperature of the filament as the cathode is relatively high (its working temperature can reach 2000 °C), which easily generates thermal radiation to the target material as the anode, leading to an exacerbation of the heat accumulation problem of the target material. Summary of the Invention

[0003] Based on this, it is necessary to provide an X-ray tube for solving the heat accumulation problem of the target material of traditional X-ray tubes.

[0004] This application provides an X-ray tube, including:

[0005] A tube body, which has a vacuum chamber inside;

[0006] An electron source, including an optical fiber and an electron emission layer. The light-emitting end of the optical fiber is located inside the vacuum chamber. The electron emission layer is arranged at the light-emitting end of the optical fiber, and the electron emission layer at least includes an electron excitation layer. The electron excitation layer is arranged on the light path of the laser emitted by the optical fiber, so that the electron excitation layer can emit electrons under the excitation of the laser; and

[0007] An anode target, arranged inside the vacuum chamber, and the anode target is opposite to and spaced from the light-emitting end of the optical fiber. The anode target is used to receive the electrons emitted by the electron excitation layer to emit X-rays;

[0008] Wherein, an output window is provided on the tube body and is arranged towards the anode target. The output window is configured to be able to guide the X-rays out of the vacuum chamber;

[0009] The electron excitation layer includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials.

[0010] In one embodiment, along the extending direction of the optical fiber, the electron source is spaced from the anode target;

[0011] The anode target has a reflective target surface facing the light-emitting end, and the reflective target surface is arranged at an angle with the extending direction of the optical fiber;

[0012] The output window is arranged on the side wall of the tube body and is arranged towards the reflective target surface.

[0013] In one embodiment, the anode target includes a transmissive anode;

[0014] Along the longitudinal extension direction of the tube body, the electron source and the output window are arranged at opposite ends of the tube body, and the transmissive anode is located between the electron source and the output window.

[0015] In one embodiment, along the extension direction of the optical fiber, the anode target is spaced from the light-emitting end of the optical fiber, and a preset electric field is provided between the anode target and the electron excitation layer, so that the electrons emitted from the electron excitation layer can be linearly accelerated along the extension direction of the optical fiber.

[0016] In one embodiment, the electron source further includes a conductive connection layer, and the conductive connection layer is at least disposed on the light-emitting end of the optical fiber and is electrically connected to the electron excitation layer.

[0017] In one embodiment, the tube body is sleeved on the optical fiber and the anode target respectively.

[0018] In one embodiment, the tube body has a first port communicating with the vacuum chamber;

[0019] The light-emitting end of the optical fiber extends into the vacuum chamber through the first port, and the outer peripheral wall of the optical fiber is hermetically connected to the inner peripheral wall of the first port.

[0020] In one embodiment, the tube body further has a second port opposite to the first port, and the side of the anode target facing away from the light-emitting end extends out of the vacuum chamber through the second port;

[0021] The outer peripheral wall of the anode target is hermetically connected to the inner peripheral wall of the second port.

[0022] In one embodiment, the X-ray tube further includes an external electrode, and the external electrode is disposed between the outer peripheral wall of the anode target and the inner peripheral wall of the second port;

[0023] Along the longitudinal extension direction of the tube body, one end of the external electrode is located in the vacuum chamber, and the other end extends out of the vacuum chamber.

[0024] In one embodiment, the optical fiber has a light-incident end opposite to the light-emitting end, and the end face of the light-incident end is flush with the plane where the first port is located; or

[0025] The light-incident end extends out of the vacuum chamber through the first port.

[0026] In one embodiment, the tube body includes an inner tube sleeved on the optical fiber and the anode target, and an outer tube sleeved on the inner tube. An opening is provided on the outer tube, and a part of the structure of the inner tube is exposed through the opening to form the output window.

[0027] The material of the inner tube includes an X-ray transmissive material, and the material of the outer tube includes an X-ray blocking material.

[0028] In one embodiment, the outer diameter of the tube body is 125 μm - 2000 μm, and the length of the tube body is 3 cm - 9 cm.

[0029] In one embodiment, the optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core. The end face of the light-emitting end of the optical fiber is arranged at an angle with the extending direction of the core.

[0030] The electron emission layer is arranged on the end face of the light-emitting end of the optical fiber, and the electron excitation layer covers the core of the optical fiber. The laser emitted from the core can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the core and emits electrons.

[0031] In one embodiment, the optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core.

[0032] A light leakage notch is formed in the radial direction of the light-emitting end of the optical fiber.

[0033] The electron emission layer is arranged on the bottom wall surface of the light leakage notch. The bottom wall surface of the light leakage notch is configured as a plane. The projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface.

[0034] The electron excitation layer also extends to the light-emitting end of the optical fiber.

[0035] In one embodiment, the optical fiber includes a perforated optical fiber, and the perforated optical fiber has a light guiding hole.

[0036] The electron excitation layer is at least arranged on the side wall of the light guiding hole and extends along the extending direction of the light guiding hole to the light-emitting end of the optical fiber.

[0037] In one embodiment, the optical fiber includes a perforated optical fiber, and the perforated optical fiber has a light guiding hole.

[0038] The electron emission layer is arranged on the end face of the light-emitting end of the perforated optical fiber, and the electron excitation layer covers one end of the light guiding hole located at the end face of the light-emitting end.

[0039] The laser emitted from the holey optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the holey optical fiber and emits electrons.

[0040] In one embodiment, the light-emitting end of the optical fiber is provided with a pointed end;

[0041] The electron excitation layer covers the surface of the pointed end of the optical fiber;

[0042] The optical fiber includes a core for transmitting laser. The laser emitted from the core can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the core and emits electrons.

[0043] In one embodiment, the thickness of the electron excitation layer is less than or equal to 50 nm.

[0044] In the above X-ray tube, during the process that the laser transmitted in the core of the optical fiber is transmitted to the light-emitting end of the optical fiber and emitted, this part of the laser can interact with the electron excitation layer, so that the electrons in the electron excitation layer absorb the photons of the laser, and undergo energy transition and escape from the electron excitation layer, and electrons are emitted out from the light-emitting end. Considering that the anode target and the light-emitting end of the optical fiber are relatively and spaced apart, this part of the electrons can be incident on the anode target, and then the anode target is excited to emit X-rays, and this part of the X-rays can be emitted out of the vacuum chamber through the output window. In this way, the cold emission of electrons can be realized by using the electron source of the X-ray tube, and excessive heat will not be generated like a hot electrode such as a filament, which can significantly improve the heat accumulation problem of the anode target. At the same time, since the electron emission layer is arranged on the optical fiber, it is beneficial to save the space in the vacuum chamber, and thus beneficial to reduce the volume of the X-ray tube. Description of the Drawings

[0045] Figure 1 Shows a schematic structural diagram of an X-ray tube according to an embodiment of the present application.

[0046] Figure 2 Shows Figure 1 An enlarged schematic view of part A.

[0047] Figure 3 Shows Figure 1 An enlarged schematic view of part B.

[0048] Figure 4 Shows a schematic structural diagram of an electron source according to the first embodiment of the present application.

[0049] Figure 5 Shows a schematic structural diagram of an electron source according to the second embodiment of the present application.

[0050] Figure 6 Shows Figure 5 A side view of.

[0051] Figure 7 Shows a schematic structural diagram of the electron source according to the third embodiment of the present application.

[0052] Figure 8 Shows Figure 7 An enlarged schematic diagram at position C of

[0053] Figure 9 Shows a schematic structural diagram of the electron source according to the fourth embodiment of the present application.

[0054] Figure 10 Shows Figure 9 An enlarged schematic diagram at position D of

[0055] Figure 11 Shows a schematic structural diagram of the electron source according to the fifth embodiment of the present application.

[0056] Figure 12 Shows Figure 11 An enlarged schematic diagram at position E of

[0057] Figure 13 Shows a schematic structural diagram of the electron source according to the sixth embodiment of the present application.

[0058] Figure 14 Shows a schematic structural diagram of an X-ray tube according to another embodiment of the present application.

[0059] Figure 15 Shows Figure 14 An enlarged schematic diagram at position F of

[0060] Figure 16 Shows a process schematic diagram of a method for preparing an electron source according to an embodiment of the present application.

[0061] Reference numerals:

[0062] 10, X-ray tube;

[0063] 100, electron source; 110, optical fiber; 111, core; 112, cladding layer; 1101, light incident end; 1102, light exit end; 11021, end face; h, light leakage notch; h1, bottom wall surface; h2, side wall surface; k, side wall of light guiding hole; j, tip; j1, surface; 120, electron emission layer; 121, electron excitation layer; 1211, first part; 1212, second part; 122, auxiliary layer; 130, conductive connection layer; 131, first conductive part; 132, second conductive part;

[0064] 200, anode target; 210, reflective target surface; 220, transmissive anode;

[0065] 300, tube body; 310, inner tube; 311, output window; 320, outer tube; 321, opening; 301, vacuum chamber; 302, first port; 303, second port;

[0066] 400, external electrode;

[0067] 20, temporary substrate;

[0068] 30, perforated glass slide;

[0069] 40, annular heating sheet. Detailed implementation mode

[0070] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation mode of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0071] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0072] In addition, if there are terms such as "first" and "second", these terms are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if there is a term "plurality", the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0073] In this application, unless otherwise clearly defined and limited, if terms such as "installed", "connected", "linked", "fixed", etc. appear, these terms shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0074] In this application, unless otherwise clearly defined and limited, if there is a description such as a first feature being "on" or "under" a second feature, its meaning can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath", and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0075] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If so, the terms "vertical", "horizontal", "up", "down", "left", "right", and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.

[0076] In the traditional technology, the thermionic electron source mainly selects materials with metallic properties such as tungsten filaments and lanthanum hexaboride. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the material surface to form vacuum electrons. The field emission electron source mainly selects metal tips such as tungsten. Under the action of a strong electric field applied from the outside, a tip discharge effect is generated. Among them, the electron beam emitted by the thermionic electron source can work in a relatively poor vacuum environment, has good adaptability to the environment and good stability, but has a low brightness and poor coherence. The electron beam of the field emission electron source has a high brightness and good coherence, but has high requirements for the vacuum degree and is very sensitive to vibrations. Whether it is a thermionic electron source or a field emission electron source, the regulation of electron emission properties is limited, and it is impossible to balance the performance and stability of the emitted electrons.

[0077] In the traditional technology, metal materials such as Au are used as the material of the electron emission layer for the photoemission electron source, and the thickness is above 50 nm, even reaching several hundred nanometers. However, the inventors of the present application have found through research that the electron emission layer of the metal material has a relatively large thickness, and the distance between the bottom layer directly interacting with the laser and the surface layer for electron emission is relatively far (50 nm to several hundred nanometers). During the process of electrons excited from the bottom layer passing through the electron emission layer, they are easily affected by metal lattice scattering, thereby affecting the emission efficiency. Moreover, the metal material is easily damaged under high-power laser irradiation, affecting the service life of the electron emission layer, and thus affecting the emission efficiency and stability of electrons.

[0078] In the traditional technology, there is also a case where a photoemission electron source excites electrons by an external laser incident on the surface of a metal tip, and the size of the metal tip is in the nanometer range, resulting in a relatively high difficulty in aligning the laser spot to the metal tip. If a high-magnification microscope is set up to align the external laser to the metal tip, it will lead to an increase in the overall cost.

[0079] In addition, in the traditional technology, graphene is used as a saturable absorber. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in the Q-switching and mode-locking of lasers, or the laser spectrum is adjusted by graphene to achieve sensing detection.

[0080] Based on this, it is necessary to provide an electron source that can take into account both electron emission efficiency and stability.

[0081] The present application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the material of the electron excitation layer. The low-dimensional materials emit electrons under the effects of the photoelectric effect, multi-photon emission, and optical field emission under laser irradiation. The low-dimensional materials have an atomic-level thickness, no dangling bonds, and stable properties, thus having characteristics such as good stability and high service life; moreover, the low-dimensional materials can be directly integrated with optical fibers, and the optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, and can be applicable to different application scenarios, such as being applicable to the X-ray tube described below.

[0082] Figure 1 The structural schematic diagram of the X-ray tube 10 in an embodiment of the present application is shown.

[0083] Please refer to Figure 1 and, please refer to in combination Figure 2 and Figure 3 An X-ray tube 10 provided by an embodiment of the present application includes an electron source 100, an anode target 200, and a tube body 300.

[0084] The electron source 100 includes an optical fiber 110 and an electron emission layer 120. Among them, if the optical fiber 110 is configured as a solid optical fiber, the optical fiber 110 includes a core 111 for transmitting laser light and a cladding layer 112 wrapped around the core 111. The refractive index of the cladding layer 112 is lower than that of the core 111. Therefore, the laser light can be confined within the core 111 by the cladding layer 112 for propagation. A coating layer is also provided on the outer surface of the cladding layer 112 to protect the cladding layer 112 and the core 111.

[0085] The optical fiber 110 has an incident light end 1101 and an exit light end 1102. The incident light end 1101 is used to couple to a laser source so that the laser light emitted by the laser source can be transmitted through the core 111 of the optical fiber 110. Among them, the laser source can be a laser.

[0086] The optical fiber 110 is a transmission medium for laser light and a carrier for the low-dimensional material of the electron excitation layer 121. The optical fiber 110 can be a single-mode optical fiber, a multi-mode optical fiber, a polarization-maintaining optical fiber, a holey optical fiber, or a multi-core optical fiber, etc. It should be noted that regardless of which of the above types the optical fiber 110 adopts, the electron emission layer 120 is located in the vacuum chamber 301.

[0087] The tube body 300 has a vacuum chamber 301. The exit light end 1102 of the optical fiber 110 is located in the vacuum chamber 301. The electron excitation layer 121 is provided at the exit light end 1102 of the optical fiber 110, and the electron emission layer 120 at least includes the electron excitation layer 121. The electron excitation layer 121 is disposed on the light exit path of the laser light emitted by the optical fiber 110 so that the electron excitation layer 121 can emit electrons under the excitation of the laser light. Among them, the electron excitation layer 121 includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

[0088] In this way, during the process of the laser light transmitted in the core 111 of the optical fiber 110 reaching the exit light end 1102 and exiting, this part of the laser light can interact with the electron excitation layer 121, so that the electrons in the electron excitation layer 121 absorb the photons of the laser light, and undergo an energy transition to escape outside the electron excitation layer 121, and the electrons are emitted outward from the exit light end 1102.

[0089] It should be noted that the wavelength of the laser light can be the wavelength at which the electrons in the electron excitation layer 121 absorb one photon and transition, for example, the wavelength is in the visible light-near infrared-ultraviolet range, or it can be the wavelength at which the electrons in the electron excitation layer 121 absorb multiple photons and transition, for example, the wavelength is outside the visible light-near infrared-ultraviolet range. No specific limitation is made here.

[0090] The anode target 200 is disposed within the vacuum chamber 301, and the anode target 200 is opposite to and spaced apart from the light-emitting end 1102 of the optical fiber 110. The anode target 200 is configured to receive the electrons emitted by the electron excitation layer 121 to emit X-rays. An output window 311 is provided on the tube body 300 and is oriented towards the anode target 200. The output window 311 is configured to guide the X-rays out of the vacuum chamber 301.

[0091] When the X-ray tube 10 is in use, the electrons of the electron excitation layer 121 of the electron source 100 can be used to emit electrons towards the anode target 200, which can excite the anode target 200 to emit X-rays, and this part of the X-rays can pass through the output window 311 and out of the vacuum chamber 301. In this way, the cold emission of electrons can be realized by using the electron source 100 of the X-ray tube 10, and excessive heat will not be generated like a hot electrode such as a filament, which can significantly improve the heat accumulation problem of the anode target 200. At the same time, since the electron excitation layer 121 is disposed on the optical fiber 110, it is beneficial to save the space within the vacuum chamber 301, and thus beneficial to reduce the volume of the X-ray tube 10.

[0092] The electron source 100 of the present application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials or two-dimensional materials as the material of the electron excitation layer 121, and the electron excitation layer 121 is disposed on the optical fiber 110 to realize the excitation of electrons, eliminating the complex spatial light coupling structure set due to the introduction of external lasers, and also eliminating the high-magnification microscope set to solve the alignment problem of metal tips, which can reduce the process cost of the X-ray tube 10.

[0093] Compared with setting a metal layer on the optical fiber tip and directly interacting the laser transmitted in the optical fiber with the metal layer to excite electrons (electrons are easily affected by lattice scattering during the process of passing through the metal layer, resulting in low electron emission efficiency, wide energy dispersion, and serious heat accumulation), the present application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials or two-dimensional materials as the material of the electron excitation layer 121. The low-dimensional materials have an atomic-level thickness, and the back-incident electrons can be emitted without passing through in-body transmission, with high electron emission efficiency; moreover, the low-dimensional materials have no dangling bonds, are stable in nature and have a high melting point, are not easily damaged, can be applied to high-power excitation scenarios, and have characteristics such as good stability and high service life; in addition, the low-dimensional materials also have strong light-material interaction and rich electron band gaps, enabling the laser to better interact with the electron excitation layer 121 to excite the electrons in the electron excitation layer 121. These electrons are excited and detached into the vacuum to form an electron beam, and the electron beam tunneling-emitted from the electron excitation layer 121 has characteristics such as small energy dispersion, high brightness and high stability.

[0094] In addition, low-dimensional materials can be directly integrated with the optical fiber 110. The optical fiber 110 transmits laser light and serves as a carrier for the low-dimensional materials, capable of providing a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without the need to provide a complex optical path, and has the characteristics of small size and high integration.

[0095] In some embodiments, the thickness of the electron excitation layer 121 is less than or equal to 50 nm.

[0096] It can be understood that the thickness of the electron excitation layer 121 is in the nanometer range and is relatively small. In this way, it is more conducive to reducing the in-body transmission process of the excited electrons within the electron excitation layer 121, more conducive to improving the emission efficiency and emission density of electrons, and thus an electron beam with ultrashort pulses can be realized using this electron source 100.

[0097] Optionally, the electron excitation layer 121 may include zero-dimensional materials. Zero-dimensional materials refer to materials whose dimensions in the three spatial dimensions are in the nanometer scale, such as nanoparticles, atomic clusters, and quantum dots, etc., which are generally composed of a small number of atoms and molecules. There are many zero-dimensional carbon nanomaterials, such as carbon black, nanodiamond, diamond color center, nanometer fullerene C 60 or carbon-coated nanometal particles, etc. Zero-dimensional materials have typical discrete energy levels. Under the action of laser excitation, electrons are mainly excited by tunneling from the discrete energy levels, making the electron beam tunneling and emitting from the electron excitation layer 121 have the characteristics of small energy dispersion, high brightness, and high stability.

[0098] Optionally, the electron excitation layer 121 may also include one-dimensional materials. Electrons in one-dimensional materials can be transported along the linear chain of the one-dimensional materials. Combining with the fact that the electron excitation layer 121 is disposed on the light-emitting end 1102 of the optical fiber 110, it is beneficial for the electrons emitted by the electron source 100 to be emitted efficiently along the extension direction of the optical fiber 110. One-dimensional materials have the characteristics of a small radius of curvature (nanoscale), can enhance the light-matter interaction and provide a large field enhancement factor, ensuring multi-photon emission, optical field emission, etc., and are applied to scenarios requiring a high-brightness electron source.

[0099] One-dimensional materials can be nanotubes, nanorods, nanowires, nanoribbons, or coaxial nanocables, etc.

[0100] The nanotubes can be carbon nanotubes. Carbon nanotubes can be regarded as seamless tubular structures formed by winding single-layer or multi-layer graphite according to certain rules. Nanotubes can also be silicon (Si) nanotubes, selenium (Se) nanotubes, tellurium (Te) nanotubes, bismuth (Bi) nanotubes, boron nitride (BN) nanotubes, boron-nitrogen co-doped carbon nanotubes (BCN nanotubes), tungsten disulfide (WS2) nanotubes, molybdenum disulfide (MoS2) nanotubes, or titanium dioxide (TiO2) nanotubes, etc.

[0101] The material of the nanowire can be silicon (Si) or germanium (Ge); oxide nanowires can also be selected for the nanowire, such as tin oxide (SnO) or zinc oxide (ZnO), etc.; of course, nitride nanowires can also be selected for the nanowire, such as gallium nitride (GaN) or silicon nitride (Si3N4), etc.; sulfide nanowires can also be selected for the nanowire, such as cadmium sulfide (CdS) and zinc sulfide (ZnS), etc.; ternary compound nanowires can also be selected for the nanowire, such as barium titanate (BaTiO3) and lead titanate (PbTiO3), etc.

[0102] There are significant differences between the nanoribbon and the above two nanostructures (nanotubes and nanowires). Its cross-section is different from that of nanotubes or nanowires, which is close to circular, but presents as a quadrilateral, and the aspect ratio distribution range is generally from several to more than a dozen. The material of the nanoribbon can be an oxide, such as tin oxide (SnO) or zinc oxide (ZnO), etc.

[0103] The nanocoaxial cable can be a graphite / boron nitride (C / BN) nanocoaxial cable or a silicon carbide / sulfur dioxide (CSi / SiO2) nanocoaxial cable, etc.

[0104] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer 121 and the emission direction of the emitted laser is 0 to 90°, for example, it can be 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° or 90°.

[0105] In some embodiments, the axial direction of the one-dimensional material is the same as the emission direction of the laser, so as to achieve point emission of the electron source 100 and have high resolution. If a low-density arrangement of one-dimensional materials is adopted, the energy dispersion of the emitted electrons is low and the brightness is high. If a high-density arrangement of one-dimensional materials is adopted, a large beam current of the electron source 100 can be achieved. Among them, low density refers to the number of one-dimensional materials per unit area. For example, a density less than 1 / nm 2 is low density, and greater than 1 / nm 2 is high density.

[0106] In some embodiments, the axial direction of the one-dimensional material has an angle with the emission direction of the laser, and the angle can be a right angle or an acute angle. Laser excitation of the one-dimensional material can generate a linear electron source.

[0107] Optionally, the electron excitation layer 121 may also include a two-dimensional material. The electrons in the two-dimensional material can be transmitted along a two-dimensional plane. Considering that the electron excitation layer 121 is disposed on the light-emitting end 1102 of the optical fiber 110, this is conducive to the efficient emission of the electrons emitted by the electron source 100 along the extension direction of the optical fiber 110. Moreover, compared with setting a thin metal layer on the optical fiber, it will cause a decrease in the melting point of the metal layer, which will further lead to the problem that the metal layer is easily damaged. The two-dimensional material selected in this application has no dangling bonds, is relatively stable, has a high melting point, and is not easily damaged. It is suitable for high-power excitation and high-beam-current electron sources 100. In addition, the energy levels of the two-dimensional material are more discrete, and the energy of the electron beam emitted by tunneling is more concentrated and the energy dispersion is smaller.

[0108] The two-dimensional material has the characteristic of atomic layer thickness. The thickness of the two-dimensional material can be the thickness of a single atomic layer or the thickness of multiple atomic layers. During the interaction between the laser and the two-dimensional material, it hardly affects the light transmission mode and has high stability. Moreover, the excited electrons can be directly emitted without scattering inside the material, ensuring the purity of the properties of the emitted electrons and an extremely narrow pulse width.

[0109] The two-dimensional material can be graphene, transition metal sulfide, two-dimensional perovskite, two-dimensional diamond, boron nitride, etc.

[0110] Taking graphene as an example of the two-dimensional material for illustration, the carbon atoms of graphene are bonded in the plane in the form of covalent bonds to form a hexagonal honeycomb planar structure. The electron excitation layer 121 can have a thickness of one atomic layer, about 0.34 nanometers; the electron excitation layer 121 can also have a thickness of several or dozens of atomic layers.

[0111] In some embodiments, the electron excitation layer 121 includes at least one layer of two-dimensional material.

[0112] Optionally, the electron excitation layer 121 includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction, or the electron excitation layer 121 includes at least two two-dimensional materials with different materials connected to each other on the same plane.

[0113] In some embodiments, at least two layers of two-dimensional materials are stacked, or the electron excitation layer 121 includes at least two two-dimensional materials with different materials connected to each other on the same plane, thereby forming a vertical heterojunction or a planar heterojunction. The heterojunction structure can enhance the interaction between light and the two-dimensional material and achieve efficient electron emission under laser power. Moreover, the heterojunction has the function of interfacial energy band regulation. Through material design and twist angle regulation, special interfacial states can be obtained to achieve high-brightness and low-energy-dispersion electron emission.

[0114] Of course, this application is not limited to this. The electron excitation layer 121 also includes two or more of zero-dimensional materials, one-dimensional materials, and two-dimensional materials.

[0115] In some embodiments, the material in the electron excitation layer 121 includes one-dimensional materials and zero-dimensional materials disposed at the ends and / or sides of the one-dimensional materials.

[0116] In this application, by combining zero-dimensional materials with one-dimensional materials and disposing the zero-dimensional materials at the ends and / or sides of the one-dimensional materials, that is, using zero-dimensional materials to modify the surface structure of one-dimensional materials. Both zero-dimensional materials and one-dimensional materials have typical discrete energy levels. Under the action of laser, electrons are mainly excited by tunneling from discrete energy levels, and the emitted electrons have characteristics such as concentrated energy, small energy dispersion, and high emission efficiency.

[0117] In some embodiments, the electron excitation layer 121 includes zero-dimensional materials and two-dimensional materials, and the zero-dimensional materials are disposed on the surface of the two-dimensional materials.

[0118] In this application, the zero-dimensional materials are disposed on the surface of the two-dimensional materials. The two-dimensional materials can not only serve as a support layer for carrying the zero-dimensional materials, but also avoid the addition of the following conductive connection layer 130 by using conductive two-dimensional materials. That is, the two-dimensional materials can serve as an auxiliary layer for the zero-dimensional materials to achieve the functions of support and conduction.

[0119] In some embodiments, the electron excitation layer 121 includes one-dimensional materials and two-dimensional materials, and the one-dimensional materials are disposed on the surface of the two-dimensional materials; optionally, the angle between the axial direction of the one-dimensional materials and the surface of the two-dimensional materials is 0 to 90°.

[0120] In this application, the one-dimensional materials are disposed on the surface of the two-dimensional materials. The two-dimensional materials can not only serve as a support layer for carrying the one-dimensional materials, but also avoid the addition of the following conductive connection layer 130 by using conductive two-dimensional materials. That is, the two-dimensional materials can serve as an auxiliary layer for the one-dimensional materials to achieve the functions of support and conduction.

[0121] In some embodiments, the zero-dimensional materials, one-dimensional materials or two-dimensional materials each independently include doping elements.

[0122] In this application, by doping elements into low-dimensional materials, the conductivity of the low-dimensional materials is improved, the work function is changed, and the electron emission performance is adjusted. For example, alkali metals and alkaline earth metal elements can improve the conductivity of low-dimensional materials, and at the same time can reduce the work function of low-dimensional materials to enhance the emission beam current. Elements such as B, C, N, O, F, and rare earths can create discrete energy levels to obtain electron beams with narrow energy.

[0123] Optionally, the doping elements include at least one of alkali metals, alkaline earth metals, transition metals, rare earth elements, halogen elements, and light elements (B, C, N, O, F).

[0124] In some embodiments, please refer to Figure 4, the end face 11021 of the light-emitting end 1102 of the optical fiber 110 is arranged at an angle α with the extending direction of the fiber core 111, and the angle α is selected between 0 and 90 degrees. The electron emission layer 120 is arranged on the end face 11021 of the light-emitting end 1102 of the optical fiber 110, and the electron excitation layer 121 covers the fiber core 111 of the optical fiber 110. The laser emitted from the fiber core 111 can directly irradiate the electron emission layer 120, so that the electron excitation layer 121 is excited by the laser emitted from the fiber core 111 and emits electrons.

[0125] It can be understood that the electron excitation layer 121 is located on the light-emitting path of the laser emitted from the fiber core 111.

[0126] In this way, the oblique incidence on the electron excitation layer 121 can be realized, and the photoelectric field perpendicular to the end face 11021 of the light-emitting end 1102 can be realized. The emission angle of electrons can be changed by changing the angle α, and the emission angle of electrons can also be adjusted by adjusting the polarization state of the laser in the optical fiber 110, which is beneficial to broadening the application range of the electron source 100.

[0127] In some embodiments, please refer to Figure 5 and Figure 6 , a light leakage notch h is formed in the radial direction of the optical fiber 110 at the light-emitting end 1102 of the optical fiber 110. The electron emission layer 120 is arranged on the bottom wall surface h1 of the light leakage notch h, and the electron emission layer 120 at least includes an electron excitation layer 121. The bottom wall surface h1 of the light leakage notch h is configured as a plane, and the projection of the electron excitation layer 121 on the bottom wall surface h1 covers the projection of the fiber core 111 on the bottom wall surface h1. The electron excitation layer 121 also extends to the light-emitting end 1102 of the optical fiber 110.

[0128] Optionally, the light leakage notch h further has a side wall surface h2 extending in the radial direction of the optical fiber 110, and the bottom wall surface h1 and the side wall surface h2 together define the light leakage notch h.

[0129] Optionally, the bottom wall surface h1 of the light leakage notch h is configured as a plane, and the bottom wall surface h1 of the light leakage notch h extends along the extending direction of the optical fiber 110.

[0130] It can be that the bottom wall surface h1 of the light leakage notch h is spaced from the fiber core 111, and the bottom wall surface h1 of the light leakage notch h is parallel to the tangent plane of the outer surface of the fiber core 111; it can also be that the bottom wall surface h1 of the light leakage notch h is tangent to the outer surface of the fiber core 111 (as shown in Figure 6 ); of course, it can also be that the bottom wall surface h1 of the light leakage notch h is configured as a plane partially formed on the fiber core 111. For example, by cutting the fiber core 111 and the cladding layer 112 simultaneously to form the light leakage notch h, and making a part of the bottom wall surface h1 of the light leakage notch h be formed on the fiber core 111 and another part of the bottom wall surface h1 of the light leakage notch h be formed on the cladding layer 112.

[0131] In this way, the laser transmitted in the core 111 of the optical fiber 110 can generate an evanescent wave at the bottom wall surface h1 of the light leakage notch h. Since the electron excitation layer 121 is disposed on the bottom wall surface h1 of the light leakage notch h, and the projection of the electron excitation layer 121 on the bottom wall surface h1 covers the projection of the core 111 on the bottom wall surface h1, the laser transmitted in the core 111 of the optical fiber 110 can interact with the electron excitation layer 121 through the evanescent wave, so that the electrons in the electron excitation layer 121 absorb the energy of the evanescent wave and transition. These electrons can escape from the electron excitation layer 121, and thus the excitation of electrons can be achieved.

[0132] In some embodiments, please refer to Figure 7 and Figure 8 , the optical fiber 110 includes a porous optical fiber. The porous optical fiber has a light guiding hole. The porous optical fiber may include a hollow porous optical fiber. The hollow porous optical fiber may be a single-hole or multi-hole hollow optical fiber. Of course, the porous optical fiber may also include a solid-core porous optical fiber. The solid-core porous optical fiber may be a single-hole or multi-hole solid-core optical fiber, which is not specifically limited herein. Figure 7 - Figure 8 An example of the porous optical fiber being a single-hole hollow optical fiber is given.

[0133] Specifically, in the embodiment as shown in Figure 7 - Figure 8 , a core 111 formed of air is provided in the light guiding hole. The porous optical fiber further includes a cladding layer 112 surrounding the core 111. The cladding layer 112 is specifically configured as an annular light guiding tube body. The side wall k of the light guiding hole is formed on the inner side wall of the annular light guiding tube body. Specifically, the material of the annular light guiding tube body may be high borosilicate, glass or quartz, etc. More specifically, the porous optical fiber is a capillary optical fiber.

[0134] The electron excitation layer 121 is at least disposed on the side wall k of the light guiding hole, and the electron excitation layer 121 extends along the extending direction of the light guiding hole to the light output end 1102 of the optical fiber 110.

[0135] When the electron source 100 is in use, during the process of the laser transmitting in the porous optical fiber by means of the light guiding medium, an evanescent wave can be generated at the side wall k of the light guiding hole. Since the electron excitation layer 121 is disposed on the side wall k of the light guiding hole, the laser can interact with the electron excitation layer 121 through the evanescent wave, so that the electrons in the electron excitation layer 121 absorb the energy of the evanescent wave and transition. These electrons can escape from the electron excitation layer 121, and thus the excitation of electrons can be achieved.

[0136] In some embodiments, please refer to Figure 9 and Figure 10, the optical fiber 110 includes a porous optical fiber. The porous optical fiber has a light guiding hole. The porous optical fiber may include a hollow porous optical fiber, and the hollow porous optical fiber may be a single-hole or multi-hole hollow optical fiber. Of course, the porous optical fiber may also include a solid-core porous optical fiber, and the solid-core porous optical fiber may be a single-hole or multi-hole solid-core optical fiber, which is not specifically limited herein. Figure 9 - Figure 10 An example of the porous optical fiber being a single-hole hollow optical fiber is given.

[0137] Specifically, such as Figure 9 - Figure 10 In the embodiment shown, a core 111 composed of air is provided in the light guiding hole. The porous optical fiber further includes a cladding layer 112 surrounding the core 111. The cladding layer 112 is specifically configured as an annular light guiding tube body, and the side wall k of the light guiding hole is formed on the inner side wall of the annular light guiding tube body. Specifically, the material of the annular light guiding tube body may be high borosilicate, glass or quartz, etc. More specifically, the porous optical fiber is a capillary optical fiber.

[0138] The electron emission layer 120 is provided on the end face 11021 of the light output end 1102 of the porous optical fiber, and the electron excitation layer 121 covers one end of the light guiding hole located at the end face 11021 of the light output end 1102. The laser emitted from the porous optical fiber can directly irradiate on the electron emission layer 120, so that the electron excitation layer 121 is excited by the laser emitted from the porous optical fiber and emits electrons.

[0139] Exemplarily, the porous optical fiber is a capillary optical fiber, and the electron excitation layer 121 covers the core 111 of the porous optical fiber. It can be that the electron excitation layer 121 directly covers the core 111 of the porous optical fiber, or it can be that the electron excitation layer 121 indirectly covers the core 111 of the porous optical fiber, which is not specifically limited herein.

[0140] Thus, during the process that the laser transmitted in the porous optical fiber propagates to the end face 11021 of the light output end 1102 and exits, this part of the laser can interact with the electron excitation layer 121, so that the electrons in the electron excitation layer 121 absorb the photons of the laser and undergo energy transition to escape outside the electron excitation layer 121, realizing the excitation of electrons.

[0141] In some embodiments, please refer to Figure 11 and Figure 12 , the light output end 1102 of the optical fiber 110 is provided with a pointed end portion j, the electron excitation layer 121 covers the surface j1 of the pointed end portion j of the optical fiber 110, the optical fiber 110 includes a core 111 for transmitting laser, and the laser emitted from the core 111 can directly irradiate on the electron emission layer 120, so that the electron excitation layer 121 is excited by the laser emitted from the core 111 and emits electrons.

[0142] During the process that the laser transmitted within the core 111 of the optical fiber 110 is transmitted to the tip j and emitted, a part of this laser can interact with the electron excitation layer 121, enabling the electrons within the electron excitation layer 121 to absorb the photons of the laser, undergo energy transitions, and escape outside the electron excitation layer 121, thereby achieving the excitation of electrons.

[0143] Optionally, along the extending direction of the core 111, the radial dimension of the tip j gradually decreases.

[0144] The electron excitation layer 121 of the present application is disposed on the tip j of the optical fiber 110 and covers the surface j1 of the tip j of the optical fiber 110. Since the tip j of the optical fiber 110 has a geometric structure similar to that of a needle tip, the field emission enhancement factor is increased, and an electron source 100 with higher brightness can be obtained.

[0145] Optionally, in this embodiment, along the extending direction of the core 111, the dimension of the tip j is L1, and the dimension of the electron excitation layer 121 is L2, where L1 is greater than L2. Specifically, the dimensions of the tip j and the electron excitation layer 121 satisfy the following relationship: L2 > 1 / 2 * L1.

[0146] The electron excitation layer 121 covers the surface j1 of the tip j, and the electron excitation layer 121 is disposed around the tip j. Since L2 > 1 / 2 * L1, in this way, the contact area between the electron excitation layer 121 and the surface j1 of the tip j can be increased, the bonding strength between the electron excitation layer 121 and the optical fiber 110 can be improved, and it is also beneficial to use the laser transmitted by the core 111 to excite the electron excitation layer 121 to emit electrons outward.

[0147] In some embodiments, the electron source 100 further includes a conductive connection layer 130, and the conductive connection layer 130 is at least disposed on the light-emitting end 1102 of the optical fiber 110 and is electrically connected to the electron excitation layer 121.

[0148] The conductive connection layer 130 can be a conductive thin film. Specifically, the conductive connection layer 130 can be a metal thin film, a graphite thin film, or a low-dimensional material thin film, etc.

[0149] It should be supplemented and explained that the conductive connection layer 130 is not disposed on the light-emitting path of the laser emitted from the core 111.

[0150] In this way, the electron excitation layer 121 can be electrically connected to the negative electrode of the power supply through the conductive connection layer 130. On the one hand, the power supply can be used to supply electrons to the electron excitation layer 121, which is beneficial for the electron excitation layer 121 to continuously emit electrons under the excitation of the laser. On the other hand, the direction and convergence of the electrons emitted from the electron excitation layer 121 can be regulated by the voltage applied to the conductive connection layer 130 by the power supply. For example, the direction of the electrons emitted from the electron excitation layer 121 can be regulated by the voltage applied to the anode target 200 and the conductive connection layer 130 by the power supply.

[0151] Optionally, the electron excitation layer 121 includes a first portion 1211 located on the light-emitting path of the laser emitted from the core 111, and a second portion 1212 connected to the periphery of the first portion 1211, and the second portion 1212 is electrically connected to the conductive connection layer 130. Among them, the second portion 1212 can be directly in electrical contact with the conductive connection layer 130 to be electrically connected to the conductive connection layer 130; the second portion 1212 can also be electrically connected to the conductive connection layer 130 through other conductive structures.

[0152] Specifically, in the embodiment as Figure 4 shown, the first portion 1211 and the second portion 1212 are provided on the end face 11021 of the light-emitting end 1102. The first portion 1211 covers the core 111 of the optical fiber 110, and the second portion 1212 is disposed around the first portion 1211 and is electrically connected to the conductive connection layer 130.

[0153] The first portion 1211 can directly cover the core 111 of the optical fiber 110, or the first portion 1211 can also indirectly cover the core 111 of the optical fiber 110, and no specific limitation is made here.

[0154] Specifically, in the embodiment as Figure 5 and Figure 6 shown, the first portion 1211 and the second portion 1212 are provided on the bottom wall surface h1 of the light leakage gap h. The projection of the first portion 1211 on the bottom wall surface h1 covers the projection of the core 111 on the bottom wall surface h1. The second portion 1212 is located on the periphery of the first portion 1211 and is electrically connected to the conductive connection layer 130.

[0155] Specifically, in the embodiment as Figure 7 and Figure 8 shown, the electron excitation layer 121 includes a first portion 1211 that completely covers the side wall k of the light guide hole, and a second portion 1212 provided on the end face 11021 of the light-emitting end 1102 of the fiber with holes. The first portion 1211 is connected to the second portion 1212, and the second portion 1212 is electrically connected to the conductive connection layer 130.

[0156] Specifically, in the embodiment as Figure 9 and Figure 10In the illustrated embodiment, the electron excitation layer 121 includes a first portion 1211 and a second portion 1212 that are disposed on the end face 11021 of the light output end 1102 and are connected to each other. The first portion 1211 covers one end of the light guiding hole located on the end face 11021 of the light output end 1102, and the second portion 1212 is disposed around the first portion 1211 and is electrically connected to the conductive connection layer 130.

[0157] Specifically, in the embodiment as Figure 11 and Figure 12 shown, the electron excitation layer 121 includes a first portion 1211 and a second portion 1212 that are connected. The projection of the first portion 1211 in the target plane perpendicular to the extending direction of the fiber core 111 covers the projection of the fiber core 111 in the target plane. The projection of the second portion 1212 in the target plane is located on the periphery of the projection of the first portion 1211 in the target plane, and the second portion 1212 overlaps with the conductive connection layer 130.

[0158] In this way, by electrically connecting the conductive connection layer 130 to the second portion 1212 of the electron excitation layer 121, and considering that the second portion 1212 is located on the periphery of the first portion 1211, the conductive connection layer 130 can supply electrons to the electron excitation layer 121 without affecting the interaction between the fiber core 111 and the electron excitation layer 121, which is beneficial for the electron excitation layer 121 to continuously emit electrons outward under the excitation of the laser.

[0159] Optionally, the conductive connection layer 130 includes a first conductive portion 131 disposed on the light output end 1102 and a second conductive portion 132 disposed on the circumferential side surface of the optical fiber 110. The first conductive portion 131 is connected to the second conductive portion 132, and the first conductive portion 131 overlaps with the second portion 1212 of the electron excitation layer 121.

[0160] Specifically, in the embodiment as Figure 4 and Figure 7 - Figure 10 shown, the first conductive portion 131 is disposed on the end face 11021 of the light output end 1102 and overlaps with the second portion 1212 of the electron excitation layer 121. Specifically, in the embodiment as Figure 5 and Figure 6 shown, the first conductive portion 131 is disposed on the bottom wall surface h1 of the light leakage notch h and overlaps with the second portion 1212 of the electron excitation layer 121. The first conductive portion 131 further extends to the light output end 1102. Specifically, in the embodiment as Figure 11 and Figure 12 shown, the first conductive portion 131 is disposed on the tip portion j on the light output end 1102 and overlaps with the second portion 1212 of the electron excitation layer 121.

[0161] In this way, the conductive connection layer 130 can cover more of the optical fiber 110 , thereby improving the bonding strength between the conductive connection layer 130 and the optical fiber, and also facilitating better use of the conductive connection layer 130 to supplement electrons to the electron excitation layer 121 .

[0162] Optionally, the conductive connection layer 130 includes a first metal layer and a second metal layer which are stacked, the adhesion of the first metal layer is greater than that of the second metal layer, and the corrosion resistance of the first metal layer is less than that of the second metal layer.

[0163] For example, the first metal layer is made of titanium, and the second metal layer is made of gold.

[0164] In this way, the first metal layer with higher adhesion can make the conductive connection layer 130 better adhere to the optical fiber 110, and the second metal layer with better corrosion resistance can protect the first metal layer, thereby improving the bonding strength between the conductive connection layer 130 and the optical fiber 110, which is also beneficial to improving the service life of the conductive connection layer 130.

[0165] In some embodiments, the electron emission layer 120 further includes an auxiliary layer 122 , which is stacked on a side of the electron excitation layer 121 close to the optical fiber 110 , or stacked on a side of the electron excitation layer 121 away from the optical fiber 110 .

[0166] The auxiliary layer 122 may be stacked on a side of the electron excitation layer 121 close to the end face 11021 of the light output end 1102 of the optical fiber 110 , or may be stacked on a side of the electron excitation layer 121 away from the end face 11021 of the light output end 1102 of the optical fiber 110 .

[0167] Of course, the auxiliary layer 122 may also be stacked on a side of the electron excitation layer 121 close to or far from the bottom wall surface h1 of the light leakage gap h.

[0168] Of course, the auxiliary layer 122 may also be stacked on a side of the electron excitation layer 121 close to or away from the surface j1 of the tip j of the optical fiber 110 .

[0169] Figure 9 , Figure 10 and Figure 13 An example is given in which the auxiliary layer 122 is stacked on one side of the end surface 11021 of the electron excitation layer 121 close to the light output end 1102 .

[0170] In this application, an auxiliary layer 122 is added. When the electron excitation layer 121 requires structural support, the auxiliary layer 122 is used to provide structural support for the electron excitation layer 121, that is, the electron excitation layer 121 is disposed on the auxiliary layer 122; or, when the electron excitation layer 121 cannot be directly connected and conductively connected to the conductive connection layer 130, it is connected to the conductive connection layer 130 through the conductive auxiliary layer 122, and the electron excitation layer 121 and the conductive connection layer 130 are electrically connected by means of the auxiliary layer 122.

[0171] Optionally, the auxiliary layer 122 includes at least one of a conductive support layer and a heat dissipation support layer.

[0172] Optionally, the thickness of the auxiliary layer 122 is 0.1 nm to 100 nm.

[0173] Optionally, the light transmittance of the auxiliary layer 122 is 10% or more, such as 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.

[0174] Optionally, the auxiliary layer 122 includes a conductive support layer, and the conductive support layer is electrically connected to the conductive connection layer 130.

[0175] In some embodiments, the auxiliary layer 122 includes a conductive support layer, the material of the conductive support layer includes a conductive metal, the laser wavelength in the optical fiber 110 is 200 nm to 10 μm, the pulse power is 1 nw to 1 w, and the repetition frequency is 0 Hz to 10 GHz.

[0176] In this application, the auxiliary layer 122 is made of a conductive metal, and the laser parameters are controlled to avoid the problem of melting caused by laser irradiation of the conductive metal, ensuring that the auxiliary layer has the functions of support and conductivity.

[0177] The auxiliary layer 122 may also include a conductive support layer, such as Figure 9 and Figure 10 As shown, the electron excitation layer 121 is disposed on the end face 11021 of the light output end 1102 through the auxiliary layer 122, and the auxiliary layer 122 has a bearing plane for carrying the electron excitation layer 121. The auxiliary layer 122 may be a light-transmitting material; the auxiliary layer 122 may also be a non-light-transmitting material, and the auxiliary layer 122 has an annular structure, and the orthographic projection of the auxiliary layer 122 on the end face 11021 of the light output end 1102 is located outside the core 111 of the optical fiber 110.

[0178] In this way, on the one hand, the bearing plane of the auxiliary layer 122 can be utilized to make the electron excitation layer 121 more flatly disposed on the end face 11021 of the light output end 1102, and on the other hand, it will not affect the interaction between the electron excitation layer 121 and the core 111 of the optical fiber 110, which is beneficial to the formation of an electron beam with concentrated energy and small energy dispersion from the electrons tunneling and emitting within the electron excitation layer 121.

[0179] The auxiliary layer 122 may also include a heat dissipation support layer. Exemplarily, the material of the auxiliary layer 122 may be hexagonal boron nitride. Of course, other materials that can dissipate heat from the electron excitation layer 121 and enable the electron excitation layer 121 to be flatly disposed on the end face 11021 of the light output end 1102 can also be selected for the material of the auxiliary layer 122. In this way, the heat dissipation efficiency of the electron excitation layer 121 can be increased by using the auxiliary layer 122, so that the electron excitation layer 121 can emit a larger electron beam current.

[0180] In some embodiments, along the extending direction of the optical fiber 110, the anode target 200 is spaced apart from the light output end 1102 of the optical fiber 110, and a preset electric field is provided between the anode target 200 and the electron excitation layer 121, so that the electrons emitted by the electron excitation layer 121 can be linearly accelerated along the extending direction of the optical fiber 110.

[0181] Compared with using a gate structure as an accelerating electrode, in the X-ray tube 10 of the present application, a preset electric field is provided between the anode target 200 and the electron excitation layer 121 to form a linear acceleration of electrons in the direction from the electron excitation layer 121 to the anode target 200, greatly simplifying the structure of the X-ray tube 10. In this way, it is beneficial to reduce the volume of the X-ray tube 10.

[0182] In this embodiment, the electron excitation layer 121 is externally connected to the negative pole of a power supply through a conductive connection layer 130, and the anode target 200 is used to externally connect to the positive pole of the power supply, so that a preset electric field is provided between the anode target 200 and the electron excitation layer 121. And because the anode target 200 and the light output end 1102 of the optical fiber 110 are spaced apart along the extending direction of the optical fiber 110, in this way, the electrons emitted from the electron excitation layer 121 can be emitted toward the anode target 200 along the extending direction of the optical fiber 110 under the action of the preset electric field, and the anode target 200 can be better excited to emit X-rays with relatively concentrated energy.

[0183] Optionally, the light input end 1101 of the optical fiber 110 extends out of the vacuum chamber 301 through the following first port 302, the second conductive part 132 of the conductive connection layer 130 is disposed on the circumferential side surface of the optical fiber 110, and a part of the structure of the second conductive part 132 is disposed on the part of the circumferential side surface of the optical fiber 110 located outside the vacuum chamber 301, which is convenient for the conductive connection layer 130 to be externally connected to the negative pole of the power supply.

[0184] In some embodiments, the conductive connection layer 130 is disposed around the optical fiber 110.

[0185] In this way, the contact area between the conductive connection layer 130 and the optical fiber 110 can be increased, and further the bonding strength between the conductive connection layer 130 and the optical fiber 110 can be improved.

[0186] In some embodiments, the tube body 300 is sleeved on the optical fiber 110 and the anode target 200 respectively.

[0187] The inner peripheral wall of the tube body 300 can be adaptively connected to the outer peripheral wall of the optical fiber 110 by bonding, and the outer peripheral wall of the anode target 200 can also be bonded to the inner peripheral wall of the tube body 300 by bonding. While realizing the assembly of the X-ray tube 10, the outer peripheral walls of the optical fiber 110 and the anode target 200 are respectively designed to have dimensions equivalent to those of the inner peripheral wall of the tube body 300, which can reduce the radial size of the X-ray tube 10, and thus is beneficial to reducing the volume of the X-ray tube 10, making the X-ray tube 10 occupy less space and have a higher material utilization rate, and further enabling the electron source 100 to have the advantage of high integration.

[0188] In some embodiments, the tube body 300 has a first port 302 communicating with the vacuum chamber 301. The light-emitting end 1102 of the optical fiber 110 extends into the vacuum chamber 301 through the first port 302, and the outer peripheral wall of the optical fiber 110 is hermetically connected to the inner peripheral wall of the first port 302.

[0189] In this way, the sealing performance of the vacuum chamber 301 can be improved. The electron excitation layer 121 can emit electrons outward from the light-emitting end 1102 under the excitation of the laser transmitted by the core 111, and the electron excitation layer 121 can better emit electrons toward the anode target 200 in the vacuum chamber 301, which can improve the reliability of the X-ray tube 10.

[0190] Specifically, the assembly of the tube body 300 and the optical fiber 110 can be carried out in a vacuum environment, and the inner peripheral wall of the tube body 300 can be hermetically connected to the outer peripheral wall of the optical fiber 110, which can improve the sealing performance of the vacuum chamber 301.

[0191] In some embodiments, the tube body 300 further has a second port 303 disposed opposite to the first port 302. The side of the anode target 200 facing away from the light-emitting end 1102 extends out of the vacuum chamber 301 through the second port 303, and the outer peripheral wall of the anode target 200 is hermetically connected to the inner peripheral wall of the second port 303.

[0192] In this way, on the one hand, the outer peripheral wall of the anode target 200 is hermetically connected to the inner peripheral wall of the second port 303, which can assemble the anode target 200 and the tube body 300 together and is also beneficial to improving the sealing performance of the vacuum chamber 301; on the other hand, the side of the anode target 200 facing away from the light-emitting end 1102 extends out of the vacuum chamber 301, which is convenient for connecting the positive electrode of the external power supply to the anode target 200.

[0193] Specifically, the assembly of the anode target 200 and the optical fiber 110 can be carried out in a vacuum environment, and the inner peripheral wall of the tube body 300 and the outer peripheral wall of the anode target 200 can be bonded together with a sealant, which can improve the sealing performance of the vacuum chamber 301.

[0194] In some embodiments, the X-ray tube 10 further includes an external electrode 400 disposed between the outer peripheral wall of the anode target 200 and the inner peripheral wall of the second port 303. Along the longitudinal extension direction of the tube body 300, one end of the external electrode 400 is located inside the vacuum chamber 301, and the other end extends outside the vacuum chamber 301.

[0195] On the one hand, the anode target 200 can be externally connected to the positive electrode of a power source through the external electrode 400. On the other hand, the external electrode 400 is disposed around the outer peripheral wall of the anode target 200 and partially located inside the vacuum chamber 301, which can increase the contact area between the external electrode 400 and the anode target 200, improve the bonding strength between the external electrode 400 and the anode target 200, and also better utilize the external electrode 400 to provide a preset voltage to the anode target 200.

[0196] In some embodiments, please refer to Figure 1 - Figure 3 , along the extension direction of the optical fiber 110, the electron source 100 and the anode target 200 are spaced apart. The anode target 200 has a reflective target surface 210 facing the light output end 1102, and the reflective target surface 210 is disposed at an angle β with the extension direction of the optical fiber 110. Wherein, β is greater than 0 degrees and less than 90 degrees. The output window 311 is disposed on the side wall of the tube body 300 and faces the reflective target surface 210.

[0197] Optionally, the material of the anode target 200 provided with the reflective target surface 210 can be materials such as tungsten, silver, palladium, rhodium, molybdenum, copper, nickel, cobalt, iron or chromium.

[0198] In this way, the electron source 100 can emit electrons towards the reflective target surface 210 of the anode target 200, which can excite the anode target 200 to emit X-rays, and the X-rays are reflected by the reflective target surface 210 and emitted outside the vacuum chamber 301 through the output window 311.

[0199] In some other embodiments, please refer to Figure 14 and Figure 15 , the anode target 200 includes a transmissive anode 220. Along the longitudinal extension direction of the tube body 300, the electron source 100 and the output window 311 are disposed at opposite ends of the tube body 300, and the transmissive anode 220 is located between the electron source 100 and the output window 311.

[0200] The transmissive anode 220 may include a substrate and a metal layer disposed on one side of the substrate facing the light output end 1102, and the thickness of the metal layer is less than 100 nm. Wherein, the material of the substrate can be the following X-ray transmissive material. By way of example, the material of the substrate is glass. The material of the metal layer can be tungsten, silver, palladium, rhodium, molybdenum, copper, nickel, cobalt, iron or chromium, etc., and the metal layer can be a metal coating.

[0201] Thus, the electron source 100 at one end of the tube body 300 emits electrons towards the anode target 200, which can excite the anode target 200 to emit X-rays that penetrate the anode target 200 and then exit through the output window 311 at the other end of the tube body 300.

[0202] It can be, for example Figure 1 and Figure 14 As shown, the light incident end 1101 of the optical fiber 110 extends out of the vacuum chamber 301 through the first port 302. Thus, a part of the structure of the second conductive part 132 can be arranged on the circumferential side of the optical fiber 110 located outside the vacuum chamber 301, which is convenient for the conductive connection layer 130 to be externally connected to the negative pole of the power supply.

[0203] Of course, it can also be that the end face of the light incident end 1101 of the optical fiber 110 is flush with the plane where the first port 302 is located (not shown in the figure). Thus, the optical fiber 110 can be roughly encapsulated in the tube body 300, and the end face of the light incident end 1101 of the optical fiber 110 is exposed through the first port 302, so that the laser source can be coupled to the light incident end 1101 of the optical fiber 110. While better protecting the optical fiber 110, it is also convenient for the laser emitted by the laser source to be transmitted through the optical fiber 110.

[0204] In some embodiments, the tube body 300 includes an inner tube 310 sleeved on the optical fiber 110 and the anode target 200, and an outer tube 320 sleeved on the inner tube 310. An opening 321 is provided on the outer tube 320, and a part of the structure of the inner tube 310 is exposed through the opening 321 to form the output window 311. The material of the inner tube 310 includes X-ray transmissive materials, and the material of the outer tube 320 includes X-ray blocking materials.

[0205] Specifically, in the embodiment as Figure 1 shown, the opening 321 is provided on one side of the outer tube 320. Specifically, in the embodiment as Figure 14 shown, the opening 321 is provided at one end of the outer tube 320 away from the electron source 100, so that the electron source 100 and the output window 311 can be arranged opposite to each other along the extending direction of the optical fiber 110.

[0206] Optionally, the X-ray transmissive materials include glass, beryllium, aluminum, titanium or sapphire.

[0207] Optionally, the X-ray blocking materials include, for example, lead or barium sulfate.

[0208] Thus, it is possible to use the outer tube 320 to block X-rays, and use the inner tube 310 to emit X-rays outwards through the exposed output window 311, reducing the possibility of X-rays emitting from other parts of the inner tube 310 except the output window 311. While improving the safety and reliability of the X-ray tube 10, it also realizes the concentrated emission of X-rays and the low-loss emission of X-rays from the vacuum to the outside world.

[0209] In some embodiments, the outer diameter of the tube body 300 is 125 μm - 2000 μm, and the length of the tube body 300 is 3 cm - 9 cm.

[0210] The combined tube body 300 is sleeved on the optical fiber 110 and the anode target 200 respectively, so that the radial dimension of the X-ray tube 10 is smaller, the volume of the X-ray tube 10 can be greatly reduced, and the electron excitation layer 121 and the anode target 200 can accelerate electrons well in a smaller vacuum chamber 301, which is beneficial to the high integration and miniaturization of the electron source 100 and the X-ray emission structure, and helps to realize the portable application of the X-ray tube 10 and the metal flaw detection in a narrow space.

[0211] In some embodiments, along the extending direction of the optical fiber 110, the distance between the light-emitting end 1102 of the optical fiber 110 and the anode target 200 can be 3 cm - 5 cm. Of course, the distance between the light-emitting end 1102 of the optical fiber 110 and the anode target 200 in this application is not limited to this, and 3 cm - 5 cm is taken as an example for illustration here.

[0212] In this application, the distance between the electron excitation layer 121 and the anode target 200 is small, so that the electric field lines between the electron excitation layer 121 and the anode target 200 are more uniform, and thus more electrons are effectively accelerated, and then incident on the anode target 200 to excite the anode target 200 to emit X-rays, which is also beneficial to the miniaturization of the X-ray tube 10.

[0213] The preparation method of the X-ray tube 10 includes the following steps:

[0214] S20. Provide an electron source 100, an anode target 200 and a tube body 300.

[0215] Taking the formation of the electron excitation layer 121 covering the core 111 on the light-emitting end 1102 of the optical fiber 110 as an example to illustrate the preparation method of the electron source 100, the preparation method of the electron source 100 includes the following steps:

[0216] S210. Provide an optical fiber 110. Wherein, the optical fiber 110 includes a core 111 for transmitting laser and a cladding layer 112 wrapped around the core 111.

[0217] Optionally, an appropriate length of the optical fiber 110 can be intercepted, the end coating layer of the optical fiber 110 can be removed, and one end of the cut optical fiber 110 can be processed to form the light-emitting end 1102. Specifically, a cutting mechanism can be used to cut one end of the cut optical fiber 110 to form the light-emitting end 1102. By using the cutting method to form the light-emitting end 1102, the cross section where the end face 11021 of the light-emitting end 1102 is located can be made relatively flat, which is beneficial to forming a flat electron emission layer 120 on the end face 11021 of the light-emitting end 1102.

[0218] S220. Form an electron emission layer 120 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110. The electron emission layer 120 includes at least an electron excitation layer 121, and the electron excitation layer 121 covers the core 111 of the optical fiber 110 so that the electron excitation layer 121 is located on the light-emitting path of the laser emitted from the core 111.

[0219] The electron excitation layer 121 can be formed by at least one of dry transfer, wet transfer, and direct growth.

[0220] In some embodiments, the electron excitation layer 121 is prepared by dry transfer. The preparation method includes: transferring zero-dimensional materials, one-dimensional materials, and / or two-dimensional materials to the tape by mechanical exfoliation, and transferring the zero-dimensional materials, one-dimensional materials, and / or two-dimensional materials to the end face 11021 of the light-emitting end 1102 of the optical fiber 110.

[0221] Taking two-dimensional materials as an example for illustration, the preparation process of forming the electron emission layer 120 by dry transfer is as follows:

[0222] (1) The two-dimensional material can be thinned by mechanical exfoliation until an electron excitation layer 121 with a preset thickness is formed. Specifically, the two-dimensional material is adhered to the highly adhesive tape A, and the low-adhesive tape B can be used to mechanically exfoliate along the crystal cleavage plane of the two-dimensional material repeatedly until the electron excitation layer 121 with a preset thickness is formed.

[0223] (2) Transfer the electron excitation layer 121 with a preset thickness to the temporary substrate 20 and remove the tape B on the electron excitation layer 121. Specifically, the tape B can be melted by heating to peel the tape B from the electron excitation layer 121.

[0224] (3) Transfer the electron excitation layer 121 on the temporary substrate 20 to the end face 11021 of the light-emitting end 1102 of the optical fiber 110.

[0225] Optionally, the electron excitation layer 121 is selected as a two-dimensional material, and the material of the temporary substrate 20 can be selected as a polycarbonate propylene ester film.

[0226] Of course, the present application is not limited thereto. The dry transfer method can also be combined with the direct growth method (such as chemical vapor deposition). For example, an electron excitation layer 121 with a preset thickness is grown on the substrate to be peeled, and then the electron excitation layer 121 is transferred from the substrate to be peeled to the temporary substrate 20 by acid etching to remove the substrate to be peeled or by hand tearing, and then the electron excitation layer 121 on the temporary substrate 20 is transferred to the end face 11021 of the light-emitting end 1102 of the optical fiber 110. Among them, the substrate to be peeled can be a metal or other materials that can be acid-etched or torn by hand.

[0227] In some other embodiments, the electron excitation layer 121 is prepared by a wet transfer method. The preparation method includes: directly preparing zero-dimensional materials, one-dimensional materials or two-dimensional materials in a solution and floating them on the liquid surface, making the end face 11021 of the light-emitting end 1102 of the optical fiber 110 contact the zero-dimensional materials, one-dimensional materials or two-dimensional materials on the liquid surface, and drying the zero-dimensional materials, one-dimensional materials and / or two-dimensional materials on the end face 11021 of the light-emitting end 1102 of the optical fiber 110.

[0228] In still some other embodiments, the electron excitation layer 121 is prepared by a direct growth method. The preparation method includes: directly preparing the electron excitation layer 121 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110 by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy and liquid filling.

[0229] Optionally, before or after forming the electron emission layer 120 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110, the preparation method of the electron source 100 further includes:

[0230] S230. Forming a conductive connection layer 130 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110, so that the conductive connection layer 130 overlaps with the electron excitation layer 121.

[0231] That is to say, the conductive connection layer 130 can be formed first and then the electron excitation layer 121; or the electron excitation layer 121 can be formed first and then the conductive connection layer 130; as long as the electron excitation layer 121 and the conductive connection layer 130 are electrically connected to each other, in this way, electrons can be supplied to the electron excitation layer 121 by means of the conductive connection layer 130, which is beneficial to the continuous emission of electrons from the electron excitation layer 121 under the excitation of laser light.

[0232] Optionally, forming a conductive connection layer 130 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110, so that the conductive connection layer 130 overlaps with the electron excitation layer 121, specifically includes:

[0233] S231. Forming a core protection layer on the end face 11021 of the light-emitting end 1102 of the optical fiber 110, and the core protection layer covers the core 111 of the optical fiber 110.

[0234] It may be that the core protection layer directly covers the core 111 of the optical fiber 110, or the core protection layer indirectly covers the core 111 of the optical fiber 110, and no specific limitation is made here.

[0235] Optionally, the polymer microsphere solution can be coated on the end face 11021 of the light-emitting end 1102 of the optical fiber 110 to form a core protection layer covering the core 111. Exemplarily, the polymer microsphere solution is a polymethyl methacrylate suspension.

[0236] S232. Form a conductive material layer covering the core protection layer on the optical fiber 110.

[0237] The conductive material layer can be formed by evaporation coating. Specifically, a metal evaporation coating device can be used to form the conductive material layer on the optical fiber 110.

[0238] S233. Remove the core protection layer and the part of the conductive material layer provided on the core protection layer to form the conductive connection layer 130.

[0239] Optionally, a solvent that can dissolve the core protection layer and does not interact with the conductive material layer can be used to remove the core protection layer. Specifically, the light-emitting end 1102 of the optical fiber 110 can be immersed in acetone, so that the core protection layer (polymer microspheres) is dissolved, and the part of the conductive material layer provided on the core protection layer (part of the metal coating) flakes off to obtain the conductive connection layer 130.

[0240] It can be understood that the core protection layer can be used to make the orthographic projection of the conductive connection layer 130 on the end face 11021 of the light-emitting end 1102 not coincide with the orthographic projection of the core 111 of the optical fiber 110 on the end face 11021 of the light-emitting end 1102, so that the laser transmitted in the core 111 of the optical fiber 110 can better interact with the electron excitation layer 121 covering the core 111 of the optical fiber 110.

[0241] In some embodiments, please refer to Figure 16 , the step S220 of forming the electron emission layer 120 on the end face 11021 of the light-emitting end 1102 of the optical fiber 110 specifically includes the following steps. Specifically, the specific steps of transferring the electron excitation layer 121 on the temporary substrate 20 to the end face 11021 of the light-emitting end 1102 of the optical fiber 110 are as follows:

[0242] S221. Arrange the electron excitation layer 121 and the end face 11021 of the light-emitting end 1102 of the optical fiber 110 opposite to each other and parallel to each other along the first direction F1.

[0243] Specifically, observe the end face 11021 of the light-emitting end 1102 of the optical fiber 110 and the electron excitation layer 121 under a microscope, and arrange the electron excitation layer 121 and the end face 11021 of the light-emitting end 1102 of the optical fiber 110 opposite to each other and parallel to each other along the first direction F1, and make the center connection line of the two extend along the first direction F1.

[0244] S222. Drive the optical fiber 110 to move along the first direction F1 to contact the electron excitation layer 121.

[0245] S223. At a preset temperature, attach the electron excitation layer 121 to the end face 11021 of the light output end 1102 of the optical fiber 110.

[0246] In this way, it is possible to align the center of the electron excitation layer 121 with the center of the end face 11021 of the light output end 1102 of the optical fiber 110 by using a microscope, and attach the two to each other at a certain temperature, so that the electron excitation layer 121 and the end face 11021 of the light output end 1102 of the optical fiber 110 can be closely attached under the action of van der Waals force, improving the bonding strength of the electron excitation layer 121 on the optical fiber 110, and also facilitating the complete coverage of the electron excitation layer 121 on the fiber core 111 of the optical fiber 110, enabling the laser transmitted by the fiber core 111 to better interact with the electron excitation layer 121.

[0247] In some specific embodiments, the step S220 of forming the electron emission layer 120 on the end face 11021 of the light output end 1102 of the optical fiber 110 specifically includes the following steps. Specifically, the specific steps of transferring the electron excitation layer 121 on the temporary substrate 20 to the end face 11021 of the light output end 1102 of the optical fiber 110 are as follows:

[0248] S2201. Attach an annular heating sheet 40 to the back of the perforated glass slide 30 of the microscope, fix the temporary substrate 20 with the electron excitation layer 121 on the bottom side of the annular heating sheet 40 (the temporary substrate 20 can be fixed on the bottom side of the annular heating sheet 40 by an adhesive fixing method), and arrange the electron excitation layer 121 on the temporary substrate 20 downward, and fix the optical fiber 110 below the electron excitation layer 121, so that the central axes of the objective lens of the microscope, the perforated glass slide 30, the annular heating sheet 40, the center of the electron excitation layer 121, and the center of the fiber core 111 coincide, and the objective lens of the microscope, the perforated glass slide 30, the annular heating sheet 40, the electron excitation layer 121, and the optical fiber 110 are arranged in sequence from top to bottom.

[0249] Optionally, the optical fiber 110 can be fixed on a moving platform by using a fixture, and the end face 11021 of the light output end 1102 of the optical fiber 110 is arranged upward. The moving platform is used to adjust the position of the optical fiber 110 along the first direction F1 and the angle of the end face 11021 of the light output end 1102 of the optical fiber 110 relative to the horizontal plane to make it horizontal.

[0250] Optionally, the fixture can be a pneumatic gripper or an electric gripper.

[0251] Optionally, the mobile platform can be a six-degree-of-freedom platform. The mobile platform can also include a linear drive mechanism and a rotary drive mechanism connected to the linear drive mechanism. The output end of the rotary drive mechanism is connected to the fixture to drive the fixture and the optical fiber 110 clamped by the fixture to rotate around an axis parallel to the horizontal plane, so that the end face 11021 of the light-emitting end 1102 is horizontally arranged. The linear drive mechanism is used to drive the rotary drive mechanism, the fixture, and the optical fiber 110 to move in the first direction F1.

[0252] Among them, the linear drive mechanism can be a motor or a cylinder, and the rotary drive mechanism can be a motor or a rotary cylinder.

[0253] S2202. Observe the end face 11021 of the light-emitting end 1102 of the optical fiber 110 and the electron excitation layer 121 under a microscope, and arrange the electron excitation layer 121 and the end face 11021 of the light-emitting end 1102 of the optical fiber 110 to be opposite to each other and parallel to each other in the first direction F1, and make the center connection line of the two extend in the first direction F1.

[0254] The center alignment of the end face 11021 of the light-emitting end 1102 and the electron excitation layer 121 can be completed with the aid of a microscope.

[0255] S2203. Connect the annular heating sheet 40 to an external power supply to apply a first preset voltage to the annular heating sheet 40, and preheat the electron excitation layer 121 on the temporary substrate 20 (heat it to the preheating temperature), which is beneficial to making the electron excitation layer 121 flatter.

[0256] Optionally, the first preset voltage is 1v - 1.5v, and the preheating temperature is 50 - 60°C.

[0257] S2204. Drive the optical fiber 110 to move in the first direction F1 to contact the electron excitation layer 121. It is possible to make the end face 11021 of the light-emitting end 1102 and the electron excitation layer 121 contact to form Newton's rings.

[0258] S2205. Make the electron excitation layer 121 closely adhere to the end face 11021 of the light-emitting end 1102 of the optical fiber 110 at a preset temperature, which specifically includes: applying a second preset voltage to the annular heating sheet 40 and heating the electron excitation layer 121 on the temporary substrate 20 to the preset temperature, which is beneficial to making the electron excitation layer 121 more closely arranged on the end face 11021 of the light-emitting end 1102.

[0259] Optionally, the second preset voltage is 2.5v - 4v, and the preset temperature is 90 - 100°C.

[0260] S2206. Remove the temporary substrate 20. The temporary substrate 20 can be removed by means of melting heating combined with solvent immersion. Specifically, apply a third preset voltage to the annular heating sheet 40 and heat the temporary substrate 20 to the melting temperature until it melts. It should be noted that the melting point of the electron excitation layer 121 is much higher than that of the temporary substrate 20.

[0261] Optionally, the third preset voltage is 5.5V - 6V, and the melting temperature is 130 - 150 °C.

[0262] After the electron excitation layer 121 is tightly disposed on the end face 11021 of the light output end 1102, the portion of the temporary substrate 20 in contact with the annular heating sheet 40 can be melted by melting heating. The electron excitation layer 121 can be separated from the annular heating sheet 40 and closely adhered to the end face 11021 of the light output end 1102 of the optical fiber 110, which is convenient for subsequent removal of the temporary substrate 20 remaining on the electron excitation layer 121. The portion of the temporary substrate 20 not in contact with the annular heating sheet 40 remains on the electron excitation layer 121. The optical fiber 110 can be taken off the fixture and the light output end 1102 of the optical fiber 110 can be immersed in acetone to dissolve the remaining temporary substrate 20 on the electron excitation layer 121 and completely remove the temporary substrate 20.

[0263] The preparation method of the anode target 200 includes the following steps:

[0264] S310. Select a copper wire according to the inner diameter of the tube body 300 as the anode target 200. The outer diameter of the copper wire is approximately equal to the inner diameter of the tube body 300 so that the tube body 300 can be sleeved on the anode target 200.

[0265] S320. Cut one end of the anode target 200 to form a reflection target surface 210, polish the reflection target surface 210, and straighten and shape the anode target 200. Exemplarily, the reflection target surface 210 is disposed at an angle of 45° with respect to the longitudinal extension direction of the anode target 200.

[0266] By polishing the reflection target surface 210, the reflection target surface 210 can be made smoother, which is more conducive to the regulation of the X-ray emission angle and performance. Considering that the copper wire is prone to bending during the processing, in this application, by straightening and shaping the anode target 200, it is more conducive to the subsequent assembly of the anode target 200 in the tube body 300.

[0267] S330. Weld an external electrode 400 to the end of the anode target 200 far from the reflection target surface 210. The external electrode 400 is sleeved on the anode target 200 and is used for electrical connection to the positive electrode of the power supply.

[0268] The conductive connection layer 130 combined with the electron source 100 is used for electrically connecting to the negative electrode of the power supply. When the X-ray tube 10 is in use, the electrons emitted from the electron excitation layer 121 can be emitted towards the anode target 200 along the extending direction of the optical fiber 110 under the action of a preset electric field, which can better excite the anode target 200 to emit X-rays with relatively concentrated energy.

[0269] S40. Determine the installation positions of the electron source 100 and the anode target 200 on the tube body 300 and make marks.

[0270] S60. In a vacuum environment, install the electron source 100 and the anode target 200 at the corresponding marked positions respectively. The electron source 100 and the anode target 200 can be adhesively bonded to the corresponding marked positions respectively, so that the tube body 300 is sleeved on the optical fiber 110 of the electron source 100 and the anode target 200 respectively, and the external electrode 400 is arranged between the outer peripheral wall of the anode target 200 and the inner peripheral wall of the second port 303. Then, the parts of the tube body 300 sleeved on the optical fiber 110 and the parts of the tube body 300 sleeved on the anode target 200 are clamped and fixed to seal the tube body 300 to form a vacuum chamber 301.

[0271] The implementation schemes of the present invention will be described in detail below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following embodiments, the guidance given in the present invention is preferably referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0272] Example 1

[0273] The optical fiber 110 is a single-mode optical fiber. The diameter of the core 111 of the optical fiber 110 is 8.2 μm, the diameter of the optical fiber 110 is 125 μm, the angle ɑ is selected to be 30 degrees, that is, the bevel angle of the optical fiber 110 forms a 30-degree angle with the axis of the optical fiber 110. The wavelength of the laser transmitted in the optical fiber 110 is 1550 nm. The conductive connection layer 130 includes 5 nm of titanium and 60 nm of gold laminated on the optical fiber 110. Among them, the core 111 at the end face 11021 of the light output end 1102 is exposed (without being covered by the conductive connection layer 130). The electron excitation layer 121 is made of graphene two-dimensional material (the thickness of the graphene two-dimensional material is 1 nm). The shape of the graphene two-dimensional material is not limited and can be polygonal, circular, elliptical, etc. The electron excitation layer 121 is disposed on the end face 11021 of the light output end 1102 of the optical fiber 110 and completely covers the core 111 of the optical fiber 110. Exemplarily, in the radial direction of the optical fiber 110, the size of the electron excitation layer 121 is 30 - 60 μm (much larger than the diameter of the core 111). In this embodiment, in the radial direction of the optical fiber 110, the size of the electron excitation layer 121 is 50 μm. A copper wire with a diameter of 125 microns is selected as the anode target 200, and β is 45°, that is, the reflection target surface 210 forms a 45° angle with the extending direction of the optical fiber 110. The inner tube 310 of the tube body 300 is a beryllium hollow tube. The inner diameter of the inner tube 310 is 125 microns, the outer diameter of the inner tube 310 is 300 microns, and the length of the inner tube 310 is 6 cm. The outer tube 320 is made of a lead hollow tube. The inner diameter of the outer tube 320 is 300 microns, the outer diameter of the outer tube 320 is 1000 microns, and the length of the outer tube 320 is 6 cm. The output window 311 is square, and the length and width of the output window 311 are 200 microns respectively.

[0274] Embodiment 2

[0275] The optical fiber 110 is a single-mode optical fiber. The diameter of the core 111 of the optical fiber 110 is 8.2 μm, the diameter of the optical fiber 110 is 125 μm, and the wavelength of the laser transmitted in the optical fiber 110 is 1550 nm. The conductive connection layer 130 includes 5 nm of titanium and 60 nm of gold laminated on the optical fiber 110. Among them, the core 111 at the light-emitting end 1102 is exposed (without being covered by the conductive connection layer 130). The electron excitation layer 121 is made of a two-dimensional graphene material (the thickness of the two-dimensional graphene material is 8 nm). The shape of the two-dimensional graphene material is not limited and can be polygonal, circular, elliptical, etc. The electron excitation layer 121 is disposed on the end face 11021 of the light-emitting end 1102 of the optical fiber 110 and completely covers the core 111 of the optical fiber 110. For example, in the radial direction of the optical fiber 110, the size of the electron excitation layer 121 is 30 - 60 μm (much larger than the diameter of the core 111. In this embodiment, in the radial direction of the optical fiber 110, the size of the electron excitation layer 121 is 40 μm). A copper wire with a diameter of 125 microns is selected as the anode target 200, and β is 30°, that is, the reflection target surface 210 forms an angle of 30° with the extending direction of the optical fiber 110; the inner tube 310 of the tube body 300 is a beryllium hollow tube, the inner diameter of the inner tube 310 is 125 microns, the outer diameter of the inner tube 310 is 300 microns, the length of the inner tube 310 is 6 cm, the outer tube 320 is made of a lead hollow tube, the inner diameter of the outer tube 320 is 300 microns, the outer diameter of the outer tube 320 is 1000 microns, the length of the outer tube 320 is 6 cm, and the output window 311 is square, and the length and width of the output window 311 are 200 microns respectively.

[0276] Example 3

[0277] Please refer to Figure 13, the optical fiber 110 is a single-mode optical fiber. The diameter of the core 111 of the optical fiber 110 is 8.2 μm, the diameter of the optical fiber 110 is 125 μm, and the wavelength of the laser transmitted in the optical fiber 110 is 1550 nm. The above-mentioned conductive connection layer 130 is formed on the outer surface of the optical fiber 110. The conductive connection layer 130 includes 5 nm of titanium and 50 nm of gold laminated on the light-emitting end 1102 of the optical fiber 110. Among them, the core 111 at the light-emitting end 1102 is exposed (not covered by the conductive connection layer 130). By adopting the above operation step of "transferring the electron excitation layer 121 on the temporary substrate 20 to the end face 11021 of the light-emitting end 1102 of the optical fiber 110", an auxiliary layer 122 with a thickness of 1 nm and made of graphene is formed on the end face 11021 of the light-emitting end 1102 of the optical fiber 110; then, a plurality of nanotubes are deposited on the auxiliary layer 122. The axial direction of the nanotubes is parallel to the extending direction of the core 111 to obtain the electron excitation layer 121, and then the electron source 100 is obtained. Among them, the first conductive part 131 of the conductive connection layer 130 is arranged on the end face 11021 of the light-emitting end 1102 of the optical fiber 110 and overlaps with the auxiliary layer 122, and the second conductive part 132 of the conductive connection layer 130 is arranged on the circumferential side surface of the optical fiber 110.

[0278] Comparative Example 1

[0279] An electron source is prepared according to the structure of Example 1, and the difference is only that the electron excitation layer 121 in Example 1 is replaced by a gold layer with a thickness of 100 nm, and the gold layer is prepared by deposition.

[0280] Comparative Example 2

[0281] An electron source is prepared according to the structure of Comparative Example 1, and the difference is only that the electron excitation layer 121 in Comparative Example 1 is replaced by a gold layer with a thickness of 1 nm.

[0282] The electron sources are prepared by using the above-mentioned examples and comparative examples, and the performance of the prepared electron sources is tested. The test results are as follows in the table:

[0283] Table 1

[0284] Number Stability Lifespan Working vacuum degree Example 1 1％ 2000h 10Pa Example 2 1％ 2000h 10Pa Example 3 2％ 500 h <![CDATA[10 -3 Pa]]> Comparative Example 1 10％ 100 h <![CDATA[10 -5 Pa]]> Comparative Example 2 20％ 20 h <![CDATA[10 -5 Pa]]>

[0285] Among them, stability refers to when the excitation power of the electron source is 50% or more of the damage power and the vacuum degree is 2×10 -5 Pa, the continuous emission current is 1 hour. After removing the bad points, the ratio of the difference between the maximum current and the minimum current to the average current is the stability. The stability can reflect the working stability of the electron source. Lifetime refers to when the excitation power of the electron source is 50% or more of the damage power and the vacuum degree is 2×10 -5When the pressure is Pa, the continuous emission current is measured until the current decays to less than 10% of the initial value, which is defined as the lifetime. The operating vacuum refers to the continuous emission current when the excitation power of the electron source is 50% or more of the damage power. The vacuum is gradually increased until a rapid decay of the current occurs (rapid decay is defined as a current decay of more than 50% within 1 minute). The vacuum at this time is defined as the operating vacuum. As can be seen from the above table: The electron source of the present application has good stability, a long lifetime, and a good operating vacuum.

[0286] Through testing, it was found that the lifetime of the electron source prepared by Examples 1-3 is higher than that of the electron source prepared by the comparative example; the stability of the electron source prepared by Examples 1-3 is better than that of the electron source prepared by the comparative example.

[0287] In summary, low-dimensional materials such as zero-dimensional materials, one-dimensional materials, and two-dimensional materials in the present application have atomic-level dimensions. Electrons incident from the back can be emitted into the vacuum without passing through in-body transmission, which is very suitable for ultrafast electron sources with narrow pulse widths; moreover, low-dimensional materials and different types of optical fibers can be directly integrated, bringing ultra-high stability and integration; in addition, low-dimensional materials have no dangling bonds, are stable, have a high melting point, and are not easily damaged, making them suitable for large-beam electron sources with high-power excitation; low-dimensional materials and needle tips can be integrated to obtain very sharp optical fiber tips, with large optical field and electric field enhancement factors, providing a large emission beam current; there are many combinations of low-dimensional materials, suitable for optoelectronic sources with various properties. Finally, the optical fiber integrated low-dimensional material electron source and the low-dimensional material integration have significant advantages. The optical fiber can not only transmit laser light, but also, as a carrier of low-dimensional materials, provide a stable excitation source with adjustable wavelength, polarization, and optical mode, which can be applied to different application scenarios, and there is no need to provide a complex optical path, with the characteristics of small volume and high integration. When integrated with other devices, it is possible to achieve stable integration without performing a cracking transformation on the vacuum electronic device.

[0288] Compared with the X-ray tube in the related art that uses a grid structure as the accelerating electrode, in the present application, there is a preset electric field between the anode target 200 and the electron excitation layer 121, so that the electrons emitted from the electron excitation layer 121 can be emitted towards the anode target 200 along the extension direction of the optical fiber 110 under the action of the preset electric field, saving space in the vacuum chamber 301, simplifying the optical system and the electrical system, and making it easier to form an integrated and miniaturized X-ray tube 10.

[0289] Compared with traditional X-ray tubes, a part of the inner tube 310 of the tube body 300 of the present application serves as the output window 311, which maximally simplifies the window structure and is more conducive to the miniaturization of the X-ray tube 10. In addition, different from the relatively macroscopic and complex mechanical structures in the prior art, this solution adopts a highly integrated optical fiber structure, and reduces the existing centimeter-scale small X-ray source to the micron scale while ensuring that the power is not much different.

[0290] The electron source 100 and the anode target 200 are assembled in the tube body 300 with a smaller diameter, so that the electron excitation layer 121 and the anode target 200 can well accelerate electrons in the smaller vacuum chamber 301, which is conducive to the high integration and miniaturization of the electron source 100 and the X-ray emission structure, and helps to realize the portable application of the X-ray tube 10 and the metal flaw detection in a narrow space.

[0291] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0292] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An X-ray tube, characterized in that, include: A tube body, wherein the tube body has a vacuum chamber; An electron source, comprising an optical fiber and an electron emission layer, wherein the light-emitting end of the optical fiber is located in the vacuum chamber, the electron emission layer is arranged at the light-emitting end of the optical fiber, and the electron emission layer at least comprises an electron excitation layer, and the electron excitation layer is arranged on the light-emitting path of the optical fiber emitting laser, so that the electron excitation layer can emit electrons under the excitation of the laser; as well as an anode target, arranged in the vacuum chamber, and opposite to and spaced from the light-emitting end of the optical fiber, and used to receive electrons emitted by the electron excitation layer to emit X-rays; Wherein, the tube body is provided with an output window arranged toward the anode target, and the output window is configured to guide the X-rays to be emitted out of the vacuum chamber; The electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

2. The X-ray tube according to claim 1, characterized in that, Along the extending direction of the optical fiber, the electron source and the anode target are arranged at intervals; The anode target has a reflective target surface facing the light output end, and the reflective target surface is arranged at an angle to the extension direction of the optical fiber; The output window is arranged on the side wall of the tube body and faces the reflective target surface.

3. The X-ray tube according to claim 1, characterized in that, The anode target includes a transmission anode; Along the longitudinal extension direction of the tube body, the electron source and the output window are arranged at opposite ends of the tube body, and the transmission anode is located between the electron source and the output window.

4. The X-ray tube according to any one of claims 1 to 3, characterized in that, Along the extension direction of the optical fiber, the anode target is spaced apart from the light-emitting end of the optical fiber, and there is a preset electric field between the anode target and the electron excitation layer, so that the electrons emitted from the electron excitation layer can be accelerated linearly along the extension direction of the optical fiber.

5. The X-ray tube according to claim 4, characterized in that, The electron source further comprises a conductive connection layer, which is at least arranged on the light-emitting end of the optical fiber, and the conductive connection layer is electrically connected to the electron excitation layer.

6. The X-ray tube according to any one of claims 1-3, characterized in that, The tube body is respectively sleeved on the optical fiber and the anode target.

7. The X-ray tube according to claim 6, characterized in that, The tube body has a first port communicating with the vacuum chamber; The light-emitting end of the optical fiber extends into the vacuum chamber through the first port, and the outer peripheral wall of the optical fiber is sealed and connected to the inner peripheral wall of the first port.

8. The X-ray tube according to claim 7, characterized in that, The tube body further has a second port arranged opposite to the first port, and a side of the anode target away from the light-emitting end extends out of the vacuum chamber through the second port; The outer peripheral wall of the anode target is sealed and connected to the inner peripheral wall of the second port.

9. The X-ray tube according to claim 8, characterized in that, The X-ray tube further comprises an external electrode, wherein the external electrode is disposed between the outer peripheral wall of the anode target and the inner peripheral wall of the second port; Along the longitudinal extension direction of the tube body, one end of the external electrode is located in the vacuum chamber, and the other end extends out of the vacuum chamber.

10. The X-ray tube according to claim 7, characterized in that, The optical fiber has a light input end arranged opposite to the light output end, and an end face of the light input end is arranged flush with the plane where the first port is located; or The light incident end extends out of the vacuum chamber through the first port.

11. The X-ray tube according to claim 6, characterized in that, The tube body includes an inner tube sleeved on the optical fiber and the anode target, and an outer tube sleeved on the inner tube. An opening is provided on the outer tube, and a part of the structure of the inner tube is exposed through the opening to form the output window; The material of the inner tube includes an X-ray transmissive material, and the material of the outer tube includes an X-ray blocking material.

12. The X-ray tube according to claim 6, characterized in that, The outer diameter of the tube body is 125 μm - 2000 μm, and the length of the tube body is 3 cm - 9 cm.

13. The X-ray tube according to any one of claims 1-3, characterized in that, The optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core. The end face of the light-emitting end of the optical fiber is arranged at an angle with the extending direction of the core; The electron emission layer is arranged on the end face of the light-emitting end of the optical fiber, and the electron excitation layer covers the core of the optical fiber. The laser emitted from the core can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the core and emits electrons.

14. The X-ray tube according to any one of claims 1-3, characterized in that, The optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core; A light leakage notch is formed in the radial direction of the light-emitting end of the optical fiber; The electron emission layer is arranged on the bottom wall surface of the light leakage notch. The bottom wall surface of the light leakage notch is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface; The electron excitation layer also extends to the light-emitting end of the optical fiber.

15. The X-ray tube according to any one of claims 1 to 3, characterized in that, The optical fiber includes a perforated optical fiber, and the perforated optical fiber has a light guiding hole; The electron excitation layer is at least arranged on the side wall of the light guiding hole and extends to the light-emitting end of the optical fiber along the extending direction of the light guiding hole.

16. The X-ray tube according to any one of claims 1-3, characterized in that, The optical fiber includes a perforated optical fiber, and the perforated optical fiber has a light guiding hole; The electron emission layer is arranged on the end face of the light-emitting end of the perforated optical fiber, and the electron excitation layer covers one end of the light guiding hole located at the end face of the light-emitting end; The laser emitted from the perforated optical fiber can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the perforated optical fiber and emits electrons.

17. The X-ray tube according to any one of claims 1 to 3, characterized in that, The light-emitting end of the optical fiber is provided with a pointed end; The electron excitation layer covers the surface of the pointed end of the optical fiber; The optical fiber includes a core for transmitting laser. The laser emitted from the core can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the laser emitted from the core and emits electrons.

18. The X-ray tube according to any one of claims 1 to 3, characterized in that, The thickness of the electron excitation layer is less than or equal to 50 nm.

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