Electron source, electron gun and use of electron source

Abstract

The present application provides an electronic source, an electron gun and the use of the electron source. The electron source comprises an optical fiber, a conductive connection layer and an electron emission layer, the conductive connection layer being arranged on the outer surface of the optical fiber, and the electron emission layer comprising an electron excitation layer electrically connected to the conductive connection layer. The electron excitation layer comprises at least one of a zero-dimensional material, an one-dimensional material and a two-dimensional material; the electron excitation layer is arranged on a laser emission path of the optical fiber, and laser emitted by the optical fiber can be directly irradiated on the electron emission layer, such that the electron excitation layer is excited by the laser and emits electrons.

Description

Electron source, electron gun, and application of electron source

[0001] Related applications

[0002] This application claims priority to Chinese patent applications filed on December 29, 2023, with application numbers 2023118662886, 202311869450X, 2023118659205, 202311865833X, 2023118694478, 2023118663111, 2023118662693, 2023118663041, 2023118694209, 2023118662763, 2023118659173 and 202311865921X, the entireties of which are hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of electron sources, and in particular to an electron source, an electron gun, and applications of the electron source. Background Art

[0004] An electron source is a device that generates vacuum electrons. Traditional electron sources are categorized by their excitation method as thermal emission, field emission, and photoemission. Thermal emission electron sources primarily use metal materials. When heated to thousands of degrees Celsius, electrons are thermally excited and detach from the material's surface, forming vacuum electrons. Field emission electron sources primarily use metal needle tips. Under the influence of a strong external electric field, a tip discharge effect is generated. Photoemission electron sources use metal materials as photocathodes, irradiating the photocathode material with laser light to generate electrons.

[0005] However, the electron source in traditional technology cannot take into account both emission efficiency and stability. How to provide an electron source with high electron emission efficiency and good stability has become a technical problem that urgently needs to be solved. Summary of the Invention

[0006] According to various embodiments of the present application, an electron source, an electron gun, and applications of the electron source are provided.

[0007] In a first aspect, the present application provides an electron source, comprising an optical fiber, a conductive connection layer, and an electron emission layer, wherein the conductive connection layer is disposed on the outer surface of the optical fiber;

[0008] The electron emission layer includes an electron excitation layer electrically connected to the conductive connection layer, and the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material;

[0009] The electron excitation layer is arranged on the laser emission path of the optical fiber, and the laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons.

[0010] In some embodiments, the thickness of the electron excitation layer is 0.1 nm to 100 nm.

[0011] In some embodiments, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on a side of the electron emission layer close to the optical fiber; or,

[0012] The auxiliary layer is stacked on a side of the electron excitation layer away from the optical fiber.

[0013] In some embodiments, the auxiliary layer includes at least one of a conductive support layer and a heat dissipation support layer.

[0014] In some embodiments, the auxiliary layer has a thickness of 0.1 nm to 100 nm and a light transmittance of ≥10%.

[0015] In some embodiments, the auxiliary layer includes a conductive supporting layer, and the conductive supporting layer is electrically connected to the conductive connecting layer.

[0016] In some embodiments, the material of the conductive support layer includes a conductive metal, the laser wavelength in the optical fiber is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W.

[0017] In some embodiments, the electron excitation layer includes a zero-dimensional material.

[0018] In some embodiments, the density of the zero-dimensional material in the electron excitation layer is 10 / mm 2 ~10 12 Pieces / mm 2 .

[0019] In some embodiments, the gap between two adjacent particles of the zero-dimensional material is zero.

[0020] In some embodiments, the average particle size of the zero-dimensional material is 1 nm to 100 μm.

[0021] In some embodiments, the electron excitation layer includes a one-dimensional material.

[0022] In some embodiments, the one-dimensional material has a diameter of 1 nm to 20 nm.

[0023] In some embodiments, the electron excitation layer comprises a plurality of the one-dimensional materials, and the axes of any two of the one-dimensional materials are parallel.

[0024] In some embodiments, the electron excitation layer comprises a plurality of the one-dimensional materials, and a gap between two adjacent one-dimensional materials along a radial direction of the one-dimensional material is zero.

[0025] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer and the emitting direction of the laser is 0 to 90°.

[0026] In some embodiments, the axial direction of the one-dimensional material in the electron excitation layer is the same as the emission direction of the laser, and the length of the one-dimensional material is 0.1 μm to 1 μm.

[0027] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°, and the length of the one-dimensional material is 1 μm to 200 μm.

[0028] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°, and the length of the one-dimensional material is 10 μm to 30 μm.

[0029] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer and the emitting direction of the laser is 45° to 90°.

[0030] In some embodiments, the electron excitation layer includes at least one layer of two-dimensional material.

[0031] In some embodiments, the two-dimensional material has a thickness of 0.1 nm to 50 nm.

[0032] In some embodiments, the electron excitation layer includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction of the optical fiber, and the two-dimensional materials are all conductive two-dimensional materials; the two adjacent layers of the two-dimensional materials are the same or different.

[0033] In some embodiments, the angle between the crystal axes of two adjacent layers of the two-dimensional material is 0° to 360°.

[0034] In some embodiments, the electron excitation layer is formed by splicing at least two different two-dimensional materials, and the laser of the optical fiber is irradiated at the splicing site of adjacent two-dimensional materials.

[0035] In some embodiments, the material in the electron excitation layer includes a one-dimensional material and a zero-dimensional material disposed at an end and / or a side of the one-dimensional material.

[0036] In some embodiments, the diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm.

[0037] In some embodiments, the average particle size of the zero-dimensional material is 1 nm to 100 nm.

[0038] In some embodiments, the electron excitation layer includes a zero-dimensional material and a two-dimensional material, and the zero-dimensional material is disposed on a surface of the two-dimensional material.

[0039] In some embodiments, the electron excitation layer includes a one-dimensional material and a two-dimensional material, and the one-dimensional material is disposed on the surface of the two-dimensional material.

[0040] In some embodiments, the electron source further satisfies at least one of the following conditions:

[0041] (1) The zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals;

[0042] (2) The one-dimensional material comprises at least one of a nanotube, a nanobelt, and a nanowire;

[0043] (3) The two-dimensional material includes at least one of graphene, black phosphorus, transition metal chalcogenides and hexagonal boron nitride.

[0044] In some embodiments, the optical fiber is a solid core optical fiber, a needle-tip optical fiber, a side-section optical fiber, or a holey optical fiber.

[0045] In some embodiments, the optical fiber includes a core for transmitting laser light and a cladding layer wrapped around the core, and an end face of the light-emitting end of the optical fiber is arranged at an angle to an extension direction of the core;

[0046] 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 pulse laser emitted from the core can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the pulse laser emitted from the core and emits electrons.

[0047] In some embodiments, the optical fiber is a holey optical fiber having a light-guiding hole; the electron excitation layer is at least provided on a side wall of the light-guiding hole and extends along an extension direction of the light-guiding hole.

[0048] In some embodiments, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on a side of the electron excitation layer close to the sidewall of the light guide hole; or,

[0049] The auxiliary layer is stacked on a side of the electron excitation layer away from a sidewall of the light guide hole.

[0050] In some embodiments, the electron excitation layer includes a first portion that completely covers the sidewall of the light guide hole, and a second portion that is provided on the end face of the light output end of the holey fiber;

[0051] The second portion is connected to the first portion and is electrically connected to the conductive connection layer.

[0052] In some embodiments, the conductive connection layer includes a first conductive portion provided on an end face of the light-emitting end of the holey fiber, and a second conductive portion provided on a circumferential side surface of the holey fiber;

[0053] The first conductive portion is connected to the second conductive portion and overlaps with the second portion of the electron excitation layer.

[0054] In some embodiments, the optical fiber is a holey optical fiber, the electron emission layer is arranged on the end face of the light-emitting end of the holey optical fiber, and the electron excitation layer covers one end of the end face of the light-guiding hole located at the light-emitting end; the pulsed laser emitted by the holey optical fiber can be directly irradiated on the electron emission layer, so that the electron excitation layer is excited by the pulsed laser emitted by the holey optical fiber and emits electrons.

[0055] In some embodiments, the light-emitting end of the optical fiber is provided with a tip portion; and the electron excitation layer covers the surface of the tip portion of the optical fiber.

[0056] In some embodiments, the electron excitation layer includes a first portion;

[0057] The projection of the first portion in a target plane perpendicular to the extending direction of the fiber core covers the projection of the fiber core in the target plane;

[0058] The first portion is electrically connected to the conductive connection layer.

[0059] In some embodiments, the electron excitation layer further includes a second portion connected to the first portion; the projection of the second portion in the target plane is located outside the projection of the first portion in the target plane; and the second portion overlaps the conductive connection layer.

[0060] In some embodiments, the conductive connection layer includes a first conductive portion provided at the tip of the optical fiber, and a second conductive portion connected to the first conductive portion and provided on the circumferential side of the optical fiber; the first conductive portion overlaps the second portion.

[0061] In some embodiments, along the extension direction of the fiber core, the size of the tip portion is L1, and the size of the electron excitation layer is L2, wherein L1 is larger than L2.

[0062] In some embodiments, the size of the tip portion and the size of the electron excitation layer satisfy the following relationship: L2>1 / 2×L1.

[0063] In some embodiments, the optical fiber includes a core for transmitting laser light and a cladding layer wrapping the core;

[0064] The light-emitting end of the optical fiber is provided with a light leakage notch along the radial direction of the optical fiber;

[0065] The electron emission layer is provided on the bottom wall surface of the light leakage gap, the bottom wall surface of the light leakage gap is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the fiber core on the bottom wall surface;

[0066] The electron excitation layer also extends to the light-emitting end of the optical fiber.

[0067] In a second aspect, the present application provides an electron gun, comprising a housing, a grid, an anode, and the electron source as described in the first aspect;

[0068] The electron source is fixed in the shell, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

[0069] In a third aspect, the present application provides an application of the electron source as described in the first aspect, wherein the application of the electron source includes at least one of an electron microscope, an electron beam exposure machine, an X-ray tube, a free electron laser, and a display.

[0070] In a fourth aspect, the present application provides a four-dimensional electron microscope for scanning a sample, the four-dimensional electron microscope comprising:

[0071] A light source assembly, for emitting pulsed laser;

[0072] The electron source according to the first aspect comprises an excitation optical fiber coupled to the light source assembly, and an electron emission layer, wherein the electron emission layer comprises at least an electron excitation layer, the electron excitation layer being arranged on a light output path of the pulsed laser emitted by the excitation optical fiber so that the electron excitation layer can emit an electron beam under the excitation of the pulsed laser; the electron excitation layer comprises at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material;

[0073] an electron optical component, disposed on the electron beam exit side of the electron source, the electron optical component being used to adjust the deflection direction of the electron beam so that the electron beam is incident on the sample; and

[0074] The detector is arranged at one side of the sample and is used for collecting the reflected electron signal of the electron beam incident on the sample or the transmitted electron signal of the electron beam penetrating the sample.

[0075] In some embodiments, the light source assembly includes a light source and a first optical fiber, the light source is coupled to one end of the first optical fiber, and the excitation optical fiber is connected to the other end of the first optical fiber;

[0076] The light source is used to emit the pulse laser, and the first optical fiber is used to transmit the pulse laser emitted by the light source to the excitation optical fiber.

[0077] In some embodiments, the light source assembly further comprises a first fiber optic beam splitter, a second optical fiber, and a first fiber optic delay device;

[0078] The first fiber optic beam splitter has a first input end coupled to the light source, and a first output end opposite to the first input end, the first output end being connected to the first optical fiber and the second optical fiber respectively;

[0079] One end of the second optical fiber away from the first optical fiber beam splitter extends toward the sample;

[0080] The first optical fiber delay device is coupled to the second optical fiber to perform time delay on the light beam propagating in the second optical fiber.

[0081] In some embodiments, the reflected electron signal comprises a secondary electron signal or a backscattered electron signal;

[0082] The sample has an incident surface arranged opposite to the electron beam exit side of the electron source;

[0083] The detector includes a backscatter detector or a secondary detector, and the backscatter detector or the secondary detector is used to face the incident surface of the sample, so that the secondary detector receives the secondary electron signal or the backscatter detector receives the backscattered electron signal.

[0084] In some embodiments, the reflected electronic signal comprises a cathodoluminescent signal;

[0085] The sample has an incident surface arranged opposite to the electron beam exit side of the electron source;

[0086] The detector includes a cathode fluorescence analysis system, which is used to face the incident surface of the sample to receive the cathode fluorescence signal.

[0087] In some embodiments, the sample has an incident surface disposed opposite to an electron beam exit side of the electron source, and an exit surface opposite to the incident surface;

[0088] The detector includes a receiving screen, which is used to face the exit surface of the sample to receive the electron beam that penetrates the sample.

[0089] In some embodiments, the light source assembly further comprises a second fiber optic beam splitter, a third optical fiber, and a second fiber optic delay device;

[0090] The second fiber optic beam splitter has a second input end coupled to the light source, and a second output end opposite to the second input end, the second output end being connected to the first optical fiber and the third optical fiber respectively;

[0091] One end of the third optical fiber away from the second optical fiber beam splitter is extended toward the sample;

[0092] The second optical fiber delay device is coupled to the third optical fiber and is used to time delay the light beam propagating in the third optical fiber.

[0093] In some embodiments, the four-dimensional electron microscope further comprises a housing;

[0094] The housing has a vacuum chamber, and the electron source and the electron optical component are sequentially arranged in the vacuum chamber;

[0095] The housing is provided with an opening communicating with the vacuum chamber, and the light incident end of the excitation optical fiber of the electron source is exposed through the opening and coupled to the light source assembly.

[0096] In some embodiments, the outer peripheral wall of the excitation optical fiber is sealed to the inner side wall of the opening.

[0097] In some embodiments, the electron source further comprises an anode, the anode having a first electron channel, and the electron optical assembly having a second electron channel communicating with the first electron channel;

[0098] There is a preset electric field between the anode and the electron excitation layer. Driven by the preset electric field, the electron beam can pass through the first electron channel and the second electron channel and be incident on the sample.

[0099] In a fifth aspect, the present application provides an electronic exposure machine for exposing a sample, the electronic exposure machine comprising:

[0100] a light source for emitting laser light;

[0101] The electron source according to the first aspect comprises an optical fiber coupled to the light source, and an electron emission layer, wherein the electron emission layer comprises at least an electron excitation layer, and the electron excitation layer is arranged on a light output path of the laser emitted by the optical fiber so that the electron excitation layer can emit an electron beam under the excitation of the laser; the electron excitation layer comprises at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material; and

[0102] The electron optical component is arranged on the electron beam exit side of the electron source, and is used to adjust the focus and deflection direction of the electron beam so that the electron beam is incident on the sample to form a preset exposure pattern on the sample.

[0103] In some embodiments, the electronic exposure machine further comprises a housing;

[0104] The housing has a vacuum chamber, and the light-emitting end of the optical fiber of the electron source and the electron optical component are arranged in the vacuum chamber at intervals from each other;

[0105] The electron excitation layer is arranged on the light-emitting end of the optical fiber so as to be located on the light-emitting path of the laser emitted by the optical fiber.

[0106] In some embodiments, the housing is provided with an opening communicating with the vacuum chamber, and the light incident end of the optical fiber of the electron source is exposed through the opening and coupled to the light source;

[0107] The outer peripheral wall of the optical fiber is sealed and connected to the inner side wall of the opening.

[0108] In some embodiments, the light input end of the optical fiber of the electron source extends through the opening to the outside of the vacuum chamber to be coupled to the light source; or

[0109] The end face of the light incident end of the optical fiber of the electron source is arranged flush with the plane where the opening is located.

[0110] In some embodiments, the electron source further includes a light modulator connected between the light source and the optical fiber, and configured to control whether the laser light is transmitted to the optical fiber.

[0111] In some embodiments, the electron optical assembly includes a focusing magnetic lens and a deflection coil, and the focusing magnetic lens and the deflection coil are arranged at intervals on the electron beam exit side of the electron source along the exit direction of the electron beam.

[0112] In some embodiments, the optical modulator includes an electro-optical modulator or an optical switch.

[0113] In some embodiments, the electron source further comprises an anode, the anode having a first electron channel, and the electron optical assembly having a second electron channel communicating with the first electron channel;

[0114] There is a preset electric field between the anode and the electron excitation layer. Driven by the preset electric field, the electron beam can pass through the first electron channel and the second electron channel and be incident on the sample.

[0115] In a sixth aspect, the present application provides a multi-beam fiber optic electronic exposure machine for exposing a sample, the multi-beam fiber optic electronic exposure machine comprising:

[0116] a light source for emitting laser light;

[0117] The electron source according to the first aspect comprises an optical fiber assembly coupled to the light source, and an electron emission layer, wherein the electron emission layer comprises at least an electron excitation layer, and the optical fiber assembly comprises a plurality of fiber cores for transmitting the laser light; the electron excitation layer is arranged on a light exit path of the fiber cores for emitting the laser light, so that the electron excitation layer can emit an electron beam under the excitation of the laser light; the electron excitation layer comprises at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material;

[0118] The electron source further includes a light modulator, one end of which is connected to the light source, and the other end of which is connected to the plurality of fiber cores of the optical fiber assembly, and the light modulator is used to control whether the laser light emitted by the light source is transmitted into the corresponding fiber cores; and

[0119] The electron optical component is arranged on the electron beam exit side of the electron source, and is used to adjust the focus and deflection direction of the electron beam so that the electron beam is incident on the sample to form a preset exposure pattern on the sample.

[0120] In some embodiments, the optical fiber assembly includes a plurality of optical fibers arranged in an array, and the electron excitation layer is provided on the end face of one end of each optical fiber emitting the laser, so that the electron excitation layer is located on the light output path of the laser emitted from the core of the corresponding optical fiber.

[0121] In some embodiments, the optical modulator includes one of a spatial light modulator, an optical switch, and an electro-optical modulator.

[0122] In some embodiments, the electron optical assembly includes a focusing magnetic lens and a deflection coil, and the focusing magnetic lens and the deflection coil are arranged at intervals on the electron beam exit side of the electron source along the exit direction of the electron beam.

[0123] In some embodiments, the multi-beam fiber electronic exposure machine further comprises a housing;

[0124] The housing has a vacuum chamber, and the electron source and the electron optical component are sequentially arranged in the vacuum chamber;

[0125] The housing is provided with an opening communicating with the vacuum chamber, and the light incident end of the optical fiber assembly of the electron source is exposed through the opening and coupled to the light source;

[0126] The outer peripheral wall of the optical fiber assembly is sealed and connected to the inner side wall of the opening.

[0127] In some embodiments, the electron source further comprises an anode, the anode having a first electron channel, and the electron optical assembly having a second electron channel communicating with the first electron channel;

[0128] There is a preset electric field between the anode and the electron excitation layer. Driven by the preset electric field, the electron beam can pass through the first electron channel and the second electron channel and be incident on the sample.

[0129] In a seventh aspect, the present application provides an X-ray tube, comprising:

[0130] A tube body, wherein the tube body has a vacuum chamber;

[0131] The electron source according to the first aspect comprises 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 laser emitted by the optical fiber, so that the electron excitation layer can emit electrons under the excitation of the laser; and

[0132] an anode target disposed in the vacuum chamber, and opposite to and spaced from the light-emitting end of the optical fiber, the anode target being configured to receive electrons emitted by the electron excitation layer to emit X-rays;

[0133] The tube body is provided with an output window disposed toward the anode target, and the output window is configured to guide the X-rays to exit the vacuum chamber.

[0134] The electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

[0135] In some embodiments, along the extension direction of the optical fiber, the electron source and the anode target are spaced apart;

[0136] The anode target has a reflective target surface facing the light-emitting end, and the reflective target surface is arranged at an angle to the extending direction of the optical fiber;

[0137] The output window is arranged on the side wall of the tube body and faces the reflective target surface.

[0138] In some embodiments, the anode target comprises a transmissive anode;

[0139] 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.

[0140] In some embodiments, the anode target is spaced apart from the light-emitting end of the optical fiber along the extension direction 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 accelerated linearly along the extension direction of the optical fiber.

[0141] In some embodiments, the tube is respectively sleeved on the optical fiber and the anode target.

[0142] In some embodiments, the tube has a first port communicating with the vacuum chamber;

[0143] 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.

[0144] In some embodiments, the tube body further has a second port disposed opposite to the first port, and a side of the anode target facing away from the light-emitting end extends out of the vacuum chamber through the second port;

[0145] The outer peripheral wall of the anode target is sealed and connected to the inner peripheral wall of the second port.

[0146] In some embodiments, 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;

[0147] 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.

[0148] In some embodiments, the optical fiber has a light input end opposite to the light output end, and an end face of the light input end is flush with the plane where the first port is located; or

[0149] The light incident end extends out of the vacuum chamber through the first port.

[0150] In some embodiments, the tube body includes an inner tube sleeved over the optical fiber and the anode target, and an outer tube sleeved over the inner tube, wherein the outer tube is provided with an opening, and a portion of the structure of the inner tube is exposed through the opening to form the output window;

[0151] The material of the inner tube includes an X-ray transmitting material, and the material of the outer tube includes an X-ray blocking material.

[0152] In some embodiments, the outer diameter of the tube is 125 μm-2000 μm, and the length of the tube is 3 cm-9 cm.

[0153] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0154] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0155] FIG1 is a schematic structural diagram of an electron source provided in one embodiment of the present application;

[0156] FIG2 is a schematic structural diagram of an electron source with an auxiliary layer provided in one embodiment of the present application;

[0157] FIG3 is a schematic diagram of an electron source structure using densely arranged zero-dimensional materials provided in one embodiment of the present application;

[0158] FIG4 is a schematic diagram of a high-density arrangement of a zero-dimensional material provided in one embodiment of the present application;

[0159] FIG5 is a schematic diagram of an electron source structure using a zero-dimensional material combined with an auxiliary layer provided in one embodiment of the present application;

[0160] FIG6 is a schematic diagram of a low-density arrangement of a zero-dimensional material provided in one embodiment of the present application;

[0161] FIG7 is a schematic diagram of the structure of an electron source using a one-dimensional material provided in one embodiment of the present application;

[0162] FIG8 is a schematic diagram of the AA section in FIG7 of the present application;

[0163] FIG9 is a schematic diagram of an electron source structure using a one-dimensional material combined with an auxiliary layer provided in one embodiment of the present application;

[0164] FIG10 is a schematic diagram of the BB section in FIG9 of the present application;

[0165] FIG11 is a schematic diagram of an electron source structure using an obliquely arranged one-dimensional material provided in one embodiment of the present application;

[0166] FIG12 is a partial enlarged view of point A in FIG11 of the present application;

[0167] FIG13 is a schematic diagram of the BB section in FIG11 of the present application;

[0168] FIG14 is a schematic diagram of an electron source structure using an obliquely arranged one-dimensional material combined with an auxiliary layer, provided in one embodiment of the present application;

[0169] FIG15 is a CC cross-sectional view of FIG14 of the present application;

[0170] FIG16 is a schematic diagram of an electron source structure using two layers of different two-dimensional materials stacked together, provided in one embodiment of the present application;

[0171] FIG17 is a schematic diagram of another electron source structure provided in one embodiment of the present application using two layers of different two-dimensional materials stacked;

[0172] FIG18 is a schematic diagram of an electron source structure combining a two-dimensional material and an auxiliary layer provided in one embodiment of the present application;

[0173] FIG19 is a schematic structural diagram of an electron source using a planar heterojunction two-dimensional material provided in one embodiment of the present application;

[0174] FIG20 is a schematic plan view of a planar heterojunction two-dimensional material provided in one embodiment of the present application;

[0175] FIG21 is a schematic diagram of the structure of an electron source combining a two-dimensional material and an auxiliary layer provided in one embodiment of the present application;

[0176] FIG22 is a schematic diagram of an electron source structure with a two-dimensional material interlayer angle provided in one embodiment of the present application;

[0177] FIG23 is a schematic diagram of an electron source structure provided in one embodiment of the present application, wherein two-dimensional materials are stacked in layers within a holey optical fiber;

[0178] FIG24 is a schematic diagram of an electron source structure using a combination of zero-dimensional materials and one-dimensional materials, provided in one embodiment of the present application;

[0179] FIG25 is a schematic diagram of another electron source structure using a combination of zero-dimensional materials and one-dimensional materials provided in one embodiment of the present application;

[0180] FIG26 is a schematic diagram of the structure of an electron source using a combination of zero-dimensional materials and one-dimensional materials, provided in one embodiment of the present application;

[0181] FIG27 is a schematic diagram of another electron source structure using a combination of zero-dimensional materials and one-dimensional materials provided in one embodiment of the present application;

[0182] FIG28 is a schematic diagram of another electron source structure provided in one embodiment of the present application;

[0183] FIG29 is a schematic diagram of the structure of an electron source using a side-section optical fiber provided in one embodiment of the present application;

[0184] FIG30 is a schematic diagram of the structure of an electron source using a holey fiber provided in one embodiment of the present application;

[0185] FIG31 is a schematic diagram of the AA section in FIG30 of the present application;

[0186] FIG32 is a partial enlarged view of point B in FIG30 of the present application;

[0187] FIG33 is a circuit block diagram of an electron source and an anode using a holey fiber provided in one embodiment of the present application;

[0188] FIG34 is a schematic diagram of another structure of an electron source using a holey fiber provided in one embodiment of the present application;

[0189] FIG35 is a partial enlarged view of point C in FIG34 of the present application;

[0190] FIG36 is a schematic diagram of the structure of an electron source using a needle-tip optical fiber provided in one embodiment of the present application;

[0191] FIG37 is a partial enlarged view of point A in FIG36 of the present application;

[0192] FIG38 is a circuit block diagram of an electron source and an anode using a needle-tip optical fiber provided in one embodiment of the present application;

[0193] FIG39 is a schematic diagram of another structure of an electron source using a needle-tip optical fiber provided in one embodiment of the present application;

[0194] FIG40 is a partial enlarged view of point A in FIG39 of the present application;

[0195] FIG41 is a schematic structural diagram of an electron gun provided in one embodiment of the present application;

[0196] FIG42 is a schematic structural diagram of an embodiment of a four-dimensional electron microscope for detecting secondary electron signals provided in one embodiment of the present application;

[0197] FIG43 is a schematic structural diagram of an embodiment of a four-dimensional electron microscope for detecting cathode fluorescent light signals provided in one embodiment of the present application;

[0198] FIG44 is a schematic structural diagram of an embodiment of a four-dimensional electron microscope for detecting an electron beam penetrating a sample, provided in one embodiment of the present application;

[0199] FIG45 is a partial enlarged view of point A in FIG42-44 of the present application;

[0200] FIG46 is a schematic structural diagram of an electronic exposure machine provided in one embodiment of the present application;

[0201] FIG47 is a partial enlarged view of point A in FIG46 of the present application;

[0202] FIG48 is a schematic structural diagram of a multi-beam electron exposure machine provided in one embodiment of the present application;

[0203] FIG49 is a partial enlarged view of point A in FIG48 of the present application;

[0204] FIG50 is a schematic diagram of the structure of the multi-beam fiber optic electron exposure apparatus shown in FIG48 of the present application, in which the electron beam is focused on the sample to form multiple focused electron beam spots;

[0205] FIG51 is a schematic structural diagram of an embodiment of an optical fiber assembly of a multi-beam electron exposure machine provided in one embodiment of the present application, in which the fiber cores are arranged in an array;

[0206] FIG52 is a schematic structural diagram of an embodiment of an optical fiber assembly of a multi-beam electron exposure machine provided in one embodiment of the present application, in which the fiber cores are closely arranged to form pixel optical fibers;

[0207] FIG53 is a schematic structural diagram of an X-ray tube provided in one embodiment of the present application;

[0208] FIG54 is an enlarged schematic diagram of point A in FIG53 of the present application;

[0209] FIG55 is an enlarged schematic diagram of point B in FIG53 of the present application;

[0210] FIG56 is a schematic structural diagram of another X-ray tube provided in one embodiment of the present application;

[0211] Figure 57 is an enlarged schematic diagram of point F in Figure 56 of this application.

[0212] 100-electron source; 110-optical fiber; 111, fiber core; 112-wrapping layer; 113-annular light guide body; 1101, light input end; 1102, light output end; 11021, end face; h, light leakage gap; h1, bottom wall surface; h2, side wall surface; k, side wall of the light guide hole; j, tip; j1, surface; 120-electron emission layer; 121-electron excitation layer; 121a-first material layer; 121b-second material layer; 1211 first part; 1212 second part; 122-auxiliary layer; 130-conductive connection layer; 131-first conductive part; 132-second conductive part; 200-gate; 210-second electron channel; 300-anode; 310-first electron channel.

[0213] 10A-four-dimensional electron microscope; 110A-excitation optical fiber; 2A-light source assembly; 29A-light source; 21A-first optical fiber; 22A-second optical fiber; 23A-third optical fiber; 24A-first optical fiber beam splitter; 25A-second optical fiber beam splitter; 26A-first optical fiber delay; 27A-second optical fiber delay; 28A-optical switch; 3A-electron optical component; 31A-magnetic lens; 32A-intermediate mirror; 33A-projection mirror; 4A-detector; 41A-receiving screen; 42A-photographic chamber; 5A-sample; 6A-housing; 20A-temporary substrate; 30A-hole slide; 40A-ring heating plate.

[0214] 10B-electronic exposure machine; 200B-light source; 300B-housing; 310B-vacuum chamber; 400B-sample stage; 410B-sample; 500B-light modulator; 600B-electron optical component; 610B-focusing magnetic lens; 620B-deflection coil; 20B-temporary substrate; 30B-hole slide; 40B-ring heating plate.

[0215] 10C-multi-beam fiber optic electronic exposure machine; 101C-fiber optic assembly; 200C-light source; 300C-housing; 310C-vacuum chamber; 400C-sample stage; 410C-sample; 500C-light modulator; 600C-electron optical assembly; 610C-focusing magnetic lens; 620C-deflection coil; 20C-temporary substrate; 30C-hole slide; 40C-ring heating plate.

[0216] 10D-X-ray tube; 200D-anode target; 210D-reflective target surface; 220D-transmission anode; 300D-tube body; 310D-inner tube; 311D-output window; 320D-outer tube; 321D-opening; 301D-vacuum chamber; 302D-first port; 303D-second port; 400D-external electrode; 20D-temporary substrate; 30D-perforated slide; 40D-ring heater. DETAILED DESCRIPTION

[0217] Below in conjunction with embodiment and example, the application is further described in detail These embodiment and example are only used to illustrate the application and are not used to limit the scope of the application, and the purpose of providing these embodiment and example is to make the understanding of the disclosure of the application more thorough and comprehensive. It should also be understood that the application can be implemented in many different forms and is not limited to the embodiment and example described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the application, and the equivalent form obtained also falls within the protection scope of the application. In addition, in the description below, a large amount of specific details are given in order to provide a more complete understanding of the application, and it should be understood that the application can be implemented without one or more of these details.

[0218] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0219] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0220] In this application, the terms "first" and "second" in "the first aspect" and "the second aspect" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first" and "second" serve only as non-exhaustive enumeration and description and should be understood not to constitute a closed-ended limitation on quantity.

[0221] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0222] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly enumerating each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0223] All documents mentioned in this application are cited as references in this application, just as each document is cited as a reference individually. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When cited documents are involved in this application, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be adaptively amended according to the description in this application.

[0224] In traditional technologies, thermal emission electron sources mainly use metallic materials such as tungsten filaments and lanthanum hexaboride. When heated to thousands of degrees Celsius, electrons are thermally excited and detach from the surface of the material to form vacuum electrons. Field emission electron sources mainly use metal needle tips such as tungsten, which produce a tip discharge effect under the action of a strong electric field applied from the outside. Among them, the electron beam emitted by the thermal electron source can operate in a poor vacuum environment, has good adaptability to the environment and good stability, but has low brightness and poor coherence. The electron beam of the field emission electron source has high brightness and good coherence, but has high requirements for vacuum degree and is very sensitive to vibration. Whether it is a thermal emission electron source or a field emission electron source, the control of the electron emission properties is limited, and it is impossible to take into account coherence, pulse properties, emission efficiency and stability.

[0225] The light-emitting electron source uses metal materials such as Au as the material of the electron emission layer, with a thickness of more than 50nm, and even reaching hundreds of nanometers. However, the inventors of this application have found that the thickness of the electron emission layer of the metal material is relatively large, and the surface of the electron emission layer on which the laser directly acts (the bottom layer of the electron emission layer) and the surface of the electron emission side (the surface layer of the electron emission layer) are far apart (50nm to hundreds of nanometers). The electrons excited by the bottom layer are easily affected by metal lattice scattering in the process of passing through the electron emission layer, thereby affecting the emission efficiency. Moreover, metal materials are easily damaged under high-power laser irradiation, which affects the service life of the electron emission layer, thereby affecting the emission efficiency and stability of the electrons. Some electron sources use laser side incidence to excite electrons. Compared with laser back incidence, side incidence requires the vacuum cavity to be modified, and the irradiation method is difficult to operate, and there are problems such as unstable excitation conditions.

[0226] In addition, graphene is used as a saturable absorber in traditional technologies. Graphene has broadband saturable absorption characteristics and fast recovery time, and is used in the Q-switching and mode-locking of lasers, or graphene is used to adjust the laser spectrum for sensing detection. However, there is a difference between graphene laser regulation and graphene electron emission. The graphene photoexcited electron source is based on the photoelectric effect to excite and emit electrons, while graphene laser regulation is based on the principle of light absorption, thereby regulating the emission parameters of the laser. Specifically, there is a clear difference between graphene laser regulation and graphene electron emission. Graphene electron emission is based on the photoelectric effect, while graphene laser regulation is based on the principle of light absorption. In laser regulation, the graphene saturable absorber mainly utilizes the fact that the absorbance (or transmittance) of graphene increases (or decreases) with the increase of the incident light power, and eventually reaches the saturation threshold. It is mainly used in lasers to generate laser pulses. For example, in the ring fiber resonator of a fiber laser, when light circulates in the resonator, when the light power passing through the graphene saturable absorber exceeds its saturation absorption threshold, the light intensity in the cavity will instantly drop below the saturation absorption threshold due to the saturable absorption effect. This part of the fallen light energy is output from the cavity's beam splitter in the form of pulses.

[0227] Based on this, it is necessary to provide an electron source that can take into account both electron emission efficiency and stability.

[0228] This application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials and two-dimensional materials as materials for the electron emission layer. The low-dimensional materials emit electrons through the photoelectric effect under laser irradiation. The low-dimensional materials have atomic-level thickness, no dangling bonds and stable properties, thus having the characteristics of good stability and long service life; and the low-dimensional materials can be directly integrated with optical fibers, which can provide a stable excitation source with adjustable wavelength, polarization and optical mode, and can be suitable for different application scenarios.

[0229] In a first aspect, the present application provides an electron source, as shown in FIG1-41 , wherein the electron source 100 includes an optical fiber 110 , a conductive connection layer 130 , and an electron emission layer 120 , wherein the conductive connection layer 130 is disposed on the outer surface of the optical fiber 110 ;

[0230] The electron emission layer 120 includes an electron excitation layer 121 electrically connected to the conductive connection layer 130 to connect the low-dimensional material with an external circuit to form a complete circuit, thereby realizing charge replenishment and electric field control. The electron emission layer 120 can be excited to emit electrons under laser irradiation to form an electron beam;

[0231] The electron excitation layer 121 includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material;

[0232] The electron excitation layer 121 is disposed on the laser emission path of the optical fiber 110 , and the laser emitted by the optical fiber 110 can directly irradiate the electron emission layer 120 , so that the electron excitation layer 121 is excited by the laser and emits electrons.

[0233] It should be noted that the electron source of the present application transmits the laser to the electron emission layer material through an optical fiber to excite electrons. This is a back irradiation method and is convenient, fast, simple and easy to operate. It is significantly different from the side irradiation method of the laser tip.

[0234] It should be noted that the low-dimensional material in this application refers to zero-dimensional material, one-dimensional material or two-dimensional material.

[0235] This application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials or two-dimensional materials as the materials of the electron excitation layer. The low-dimensional materials have atomic-level thickness, and back-incident electrons can be emitted without being transmitted through the body, and the electron emission efficiency is high; and low-dimensional materials have no dangling bonds, are stable in nature and have a high melting point, are not easy to damage, and can be used in high-power excitation scenarios, with the characteristics of good stability and long service life.

[0236] In addition, low-dimensional materials can be directly integrated with optical fibers, which transmit lasers and, as a carrier of low-dimensional materials, can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without the need for complex optical paths and has the characteristics of small size and high integration.

[0237] Zero-dimensional materials typically have discrete energy levels. Under laser excitation, electrons are primarily excited by tunneling from these discrete energy levels, free from the influence of metal lattice scattering. This allows for the excitation of highly monochromatic electrons, with concentrated energy and minimal energy dispersion. Furthermore, zero-dimensional materials are atomically thin, allowing excited electrons in the electron excitation layer to be emitted without long-distance transmission, resulting in high electron emission efficiency. Furthermore, zero-dimensional materials lack dangling bonds, are stable, have a high melting point, and are not easily damaged, making them suitable for high-power excitation scenarios. They exhibit excellent stability, a long service life, and operate at low vacuum levels.

[0238] One-dimensional materials, with their small curvature radius (nanometer scale), can enhance light-matter interactions and provide a large field enhancement factor, enabling multiphoton emission and light field emission, making them suitable for applications requiring high-brightness electron sources. Two-dimensional materials, with their atomic-layer thickness, have little impact on the light transmission pattern during laser interaction, resulting in high stability. Furthermore, the excited electrons are emitted directly without scattering within the material, ensuring the purity of the emitted electrons and extremely narrow pulse widths.

[0239] In this application, zero-dimensional materials refer to materials that are nanoscale in all three dimensions of space, where electrons cannot move freely; one-dimensional materials refer to materials where electrons can only move freely in one non-nanoscale direction; and two-dimensional materials refer to materials where electrons can only move freely in two non-nanoscale dimensions (i.e., planar motion). The nanoscale refers to 0.1nm to 100nm. Zero-dimensional materials, one-dimensional materials, and two-dimensional materials can be excited to emit electrons under laser excitation.

[0240] It should be noted that the light exit path of an optical fiber in this application refers to the path of laser irradiation in the optical fiber. Taking a solid core optical fiber as an example, the laser emission position of the solid core optical fiber is located at the end face of the fiber core, that is, the electron emission layer can be set at the fiber core; taking a side-section optical fiber as an example, the laser emission position of the side-section optical fiber is located on the side of the side section of the side-section optical fiber, that is, the electron emission layer can be set at the side section. It is understandable that the electron emission layer in this application can be directly in contact with the laser emission surface of the optical fiber, or it can be supported by other structural layers, that is, it is sufficient to enable the laser emitted from the optical fiber to irradiate the electron emission layer.

[0241] It should also be noted that the purpose of electrically connecting the conductive connection layer and the electron emission layer in the present application is to connect the low-dimensional material to the external circuit to form a complete loop, thereby realizing charge replenishment and electric field control. As an embodiment, the conductive connection layer in the present application can be directly connected to the electron emission layer. In other embodiments, the conductive connection layer and the electron emission layer can also be electrically connected through other conductive structures. For example, taking a solid core optical fiber as an example, the conductive connection layer is arranged on the side of the solid core optical fiber, the electron emission layer is arranged at the core of the solid core optical fiber, the conductive connection layer and the electron emission layer are electrically connected, and there is no conductive connection layer at the core.

[0242] In some embodiments, the zero-dimensional material, the one-dimensional material, or the two-dimensional material each independently comprises a doping element.

[0243] This application involves doping low-dimensional materials with elements to improve their conductivity, modify their work function, and tune their electron emission properties. For example, alkali and alkaline earth metals can enhance their conductivity while simultaneously reducing their work function, thereby increasing the emission beam current. Elements such as boron, carbon, nitrogen, oxygen, fluorine, and rare earth elements can create discrete energy levels to produce narrow-energy electron beams.

[0244] Optionally, the doping element includes at least one of alkali metals, alkaline earth metals, transition metals, rare earth elements, halogen elements, and light elements, wherein the light elements include at least one of B, C, N, and O.

[0245] In some embodiments, the conductive connection layer is provided with an electrode. Optionally, the conductive connection layer may fully or partially cover the outer surface of the optical fiber, and there is no conductive connection layer on the laser light output path. Further optionally, the thickness of the conductive connection layer is 10nm to 1μm, for example, 10nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, or 1μm.

[0246] In some embodiments, the thickness of the electron excitation layer is 0.1 nm to 100 nm, for example, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. The electron excitation layer thickness within the above range is beneficial for further reducing the transmission distance of excited electrons between the two surfaces of the electron layer phase, thereby further improving the electron extraction efficiency.

[0247] In some embodiments, as shown in FIG2 , the electron emission layer 120 further includes an auxiliary layer 122 , and the auxiliary layer 122 is stacked on a side of the electron excitation layer 121 close to the optical fiber 110 ; or,

[0248] The auxiliary layer 122 is stacked on a side of the electron excitation layer 121 away from the optical fiber 110 .

[0249] In the present application, an auxiliary layer is added. When the electron excitation layer requires structural support, the auxiliary layer is used to provide structural support for the electron emission layer, that is, the electron excitation layer is arranged on the auxiliary layer; or, when the electron excitation layer cannot be directly connected to the conductive connection layer, the conductive connection layer is connected to the conductive connection layer through the conductive auxiliary layer, and the auxiliary layer is used to realize electronic conduction between the electron excitation layer and the conductive connection layer.

[0250] Optionally, the auxiliary layer includes at least one of a conductive support layer and a heat dissipation support layer.

[0251] Optionally, the auxiliary layer has a thickness of 0.1 nm to 100 nm, for example, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0252] Optionally, the auxiliary layer has a light transmittance of ≥10%, and can be, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%. It is understood that the "light transmittance" herein refers to the transmittance of the laser light in the auxiliary layer. By controlling the thickness and light transmittance of the auxiliary layer, it is possible to ensure that the laser light passes through the auxiliary layer and irradiates the electron excitation layer.

[0253] In some embodiments, the auxiliary layer includes a conductive support layer, and the material of the conductive support layer includes a conductive metal. Optionally, the laser wavelength in the optical fiber is 200nm to 2000nm, for example, it can be 200nm, 400nm, 600nm, 800nm, 1000nm, 1200nm, 1400nm, 1600nm, 1800nm ​​or 2000nm; the pulse power is 1nW to 1W, for example, it can be 1nW, 100nW, 1μW, 10μW, 100μW, 1mW, 10mW, 100mW or 1W. In this application, the auxiliary layer is made of 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 conduction.

[0254] In some embodiments, the auxiliary layer is disposed on the side of the electron excitation layer from which electrons are emitted, and the thickness of the auxiliary layer is 0.1 nm to 10 nm, thereby reducing the influence of the auxiliary layer on the electron emission effect.

[0255] In some embodiments, as shown in FIG. 3-6 , the material of the electron excitation layer 121 includes a zero-dimensional material.

[0256] In some embodiments, the average particle size of the zero-dimensional material is 1 nm to 100 μm.

[0257] In some embodiments, the density of the zero-dimensional material in the electron excitation layer is 10 / mm 2 ~10 12 Pieces / mm 2 .

[0258] In some embodiments, the gap between two adjacent particles of the zero-dimensional material is zero.

[0259] It should be noted that when zero-dimensional materials are densely arranged in the electron excitation layer, the electron excitation layer can directly cover part or all of the core on the end face of the optical fiber, and achieve electrical connection between the electron excitation layer and the conductive connection layer. As shown in Figure 4, "dense arrangement" means that the gap between two adjacent zero-dimensional material particles is zero. When zero-dimensional materials are densely arranged in the electron excitation layer, it is beneficial to further increase the number of emitted electrons and the energy concentration.

[0260] Furthermore, when the electronic excitation layer cannot be directly connected to the conductive connection layer, such as when the zero-dimensional material is arranged in a low density in the electronic excitation layer, the conductive auxiliary layer is connected to the conductive connection layer to achieve electronic conduction between the electronic excitation layer and the conductive connection layer through the auxiliary layer. In addition, the auxiliary layer can also assist the electronic excitation layer in heat dissipation, thereby improving the heat dissipation effect. As shown in Figure 6, "low density arrangement" refers to the situation where the gap between two adjacent zero-dimensional material particles in the electronic excitation layer is greater than zero.

[0261] In some embodiments, as shown in FIG. 7-15 , the electron excitation layer 121 includes a one-dimensional material.

[0262] In some embodiments, the one-dimensional material has a diameter of 1 nm to 20 nm, for example, 1 nm, 3 nm, 5 nm, 7 nm, 10 nm, 13 nm, 15 nm, 17 nm, or 20 nm.

[0263] It is understandable that there can be multiple one-dimensional materials in the electron excitation layer. In this case, the angles between the axes of different one-dimensional materials and the emission direction of the laser can be different. For example, there are 10 one-dimensional materials in the electron excitation layer, of which the axes of 3 one-dimensional materials are 45° to the emission direction of the laser, the axes of 2 one-dimensional materials are 60° to the emission direction of the laser, and the axes of 5 one-dimensional materials are 80° to the emission direction of the laser. In order to take into account the difficulty of the preparation process, the angles between the axes of the one-dimensional materials in the electron excitation layer and the emission direction of the laser are the same. In some embodiments, the electron excitation layer contains a plurality of the one-dimensional materials, and the axes of any two of the one-dimensional materials are parallel.

[0264] In some embodiments, the electron excitation layer comprises a plurality of the one-dimensional materials, and a gap between two adjacent one-dimensional materials along a radial direction of the one-dimensional materials is zero.

[0265] In some embodiments, the angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is 0 to 90°, for example, it can be 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° or 90°.

[0266] In some embodiments, as shown in Figures 7-10, the axial direction of the one-dimensional material is the same as the emission direction of the laser. This enables point emission of the electron source with high resolution. If a low-density one-dimensional material arrangement is used, the emitted electron energy dispersion is low and the brightness is high. If a high-density one-dimensional material arrangement is used, a large beam current of the electron source can be achieved. Among them, low density refers to the number of one-dimensional materials per unit area. For example, the density is less than 1 / nm 2 Low density, greater than 1 / nm 2 For high density.

[0267] The axial direction of the one-dimensional material in the above-mentioned electron excitation layer is the same as the emission direction of the laser, which enables the electron source to achieve point emission and has the advantages of high resolution. When the above-mentioned electron source is working, the laser is directly transmitted through the optical fiber, and does not involve a complex and unstable external space optical path, which greatly improves the structural simplicity and operational convenience of the electron source, reduces the interference of the external space on the stability of the electron beam, and makes the electron source have ultra-high stability and integration; the one-dimensional material has an atomic-level diameter, and the back-incident electrons can be emitted into the vacuum without being transmitted through the body, and the electron emission efficiency is high, which is very suitable for ultrafast electron sources with narrow pulse widths; and the one-dimensional material has no dangling bonds, stable properties, high melting point, and is not easy to damage, and can be used in high-power excitation scenarios. The above-mentioned electron sources include but are not limited to large-beam electron sources, ultrafast electron sources or high-coherence electron sources.

[0268] In some embodiments, the one-dimensional materials in the electron excitation layer are arranged in a low-density manner. Low density means that adjacent one-dimensional materials in the electron excitation layer are not in contact and cannot achieve electronic conduction. For example, low density means that the number of one-dimensional materials per unit area is less than 1 / nm. 2 At this time, the energy dispersion of electrons emitted by the electron excitation layer is low and the brightness of the electron source is high.

[0269] In some embodiments, the one-dimensional material in the electron excitation layer is arranged in a high-density manner. For example, high density means that the number of one-dimensional materials per unit area is greater than 1 / nm. 2This allows for the formation of a high-current electron source. High density means that adjacent one-dimensional materials in the electron excitation layer are in contact, enabling electron conduction.

[0270] In some embodiments, the axial direction of the one-dimensional material in the electron excitation layer is the same as the emission direction of the laser, and the length of the one-dimensional material is 0.1μm to 1μm, and the diameter is 1nm to 20nm. For example, the length of the one-dimensional material can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or 1μm. The diameter and length of the one-dimensional material are within the above range, which can further improve the emission efficiency and stability of the electron source. If the diameter of the one-dimensional material is too large, the field enhancement factor is small, and the interaction with light is weak. If the length of the one-dimensional material is too short, it will manifest as a zero-dimensional material property, and controllable preparation is difficult; if the length of the one-dimensional material is too long, there will be large scattering and other losses during light transmission, and the interaction with the one-dimensional material will be weakened.

[0271] In some embodiments, as shown in FIG. 11-15 , the axis of the one-dimensional material forms 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.

[0272] In some embodiments, an angle between the axial direction of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°.

[0273] In the above-mentioned electron source, the angle between the axis of the one-dimensional material and the emission direction of the laser is greater than 0° and less than or equal to 90°, which can achieve linear emission and increase the emission area and efficiency. When the above-mentioned electron source is working, the laser is directly transmitted through the optical fiber, without involving a complex and unstable external space optical path. This greatly improves the structural simplicity and operational convenience of the electron source, reduces the interference of the external space on the stability of the electron beam, and makes the electron source have ultra-high stability and integration. The one-dimensional material has an atomic-level diameter, strong interaction with the light field and electric field, and high electron emission efficiency, which is very suitable for ultrafast electron sources with narrow pulse widths. In addition, the one-dimensional material has no dangling bonds, stable properties, high melting point, and is not easily damaged, making it suitable for high-power excitation scenarios.

[0274] In some embodiments, the angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°, and the length of the one-dimensional material is 1μm to 200μm. For example, it can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 20μm, 30μm, 50μm, 70μm, 100μm, 130μm, 150μm, 180μm or 200μm. It can be selected from 10μm to 30μm. If the length of the one-dimensional material is too long, it is difficult to prepare; if the length of the one-dimensional material is too short, the emission length is short, the electron emission efficiency is low, and it is difficult for the one-dimensional material in the electron excitation layer to contact the conductive connection layer.

[0275] In some embodiments, the angle between the axis of the one-dimensional material in the electron excitation layer and the laser emission direction is 45° to 90°. This ensures strong interaction between the laser and the one-dimensional material while also ensuring that electrons are emitted from the side of the one-dimensional material, further improving the emission efficiency and stability of the electron source.

[0276] In some embodiments, as shown in Figures 16-23, the electron excitation layer includes at least one layer of two-dimensional material.

[0277] This application uses at least one layer of two-dimensional material as an electron excitation layer. The two-dimensional material has an atomic-level thickness. The electrons generated by the laser irradiation surface can be emitted into the vacuum without being transmitted through the layer, which is very suitable for ultrafast electron sources with narrow pulse widths. The two-dimensional material has no dangling bonds and has good stability and a high melting point. It is not easy to damage the large-beam electron source suitable for high-power excitation. Moreover, the rich variety of two-dimensional materials and homogeneous and heterogeneous structures bring ultra-high degrees of freedom in electron emission properties, for example, pulsed electron sources and one-dimensional electron sources can be realized. In addition, this application directly integrates two-dimensional materials and optical fibers, and the optical fiber transmits lasers. As a low-dimensional material carrier, it can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without providing a complex optical path. It has the characteristics of small size and high integration.

[0278] In some embodiments, the thickness of the two-dimensional material is 0.1 nm to 50 nm, for example, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0279] In some embodiments, the electron excitation layer includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction, or the electron emission layer includes at least two two-dimensional materials of different materials connected to each other on the same plane.

[0280] In some embodiments, at least two layers of two-dimensional materials are stacked or spliced ​​to form a common plane. Furthermore, adjacent two-dimensional materials are composed of different materials, forming a vertical heterojunction or a planar heterojunction. This heterojunction structure can enhance the interaction between light and the two-dimensional material, enabling efficient electron emission at low laser power. Furthermore, the heterojunction has the ability to regulate the interface energy band. Through material design and angle control, specialized interface states can be achieved, enabling high-brightness and low-energy-dispersion electron emission.

[0281] In some embodiments, as shown in FIG16 , the electron excitation layer 121 includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction of the optical fiber, and the two-dimensional materials are all conductive two-dimensional materials; the two adjacent layers of the two-dimensional materials are the same or different. As shown in FIG21 , the electron excitation layer 121 includes a first material layer 121a and a second material layer 121b stacked in sequence. In the application, two-dimensional materials that are all conductive are used for stacking, and the charge transfer between the two-dimensional material layers is fast and stable. If the stacked two-dimensional materials contain insulating materials, the insulating materials block the electron transmission, which not only requires the additional control electrodes, but also causes additional scattering problems in the electron transfer process, resulting in low emission efficiency and high energy dispersion.

[0282] In some embodiments, as shown in Figure 22, the angle between the crystal axes of two adjacent layers of the two-dimensional material is 0° to 360°. The present application stacks multiple layers of two-dimensional materials, forming a vertical heterojunction or vertical homojunction between the two adjacent layers of two-dimensional materials. The heterojunction structure can enhance the interaction between light and the two-dimensional material, achieving efficient electron emission at low laser power. Furthermore, the heterojunction structure has the function of regulating the interface energy band. Through material design and angle regulation, special interface states can be obtained, achieving high-brightness and low-energy-dispersion electron emission.

[0283] In some embodiments, as shown in Figures 19 and 20, the electron excitation layer is formed by splicing at least two different two-dimensional materials, and the laser of the optical fiber irradiates the junction of adjacent two-dimensional materials. Optionally, the electron emission layer includes a two-dimensional material layer formed by splicing graphene and molybdenum disulfide. The junction of graphene and molybdenum disulfide forms a one-dimensional interface, and the response of this one-dimensional interface to light is different from that of graphene and molybdenum disulfide, thereby achieving one-dimensional emission from the interface state.

[0284] In some embodiments, the electron excitation layer is formed by splicing at least two different two-dimensional materials, with adjacent two-dimensional materials having the same or different thicknesses. The present application sets different thicknesses for the spliced ​​two-dimensional materials to achieve different forms of electron excitation. As shown in Figure 20, the electron excitation layer 121 includes a first material layer 121a and a second material layer 121b spliced ​​together on the same plane.

[0285] In some embodiments, the auxiliary layer includes a transparent supporting layer.

[0286] Optionally, the material of the transparent supporting layer includes at least one of boron nitride, mica and diamond.

[0287] This application uses a transparent material as a transparent support layer, and the transparent material does not affect the interaction between the laser and the two-dimensional material.

[0288] In some embodiments, the transparent supporting layer has a thickness of 0.1 nm to 1000 nm, for example, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm.

[0289] In some embodiments, the light transmittance of the transparent support layer is ≥10%, for example, it can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.

[0290] In some embodiments, the surface of the two-dimensional material is further provided with at least one of a zero-dimensional material and a one-dimensional material. Optionally, the surface of the two-dimensional material is provided with a one-dimensional material, and the angle between the axis of the one-dimensional material and the plane of the two-dimensional material is 0 to 90 degrees. This application modifies the surface of the two-dimensional material by providing a zero-dimensional material or a one-dimensional material on the surface of the two-dimensional material, thereby achieving different modes of electron source emission.

[0291] In some embodiments, as shown in Figures 24-27, the material in the electron excitation layer includes a one-dimensional material and a zero-dimensional material disposed at the end and / or side of the one-dimensional material. It is understood that when the one-dimensional material is solid, the zero-dimensional material can be disposed at the end and / or outer side wall of the one-dimensional material; and when the one-dimensional material is hollow, the zero-dimensional material can be disposed at the end and / or inner and outer side walls of the one-dimensional material. For example, as shown in Figure 24, the zero-dimensional material is disposed at the end of the one-dimensional material. As shown in Figure 25, the zero-dimensional material is disposed on the side wall of the one-dimensional material.

[0292] The present application combines zero-dimensional materials with one-dimensional materials and arranges the zero-dimensional materials at the end or side of the one-dimensional materials, that is, the surface structure of the one-dimensional materials is modified by using zero-dimensional materials. Both the zero-dimensional materials and the one-dimensional materials have typical discrete energy levels. Under the action of laser, electrons are mainly excited by tunneling from the discrete energy levels, and the emitted electrons have the characteristics of concentrated energy, small energy dispersion and high emission efficiency.

[0293] The electron source provided by this application can transmit laser light through the core of the optical fiber to the end face of the optical fiber and irradiate the electron excitation layer, which contains one-dimensional materials and zero-dimensional materials. Under the action of light excitation, the one-dimensional material and the zero-dimensional material have atomic-level thickness. The excited electrons in the electron excitation layer can be emitted without long-distance transmission, and the electron emission efficiency is high. Moreover, the one-dimensional material and the zero-dimensional material have no dangling bonds, are stable in nature and have a high melting point, are not easily damaged, and can be applied to high-power excitation scenarios. They have good stability, long service life, and low working vacuum. In addition, the one-dimensional material and the zero-dimensional material can also be directly integrated with the optical fiber. The optical fiber transmits the laser, which can effectively reduce the scattering of the laser and effectively reduce the energy loss of the emitted laser, which is conducive to improving the excitation efficiency. As a carrier of the one-dimensional material and the zero-dimensional material, it can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without providing a complex optical path, and has the characteristics of small size and high integration. In addition, the one-dimensional material and the zero-dimensional material can produce more electron energy levels and electron concentrations, achieving higher electron emission efficiency.

[0294] This application can generate more electron energy levels and electron concentrations by placing zero-dimensional materials on one-dimensional materials, that is, compounding one-dimensional materials with zero-dimensional materials. Zero-dimensional materials can also be used to adjust one-dimensional materials to achieve higher electron emission efficiency, further improving electron emission efficiency and stability.

[0295] In some embodiments, there is an angle between the axial direction of the one-dimensional material with zero-dimensional material and the laser light output path of the optical fiber, that is, there is an angle between the axial direction of the one-dimensional material and the laser emission direction, and the angle is 0 to 90°. While the laser excites the one-dimensional material to produce a linear electron source, it can also excite the zero-dimensional material to produce a point electron source, which can enhance the excited electron source and effectively improve the electron emission efficiency.

[0296] In some embodiments, the axial direction of the one-dimensional material in the electron excitation layer is parallel to the laser light exit path of the optical fiber. The axial direction of the one-dimensional material in the electron excitation layer is parallel to the laser light exit path of the optical fiber, that is, the axial direction of the one-dimensional material is aligned with the laser light exit direction. Simultaneously, the zero-dimensional material is disposed on the one-dimensional material, thereby enabling point emission of the electron source with high resolution.

[0297] In some embodiments, the electron excitation layer comprises a plurality of one-dimensional materials, with the axes of any two of the one-dimensional materials parallel to each other. The one-dimensional materials in the electron excitation layer are arranged in parallel, and the zero-dimensional material is disposed on the one-dimensional materials, which facilitates obtaining a uniformly oriented electron beam and further enhances energy concentration.

[0298] In some embodiments, the electron excitation layer comprises a plurality of one-dimensional materials, and the gap between two adjacent one-dimensional materials along the radial direction of the one-dimensional materials is zero. It should be noted that when the one-dimensional materials in the electron excitation layer are densely arranged in the electron excitation layer, the electron excitation layer can directly cover part or all of the core on the end face of the optical fiber, and achieve electrical connection between the electron excitation layer and the conductive connection layer. As shown in FIG24 , “dense arrangement” means that the gap between the one-dimensional materials in the electron excitation layer along the radial direction of the one-dimensional materials is zero.

[0299] In some embodiments, when the axis of the one-dimensional material in the electron excitation layer is parallel to the laser light output path of the optical fiber, and the gap between two adjacent one-dimensional materials along the radial direction of the one-dimensional material is greater than zero, the emitted electron energy dispersion is low and the brightness is high, which can achieve a large beam current of the electron source.

[0300] In some embodiments, as shown in FIG24 , the axial direction of the one-dimensional material in the electron excitation layer 121 is parallel to the laser light output path of the optical fiber 110 , and the gap between two adjacent one-dimensional materials along the radial direction of the one-dimensional material is zero, which is beneficial to further improve the energy concentration of the emitted electrons.

[0301] In some embodiments, the diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm. It is understood that when the one-dimensional material is hollow, the diameter of the one-dimensional material refers to its outer diameter. The average particle size of the zero-dimensional material is 1 nm to 100 nm.

[0302] In some embodiments, the one-dimensional material includes at least one of nanotubes, nanorods, nanowires, nanobelts, and nanocoaxial cables. Optionally, the one-dimensional nanomaterial includes at least one of carbon nanotubes, silicon nanowires, germanium nanowires, silver nanowires, gold nanocolumns, and boron nitride nanotubes. It is understood that the nanorods in this application refer to solid nanomaterials that are short in length and straight in longitudinal shape, one-dimensional cylinders (or whose cross-sections are polygonal); while nanowires refer to solid nanomaterials that are long in length and straight or curved in shape. The nanobelts described in this application refer to nanoribbons with a quadrilateral cross-section, and their width-to-thickness ratio distribution range is generally from a few to a dozen.

[0303] In some embodiments, the electron excitation layer includes a zero-dimensional material and a two-dimensional material, and the zero-dimensional material is disposed on the surface of the two-dimensional material. In this application, the zero-dimensional material is disposed on the surface of the two-dimensional material. The two-dimensional material not only serves as a support layer for the zero-dimensional material, but also uses a conductive two-dimensional material to avoid the need for an additional conductive layer. That is, the two-dimensional material can serve as an auxiliary layer for the zero-dimensional material, achieving both support and conductivity.

[0304] In some embodiments, the electron excitation layer includes a one-dimensional material and a two-dimensional material, wherein the one-dimensional material is disposed on the surface of the two-dimensional material; optionally, the angle between the axis of the one-dimensional material and the surface of the two-dimensional material is 0 to 90 degrees. In this application, the one-dimensional material is disposed on the surface of the two-dimensional material. The two-dimensional material not only serves as a support layer for the one-dimensional material, but also uses a conductive two-dimensional material to avoid the need for an additional conductive layer. That is, the two-dimensional material can serve as an auxiliary layer for the one-dimensional material, achieving both support and conductivity functions.

[0305] In some embodiments, the zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals. NV color centers refer to nitrogen vacancy color centers, and quantum dots include at least one of carbon quantum dots, CdSe colloidal quantum dots, and GaAs semiconductor quantum dots. For example, the zero-dimensional material includes one or more of fullerenes, carbon black, nanodiamonds, diamond color centers, nanometal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots. Optionally, the zero-dimensional material is nanometal particles and / or graphite quantum dots.

[0306] In some embodiments, the one-dimensional material comprises at least one of a nanotube, a nanobelt, and a nanowire. Alternatively, the nanotube comprises a carbon nanotube, a Si nanotube, a Se nanotube, a Te nanotube, a Bi nanotube, a BN nanotube, a BCN nanotube, a WS nanotube, a MoS2 nanotube, a TiO z At least one of nanotubes. Optionally, the nanowires include elemental nanowires, such as Si and Ge; oxide nanowires, such as SnO and ZnO; nitride nanowires, such as GaN and Si z N4, etc.; sulfide nanowires, such as Cds and ZnS; ternary compound nanowires, such as BaTiO and PbTiO. Nanobelts include ZnO nanobelts, SnO nanobelts, etc. The nanocoaxial cable refers to a core / shell quasi-one-dimensional structure with a radial diameter at the nanometer scale, including C / BN / CSi / SiO2 or SiC / SiO z Etc. Thus, the emission efficiency and stability of the electron source can be further improved.

[0307] In some embodiments, the two-dimensional material includes at least one of graphene, a transition metal chalcogenide, a two-dimensional perovskite, a two-dimensional diamond, and boron nitride. Optionally, the transition metal chalcogenide includes at least one of WS2, WSe2, and NbSe2.

[0308] In some embodiments, the optical fiber is a solid core optical fiber, a needle-tip optical fiber, a side-section optical fiber, or a holey optical fiber.

[0309] In some embodiments, as shown in FIG28 , the optical fiber 110 includes a core 111 for transmitting laser light and a wrapping layer 112 wrapping the core 111 , and the end face of the light-emitting end of the optical fiber 110 is arranged at an angle to the extension direction of the core;

[0310] 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 pulse laser emitted from the core can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the pulse laser emitted from the core and emits electrons.

[0311] In some embodiments, as shown in FIG29 , the optical fiber is a side-section optical fiber. The low-dimensional material of the present application is arranged on the side section of the side-section optical fiber, and the evanescent wave leaked from the core interacts with the low-dimensional material in the horizontal direction. For example, the low-dimensional material adopts a two-dimensional material, and obtains an edge state similar to that of a one-dimensional material at the side section, forming a new electron emission structure, realizing functions such as high brightness, low energy dispersion and narrow pulse width; the low-dimensional material adopts a one-dimensional material, and obtains an edge state of a zero-dimensional material at the side section, forming a new electron emission structure, realizing functions such as high brightness, low energy dispersion and narrow pulse width; the low-dimensional material adopts a combination of two-dimensional material, one-dimensional material and zero-dimensional material, and the energy band of the two-dimensional material can be modulated by doping one-dimensional and zero-dimensional materials, thereby improving the interaction between light and material and realizing electron emission with functions such as high brightness, low energy dispersion and narrow pulse width.

[0312] In some embodiments, as shown in FIG. 29 , a light leakage notch h is formed at the light-emitting end 1102 of the optical fiber 110 along the radial direction of the optical fiber 110. An electron excitation layer 121 is disposed on a flat bottom wall h1 of the light leakage notch h. The projection of the electron excitation layer 121 on the flat bottom wall h1 covers the projection of the fiber core 111 on the flat bottom wall h1. The electron excitation layer 121 also extends to the light-emitting end 1102 of the optical fiber 110.

[0313] Optionally, the light leakage gap h further has a side wall surface h2 extending along the radial direction of the optical fiber 110 , and the bottom wall surface h1 and the side wall surface h2 jointly define the light leakage gap h.

[0314] Optionally, the bottom wall surface h1 of the light leakage gap h is configured as a plane, and the bottom wall surface h1 of the light leakage gap h is extended along the extension direction of the optical fiber 110 .

[0315] The bottom wall surface h1 of the light leakage notch h may be spaced apart from the fiber core 111, and parallel to a tangent plane of the outer surface of the fiber core 111. Alternatively, the bottom wall surface h1 of the light leakage notch h may be tangent to the outer surface of the fiber core 111. Of course, the bottom wall surface h1 of the light leakage notch h may also be configured as a plane partially formed on the fiber core 111. For example, the fiber core 111 and the cladding layer 112 may be cut simultaneously to form the light leakage notch h, with a portion of the bottom wall surface h1 of the light leakage notch h formed on the fiber core 111 and another portion of the bottom wall surface h1 of the light leakage notch h formed on the cladding layer 112.

[0316] 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 gap h, and since the electron excitation layer 121 is arranged on the bottom wall surface h1 of the light leakage gap h, and the projection of the electron excitation layer 121 in parallel to the bottom wall surface h1 covers the projection of the core 111 in 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, and these electrons can escape from the electron excitation layer 121, thereby realizing the excitation of electrons.

[0317] In some embodiments, the optical fiber is a holey fiber. The holey fiber of the present application is a type of optical fiber with a microstructure or completely hollow, including photonic crystal fiber, antiresonant fiber or capillary fiber, etc. Low-dimensional materials can be arranged in the pores or pore walls of the holey fiber, so that the laser and the low-dimensional material have a long interaction distance, thereby achieving high-brightness electron emission. Because the holey fiber itself has a special light transmission mode, it can also continue to grow or transfer materials of different types or dimensions in the pores or pore walls that have been grown or filled with low-dimensional materials to form a heterojunction, which can achieve multifunctional electron emission.

[0318] In some embodiments, the optical fiber is a holey optical fiber having a light-guiding hole; the electron excitation layer is at least provided on a side wall of the light-guiding hole and extends along an extension direction of the light-guiding hole.

[0319] As shown in Figures 30-35, the optical fiber 1110 is a holey fiber, which has a light-guiding hole. The holey fiber serves as a transmission medium for laser light and a carrier for low-dimensional materials. The holey fiber can include a hollow-core holey fiber, which can be a single-hole or multi-hole hollow-core fiber. Of course, the holey fiber can also include a solid-core holey fiber, which can be a single-hole or multi-hole solid-core fiber, without specific limitation. Figure 30 shows an example of a holey fiber that is a single-hole hollow-core fiber.

[0320] Specifically, in the embodiment shown in Figure 30 , a core 111 composed of air is disposed within the light guide hole. The holey fiber also includes a cladding layer 112 surrounding the core 111. The cladding layer 112 comprises an annular light guide body, and the sidewall k of the light guide hole is formed on the inner sidewall of the annular light guide body. Specifically, the annular light guide body can be made of borosilicate, glass, or quartz. More specifically, the holey fiber is a capillary fiber.

[0321] The holey fiber has an oppositely positioned light input end 1101 and a light output end 1102. The light input end 1101 is coupled to a laser source, allowing the laser light emitted by the laser source to be transmitted through the holey fiber. The laser source can be a laser. The electron excitation layer 121 is entirely disposed on the sidewall k of the light guide hole; alternatively, only a portion of the electron excitation layer 121 is disposed on the sidewall k of the light guide hole. This is not a specific limitation.

[0322] In this way, when the electron source 100 is in use, the laser can generate an evanescent wave at the side wall k of the light guide hole during the transmission of the laser in the holey optical fiber. Since the electron excitation layer 121 is arranged on the side wall k of the light guide 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 jump. These electrons can escape from the electron excitation layer 121, thereby realizing the excitation of electrons.

[0323] It should be noted that, regardless of whether it is a hollow-core holey fiber or a solid-core holey fiber, the laser emitted by the laser source can be transmitted through the holey fiber 110 to the light-emitting end 1102 of the holey fiber 110. During the transmission of the laser in the holey fiber 110, an evanescent wave can be generated at 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, thereby realizing the excitation of electrons.

[0324] In some embodiments, the holey fiber comprises a hollow-core holey fiber, wherein a light-guiding medium is disposed within the light-guiding hole, and the light-guiding medium comprises air or a rare gas. The light-guiding medium can be air or a rare gas. The rare gas can produce a nonlinear optical effect, thereby converting the light pulses output by the holey fiber 110 from a single wavelength to a wavelength in the ultraviolet to infrared or terahertz band, or even generating an ultra-broadband supercontinuum spectrum. This also facilitates the excitation of the electron excitation layer 121 to emit electrons.

[0325] In some embodiments, at least a portion of electron excitation layer 121 completely covers the sidewall k of the light guide hole. Alternatively, electron excitation layer 121 may completely cover the sidewall k of the light guide hole, or a portion of electron excitation layer 121 may completely cover the sidewall k of the light guide hole, without specific limitation. This allows laser light transmitted within holey fiber 110 to better interact with electron excitation layer 121 and excite it to emit electrons.

[0326] In some embodiments, the electron emission layer further includes an auxiliary layer, which is stacked on a side of the electron excitation layer close to the sidewall of the light guide hole; or, the auxiliary layer is stacked on a side of the electron excitation layer away from the sidewall of the light guide hole.

[0327] In some embodiments, the electron excitation layer includes a first portion that completely covers the sidewalls of the light guide hole, and a second portion disposed on the end face of the light-emitting end of the holey fiber; the second portion is connected to the first portion and electrically connected to the conductive connection layer. Thus, by electrically connecting the conductive connection layer 130 to the second portion 1212 of the electron excitation layer 121, the conductive connection layer 130 can replenish electrons in the electron excitation layer 121, facilitating the continued emission of electrons from the electron excitation layer 121 under laser excitation. On the other hand, since the second part 1212 is arranged on the light-emitting end 1102 of the holey optical fiber 110, in the process of the laser transmitted in the holey optical fiber 110 transmitting toward the light-emitting end 1102, the laser can interact with the first part 1211 of the electron excitation layer 121 through the evanescent wave, and can also interact with the second part 1212 on the light-emitting end 1102, so that the electrons in the electron excitation layer 121 absorb the energy of the photons and transition. This part of the electrons can escape from the electron excitation layer 121, thereby realizing the efficient emission of electrons along the axial direction of the holey optical fiber 110.

[0328] In some embodiments, the conductive connection layer includes a first conductive portion disposed on the end face of the light-emitting end of the holey fiber, and a second conductive portion disposed on the circumferential side of the holey fiber; wherein the first conductive portion is connected to the second conductive portion and overlaps with the second portion of the electron excitation layer. This allows the conductive connection layer 130 to cover more of the holey fiber 110, improving the bonding strength between the conductive connection layer 130 and the holey fiber, and also facilitating better utilization of the conductive connection layer 130 to replenish electrons in the electron excitation layer 121. Because the first conductive portion 131 overlaps with the second portion 1212, the first conductive portion 131 is in electrical contact with the second portion 1212, and the orthographic projection of the first conductive portion 131 on the light-emitting end 1102 is located outside the sidewall k of the light-guiding hole. Furthermore, while the conductive connection layer 130 can replenish electrons in the electron excitation layer 121, it does not affect the interaction between the laser and the electron excitation layer 121.

[0329] In some embodiments, both the first portion 1211 and the second portion 1212 are annular structures, and the inner diameter of the first portion 1211 is less than or equal to the inner diameter of the second portion 1212. This facilitates the interaction of the laser light with the first portion 1211 of the electron excitation layer 121 via the evanescent wave. Furthermore, the laser light can interact with the second portion 1212 on the light output end 1102, causing electrons in the electron excitation layer 121 to absorb the energy of the evanescent wave and transition. These electrons can then escape from the electron excitation layer 121, thereby enabling efficient electron emission along the axis of the holey fiber 110.

[0330] In some embodiments, the conductive connection layer 130 includes a first metal layer and a second metal layer stacked together, with the first metal layer having greater adhesion than the second metal layer. For example, the first metal layer is made of titanium, palladium, or chromium, and the second metal layer is made of gold. The higher adhesion of the first metal layer allows the conductive connection layer 130 to adhere better to the holey fiber 110, improving the bond strength between the conductive connection layer 130 and the holey fiber 110 and extending the service life of the conductive connection layer 130.

[0331] In some embodiments, the optical fiber is a holey optical fiber, the electron emission layer is arranged on the end face of the light-emitting end of the holey optical fiber, and the electron excitation layer covers one end of the end face of the light-guiding hole located at the light-emitting end; the pulsed laser emitted by the holey optical fiber can be directly irradiated on the electron emission layer, so that the electron excitation layer is excited by the pulsed laser emitted by the holey optical fiber and emits electrons.

[0332] In some embodiments, the optical fiber is a needle-tip optical fiber. In this application, a low-dimensional material is disposed on the needle-tip optical fiber. Due to the needle-tip geometry of the needle-tip optical fiber, the field emission enhancement factor is increased, enabling a higher-brightness electron source. The low-dimensional material can be a two-dimensional material. Furthermore, at least one of a zero-dimensional material and a one-dimensional material is disposed on the two-dimensional material, thereby achieving functions such as high brightness, low energy dispersion, and narrow pulse width.

[0333] In some embodiments, as shown in Figures 36-40 , the optical fiber has a tip at its light-emitting end; the electronic excitation layer covers the surface of the tip of the optical fiber. The electronic excitation layer 121 may directly cover the surface j1 of the tip j of the optical fiber 110 or indirectly cover the surface j1 of the tip j of the optical fiber 110 , without specific limitation.

[0334] In this way, when the electron source 100 is in use, the laser transmitted in the core 111 of the optical fiber 110 can be transmitted toward the light-emitting end 1102 of the optical fiber 110. Since the light-emitting end 1102 is provided with a tip j, the electron excitation layer 121 covers the surface j1 of the tip j of the optical fiber 100, and the electron excitation layer 121 is located on the light-emitting path of the core 111. Therefore, in the process of the laser transmitted in the core 111 of the optical fiber 110 being transmitted to the tip j and emitted, 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 laser photons, undergo energy transition and escape from the electron excitation layer 121, thereby realizing the excitation of electrons. Laser light can be transmitted along the core 111 of the optical fiber 110, allowing the laser light transmitted within the core 111 to propagate to the light output end 1102 and be emitted. The laser light interacts with the electron excitation layer 121, causing the electrons within the electron excitation layer 121 to absorb laser photons and undergo energy transitions to escape from the electron excitation layer 121, thereby achieving electron excitation. The electron source 100 uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the material for the electron excitation layer 121, and arranges the electron excitation layer 121 on the optical fiber 110 to achieve electron excitation. This eliminates the complex spatial optical coupling structure required for the introduction of external laser light, and also eliminates the high-magnification microscope required to solve the alignment problem of the metal needle tip. This can reduce the process cost of the electron gun and increase stability.

[0335] Compared with setting a metal layer at the tip of the optical fiber and directly interacting with the metal layer through the laser transmitted in the optical fiber to excite electrons (electrons are easily affected by lattice scattering in the process of passing through the metal layer, which leads to low electron emission efficiency. In addition, the conduction band of the metal material is half-filled, resulting in a wide distribution of electron energy emitted by the excited metal layer), 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 material has an atomic-level thickness, and the back-incident electrons can be emitted without being transmitted through the body, and the electron emission efficiency is high; and the low-dimensional material has no dangling bonds, stable properties and high melting points, and is not easy to damage. It can be used in high-power excitation scenarios and has the characteristics of good stability and long service life; in addition, the low-dimensional material also has a high optical nonlinear effect and a rich electronic band gap, which enables the laser to better interact with the electron excitation layer 121 to generate energy resonance and excite the electrons in the electron excitation layer 121. These electrons are excited to escape into the vacuum and form an electron beam, and the electron beam emitted by tunneling from the electron excitation layer 121 has the characteristics of concentrated energy and small energy dispersion. In addition, low-dimensional materials can be directly integrated with optical fiber 110. The optical fiber transmits lasers and, as a carrier of low-dimensional materials, can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without providing a complex optical path. It has the characteristics of small size and high integration.

[0336] Optionally, the radial dimension of the tip portion j gradually decreases along the extension direction of the fiber core 111. The electron excitation layer 121 of the present application is disposed on the tip portion j of the optical fiber 110 and covers the surface j1 of the tip portion j of the optical fiber 110. Since the tip portion j of the optical fiber 110 has a geometric structure similar to a needle tip, the field emission enhancement factor is improved, and a higher brightness electron source 100 can be obtained.

[0337] In some embodiments, the electron excitation layer includes a first part; the projection of the first part in a target plane perpendicular to the extension direction of the fiber core covers the projection of the fiber core in the target plane; the first part is electrically connected to the conductive connection layer.

[0338] In some embodiments, the electron excitation layer further includes a second portion connected to the first portion; the projection of the second portion within the target plane is located outside the projection of the first portion within the target plane; and the second portion overlaps the conductive connection layer. Thus, by electrically connecting conductive connection layer 130 to second portion 1212 of electron excitation layer 121, and by allowing the projection of second portion 1212 within the target plane to be located outside the projection of first portion 1211 within the target plane, conductive connection layer 130 can replenish electrons to electron excitation layer 121 without affecting the interaction between fiber core 111 and electron excitation layer 121, thereby facilitating the continued emission of electrons from electron excitation layer 121 under laser excitation.

[0339] In some embodiments, the conductive connection layer includes a first conductive portion disposed at the tip of the optical fiber, and a second conductive portion connected to the first conductive portion and disposed on a circumferential side of the optical fiber; the first conductive portion and the second portion overlap. This allows the conductive connection layer 130 to cover a greater portion of the optical fiber 110, improving the bond strength between the conductive connection layer 130 and the optical fiber, and also facilitating better utilization of the conductive connection layer 130 to replenish electrons in the electron excitation layer 121.

[0340] In some embodiments, along the extension direction of the fiber core, the size of the tip portion is L1, and the size of the electron excitation layer is L2, wherein L1 is larger than L2.

[0341] In some embodiments, the dimensions of the tip portion and the electron excitation layer satisfy the following relationship: L2 > 1 / 2 × L1. Electron excitation layer 121 covers surface j1 of tip portion j and surrounds tip portion j. Because L2 > 1 / 2 * L1, this increases the contact area between electron excitation layer 121 and surface j1 of tip portion j, improving the bond strength between electron excitation layer 121 and optical fiber 110 and facilitating the use of laser light transmitted by fiber core 111 to excite electron excitation layer 121 and emit electrons.

[0342] In some embodiments, the optical fiber is a solid core optical fiber. The low-dimensional material of the present application is arranged at the core of the solid core optical fiber, and the evanescent wave leaked from the core can interact with the low-dimensional material surrounding the optical fiber. Under this system, a longer distance of interaction between light and material can be achieved to achieve high-brightness electron emission. In addition, different diameters of micro-nano optical fibers can be drawn, and light of different modes and intensities can interact with low-dimensional materials to achieve precise control of electron emission parameters. In addition, different types or dimensions of materials can be further grown or transferred on the grown or transferred low-dimensional material to form a heterojunction to achieve multifunctional electron emission.

[0343] It should be noted that this application does not make any specific requirements or special limitations on the size of the optical fiber. Those skilled in the art can reasonably select the size of the optical fiber according to actual usage requirements.

[0344] In some embodiments, the electron excitation layer is formed by at least one of dry transfer, wet transfer, and direct growth.

[0345] In some embodiments, the electron excitation layer is prepared by dry transfer, and the preparation method includes: transferring the zero-dimensional material, one-dimensional material or two-dimensional material to the tape by mechanical stripping, and transferring the zero-dimensional material, one-dimensional material or two-dimensional material to the laser emitting side of the optical fiber through the tape.

[0346] In some embodiments, the electron excitation layer is prepared by wet transfer, and the preparation method includes: preparing a zero-dimensional material, a one-dimensional material or a two-dimensional material directly in a solution and floating it on the liquid surface, using an optical fiber to contact the material on the liquid surface and drying it.

[0347] In some embodiments, the electron excitation layer is prepared by direct growth, and the preparation method includes: directly preparing the electron emission layer on the laser output side of the optical fiber by at least one method selected from chemical vapor deposition, physical vapor deposition, molecular beam epitaxy and liquid filling.

[0348] The second aspect of the present application provides an electron gun, as shown in Figure 41, which includes a shell, a gate 200, an anode and the electron source as described in the first aspect; the electron source is fixed in the shell, and the gate and the anode are sequentially arranged on the electron emission side of the electron source.

[0349] For example, the electron source 100 is applied to an electron gun, which also includes an anode 300, which has a first electron channel 310 for allowing electrons emitted from the electron excitation layer 121 to pass through. There is a preset voltage between the anode 300 and the conductive connection layer 130, so that a preset electric field is formed between the anode 300 and the conductive connection layer 130, so that the electrons emitted from the electron excitation layer 121 are driven by the preset electric field to be emitted toward the first electron channel 310 of the anode 300 and emitted through the first electron channel 310. Specifically, the electron excitation layer 121 is electrically connected to the negative pole of the power supply through the conductive connection layer 130, and the anode 300 is electrically connected to the positive pole of the power supply, so that there is a preset voltage between the anode 300 and the conductive connection layer 130, and the electron excitation layer 121 and the anode 300 are arranged at intervals along the extension direction of the holey optical fiber 110. In this way, it is beneficial to use the anode 300 to form a uniform electric field along the axial direction of the holey optical fiber 110, and it is more beneficial for electrons to be linearly accelerated along the axial direction of the holey optical fiber 110 and pass through the first electron channel 310.

[0350] In this application, the gate 200 is used to limit the shape of the electron beam, and the anode 300 is used to accelerate the electrons. When electrons are excited and emitted from the electron source 100, they interact with the electrostatic field established by the gate 200 and the electron's own space charge, forming an electron beam with a certain shape. The electron beam passes through the second electron channel 210 of the gate 200 and is ejected through the first electron channel 310 of the anode 300 for use.

[0351] A third aspect of the present application provides an application of the electron source as described in the first aspect, wherein the application of the electron source includes at least one of an electron microscope, an electron beam exposure machine, an X-ray tube, a free electron laser and a display.

[0352] In a fourth aspect, the present application provides a four-dimensional electron microscope 10A for scanning a sample. Referring to FIG. 42 and in conjunction with FIG. 43-45 , the four-dimensional electron microscope 10A provided by the present application includes a light source assembly 2A, an electron source 100, an electron optical assembly 3A, and a detector 4A. The light source assembly 2A is capable of emitting pulsed laser light, which propagates to the electron source 100 to excite the electron source 100 to form an electron beam. The electron beam is modulated by the electron optical assembly 3A and projected onto the sample 5A, emitting a corresponding signal. The detector 4A receives the corresponding signal and is thus able to obtain information about the sample 5 based on the corresponding signal. The electron source 100 includes an excitation fiber 110A and an electron emission layer 120. The excitation fiber 110A has a light input end 1101 coupled to the light source assembly 2, and a light output end 1102 opposite the light input end 1101, i.e., the excitation fiber 110A is coupled to the light source assembly 2. The electron emission layer 120 includes at least an electron excitation layer 121, which is arranged on the light output path of the pulsed laser emitted by the excitation optical fiber 110, so that the electron excitation layer 121 can emit an electron beam under the excitation of the pulsed laser. In other words, the excitation optical fiber 110A includes a core 111 for transmitting the pulsed laser, and the electron emission layer 120 is arranged on the light output path of the pulsed laser emitted by the core 111, so that the electron excitation layer 121 configured as the electron emission layer 120 can emit an electron beam in a direction outward from the light output end 1102 under the excitation of the pulsed laser transmitted by the core 111. It can be understood that with the excitation of the pulsed laser, the emitted electron beam has a pulsed property, that is, the electron source 100 itself can emit a pulsed electron beam, and there is no need to open an optical window at a position near the outer shell 6A of the four-dimensional electron microscope 10A to allow the pulsed electron beam to pass through, causing damage to the cavity formed by the damage of the outer shell 6A, so that four-dimensional detection can be achieved.

[0353] It can be understood that the electron source in the four-dimensional electron microscope 10A can include any of the above electron sources, wherein the optical fiber in the electron source is the excitation optical fiber.

[0354] With reference to Figures 42-44 , in some embodiments, a four-dimensional electron microscope 10A further includes a housing 6A having a vacuum chamber. An electron source 100 and an electron optical assembly 3A are sequentially disposed within the vacuum chamber. The electron source 100 is disposed at one end of the housing 6A along its longitudinal direction. In other words, the housing 6A is provided with an opening communicating with the vacuum chamber. The light input end 1101 of the excitation optical fiber 110A of the electron source 100 is exposed through the opening and coupled to the light source assembly 2A. Furthermore, the outer peripheral wall of the excitation optical fiber 110A is sealed to the inner sidewall of the opening, thereby ensuring the sealing of the cavity and improving the overall quality of the cavity. The arrangement of the electron source 100 of the present application enables the emission of a pulsed electron beam without requiring an additional optical window in the housing 6A near the electron source 100 for the pulsed electron beam to enter. This eliminates the need to damage the cavity of the electron microscope and does not affect its performance. Furthermore, the present application can modify an existing electron microscope. During the modification, only the electron source 100 needs to be replaced to achieve the output of a pulsed electron beam. There is no need to open an optical window in the outer shell 6A near the electron source 100, and there is no need to damage the cavity of the existing electron microscope. That is, the modification is simple, the modification cost is low, and the detection effect after modification is better.

[0355] In some embodiments, the housing 6A is provided with a through opening near the sample 5A for the third optical fiber 23A to extend into the housing, so that the excitation light can be irradiated on the sample and cooperate with the electron beam to characterize the sample.

[0356] It is understood that excitation fiber 110A serves as a transmission medium for the laser and a carrier for the low-dimensional material of electron emission layer 120. Excitation fiber 110A can be a single-mode fiber, a multi-mode fiber, a polarization-maintaining fiber, a holey fiber, or a multi-core fiber. It should be noted that regardless of the type of excitation fiber 110A, electron emission layer 120 is located within the vacuum chamber.

[0357] With reference to Figures 42-44, the electron optical assembly 3A is located on the electron beam exit side of the electron source 100. The electron optical assembly 3A is used to adjust the deflection direction of the electron beam so that the electron beam is incident on the sample 5A. In some embodiments, the electron optical assembly 3A includes a magnetic lens 31A and other structures, which are mainly used to modulate the deflection direction of the electron beam so that it can be projected onto the sample 5A. The detector 4A is located on one side of the sample 5A to collect the reflected electron signal of the electron beam incident on the sample 5A, or the transmitted electron signal of the electron beam that penetrates the sample 5A. That is, through the provision of the detector 4A, the four-dimensional electron microscope 10A of the present application can achieve the functions of a scanning electron microscope and a transmission electron microscope.

[0358] In some embodiments, the electron source 100 also includes an anode, and there is a preset electric field between the anode and the electron emission layer 120. The electron beam can be incident on the sample 5A under the drive of the preset electric field. That is to say, the electron emission layer 120 emits an electron beam under the excitation of the pulsed laser to form a cathode opposite to the anode. The electrons can move toward the sample 5 under the action of the electric field between the anode and the electron emission layer 120. The electron optical component 3A is arranged on the side of the electron source 100 that emits the electron beam, and is used to adjust the deflection direction of the electron beam, so that the electron beam emitted from the electron emission layer 120 can be incident on the sample 5A, and then the detector 4A receives the corresponding signal emitted through the sample 5A to detect and obtain information about the sample 5A.

[0359] In some embodiments, the anode has a first electron channel, and the electron optical component 3A has a second electron channel connected to the first electron channel, so that the electron beam can pass through the first electron channel and the second electron channel under the drive of a preset electric field and be incident on the sample 5A. That is, the electron beam is driven by the electric field to pass through the first electron channel, and is regulated by the electron optical component 3A when passing through the second electron channel. The deflection direction of the electron beam changes, and finally it is incident on the sample 5A, and then the detector 4A receives the reflected electron signal or the transmitted electron signal emitted by the sample 5A. It can be understood that the anode can be set to a hollow ring, and the middle of the ring-shaped anode is the first electron channel for the electron beam to pass through. Thereby, the anode can cooperate with the electron emission layer 120 to form an electric field that drives the electron beam without affecting the passage of the electron beam.

[0360] In some embodiments, the four-dimensional electron microscope 10A also includes a sample stage, and the electron source 100, the electron optical component 3A and the sample stage are arranged in sequence along the propagation direction of the electron beam. The sample stage is used to carry the sample 5A. In some embodiments, a channel is provided in the middle of the sample stage for the electron beam that can penetrate the sample 5A to propagate, that is, the electron beam that penetrates the sample 5A will not be blocked by the sample stage and can continue to propagate, thereby facilitating the four-dimensional electron microscope 10A to achieve transmission scanning detection.

[0361] In some embodiments, the light source assembly 2A includes a light source 29A and a first optical fiber 21A. The light source 29A is configured to emit pulsed laser light. The first optical fiber 21A is connected between the light source 29A and the excitation optical fiber 110A to transmit the pulsed laser light emitted by the light source 29A to the excitation optical fiber 110A. In other words, the light source 29A is coupled to one end of the first optical fiber 21A, and the excitation optical fiber 110A is connected to the other end of the first optical fiber 21A. In some embodiments, a device such as an optical switch 28A may be provided between the first optical fiber 21A and the excitation optical fiber 110A to control whether the optical path is open or closed.

[0362] The four-dimensional electron microscope 10A of the present application is capable of scanning and detecting the surface of a sample, that is, realizing the function of a scanning electron microscope. Referring to FIG42, in some embodiments, the reflected electron signal includes a secondary electron signal and a backscattered electron signal, that is, the four-dimensional electron microscope 10A of the present application is capable of detecting secondary electrons and backscattered electron signals excited by the surface of the sample. In this embodiment, the light source assembly 2A also includes a first fiber optic beam splitter 24A, a second optical fiber 22A, and a first optical fiber delay 26A. The first fiber optic beam splitter 24A can split the pulsed laser into two parts, one part for exciting the electron beam, and the other part after time delay modulation to illuminate the surface of the sample 5A to achieve time-resolved imaging analysis, that is, to achieve feature display in the time dimension. It can be understood that the first fiber optic beam splitter 24A has a first input end coupled to the light source 29A and a first output end relative to the first input end. The first output end is connected to the first optical fiber 21A and the second optical fiber 22A respectively. In other words, the first fiber optic beam splitter 24A splits the pulsed laser emitted by the light source 29A into two parts, which are transmitted to the first optical fiber 21A and the second optical fiber 22A respectively.

[0363] As shown in FIG42 , sample 5A has an incident surface disposed opposite the electron beam exit side of electron source 100. A second optical fiber 22A extends from one end of first optical fiber beam splitter 24A toward the incident surface of sample 5A, enabling the optical fiber transmitted within second optical fiber 22 to be emitted onto sample 5A. The receiving surface of sample 5A can be tilted relative to the propagation direction of the electron beam or can be perpendicular to the propagation direction of the electron beam, without limitation. In some embodiments, a first optical fiber delay 26A is coupled to second optical fiber 22A to time-delay the light beam propagating within second optical fiber 22A, thereby creating a predetermined time delay between the light within second optical fiber 22A and the light within first optical fiber 21A used to excite the electron beam. It will be appreciated that, based on the photoelectric effect, electron microscopes in related art utilize differences in photoelectron yields at different spatial locations of a sample as image contrast for projection imaging. The present application, combined with ultrafast optical pump-probe technology, can provide electron microscopes with high temporal resolution. In this embodiment, the electron beam excited by the pulsed laser in the first optical fiber 21A excites the sample 5A, and then the pulsed laser after the time delay in the second optical fiber 22A is used as the probe light to irradiate the sample 5A, so as to excite the material, so that the reflection or transmission condition of the electron beam incident on the sample 5A changes, and the required secondary electron signal or backscattered electron signal with time-characterized characteristics is formed. When the pulsed laser after the time delay in the second optical fiber 22A is used as the probe light, the time delay of the pulsed laser in the second optical fiber 22A can be changed by adjusting the first optical fiber delay 26A, so that the changes occurring in the material at different time points after being excited by the laser can be known, so as to realize time-resolved electron beam imaging, and can detect the ultrafast dynamic process on the surface of the sample 5A in real time at an ultra-high spatiotemporal resolution scale. In this embodiment, the detector 4A includes a backscattering detector or a secondary detector, which is arranged toward the incident surface of the sample 5A to receive the secondary electron signal and perform imaging.

[0364] Referring to FIG. 43 , in an embodiment of scanning and detecting the sample surface, the cathode fluorescence signal of sample 5A can also be detected and analyzed. By exciting the cathode fluorescence signal on the surface of sample 5A with an electron beam, detector 4A includes a cathode fluorescence analysis system. The cathode fluorescence analysis system faces the incident surface of sample 5A and is configured to receive the cathode fluorescence signal from the surface of sample 5A. The cathode fluorescence analysis system can be configured as a time-resolved single photon counting system (TCSPC), which performs time-resolved cathode fluorescence analysis on the cathode fluorescence signal. This will not be further described here.

[0365] The four-dimensional electron microscope 10A of the present application can also perform transmission detection on the sample, that is, realize the function of a transmission electron microscope. Referring to Figure 44, the sample 5A also includes an exit surface relative to the incident surface. In some embodiments, the detector 4A includes a receiving screen 41A. The receiving screen 41A is arranged on the side of the sample 5A facing away from the electron source 100 and is used to receive the electron beam that penetrates the sample 5A. The receiving screen 41A can be set as a fluorescent screen. The electron beam passes through the sample and projects the sample information on the fluorescent screen. Then, through the camera 42A and other structures, imaging and photography are performed to obtain experimental results, such as bright field images, dark field images, electron diffraction spectra, high-resolution images, and chemical information. In this embodiment, a high-angle annular dark field detector, a low-angle annular dark field detector, or annular bright field detector can also be set on the side of the exit surface relative to the sample 5A to obtain a high-angle annular dark field image, a low-angle annular dark field image, or annular bright field image of the electron transmission sample 5A, and detect the sample 5A to realize the function of a transmission scanning electron microscope.

[0366] In some embodiments, the electron optical component 3A also includes an intermediate mirror 32A and a projection mirror 33A, which are sequentially arranged between the sample 5A and the receiving screen 41A. The intermediate mirror 32A has a converging effect on the electron beam, and the projection mirror 33A is used to adjust the radial size of the electron beam so that structures such as the photographic room 42A can image the electron beam projected onto the receiving screen 41A.

[0367] In some embodiments, the light source assembly 2A further includes a second fiber optic beam splitter 25A, a third optical fiber 23A, and a second fiber optic delay device 27A. The first fiber optic beam splitter 24A is capable of splitting the pulsed laser light into two parts, one for exciting the electron beam and the other as the probe light, which is then modulated by time delay and irradiated onto the surface of the sample 5A to achieve time-resolved imaging analysis. The second fiber optic beam splitter 25A has a second input end coupled to the light source 29A and a second output end relative to the second input end. The second output end is connected to the first optical fiber 21A and the third optical fiber 23A, respectively. That is, the second fiber optic beam splitter 25A splits the pulsed laser light emitted by the light source 29A into two parts, which are transmitted to the first optical fiber 21A and the third optical fiber 23A, respectively. The third optical fiber 23A is extended toward the sample 5A at one end away from the second optical fiber splitter 25A so as to be able to emit the light transmitted inside the third optical fiber 23A onto the sample 5A. The second optical fiber delay 27A is coupled to the third optical fiber 23A and is used to time delay the light beam propagating in the third optical fiber 23A so that the light in the third optical fiber 23A and the light in the first optical fiber 21A used to excite the electron beam have a preset time delay, thereby realizing time-resolved electron beam imaging.

[0368] The present invention's arrangement of using a pulsed laser to excite the electron excitation layer 121 to form an electron beam eliminates the complex spatial optical coupling structure required for introducing an external laser. This allows the four-dimensional electron microscope 10A to be less affected by the environment and to excite a stable electron beam, thereby improving the scanning stability of the sample 5A under test. Furthermore, the present invention's electron source 100 utilizes a low-dimensional material as the electron-emitting material. Since the electron excitation layer 121 has a strong light-matter interaction and a rich electronic band gap, the pulsed laser can better interact with the electron excitation layer 121 to excite electrons within the electron excitation layer 121. Furthermore, the electrons emitted through tunneling from the electron excitation layer 121 exhibit low energy dispersion, high brightness, and high stability. Furthermore, the present application can form an electron beam with pulsed properties by exciting the electron excitation layer 121 through a pulsed laser. There is no need to open an additional window on the electron microscope to provide the pulsed electron beam, and there is no need to damage the electron microscope cavity, which facilitates the realization of miniaturized design. Moreover, the pulsed laser can be modulated by the electron optical component 3A to modulate the electron beam it excites, thereby reducing the impact of the modulated electron beam on the scanning quality, and thus being able to perform stable scanning of the sample to be tested 5A.

[0369] The fifth aspect of the present application provides an electronic exposure machine for exposing samples, which can achieve the effects of good stability, precise control, high exposure quality and easy miniaturization design.

[0370] As shown in Figures 46 and 47, the electronic exposure machine 10B includes a light source 200B, an electron source 100, a light modulator 500B and an electron optical component 600B. The light source 200B can emit laser for excitation. The laser propagates to the electron source 100 to excite the electron source 100 to form an electron beam. The electron beam is modulated by the electron optical component 600B and projected onto the sample 410B to expose the sample 410B.

[0371] It can be understood that the electron source in the electronic exposure machine can include any of the electron sources mentioned above in this application.

[0372] Continuing with FIG. 46 , the electron source 100B further includes an optical modulator 500B. The optical modulator 500B is connected between the light source 200B and the optical fiber 110 and is used to control whether the laser light is transmitted to the optical fiber 110. In some embodiments, the optical modulator 500B includes an electro-optical modulator or an optical switch. The optical switch can control whether the laser light emitted by the light source 200B is transmitted to the optical fiber 110. The electro-optical modulator can simultaneously control whether the laser light emitted by the light source 200B is transmitted to the optical fiber 110 while adjusting the phase of the laser light emitted by the light source 200B. Because the electron beam is controlled by the laser light via the optical modulator 500B, there is no need to set an electron beam gate to modulate the electron beam. Moreover, an existing electron microscope can be modified to form the electronic exposure machine 10B of the present application. During the modification, since the electron beam can be controlled by the optical modulator 500B, there is no need to consider adding an electron beam gate structure and the corresponding electric field and magnetic field distribution influence and wiring issues. After using the electron source 100 of the present application, the optical modulator 500B can be directly added to the external optical path, such as the optical fiber 110, thereby completing the hardware transformation of the electronic exposure function.

[0373] The electronic exposure machine 10B further includes an electron optical component 600B, which is disposed on the electron beam exit side of the electron source 100 . The electron optical component 600B is used to adjust the deflection direction of the electron beam so that the electron beam is incident on the sample 410B.

[0374] In some embodiments, the electron optical component 600B includes a focusing magnetic lens 610B and a deflection coil 620B. The focusing magnetic lens 610B and the deflection coil 620B are arranged at intervals on the electron beam exit side of the electron source 100 along the exit direction of the electron beam. They are mainly used to modulate the deflection direction of the electron beam so that it can be projected onto the sample 410B, thereby forming a preset exposure pattern on the sample.

[0375] In some embodiments, the electron source 100 also includes an anode, and there is a preset electric field between the anode and the electron excitation layer 121. The electron beam can be incident on the sample 410B under the drive of the preset electric field. That is to say, the electron excitation layer 121 emits an electron beam under the excitation of the laser, forming a cathode opposite to the anode. The electrons can move toward the sample 410B under the action of the electric field between the anode and the electron excitation layer 121. The electron optical component 600B is arranged on the side of the electron beam emitted by the electron source 100 and is used to adjust the deflection direction of the electron beam, so that the electron beam emitted from the electron excitation layer 121 can be incident on the sample 410B for exposure.

[0376] In some embodiments, the anode has a first electron channel, and the electron optical component 600B has a second electron channel connected to the first electron channel, so that the electron beam can pass through the first electron channel and the second electron channel under the drive of a preset electric field and be incident on the sample 410B. That is, the electron beam is driven by the electric field to pass through the first electron channel, and is regulated by the electron optical component 600B when passing through the second electron channel. The deflection direction of the electron beam changes and finally is incident on the sample 410B. It can be understood that the anode can be set to a hollow ring, and the middle of the ring-shaped anode is the first electron channel for the electron beam to pass through. Thereby, the anode can cooperate with the electron excitation layer 121 to form an electric field that drives the electron beam without affecting the passage of the electron beam.

[0377] As shown in FIG46 , in some embodiments, the electron exposure apparatus 10B further includes a sample stage 400B. The sample stage 400B is located on a side of the electron optical assembly 600B facing away from the electron source 100 along the propagation direction of the electron beam and is used to support a sample 410B. In some embodiments, a Faraday cup is also provided on the sample stage 400B to measure the electron beam current, that is, the intensity of the electron beam incident on the sample 410B, to facilitate regulation of the electron beam and thus control of the exposure effect.

[0378] In some embodiments, the electron exposure machine 10B further includes a housing 300B having a vacuum chamber 310B. The light-emitting end 1102 of the optical fiber 110 of the electron source 100, the electron optical assembly 600B, and the sample stage 400B are sequentially spaced apart within the vacuum chamber 310B. The electron excitation layer 121 is disposed on the light-emitting end 1102 of the optical fiber 110 so as to be located on the light-emitting path of the laser light emitted from the optical fiber 110, thereby emitting an electron beam from the electron source 100 into the vacuum chamber 310B. In other words, the electron source 100 is disposed through one end of the housing 300B along its longitudinal direction. The housing 300B is provided with an opening communicating with the vacuum chamber 310B. The light-incoming end 1101 of the optical fiber 110 of the electron source 100 is exposed through the opening and coupled to the light source 200B. The outer peripheral wall of the optical fiber is sealed to the inner side wall of the opening, thereby ensuring the sealing of the chamber and improving the overall quality of the chamber.

[0379] Furthermore, the present application can modify an existing electron microscope. During the modification, only the electron source 100 needs to be replaced to achieve the output of the electron beam. There is no need to open an optical window in the outer shell 300B near the electron source 100, and there is no need to damage the cavity of the existing electron exposure machine. That is, the modification is simple, the modification cost is low, and the detection effect after modification is better.

[0380] In some embodiments, multiple electron sources 100 can be configured and combined for scanning exposure, depending on the exposure pattern, to improve exposure efficiency. For high-precision areas of a preset pattern to be exposed, the optical fiber 110 in this application can be configured as a single-mode optical fiber, and the electron beam emitted by the electron source 100 can be a low-current electron beam. For large-area scanning areas, the optical fiber 110 can be configured as a multimode or other type of optical fiber, and the electron beam emitted by the electron source 100 can be a high-current electron beam. In actual operation, the spot size or exposure time of the electron beam formed by the electron source using different optical fibers can be adjusted based on the beam size calculation to achieve fast and high-precision scanning exposure.

[0381] In some embodiments, as shown in Figures 46-47, the light input end 1101 of the optical fiber 110 extends through the opening to the outside of the vacuum chamber 310B, so that the optical fiber is coupled to the light source 200B. Of course, the end face of the light input end 1101 of the optical fiber 110 can also be arranged flush with the plane of the opening. In this way, the optical fiber 110 can be roughly encapsulated within the housing 300B, and the end face of the light input end 1101 of the optical fiber 110 is exposed through the opening, so that the light source 200B is coupled to the light input end 1101 of the optical fiber 110. This not only better protects the optical fiber 110, but also facilitates the transmission of laser light emitted by the light source 200B through the optical fiber 110.

[0382] The laser-excited electron excitation layer 121 of the present application forms an electron beam, eliminating the complex spatial optical coupling structure required for introducing an external laser. This allows the electronic exposure device 10B to be less affected by the environment and to have a stable excited electron beam, thereby improving the scanning stability of the sample 410B to be tested. Furthermore, the electron source 100 of the present application uses a low-dimensional material as the electron-emitting material. Since the electron excitation layer 121 has a strong light-material interaction and a rich electronic band gap, the laser can better interact with the electron excitation layer 121 to excite the electrons within the electron excitation layer 121. Furthermore, the electrons emitted through tunneling from the electron excitation layer 121 have the characteristics of low energy dispersion, high brightness, and high stability. Furthermore, the present application can form an electron beam with pulsed properties by exciting the electron excitation layer 121 through laser. There is no need to open an additional window on the electron microscope to provide a pulsed electron beam, no need to damage the electron microscope cavity, and no need to set an electron beam gate to modulate the electron beam, which further saves space and facilitates miniaturization design. By modulating the laser through the electron optical component 600B, the electron beam it excites can be modulated, thereby reducing the impact on the scanning quality when modulating the electron beam, and thus being able to stably expose the sample 410B to be tested.

[0383] The sixth aspect of the present application provides a multi-beam fiber optic electronic exposure machine for exposing samples, which can achieve the advantages of improving exposure efficiency, precise control, improving exposure quality and facilitating miniaturized design.

[0384] As shown in Figures 48-52, the multi-beam fiber optic electron exposure machine 10C includes a light source 200C, an electron source 100 and an electron optical component 600C. The light source 200C can emit laser for excitation. The laser propagates to the electron source 100 to excite the electron source 100 to form an electron beam. The electron beam is modulated by the electron optical component 600C and projected onto the sample 410C to expose the sample 410C.

[0385] The electron source 100 includes an optical fiber assembly 101 coupled to the light source, and an electron emission layer 120. The electron emission layer includes at least an electron excitation layer 121. The optical fiber assembly 101 has a light input end 1101 coupled to the light source 200C, and a light output end 1102 opposite to the light input end 1101. Laser light emitted by the light source 200 enters the optical fiber assembly 101 from the light input end 1101 and is emitted from the light output end 1102 after propagation through the optical fiber assembly 101. The optical fiber assembly 101 includes a plurality of fiber cores 111 for transmitting laser light. The electron excitation layer 121 is disposed on the light output path of the laser light emitted from the fiber cores 111 of the optical fiber assembly 101, so that the electron excitation layer 121 can emit an electron beam under the excitation of the laser light. In other words, the electron emission layer 120 is configured to emit an electron beam outward from the light output end 1102 under the excitation of the laser light transmitted by the fiber cores 111. The laser propagates in the fiber core 111 and is emitted from the light output end 1102 to the electron excitation layer 121 , and the electron excitation layer 121 is stimulated to emit an electron beam.

[0386] It can be understood that the electron source in the multi-beam fiber electron exposure machine can include any of the electron sources mentioned above in this application.

[0387] Continuing with FIG. 48 , the electron source 100 further includes an optical modulator 500C. One end of the optical modulator 500C is connected to the light source 200C, and the other end is connected to each of the multiple fiber cores 111 of the optical fiber assembly 101. The optical modulator 500C is configured to control whether laser light from each fiber core 111 propagates. In some embodiments, the optical modulator 500C comprises one of a spatial light modulator, an optical switch, and an electro-optical modulator. The optical switch controls whether laser light emitted by the light source 200C propagates into each fiber core 111 of the optical fiber assembly 101. The electro-optical modulator and the spatial light modulator control whether laser light emitted by the light source 200C propagates into each fiber core 111 of the optical fiber assembly 101 while adjusting the phase of the laser light emitted by the light source 200C. Specifically, the optical modulator 500C controls whether laser light emitted by the light source 200C propagates into each corresponding fiber core 111, thereby regulating whether light passes through each fiber core 111.

[0388] Because the electron beam is controlled by the laser light modulator 500C, there is no need to set up an electron beam gate to modulate the electron beam. Furthermore, an existing electron microscope can be modified to form the multi-beam fiber-optic electron exposure apparatus 10C of the present application. During modification, since the electron beam can be controlled by the light modulator 500C, there is no need to consider adding an electron beam gate structure and the corresponding electric and magnetic field distribution effects and wiring issues. After using the electron source 100 of the present application, the light modulator 500C can be directly added to the external optical path, such as the optical fiber assembly 101, thus completing the hardware modification of the electronic exposure function.

[0389] Referring to FIG. 48 , the multi-beam fiber-optic electron exposure system 10C further includes an electron optical assembly 600C, located on the electron beam exit side of the electron source 100. This assembly is used to adjust the focus and deflection direction of the multiple electron beams so that they are incident on the sample 410C. In conjunction with FIG. 50 , this can be seen as an array structure that divides the sample 410C into multiple regions. The electron optical assembly 600C focuses the multiple electron beams onto their respective regions, exposing them simultaneously and thereby improving exposure efficiency for the entire sample 410C.

[0390] In some embodiments, the electron optical component 600C includes a focusing magnetic lens 610C and a deflection coil 620C. The focusing magnetic lens 610C and the deflection coil 620C are arranged at intervals on the electron beam exit side of the electron source 100 along the exit direction of the electron beam. They are mainly used to modulate the deflection direction of the electron beam so that it can be projected onto different areas on the sample 410C.

[0391] Referring to FIG51 , FIG51 shows a schematic structural diagram of an embodiment of an optical fiber assembly 101 of the present application in which the cores 111 are arranged in an array. Referring to FIG49 , the optical fiber assembly 101 in the embodiment of FIG51 includes a plurality of optical fibers 110 arranged in an array. An electron excitation layer 121 is provided on the end face of one end of each optical fiber 110 that emits laser light, so that the electron excitation layer 121 is located on the light output path of the laser light emitted from the core 111 of the corresponding optical fiber 110. In other words, in some embodiments, the optical fiber assembly 101 can be configured in the form of an optical fiber array, which includes a plurality of optical fibers 110. One end of the optical fiber 110 is connected to an optical modulator 500C, and the other end of the optical fiber is covered with an electron excitation layer 121. The optical modulator 500C is respectively connected to the plurality of optical fibers 110 in the optical fiber array to control and regulate the propagation of the laser light in each optical fiber 110, or to control whether the core 111 of each optical fiber 110 is transparent. It can be understood that the optical modulator 500C simultaneously controls the light passing through multiple fiber cores 111, excites the electron excitation layer 121 to form multiple electron beams, and then the electron optical component 600C controls the multiple electron beams to focus on different areas on the sample 410C respectively. The multiple electron beams expose the corresponding areas at the same time, that is, dot matrix exposure is realized, thereby improving the exposure efficiency of the entire sample 410C.

[0392] Referring to FIG. 52 , in the embodiment shown in FIG. 5 , the optical fiber assembly 101 includes a plurality of fiber cores 111 and a wrapping layer 112 wrapped around the plurality of fiber cores 111. The radial directions of the plurality of fiber cores 111 are parallel to each other, and the plurality of fiber cores 111 are closely arranged along the axial direction of the fiber cores 111 to form a pixel optical fiber. In other words, the optical fiber assembly 101 of the present application can adopt the setting of a pixel optical fiber. The electron excitation layer 121 is provided on the light-emitting end 1102 of the optical fiber assembly 101, so that the electron excitation layer 121 is located on the light-emitting path of the lasers emitted by the plurality of fiber cores 111, that is, one end of the pixel optical fiber is connected to the optical modulator 500C, and the other end of the pixel optical fiber is covered with the electron excitation layer 121. The optical modulator 500C simultaneously controls the light transmission of multiple cores 111 in the optical fiber assembly 101, exciting the electron excitation layer 121 to form multiple electron beams, and then the electron optical assembly 600C controls the multiple electron beams to focus on different areas on the sample 410C respectively. The multiple electron beams expose the corresponding areas at the same time, that is, dot matrix exposure is realized, thereby improving the exposure efficiency of the entire sample 410C.

[0393] Patterned exposure can also be achieved by modulating the light flux within multiple cores 111 in the pixel optical fiber using the optical modulator 500C. It is understood that the optical modulator 500C controls the corresponding cores 111 within the optical fiber assembly 101 to be either light-transmitting or light-blocking, so that the laser light emitted from the optical fiber assembly 101 can form a corresponding spot shape. The axial pattern of the electron beam excited by the laser light on the electron excitation layer 121 also changes accordingly. The electron beam is then modulated by the electron optical assembly 600C and irradiated onto the sample 410C to ultimately form a corresponding exposure pattern, thereby achieving patterned exposure. The above-described arrangement can directly form an exposure pattern without requiring a single electron beam to expose the desired exposure pattern for a long time, thereby relatively improving exposure efficiency. Furthermore, combined with the arrangement of the electron source 100 of the present application, the accuracy of the exposure pattern can be relatively improved.

[0394] The fiber cores in the pixel fiber are arranged more closely, so it can be considered that the light-excited electron beams of each fiber core in the pixel fiber cooperate with each other and finally focus into a closed pattern. By controlling whether each fiber core is transparent to light, a graphical setting can be achieved, and then the complete pattern can be obtained by scanning with electron beams of different shapes.

[0395] In the embodiment shown in FIG52 , i.e., for the pixel optical fiber, the electron excitation layer 121 can be disposed on the end face 11021 of the light-emitting end 1102 of the optical fiber assembly 101, and the end face 11021 of the light-emitting end 1102 of the optical fiber assembly 101 is angled relative to the extension direction of the fiber core 111. The laser light 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 light emitted from the fiber core 111 and emits electrons. In other words, for the pixel optical fiber, the end face 11021 of the light-emitting end 1102 can also be arranged to be tilted relative to the extension direction of the fiber core 111, or to be angled relative to the extension direction of the fiber core 111. In this way, oblique incidence on the electron excitation layer 121 can be achieved, and an optical field perpendicular to the end face 11021 of the light-emitting end 1102 can be achieved. In some embodiments, the angle between the end face 11021 of the light-emitting end 1102 of the optical fiber assembly 101 and the extension direction of the fiber core 111 is in the range of 0-90°. When the angle is 90°, the laser light propagating within the optical fiber assembly 101 is perpendicularly emitted from the end face 11021 of the light-emitting end 1102. Therefore, the electron emission angle can be changed by changing the tilt angle of the end face 11021 of the light-emitting end 1102. The electron emission angle can also be adjusted by adjusting the polarization state of the laser light in the fiber core 111 of the optical fiber assembly 101. This improves the ease of adjusting the electron beam in the multi-beam optical fiber electron exposure machine 10C and helps expand the application range of the electron source 100.

[0396] Referring to the embodiment shown in FIG. 52 , that is, for the pixel fiber embodiment, in some embodiments, the laser-emitting end of the optical fiber assembly 101 is provided with a tip portion j, and the electron excitation layer 121 covers the surface j1 of the tip portion j of the optical fiber assembly 101. The laser light emitted from the core 111 of the optical fiber assembly 101 can directly irradiate the electron emission layer 120, so that the electron excitation layer 121 is excited by the laser light emitted from the core 111 and emits electrons. In other words, the laser-emitting end of the pixel fiber can also be configured as a tip. It is understood that the electron excitation layer 121 is located on the light-emitting path of the core 111 to facilitate receiving the laser light emitted from the core 111. The tip portion j has a needle-like geometric structure, which improves the field emission enhancement factor, enabling a higher-brightness electron source 100. It also relatively increases the light-emitting area of ​​the core 111, facilitating the realization of a high-power excitation electron beam.

[0397] In some embodiments, the electron source 100 further comprises an anode and a gate. A preset electric field exists between the anode and the electron excitation layer 121. Driven by the preset electric field, the electron beam can be incident on the sample 410C. That is, the electron excitation layer 121 emits an electron beam under the excitation of the laser, forming a cathode opposite the anode. Electrons can move toward the sample 410C under the action of the electric field between the anode and the electron excitation layer 121. The gate, in conjunction with the electron source 100 and the anode, forms a fiber electron gun. The gate can be used to control the direction of the electron beam. An electron optical assembly 600C is provided on the side of the electron source 100 where the electron beam is emitted, and is used to adjust the focus and deflection direction of the electron beam, thereby enabling the electron beam emitted from the electron excitation layer 121 to be incident on the sample 410C for exposure. In some embodiments, the anode has a first electron channel, and the electron optical assembly 600C has a second electron channel connected to the first electron channel, so that the electron beam, driven by the preset electric field, can pass through the first and second electron channels and be incident on the sample 410C. Specifically, the electron beam is driven by the electric field to pass through the first electron channel. As it passes through the second electron channel, it is regulated by the electron optical assembly 600C, causing the deflection direction of the electron beam to change, ultimately impacting the sample 410C. It is understood that the anode can be configured as a hollow ring, with the center of the ring-shaped anode serving as the first electron channel for the electron beam to pass through. This allows the anode to cooperate with the electron excitation layer 121 to form an electric field that drives the electron beam without affecting the passage of the electron beam.

[0398] In some embodiments, the multi-beam fiber-optic electron exposure system 10C further includes a sample stage 400C, which is disposed on a side of the electron optical assembly 600C facing away from the electron source 100 along the propagation direction of the electron beam and is used to support a sample 410C. In some embodiments, a Faraday cup is also provided on the sample stage 400C for measuring the electron beam current, that is, measuring the intensity of the electron beam incident on the sample 410C, to facilitate regulation of the electron beam and thus control the exposure effect.

[0399] In some embodiments, the electron exposure apparatus 10 further includes a housing 300C having a vacuum chamber 310C. The light-emitting end 1102 of the optical fiber assembly 101 of the electron source 100, the electron optical assembly 600C, and the sample stage 400C are sequentially spaced apart within the vacuum chamber 310C. The electron excitation layer 121 is disposed on the light-emitting end 1102 of the optical fiber 110 so as to be located on the light-emitting path of the laser light emitted by the fiber core 111, thereby emitting an electron beam from the electron source 100 into the vacuum chamber 310C. In other words, the electron source 100 is disposed through one end of the housing 300C along its longitudinal direction. The housing 300C is provided with an opening that communicates with the vacuum chamber 310C. The light-incoming end 1101 of the optical fiber assembly 101 of the electron source 100 is exposed through the opening and coupled to the light source 200C. The outer peripheral wall of the optical fiber is sealed to the inner side wall of the opening, thereby ensuring the sealing of the cavity and improving the overall quality of the cavity. The present application can be used to modify an existing electron microscope. During the modification, only the electron source 100 needs to be replaced to achieve the output of the electron beam. There is no need to open an optical window in the outer shell 300C near the electron source 100, and there is no need to damage the cavity of the existing electron exposure machine. That is, the modification is simple, the modification cost is low, and the detection effect after the modification is better.

[0400] For example, after the electron source 100 is prepared, the electron exposure machine 10 can be prepared by setting up a shell 300C and other structures and a control system. The vacuum chamber 310C in the shell 300C is connected to an external vacuum system to keep the vacuum chamber 310C in a vacuum state. The electron source 100, the focusing magnetic lens 610C, and the deflection coil 620C are sequentially set in the vacuum chamber 310C along the axis of the vacuum chamber 310C of the shell 300C from top to bottom. Then, the sample stage 400C is correspondingly set so that the electron beam emitted by the electron source 100 can be projected to the position of the sample stage 400C, so as to facilitate exposure of the sample 410 on the sample stage 400. The sample stage 400 can be set on an electrically controlled translation stage so that the sample stage 400C can be driven to move by the electrically controlled translation stage, thereby facilitating the placement and removal of the sample 410C. After the hardware is assembled, the electron source 100, the focusing magnetic lens 610C, the deflection coil 620C and the Faraday cup can be connected to a control system respectively so as to be controlled by the control system.

[0401] The control system can connect the aforementioned components using software such as LabVIEW. The pattern data to be exposed is input into the control system, which then converts the received pattern data into exposure units. Based on the electron beam intensity during exposure, the vacuum state of the vacuum chamber 310C within the housing 300C, and the focusing effect of the electron beam, the control system automatically calculates the electron beam scanning path and the switching timing of the electron source 100. This generates two sets of commands for focus deflection and electro-optical modulation. These commands control the focusing magnetic lens 610C and deflection coil 620C to adjust the focus and deflection of the electron beam, and the optical modulator 500C to control the passage of laser light within the optical fiber 110, thereby achieving optimal exposure results. The focus deflection and electro-optical modulation commands can also be calibrated to ensure high temporal consistency, thus avoiding control system mismatch during exposure. Furthermore, multiple optical switches or spatial light modulators can be provided on the optical fiber assembly 101C, and these optical switches or spatial light modulators can be connected to the control system to separately control the propagation of light within the multiple fiber cores 111.

[0402] The laser-excited electron excitation layer 121 of the present application forms an electron beam, eliminating the complex spatial optical coupling structure required for introducing an external laser. This allows the multi-beam fiber-optic electron exposure device 10C to be less affected by the environment and to excite a stable electron beam, thereby improving the scanning stability of the sample 410C under test. Furthermore, the electron source 100 of the present application utilizes a low-dimensional material as the electron-emitting material. Since the electron excitation layer 121 has a high optical nonlinear effect and a rich electronic band gap, the laser can better interact with the electron excitation layer 121 to excite the electrons within the electron excitation layer 121. Furthermore, the electrons emitted through tunneling from the electron excitation layer 121 have the characteristics of low energy dispersion, high brightness, and high stability. Furthermore, the present application can form an electron beam with pulsed properties by exciting the electron excitation layer 121 through laser. There is no need to open an additional window on the electron microscope to provide a pulsed electron beam, and there is no need to damage the electron microscope cavity, which facilitates the realization of miniaturized design. Moreover, the laser can be modulated through the electron optical component 600C, so that the electron beam it excites can be modulated, thereby reducing the impact of the modulated electron beam on the scanning quality, and thus being able to stably expose the sample 410C to be tested.

[0403] 53-55 , the present application provides an X-ray tube, including an electron source 100, an anode target 200, and a tube body 300. It is understood that the electron source in the X-ray tube 10D may include the electron source described above in the present application.

[0404] The optical fiber 110 has an input end 1101 and an output end 1102. The input 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. The laser source can be a laser.

[0405] Optical fiber 110 is the transmission medium for the laser and the carrier of the low-dimensional material of electron excitation layer 121. Optical fiber 110 can be single-mode fiber, multimode fiber, polarization-maintaining fiber, holey fiber, or multi-core fiber. It should be noted that regardless of the type of optical fiber 110, electron emission layer 120 is located within vacuum chamber 301D.

[0406] Tube body 300D includes a vacuum chamber 301D. Light-emitting end 1102 of optical fiber 110 is located within vacuum chamber 301D. Electron excitation layer 121 is disposed at light-emitting end 1102 of optical fiber 110. Electron emission layer 120 includes at least electron excitation layer 121. Electron excitation layer 121 is disposed along the light-emitting path of laser light emitted from optical fiber 110, enabling electron excitation layer 121 to emit electrons under laser excitation. Electron excitation layer 121 comprises at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

[0407] In this way, during the process of the laser transmitted in the core 111 of the optical fiber 110 being transmitted to the light-emitting end 1102 of the optical fiber 110 and emitted, 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 laser photons, undergo energy transition and escape from the electron excitation layer 121, and emit electrons outward from the light-emitting end 1102.

[0408] The anode target 200D is arranged in the vacuum chamber 301D, and the anode target 200D is opposite to the light-emitting end 1102 of the optical fiber 110 and is spaced apart. The anode target 200D is used to receive electrons emitted by the electron excitation layer 121 to emit X-rays. An output window 311D is provided on the tube body 300D and is arranged toward the anode target 200D. The output window 311D is constructed to guide the X-rays to be emitted out of the vacuum chamber 301D.

[0409] When in use, the X-ray tube 10D utilizes the electron excitation layer 121 of the electron source 100 to emit electrons toward the anode target 200D, thereby exciting the anode target 200D to emit X-rays. These X-rays can then be emitted out of the vacuum chamber 301D through the output window 311D. This allows the electron source 100 of the X-ray tube 10D to achieve cold emission of electrons, eliminating the excessive heat generated by hot electrodes such as filaments. This significantly reduces heat accumulation within the anode target 200D. Furthermore, since the electron excitation layer 121 is disposed on the optical fiber 110, it helps conserve space within the vacuum chamber 301D, thereby reducing the size of the X-ray tube 10D.

[0410] In some embodiments, the anode target 200D is spaced apart from the light-emitting end 1102 of the optical fiber 110 along the extension direction of the optical fiber 110 , and a preset electric field is provided between the anode target 200D and the electron excitation layer 121 so that the electrons emitted from the electron excitation layer 121 can be accelerated linearly along the extension direction of the optical fiber 110 .

[0411] Compared to using a gate structure as an accelerating electrode, in the X-ray tube 10 of the present application, a preset electric field is set between the anode target 200D and the electron excitation layer 121 to form a linear acceleration of electrons along the direction of the electron excitation layer 121 pointing to the anode target 200D, which greatly simplifies the structure of the X-ray tube 10D and is conducive to reducing the volume of the X-ray tube 10D.

[0412] In this embodiment, the electron excitation layer 121 is connected to the negative pole of the external power supply through the conductive connection layer 130, and the anode target 200D is used as the positive pole of the external power supply, so that a preset electric field exists between the anode target 200D and the electron excitation layer 121. Moreover, since the anode target 200D and the light-emitting end 1102 of the optical fiber 110 are spaced apart along the extension direction of the optical fiber 110, the electrons emitted from the electron excitation layer 121 can be emitted toward the anode target 200D along the extension direction of the optical fiber 110 under the action of the preset electric field, which can better excite the anode target 200D and cause the anode target 200D to emit X-rays with more concentrated energy.

[0413] Optionally, the light input end 1101 of the optical fiber 110 extends out of the vacuum chamber 301D through the first port 302D described below, and the second conductive portion 132 of the conductive connection layer 130 is arranged on the circumferential side of the optical fiber 110, and a partial structure of the second conductive portion 132 is arranged on the portion of the circumferential side of the optical fiber 110 located outside the vacuum chamber 301D, so as to facilitate the conductive connection layer 130 to be connected to the negative pole of an external power supply.

[0414] In some embodiments, the tube body 300D is respectively mounted on the optical fiber 110 and the anode target 200D. For example, the inner circumferential wall of the tube body 300D can be connected to the outer circumferential wall of the optical fiber 110 by bonding, or the outer circumferential wall of the anode target 200D can be bonded to the inner circumferential wall of the tube body 300D by bonding. While assembling the X-ray tube 10, the outer circumferential walls of the optical fiber 110 and the anode target 200D are designed to have dimensions comparable to the inner circumferential wall of the tube body 300D. This can reduce the radial dimension of the X-ray tube 10, thereby facilitating a reduction in the volume of the X-ray tube 10D. This results in a smaller footprint and higher material utilization, thereby enabling the electron source 100 to have a high degree of integration.

[0415] In some embodiments, the tube body 300D has a first port 302D communicating with the vacuum chamber 301D. The light-emitting end 1102 of the optical fiber 110 extends into the vacuum chamber 301D through the first port 302D, and the outer circumferential wall of the optical fiber 110 is sealedly connected to the inner circumferential wall of the first port 302D. This improves the sealing of the vacuum chamber 301, and the electron excitation layer 121 can emit electrons from the light-emitting end 1102 under the excitation of the laser transmitted by the fiber core 111. Furthermore, the electron excitation layer 121 can better emit electrons within the vacuum chamber 301D toward the anode target 200D, thereby improving the reliability of the X-ray tube 10D.

[0416] Specifically, the tube body 300D and the optical fiber 110 can be assembled in a vacuum environment, and the inner circumferential wall of the tube body 300D can be sealed to the outer circumferential wall of the optical fiber 110 , thereby improving the sealing performance of the vacuum chamber 301D.

[0417] In some embodiments, the tube body 300D further includes a second port 303D disposed opposite the first port 302D. The side of the anode target 200D facing away from the light output end 1102 extends outside the vacuum chamber 301D through the second port 303D. The outer peripheral wall of the anode target 200D is sealedly connected to the inner peripheral wall of the second port 303D. This seals the outer peripheral wall of the anode target 200D and the inner peripheral wall of the second port 303D, allowing the anode target 200D to be assembled with the tube body 300D and improving the sealing of the vacuum chamber 301D. Furthermore, the side of the anode target 200D facing away from the light output end 1102 extends outside the vacuum chamber 301D, facilitating connection of the anode target 200D to the positive terminal of an external power source.

[0418] Specifically, the anode target 200D and the optical fiber 110 can be assembled in a vacuum environment, and the inner circumferential wall of the tube 300D and the outer circumferential wall of the anode target 200D can be bonded together by a sealant, thereby improving the sealing performance of the vacuum chamber 301D.

[0419] In some embodiments, the X-ray tube 10D further includes an external electrode 400D disposed between the outer circumferential wall of the anode target 200D and the inner circumferential wall of the second port 303D. Along the longitudinal extension of the tube body 300D, one end of the external electrode 400D is located within the vacuum chamber 301D, while the other end extends outside the vacuum chamber 301D. This arrangement allows the anode target 200D to be connected to the positive terminal of an external power supply via the external electrode 400D. Furthermore, the external electrode 400D, disposed around the outer circumferential wall of the anode target 200D and partially located within the vacuum chamber 301D, increases the contact area between the external electrode 400D and the anode target 200D, strengthens the bonding between the external electrode 400D and the anode target 200D, and allows the external electrode 400D to be more effectively used to provide a preset voltage to the anode target 200D.

[0420] In some embodiments, referring to Figures 53-55 , the electron source 100 and the anode target 200D are spaced apart along the extension direction of the optical fiber 110. The anode target 200D has a reflective target surface 210D facing the light output end 1102. The reflective target surface 210D is disposed at an angle β with the extension direction of the optical fiber 110. β is greater than 0 degrees and less than 90 degrees. An output window 311D is disposed on the sidewall of the tube 300D and faces the reflective target surface 210D. Optionally, the anode target 200D having the reflective target surface 210D can be made of tungsten, silver, palladium, rhodium, molybdenum, copper, nickel, cobalt, iron, or chromium. In this manner, the electron source 100 can emit electrons toward the reflective target surface 210D of the anode target 200D, thereby stimulating the anode target 200D to emit X-rays. The X-rays are then reflected by the reflective target surface 210D and emitted out of the vacuum chamber 301D through the output window 311D.

[0421] In other embodiments, referring to Figures 56 and 57, the anode target 200D includes a transmissive anode 220D. Along the longitudinal extension direction of the tube body 300D, the electron source 100 and the output window 311D are arranged at opposite ends of the tube body 300D, and the transmissive anode 220D is located between the electron source 100 and the output window 311D.

[0422] The transmissive anode 220D may include a substrate and a metal layer disposed on the side of the substrate facing the light output end 1102. The thickness of the metal layer is less than 100 nm. The substrate may be made of any of the following X-ray transmissive materials, for example, glass. The metal layer may be made of tungsten, silver, palladium, rhodium, molybdenum, copper, nickel, cobalt, iron, or chromium, and may be a metal plating layer.

[0423] In this manner, the electron source 100 at one end of the tube 300D emits electrons toward the anode target 200D, which can stimulate the anode target 200D to emit X-rays that penetrate the anode target 200D and then exit through the output window 311D at the other end of the tube 300D. For example, as shown in Figures 53 and 56 , the light input end 1101 of the optical fiber 110 can extend outside the vacuum chamber 301D through the first port 302D. In this manner, a portion of the second conductive portion 132 can be disposed on the circumferential side of the optical fiber 110 that is located outside the vacuum chamber 301D, facilitating connection of the conductive connection layer 130 to the negative pole of an external power source.

[0424] Of course, the end face of the light input end 1101 of the optical fiber 110 may also be arranged flush with the plane where the first port 302D is located (not shown in the figure). In this way, the optical fiber 110 can be roughly encapsulated in the tube body 300D, and the end face of the light input end 1101 of the optical fiber 110 is exposed through the first port 302D, so that the laser source is coupled to the light input end 1101 of the optical fiber 110, which better protects the optical fiber 110 and also facilitates the transmission of laser light emitted by the laser source through the optical fiber 110.

[0425] In some embodiments, the tube body 300D includes an inner tube 310D that is sleeved over the optical fiber 110 and the anode target 200D, and an outer tube 320D that is sleeved over the inner tube 310D. The outer tube 320D is provided with an opening 321D, through which a portion of the structure of the inner tube 310D is exposed to form an output window 311D. The inner tube 310D is made of an X-ray-transmitting material, and the outer tube 320D is made of an X-ray-blocking material. Optionally, the X-ray-transmitting material includes glass, beryllium, aluminum, titanium, or sapphire. Optionally, the X-ray-blocking material includes, for example, lead or barium sulfate.

[0426] Specifically, in the embodiment shown in FIG53 , the opening 321D is provided on one side of the outer tube 320D. Specifically, in the embodiment shown in FIG53 , the opening 321D is provided at the end of the outer tube 320D away from the electron source 100, so that the electron source 100 and the output window 311D can be arranged relative to each other along the extension direction of the optical fiber 110. In this manner, the outer tube 320D can block X-rays, while the inner tube 310D can emit X-rays outward through the opening 321D, i.e., the output window 311D, thereby reducing the possibility of X-rays being emitted from other parts of the inner tube 310D other than the output window 311D. This improves the safety and reliability of the X-ray tube 10 while also achieving concentrated X-ray emission and low-loss X-ray emission from a vacuum to the outside world.

[0427] In some embodiments, the outer diameter of the tube body 300D is 125 μm to 2000 μm, and the length of the tube body 300D is 3 cm to 9 cm. By respectively sheathing the tube body 300D on the optical fiber 110 and the anode target 200D, the radial dimension of the X-ray tube 10D is reduced, which can significantly reduce the volume of the X-ray tube 10D. This allows the electron excitation layer 121 and the anode target 200D to effectively accelerate electrons within the smaller vacuum chamber 301D, thereby facilitating high integration and miniaturization of the electron source 100 and the X-ray emission structure, and facilitating portable applications of the X-ray tube 10D and metal flaw detection in confined spaces.

[0428] In some embodiments, the distance between the light-emitting end 1102 of the optical fiber 110 and the anode target 200D may be 3 cm to 5 cm along the extension direction of the optical fiber 110. Of course, the distance between the light-emitting end 1102 of the optical fiber 110 and the anode target 200D of the present application is not limited thereto, and 3 cm to 5 cm is used as an example for illustration.

[0429] In the present application, the distance between the electron excitation layer 121 and the anode target 200D is small, so that the electric field lines between the electron excitation layer 121 and the anode target 200D are more uniform, so that more electrons are effectively accelerated and then incident on the anode target 200D to stimulate the anode target 200D to emit X-rays, which is also conducive to the miniaturization of the X-ray tube 10D.

[0430] Compared with the X-ray tube in the related art that uses a gate structure as an accelerating electrode, in the present application, there is a preset electric field between the anode target 200D and the electron excitation layer 121, so that the electrons emitted from the electron excitation layer 121 can be emitted toward the anode target 200D along the extension direction of the optical fiber 110 under the action of the preset electric field, saving space in the vacuum chamber 301D, simplifying the optical system and the electrical system, and making it easier to form an integrated and miniaturized X-ray tube 10D.

[0431] Compared with traditional X-ray tubes, a portion of the inner tube 310D of the tube body 300D of the present application serves as the output window 311D, which greatly simplifies the window structure and is more conducive to miniaturization of the X-ray tube 10D. In addition, unlike the relatively macroscopic and complex mechanical structure in the prior art, this solution adopts a highly integrated optical fiber structure, which reduces the existing centimeter-scale small X-ray source to the micron scale while ensuring that the power difference is not much different.

[0432] Assembling the electron source 100 and the anode target 200D in a tube 300D with a smaller diameter enables the electron excitation layer 121 and the anode target 200D to accelerate electrons well in a smaller vacuum chamber 301D, which is conducive to achieving 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 metal flaw detection in a narrow space.

[0433] The embodiments of the present application will be described in detail below with reference to the examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manuals or conventional conditions in this area, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0434] (I) In the following embodiments, the conductive connection layer is a gold layer with a thickness of 60 nm that covers the side of the optical fiber, and the conductive connection layer is in contact with the auxiliary layer or the electron emission layer.

[0435] Example A-1

[0436] Polypropylene carbonate and anisole in a mass ratio of 1:8 were added dropwise onto a silicon wafer, and the mixture was spin-coated at a speed of 1500 rpm for 1 min using a spin coater, and then baked at 60°C for 2 min to obtain a PPC film on the silicon wafer.

[0437] Graphene is obtained from the bulk material using a first adhesive tape by mechanical exfoliation; the first adhesive tape with graphene is then attached to a PPC film, and after pressing with a cotton swab to ensure full contact between the low-dimensional material and the PPC film, the graphene to be transferred is selected using an optical microscope;

[0438] Take a second tape and make a 3mm x 3mm square hole in the middle of the second tape. Lay the second tape on the PPC film so that the graphene to be transferred is located at the hole in the second tape. Use a cotton swab to press the PPC film and the second tape to fully fit. Peel off the second tape and the PPC film, peeling the PPC film and the first tape to transfer the graphene to the PPC film.

[0439] The second adhesive tape and the PPC film are fixed on a glass slide with a central circular hole (5 mm in diameter), and the square hole of the second adhesive tape is centered at the central circular hole. A heating plate is set on the side of the glass slide away from the PPC film, and the glass slide is placed under a light microscope with the side of the PPC with graphene facing down. The glass slide is first heated to 40°C to stretch the wrinkles of the PPC film. Then, the end face of the solid core optical fiber with a conductive connecting layer is facing the side of the PPC with graphene and in contact with the PPC film. The heating temperature is increased to 60°C and the optical fiber is continued to be moved up 50 μm to make the end face of the optical fiber fully contact with the PPC film. The temperature is increased to 130°C to melt the PPC film. The optical fiber is removed and immersed in acetone to clean the PPC film remaining on the end face of the optical fiber. An electron excitation layer made of graphene is obtained on the end face of the solid core optical fiber, and the thickness of the graphene is 1 nm. The graphene is electrically connected to the conductive connecting layer to obtain the electron source.

[0440] Example A-2

[0441] Graphene is grown on a substrate by the CVD (chemical vapor deposition) method. The substrate with graphene is placed in a water tank filled with deionized water so that the graphene floats on the water surface. The tip side of the needle-tip optical fiber is brought into contact with the graphene from above the water surface. After sufficient contact, the tip side is immersed in water, and the needle-tip optical fiber is taken out and dried. An electron excitation layer made of graphene is obtained on the tip side of the needle-tip optical fiber 110b, and the thickness of the graphene is 0.4nm. Then, a conductive connecting layer is prepared on the needle-tip optical fiber to electrically connect the graphene to the conductive connecting layer to obtain the electron source.

[0442] Example A-3

[0443] An auxiliary layer with a thickness of 10 nm and made of gold is deposited on the end face of a solid core optical fiber with a conductive connection layer; then carbon quantum dots are grown on the surface of the auxiliary layer using the CVD method to obtain an electron excitation layer on the surface of the auxiliary layer; the auxiliary layer is electrically connected to the conductive connection layer to obtain the electron source.

[0444] Example A-4

[0445] An auxiliary layer of gold with a thickness of 10 nm is deposited on the end face of a hollow-core optical fiber having a conductive connecting layer; then carbon nanotubes are grown on the surface of the auxiliary layer using the CVD method, with the axes of the carbon nanotubes being perpendicular to the plane of the auxiliary layer, and an electron excitation layer is prepared on the surface of the auxiliary layer; the auxiliary layer is electrically connected to the conductive connecting layer to obtain the electron source.

[0446] Example A-5

[0447] CVD is used to grow graphene with a thickness of 1 nm on the end face of a solid core optical fiber with a conductive connecting layer; then carbon nanotubes are grown on the surface of the graphene using the CVD method, with the axial direction of the carbon nanotubes parallel to the plane of the graphene, to obtain an electron excitation layer on the end face of the solid core optical fiber; the graphene is electrically connected to the conductive connecting layer to obtain the electron source.

[0448] Example A-6

[0449] CVD is used to grow graphene with a thickness of 1 nm on the side section of the side-section optical fiber, and then molybdenum disulfide (MoS2) quantum dots are prepared on the graphene surface by CVD method to obtain an electron excitation layer; wherein a conductive connection layer is set at the side-section optical fiber, and the conductive connection layer is electrically connected to the graphene to obtain the electron source.

[0450] Example A-7

[0451] An auxiliary layer of gold with a thickness of 10 nm is deposited and grown on the end face of a solid core optical fiber with a conductive connecting layer, and then carbon nanotubes are prepared on the surface of the auxiliary layer by CVD, with the axial direction of the carbon nanotubes perpendicular to the surface of the auxiliary layer; then molybdenum disulfide (MoS2) quantum dots are grown on the carbon nanotubes by CVD to obtain an electron excitation layer, and the auxiliary layer is electrically connected to the conductive connecting layer to obtain the electron source.

[0452] Example A-8

[0453] Graphene and black phosphorus are grown in sequence on the end face of a solid core optical fiber with a conductive connecting layer. The thickness of the graphene is 1 nm, and the thickness of the black phosphorus is 1 nm, forming an electron excitation layer stacked by graphene and black phosphorus. The graphene is electrically connected to the conductive connecting layer to obtain the electron source.

[0454] Comparative Example A-1

[0455] An electron source was prepared according to the structure of Example A-1, with the only difference being that the electron emission layer in Example A-1 was replaced by a gold layer with a thickness of 100 nm, and the gold layer was prepared by deposition.

[0456] Comparative Example A-2

[0457] An electron source was prepared according to the structure of Comparative Example A-1, with the only difference being that the electron emission layer in Comparative Example A-1 was replaced by a gold layer with a thickness of 1 nm.

[0458] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, which also included a housing, a grid, and an anode. The performance of the prepared electron gun was tested. The testing method included:

[0459] Stability test: When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5 Pa, continuous emission current for 1 hour, after removing bad pixels, calculate the difference between the maximum current and the minimum current and the average current, that is, stability parameter = (maximum current - minimum current) / average current.

[0460] Life test: When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5 Pa, the time it takes for the emission current to decay to less than 10% of the initial value is defined as the lifetime.

[0461] Working vacuum test: When the excitation power is 50% of the damage power, continuously emit current and gradually increase the vacuum degree of the electron gun's working environment until the current decays rapidly (rapid decay is defined as the current decaying by more than 50% within 1 minute). The vacuum degree at this time is defined as the working vacuum degree.

[0462] The damage power refers to the laser power when the material is damaged under 100fs pulse laser irradiation. For example, the damage power of graphene is 0.25J / cm 2 , the damage threshold of gold is 0.1J / cm 2 .

[0463] The test results are shown in Table 1.

[0464] Table 1

[0465] From the table above we can see that:

[0466] In this application, low-dimensional materials such as zero-dimensional materials, one-dimensional materials and two-dimensional materials have atomic-scale dimensions. Back-incident electrons can be emitted into a vacuum without being transmitted through the body, 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 high melting points, and are not easily damaged, making them suitable for large-beam electron sources with high-power excitation. Low-dimensional materials and needle tip integration can obtain very sharp optical fiber needle tips with large light field and electric field enhancement factors, providing large emission beams. There are many combinations of low-dimensional materials, suitable for photoelectron sources with various properties. Finally, optical fiber integrated low-dimensional material electron sources and low-dimensional material integration have significant advantages. Optical fibers can not only transmit lasers, but also, as low-dimensional material carriers, can provide stable excitation sources with adjustable wavelength, polarization, and optical modes. They can be applied to different application scenarios without providing complex optical paths. They have the characteristics of small size and high integration. When integrated with other devices, stable integration can be achieved without the need for disruptive modifications to vacuum electronic equipment.

[0467] (2) An electron source is prepared using a zero-dimensional material as an electron excitation layer. Specifically, the optical fiber is a single-mode solid-core optical fiber with a core diameter of 8.2 μm and an optical fiber diameter of 125 μm. The excitation wave wavelength transmitted in the optical fiber is 1550 nm. The conductive connection layer is a metal layer (4 nm titanium + 50 nm gold) coating the side of the optical fiber. The conductive connection layer is in contact with the auxiliary layer or the electron excitation layer.

[0468] Example B-1

[0469] Graphite quantum dots are grown on the end face of a solid core optical fiber with a conductive connection layer using chemical vapor deposition (CVD) to prepare an electron excitation layer with a thickness of about 20 nm. The electron excitation layer is electrically connected to the conductive connection layer to obtain an electron source. The average particle size of the graphite quantum dots in the electron excitation layer is 10 nm, and the density is 10 10 Pieces / mm 2 .

[0470] Example B-2

[0471] Using the optical fiber of Example B-1, an auxiliary layer with a thickness of 5 nm, a material of gold, and a transmittance of about 80% is deposited on the end face of a solid core optical fiber with a conductive connection layer. Then, graphite quantum dots are grown on the surface of the auxiliary layer by CVD to prepare an electron excitation layer with a thickness of about 20 nm. The electron excitation layer is electrically connected to the conductive connection layer to obtain an electron source. The average particle size of the graphite quantum dots in the electron excitation layer is 10 nm, and the density is 10 10 Pieces / mm 2 (High density arrangement).

[0472] Example B-3

[0473] The preparation method is similar to that of Example B-1, except that the graphite quantum dots are replaced by gold nanoparticles.

[0474] Example B-4

[0475] The preparation method is similar to that of Example B-1, except that the average particle size of the graphite quantum dots is 20 nm.

[0476] Example B-5

[0477] The preparation method is similar to that of Example B-2, except that the material of the auxiliary layer is replaced with graphene, and the obtained transmittance is about 98%.

[0478] Comparative Example B-1

[0479] An electron source was prepared according to the structure of Example B-1, except that the electron excitation layer in Example B-1 was replaced by a gold layer with a thickness of 200 nm, and the gold layer was prepared by deposition.

[0480] Comparative Example B-2

[0481] An electron source was prepared according to the structure of Example B-3, except that the electron excitation layer in Example B-3 was replaced by a gold layer with a thickness of 20 nm, and the gold layer was prepared by deposition.

[0482] The electron source 100 prepared by the above embodiment and comparative example was assembled into an electron gun, and subjected to stability test, life test and working vacuum test. The test results are shown in Table 2.

[0483] Table 2

[0484] From the above table, it can be seen that the performance of the embodiment is significantly better than that of the comparative example B-1 and the comparative example B-2 by comparing the embodiment with the comparative example B-1 and the comparative example B-2, indicating that the electron source performance of the present application using zero-dimensional materials as the electron excitation layer is better than that of traditional metal layers and metal nanolayers.

[0485] (3) Prepare an electron source using one-dimensional materials as the electron excitation layer.

[0486] Example C-1

[0487] (1) Remove the coating layer at the end of the single-mode solid optical fiber and cut the cross section of the optical fiber to make it flat. Use a polymer ball to block the core at one end. The diameter of the polymer ball is between the diameter of the core and the diameter of the cladding.

[0488] (2) Titanium and gold are plated on the optical fiber in sequence by vapor deposition, ensuring that titanium and gold are firmly deposited on the end face and the end of the optical fiber without coating layer, forming a 54nm thick conductive connection layer, wherein the thickness of the titanium layer is 4nm and the thickness of the gold layer is 50nm. Acetone is used to soak one end of the fiber core to dissolve the polymer beads and peel off the coating on the polymer beads, exposing the fiber core at the end face of the optical fiber.

[0489] (3) Carbon nanotubes are grown on the end face of an optical fiber having a conductive connection layer by chemical vapor deposition to form an electron excitation layer made of carbon nanotubes. The carbon nanotubes are electrically connected to the conductive connection layer. The diameter of the carbon nanotubes is 1 nm, the length of the carbon nanotubes is 0.1 μm, and the axial direction of the carbon nanotubes is parallel to the axial direction of the optical fiber to obtain an electron source. The diameter of the core of the optical fiber is 8.2 μm, and the diameter of the optical fiber is 125 μm.

[0490] Example C-2

[0491] The preparation method of the electron source in this embodiment is basically the same as that in Example C-1, except that step (3) is different. Step (3) includes:

[0492] An auxiliary layer made of gold is deposited and grown on the end face of an optical fiber with a conductive connection layer. The auxiliary layer has a thickness of 10 nm and is electrically connected to the conductive connection layer. Then, carbon nanotubes are grown on the surface of the auxiliary layer using chemical vapor deposition to form an electron excitation layer made of carbon nanotubes. The carbon nanotubes are electrically connected to the conductive connection layer. The carbon nanotubes have a diameter of 1 nm and a length of 0.1 μm, and the axes of the carbon nanotubes are parallel to the axis of the optical fiber. This produces an electron source. The diameter of the optical fiber core is 8.2 μm, and the diameter of the optical fiber is 125 μm. The electron excitation layer and the auxiliary layer constitute the electron emission layer.

[0493] Example C-3

[0494] The preparation method of the electron source is basically the same as that of Example C-2, except that the diameter of the carbon nanotubes in step (3) is 10 nm.

[0495] Example C-4

[0496] The preparation method of the electron source is basically the same as that of Example C-2, except that the diameter of the carbon nanotubes in step (3) is 20 nm.

[0497] Example C-5

[0498] The preparation method of the electron source is basically the same as that of Example C-2, except that the length of the carbon nanotubes in step (3) is 1 μm.

[0499] Example C-6

[0500] The preparation method of the electron source is basically the same as that of Example C-2, except that the diameter of the carbon nanotubes in step (3) is 0.5 nm.

[0501] Example C-7

[0502] The preparation method of the electron source is basically the same as that of Example C-2, except that the diameter of the carbon nanotubes in step (3) is 21 nm.

[0503] Example C-8

[0504] The preparation method of the electron source is basically the same as that of Example C-1, except that the carbon nanotubes in Example C-1 are replaced by gold nanowires.

[0505] Comparative Example C-1

[0506] An electron source was prepared according to the structure of Example C-1, except that the electron excitation layer in Example C-1 was replaced by a gold layer with a thickness of 100 nm, and the gold layer was obtained by deposition.

[0507] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, which also included a housing, a grid, and an anode. Performance tests were performed on the prepared electron gun.

[0508] Table 3

[0509] It can be seen from the above table that compared with the electron gun of comparative example C-1, the electron guns of Examples C-1 to C-8 have a higher working vacuum degree, better stability, and longer life, indicating that Examples C-1 to C-8 provided in the present application effectively improve the electron emission efficiency and stability of the electron source.

[0510] (IV) Preparing an electron source using a one-dimensional material as the electron excitation layer. In the following examples, the conductive connection layer is a 60 nm thick metal layer covering the side of the optical fiber. The conductive connection layer is in contact with the auxiliary layer or the electron excitation layer, and the metal layer is made of gold.

[0511] Example D-1

[0512] Carbon nanotubes were grown on silicon wafers using chemical vapor deposition and then transferred to polypropylene carbonate films by acid etching.

[0513] The preparation method of the electron source comprises the following steps:

[0514] (1) Remove the coating from the end of a single-mode solid optical fiber and cut the fiber section to make it flat. Use a polymer ball to plug the core at one end. The diameter of the polymer ball is between the diameter of the core and the diameter of the cladding. The core diameter of a single-mode optical fiber is 8.2μm, and the diameter of the optical fiber is 125μm.

[0515] (2) The optical fiber is plated with gold by vapor deposition to ensure that gold is firmly deposited on the end face and the end of the optical fiber without coating layer, forming a conductive connection layer with a thickness of 54nm and a material of gold. One end of the fiber core is blocked by immersion in acetone to dissolve the polymer beads and peel off the coating on the polymer beads, exposing the fiber core at the end face of the optical fiber, so as to form a relatively flat annular electrode at the electron emission end.

[0516] (3) The carbon nanotubes on the polypropylene carbonate film are transferred to the front of the perforated glass slide and suspended so that they can be observed under a microscope. A ring-shaped heating plate is attached to the back, and the heating plate is connected to a power supply. The perforated glass slide is fixed to the microscope stage, and the prefabricated electrode fiber obtained in step (2) is fixed to the substage translation stage so that the objective lens, the hole in the heating plate, the glass slide, the carbon nanotubes, and the end faces of the prefabricated electrode fiber are collinear and arranged in order from top to bottom.

[0517] (4) Observe and prefabricate the electrode position under a microscope and complete the horizontal alignment. Apply voltage for preheating. Move the fiber optic translation stage to make the annular electrode and the carbon nanotube contact to form Newton rings. Slowly increase the voltage to make the annular electrode and the carbon nanotube contact closer.

[0518] (5) After the annular electrode and the carbon nanotubes are completely bonded, the heating voltage is increased to completely melt the polypropylene carbonate film. The optical fiber is removed and soaked in acetone to dissolve it.

[0519] In the electron source prepared in this embodiment, the carbon nanotubes form an electron excitation layer, the angle θ between the axis of the carbon nanotubes and the emission direction of the laser is 10°, the diameter of the carbon nanotubes is 1 nm, and the length is 200 μm.

[0520] Example D-2

[0521] Carbon nanotubes were grown on silicon wafers using chemical vapor deposition and then transferred to polypropylene carbonate films by acid etching.

[0522] The preparation method of the electron source comprises the following steps:

[0523] (1) Remove the coating from the end of a single-mode solid optical fiber and cut the fiber section to make it flat. Use a polymer ball to plug the core at one end. The diameter of the polymer ball is between the diameter of the core and the diameter of the cladding. The core diameter of a single-mode optical fiber is 8.2μm, and the diameter of the optical fiber is 125μm.

[0524] (2) Gold is plated on the optical fiber using the vapor deposition method, ensuring that gold is firmly deposited on the end face and the end of the optical fiber without coating layer, forming a conductive connection layer made of gold and 54nm thick. Acetone is used to soak one end of the fiber core to dissolve the polymer beads and peel off the coating on the polymer beads, exposing the fiber core at the end face of the optical fiber to form a relatively flat annular electrode at the electron emission end. An auxiliary layer made of gold is deposited and grown on the end face of the optical fiber with the conductive connection layer. The thickness of the auxiliary layer is 10nm, and the auxiliary layer is electrically connected to the conductive connection layer.

[0525] (3) Transfer the carbon nanotubes on the polypropylene carbonate film to the front of the perforated glass slide and suspend it in the air so that it can be observed under a microscope. A ring-shaped heating plate is attached to the back, and the heating plate is connected to a power supply. The perforated glass slide is fixed to the stage under the microscope, and the prefabricated electrode optical fiber obtained in step (2) is fixed to the displacement stage under the stage so that the objective lens, the hole in the heating plate, the glass slide, the carbon nanotubes, and the end faces of the prefabricated electrode optical fiber are collinear and arranged in order from top to bottom;

[0526] (4) Observe and prefabricate the electrode position under a microscope and complete the horizontal alignment. Apply voltage for preheating. Move the fiber optic translation stage to make the annular electrode and the carbon nanotube contact to form Newton rings. Slowly increase the voltage to make the annular electrode and the carbon nanotube contact closer.

[0527] (5) After the annular electrode and the carbon nanotubes are completely bonded, the heating voltage is increased to completely melt the polypropylene carbonate film. The optical fiber is removed and soaked in acetone to dissolve it.

[0528] In the electron source prepared in this embodiment, carbon nanotubes form an electron excitation layer, the angle between the axis of the carbon nanotubes and the emission direction of the laser is 10°, the diameter of the carbon nanotubes is 1nm, and the length is 200μm. The electron excitation layer and the auxiliary layer constitute the electron emission layer.

[0529] Example D-3

[0530] An electron source was prepared according to the structure of Example D-2, except that the angle between the axis of the carbon nanotube and the emission direction of the laser was 90°.

[0531] Example D-4

[0532] An electron source was prepared according to the structure of Example D-2, except that the diameter of the carbon nanotubes was 3 nm.

[0533] Example D-5

[0534] An electron source was prepared according to the structure of Example D-1, except that the carbon nanotubes in Example D-1 were replaced with gold nanowires.

[0535] Comparative Example D-1

[0536] An electron source was prepared according to the structure of Example D-1, except that the electron excitation layer in Example D-1 was replaced by a gold layer with a thickness of 100 nm, and the gold layer was obtained by deposition.

[0537] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, which also included a housing, a grid, and an anode. The performance of the prepared electron gun was tested, and the test results are shown in Table 4.

[0538] Table 4

[0539] It can be seen from Table 4 that compared with the electron gun of the comparative example, the electron gun of the embodiment of the present application has a higher working vacuum degree, better stability and longer life, which shows that the embodiment provided by the present application effectively improves the electron emission efficiency and stability of the electron source.

[0540] (5) Electron sources are prepared by combining one-dimensional and zero-dimensional materials. In the following examples, the optical fiber is a single-mode solid-core optical fiber with a core diameter of 8.2 μm and a fiber diameter of 125 μm. The excitation wave wavelength transmitted in the optical fiber is 1550 nm. The conductive connection layer is a metal layer (4 nm titanium + 50 nm gold) coating the side of the optical fiber. The conductive connection layer is in contact with the auxiliary layer or the electron excitation layer.

[0541] Example E-1

[0542] Carbon nanotubes with an outer diameter of approximately 20 nm and a length of approximately 5 μm are grown on the end face of a solid-core optical fiber with a conductive connecting layer using the CVD method. The axial direction of the carbon nanotubes is parallel to the laser light output path of the optical fiber. Graphite quantum dots with an average particle size of approximately 5 nm are then grown on the ends of the carbon nanotubes to prepare an electron excitation layer with a thickness of approximately 20 nm. The electron excitation layer is electrically connected to the conductive connecting layer to obtain an electron source.

[0543] Example E-2

[0544] An auxiliary layer with a thickness of 5 nm, a material of gold, and a transmittance of 60% is deposited on the end face of a solid-core optical fiber with a conductive connecting layer. Then, carbon nanotubes with an outer diameter of about 20 nm and a length of about 5 μm are grown on the surface of the auxiliary layer by the CVD method. The axial direction of the carbon nanotubes is parallel to the laser light output path of the optical fiber. Thereafter, graphite quantum dots with an average particle size of about 5 nm are grown at the ends of the carbon nanotubes to prepare an electron excitation layer with a thickness of about 20 nm. The electron excitation layer is electrically connected to the conductive connecting layer to obtain an electron source.

[0545] Example E-3

[0546] The preparation method is similar to that of Example E-1, except that the graphite quantum dots are replaced by gold nanoparticles.

[0547] Example E-4

[0548] The preparation method is similar to that of Example E-1, except that the carbon nanotubes are replaced by silicon nanowires.

[0549] Example E-5

[0550] The preparation method is similar to that of Example E-2, except that the material of the auxiliary layer is replaced with graphene, and the obtained transmittance is 98%.

[0551] Comparative Example E-1

[0552] An electron source was prepared according to the structure of Example E-1, except that the electron excitation layer in Example E-1 was replaced by a gold layer with a thickness of 200 nm, and the gold layer was prepared by deposition.

[0553] Comparative Example E-2

[0554] An electron source was prepared according to the structure of Example E-3, except that the electron excitation layer in Example E-3 was replaced by a gold layer with a thickness of 20 nm, and the gold layer was prepared by deposition.

[0555] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, and stability tests, life tests and working vacuum tests were performed. The test results are shown in Table 5.

[0556] Table 5

[0557] In Table 5 above, it can be seen from the comparison of the embodiment and the comparative example that the performance of the embodiment is significantly better than that of the comparative example, indicating that the electron source performance of the present application using one-dimensional materials and zero-dimensional materials as electron excitation layers is better than that of traditional metal layers and metal nanolayers.

[0558] (VI) Preparation of an electron source using two-dimensional materials. In the following examples, the conductive connection layer includes a Ti layer with a thickness of 5 nm and an Au layer with a thickness of 60 nm.

[0559] Example F-1

[0560] This embodiment provides an electron source, including a solid core optical fiber, an electron excitation layer and a conductive connection layer, wherein the conductive connection layer covers the side wall of the solid core optical fiber and forms an annular layer on the laser emission end face of the solid core optical fiber. The annular layer does not cover the core of the solid core optical fiber. An electron excitation layer with a thickness of 1 nm and a material of graphene is set on the laser emission end face of the solid core optical fiber. The electron excitation layer covers the core of the solid core optical fiber and is arranged on the annular layer and electrically connected to the conductive connection layer.

[0561] This embodiment also provides a method for preparing the electron source, comprising:

[0562] Use the first tape to peel off the graphite, then use the second tape to perform a secondary dissociation of the graphene material on the first tape, and then use the third tape to repeat the dissociation until the thickness of the graphene is 1nm;

[0563] The tape with graphene was then transferred to a polypropylene carbonate film, baked at 50°C for 2 minutes, and then the tape was peeled off to obtain a polypropylene carbonate film with graphene;

[0564] A conductive connecting layer is evaporated on a solid core optical fiber, and an annular layer is formed on the laser emitting side of the solid core optical fiber. Then, a polypropylene carbonate film with graphene is transferred to the laser emitting side of the solid core optical fiber, so that the polypropylene carbonate film with graphene is adhered to the annular layer and covers the core of the solid core optical fiber. After the polypropylene carbonate is heated and melted, the residual polypropylene carbonate film is removed by immersion in acetone to form an electron excitation layer, thereby preparing the electron source.

[0565] Example F-2

[0566] An electron source is prepared according to the method of Example F-1, with the only difference being that the electron source includes a solid core optical fiber, an electron excitation layer and a conductive connection layer, and the electron excitation layer includes a first material layer and a second material layer sequentially arranged along the laser emission direction, wherein the first material layer is a graphene layer with a thickness of 5 nm, and the second material layer is molybdenum disulfide with a thickness of 2 nm.

[0567] Example F-3

[0568] An electron source is prepared according to the method of Example F-1, with the only difference being that the electron source includes a solid core optical fiber, an electron excitation layer, a conductive connecting layer and a transparent support layer, and the transparent support layer is arranged on the side of the electron excitation layer close to the solid core optical fiber, and the transparent support layer is boron nitride with a thickness of 100 nm.

[0569] Example F-4

[0570] An electron source was prepared according to the method of Example F-1, with the only difference being that the electron source included a solid core optical fiber, an electron excitation layer, a conductive connecting layer and a conductive support layer, and the material of the electron excitation layer was a molybdenum disulfide layer with a thickness of 2 nm; the conductive support layer was arranged on the side of the electron excitation layer close to the solid core optical fiber, and the conductive support layer was a gold layer with a thickness of 5 nm, and the conductive support layer was in contact with and electrically connected to the conductive connecting layer.

[0571] Example F-5

[0572] An electron source is prepared according to the method of Example F-1, with the only difference being that the electron source includes a solid core optical fiber 110e, an electron excitation layer and a conductive connection layer, and the electron excitation layer is formed by splicing a first material layer and a second material layer, the first material layer is graphene with a thickness of 1 nm, and the second material layer is molybdenum disulfide with a thickness of 3 nm, and the shape of the splicing portion is a straight line.

[0573] Example F-6

[0574] An electron source is prepared according to the method of Example F-1, with the only difference being that the electron source includes a solid core optical fiber 110f, an electron excitation layer, a conductive connecting layer and a conductive support layer, the conductive support layer being arranged on one side of the electron excitation layer located on the solid core optical fiber, the conductive support layer being electrically connected to the conductive connecting layer, the electron excitation layer being a first material layer and a second material layer stacked along the laser emission direction, the first material layer and the second material layer being both perovskite layers with a thickness of 2 nm, and the crystal axis angle between the two perovskite layers being 90°.

[0575] Example F-7

[0576] An electron source is prepared according to the method of Example F-1, with the only difference being that the electron source includes a holey optical fiber, an electron excitation layer and a conductive connection layer, the electron excitation layer is arranged on a first material layer and a second material layer on the inner wall of the holey optical fiber, the first material layer and the second material layer are stacked in sequence in a direction away from the inner wall of the holey optical fiber, the first material layer is graphene with a thickness of 5 nm, the second material layer is a molybdenum disulfide layer with a thickness of 3 nm, and the conductive connection layer is conductively connected to the first material layer.

[0577] Comparative Example F-1

[0578] An electron source was prepared according to the structure of Example F-1, with the only difference being that the electron excitation layer in Example F-1 was replaced by a gold layer with a thickness of 60 nm, and the gold layer was prepared by deposition.

[0579] Comparative Example F-2

[0580] An electron source was prepared according to the structure of Comparative Example F-1, with the only difference being that the electron excitation layer in Comparative Example F-1 was replaced by a gold layer with a thickness of 1 nm.

[0581] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, and stability tests, life tests and working vacuum tests were performed. The test results are shown in Table 6.

[0582] Table 6

[0583] From the table above we can see that:

[0584] The present application uses at least one layer of two-dimensional material as the electron emission layer. The two-dimensional material has an atomic-level thickness. The electrons generated by the laser irradiation surface can be emitted into the vacuum without being transmitted through the layer, which is very suitable for ultrafast electron sources with narrow pulse widths. The two-dimensional material has no dangling bonds and has good stability and a high melting point. It is not easy to damage the large-beam electron source suitable for high-power excitation. Moreover, the rich variety of two-dimensional materials and homogeneous and heterogeneous structures bring ultra-high degrees of freedom in electron emission properties, for example, pulsed electron sources and one-dimensional electron sources can be realized. In addition, the present application directly integrates two-dimensional materials and optical fibers, and the optical fiber transmits lasers. As a low-dimensional material carrier, it can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without providing a complex optical path. It has the characteristics of small size and high integration.

[0585] (VII) Preparation of an electron source using holey optical fiber. This includes the following examples and comparative examples.

[0586] Example G-1

[0587] The holey fiber uses a capillary fiber tube. The diameter of the holey fiber core is 10μm, the diameter of the holey fiber is 125μm, and the wavelength of the laser transmitted in the holey fiber is 1550nm. The conductive connection layer includes 4nm titanium and 50nm gold located on the periphery of the core and stacked on the holey fiber. The electron excitation layer is formed on the side wall k of the light guide hole and the end face of the light output end of the holey fiber by CVD. The electron excitation layer uses graphene two-dimensional material (the thickness of the graphene two-dimensional material is 0.3nm). Among them, the first part of the electron excitation layer completely covers the side wall of the light guide hole, and the second part of the electron excitation layer is provided on the end face of the light output end of the holey fiber.

[0588] Example G-2

[0589] The holey fiber uses a capillary fiber tube. The core diameter of the holey fiber is 10μm, and the diameter of the holey fiber is 125μm. The wavelength of the laser transmitted in the holey fiber is 1550nm. The conductive connection layer consists of 4nm titanium and 50nm gold, located outside the core and stacked on the holey fiber. The electron excitation layer is formed on the sidewalls of the light guide hole by CVD. The electron excitation layer uses a two-dimensional graphene material (the thickness of the graphene two-dimensional material is 3nm).

[0590] Example G-3

[0591] A 50nm-thick auxiliary layer of gold was deposited using CVD on the sidewalls of the light-guiding hole and the end face of the light-emitting end of the holey fiber. Carbon nanotubes were then grown on the surface of the auxiliary layer using CVD, with the axis of the carbon nanotubes perpendicular to the surface of the auxiliary layer, to form an electron excitation layer. The auxiliary layer was then electrically connected to the conductive connecting layer to create an electron source. In this embodiment, the auxiliary layer overlapped the first conductive portion of the conductive connecting layer, and the second conductive portion of the conductive connecting layer was located on the circumferential side of the optical fiber.

[0592] Example G-4

[0593] Graphene with a thickness of 2 nm is deposited and grown on the sidewalls of the light-guiding hole and the end face of the light-emitting end of the holey optical fiber using CVD. Carbon nanotubes are then coated on the surface of the graphene, with the axial direction of the carbon nanotubes parallel to the plane of the graphene. Multiple quantum dots are then grown on the carbon nanotubes using CVD to obtain an electron excitation layer, wherein the graphene is electrically connected to the conductive connection layer to obtain an electron source.

[0594] Comparative Example G-1

[0595] An electron source was prepared according to the structure of Example G-1, with the only difference being that the electron excitation layer in Example G-1 was replaced by a gold layer with a thickness of 100 nm, and the gold layer was prepared by deposition.

[0596] Comparative Example G-2

[0597] An electron source was prepared according to the structure of Comparative Example G-1, with the only difference being that the electron excitation layer in Comparative Example G-1 was replaced by a gold layer with a thickness of 2 nm (the thickness is the same as that of graphene).

[0598] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, which also included a housing, a grid, and an anode. The performance of the prepared electron gun was tested, and the test results are shown in the following table:

[0599] Table 7

[0600] Through testing, it was found that the lifespan of the electron source prepared by the embodiment was longer than that of the electron source prepared by the comparative example; and the stability of the electron source prepared by the embodiment was better than that of the electron source prepared by the comparative example.

[0601] In summary, the low-dimensional materials such as zero-dimensional materials, one-dimensional materials, and two-dimensional materials in this application have atomic-scale dimensions. The excited electrons can be emitted into the vacuum without being transported through the body, which is beneficial to improving the electron emission efficiency and emission power, and is very suitable for ultrafast electron sources with narrow pulse widths. Moreover, the electron source of this application uses low-dimensional materials as the material for emitting electrons. Because low-dimensional materials have high optical nonlinear effects and discrete electronic energy levels, the laser can better interact with the electron excitation layer to generate energy resonance and excite electrons in the electron excitation layer. These electrons are excited and released into the vacuum to form an electron beam. The electron beam emitted by tunneling from the electron excitation layer has the characteristics of concentrated energy and small energy dispersion. In addition, low-dimensional materials and different types of optical fibers can be directly integrated, bringing ultra-high stability and integration. At the same time, the nanoscale electron excitation layer will not affect the transmission mode of the holey fiber, so that the transmission mode of the electron source is mainly determined by the holey fiber, which can make the electrons emitted by the electron source efficiently emitted along the extension direction of the holey fiber, which provides great convenience for controlling the transmission mode of the electron source. Moreover, low-dimensional materials have no dangling bonds, are stable, have high melting points, and are not easily damaged, making them suitable for high-power excitation and large-beam electron sources. The integration of low-dimensional materials and needle tips can produce very sharp optical fiber needle tips with large optical and electric field enhancement factors, providing large emission beams. Low-dimensional materials have many combinations and are suitable for photoelectron sources with various properties. Finally, optical fiber-integrated low-dimensional material electron sources and low-dimensional material integration have significant advantages. Optical fiber can not only transmit lasers, but also, as a carrier of low-dimensional materials, can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, which can be applied to different application scenarios. In addition, this electron source abandons the complex spatial optical coupling structure set up due to the introduction of external lasers, and has the characteristics of small size and high integration, which can be easily assembled into the housing of the electron gun. When integrated with other equipment, stable integration can be achieved without the need for disruptive modifications to vacuum electronic equipment.

[0602] (8) Preparation of electron source using needle-tip optical fiber, including the following examples and comparative examples.

[0603] Example H-1

[0604] Optical fiber 110 uses a single-mode optical fiber with a core diameter of 8.2μm and an optical fiber diameter of 125μm. It is conical at the tip of the optical fiber, and the diameter gradually decreases to 500nm. The excitation wavelength transmitted in the optical fiber is 1550nm. Graphene can be mechanically stripped using tape to obtain 6 layers of graphene. 6 layers of graphene are used as a graphene unit, and multiple graphene units can be suspended on the liquid surface. Then, the light input end of the optical fiber is clamped, and the tip of the optical fiber is extended downward below the above-mentioned liquid surface to dip the graphene unit floating on the liquid surface. The number of dips is 3, so that the tip of the optical fiber is provided with an electron excitation layer, that is, 18 layers of graphene, about 6.12nm. Then, the above-mentioned conductive connection layer is formed on the outer surface of the optical fiber to obtain an electron source.

[0605] Example H-2

[0606] The optical fiber is a single-mode optical fiber with a core diameter of 8.2μm and an optical fiber diameter of 125μm. It is conical at the tip of the optical fiber, and the diameter gradually decreases to 500nm. The excitation wavelength transmitted in the optical fiber is 1550nm. Chemical vapor deposition can also be used to grow 5 layers of graphene on a copper substrate, and the metallic copper of the substrate is etched away in an etching solution (such as ammonium persulfate solution) to obtain 5 layers of graphene suspended on the liquid surface. In this way, 5 layers of graphene can be regarded as a graphene unit, and multiple graphene units can be suspended on the liquid surface. Then, the light input end of the optical fiber is clamped, and the tip of the optical fiber is extended downward below the above-mentioned liquid surface to dip the graphene unit floating on the liquid surface. The number of dippings is 2, so that the tip of the optical fiber is provided with 10 layers of graphene, about 3.4nm. Then, the above-mentioned conductive connection layer is formed on the outer surface of the optical fiber to obtain an electron source.

[0607] Example H-3

[0608] Based on Example H-1, a layer of CdSe quantum dots was coated on the surface of graphene, forming a graphene + quantum dot composite structure to produce the electron excitation layer of this embodiment. The strong interaction between quantum dots and light can improve the overall structure's responsiveness to light, increase the beam current, and enhance the brightness of the electron source. Furthermore, the concentrated energy levels of the quantum dots enable electron emission with a narrow energy linewidth.

[0609] Example H-4

[0610] The optical fiber is a single-mode optical fiber with a core diameter of 8.2μm and an optical fiber diameter of 125μm. It is conical at the tip of the optical fiber, and the diameter gradually decreases to 500nm. The excitation wavelength transmitted in the optical fiber is 1550nm. An auxiliary layer with a thickness of 1nm and made of graphene is deposited on the tip of the optical fiber; then, a plurality of nanotubes are deposited on the auxiliary layer, and the axial direction of the nanotubes is parallel to the extension direction of the core to obtain an electron excitation layer; finally, the above-mentioned conductive connection layer is formed on the outer surface of the optical fiber to obtain an electron source. Among them, the first conductive part of the conductive connection layer is provided on the surface of the tip of the optical fiber and overlaps with the auxiliary layer, and the second conductive part of the conductive connection layer is provided on the circumferential side of the optical fiber.

[0611] Comparative Example H-1

[0612] An electron source was prepared according to the structure of Example H-1, with the only difference being that the electron excitation layer in Example H-1 was replaced by a gold layer with a thickness of 100 nm, and the gold layer was prepared by deposition.

[0613] Comparative Example H-2

[0614] An electron source was prepared according to the structure of Comparative Example H-1, with the only difference being that the electron excitation layer in Comparative Example H-1 was replaced by a gold layer with a thickness of 6.12 nm.

[0615] The electron sources prepared in the above embodiments and comparative examples were assembled into an electron gun, which also included a housing, a grid, and an anode. The performance of the prepared electron gun was tested, and the test results are shown in the following table:

[0616] Table 8

[0617] Through testing, it was found that the lifespan of the electron source prepared by the embodiment was longer than that of the electron source prepared by the comparative example; and the stability of the electron source prepared by the embodiment was better than that of the electron source prepared by the comparative example.

[0618] In summary, the low-dimensional materials such as zero-dimensional materials, one-dimensional materials and two-dimensional materials in this application have atomic-scale dimensions, and the back-incident electrons can be emitted into the vacuum without being transmitted through the body, which is very suitable for ultrafast electron sources with narrow pulse widths; and 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 high melting points, are not easily damaged, and are suitable for large-beam electron sources with high-power excitation; low-dimensional materials and needle tips are integrated to obtain very sharp optical fiber needle tips with large light field and electric field enhancement factors, providing large emission beams; there are many combinations of low-dimensional materials, suitable for photoelectron sources of various properties. Finally, optical fiber integrated low-dimensional material electron sources and low-dimensional material integration have significant advantages. Optical fiber can not only transmit lasers, but also, as a low-dimensional material carrier, can provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without providing a complex optical path. It has the characteristics of small size and high integration. When integrated with other devices, stable integration can be achieved without the need for disruptive modifications to vacuum electronic equipment.

[0619] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0620] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An electron source, the electron source comprising an optical fiber, a conductive connection layer, and an electron emission layer, the conductive connection layer being disposed on the outer surface of the optical fiber; The electron emission layer includes an electron excitation layer electrically connected to the conductive connection layer, and the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material; The electron excitation layer is disposed on the laser emission path of the optical fiber, and the laser emitted from the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons.

2. The electron source according to claim 1, wherein The thickness of the electron excitation layer is 0.1 nm to 100 nm.

3. The electron source according to claim 1 or 2, wherein, The electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on the side of the electron emission layer close to the optical fiber; or, The auxiliary layer is stacked on the side of the electron excitation layer away from the optical fiber.

4. The electron source according to claim 3, wherein, The auxiliary layer includes at least one of a conductive support layer and a heat dissipation support layer.

5. The electron source according to claim 3 or 4, wherein The thickness of the auxiliary layer is 0.1 nm to 100 nm, and the light transmittance is ≥10%.

6. The electron source according to any one of claims 3-5, wherein, The auxiliary layer includes a conductive support layer, and the conductive support layer is electrically connected to the conductive connection layer.

7. The electron source according to any one of claims 4-6, wherein, The material of the conductive support layer includes a conductive metal, the laser wavelength in the optical fiber is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W.

8. The electron source according to any one of claims 1-7, wherein, The electron excitation layer includes a zero-dimensional material.

9. The electron source according to claim 8, wherein, The density of the zero-dimensional material in the electron excitation layer is 10 / mm 2 ~10 12 / mm 2 .

10. The electron source according to claim 8 or 9, wherein The gap between the particles of two adjacent zero-dimensional materials is zero.

11. The electron source according to any one of claims 8-10, wherein, The average particle size of the zero-dimensional material is 1 nm to 100 μm.

12. The electron source according to any one of claims 1-11, wherein, The electron excitation layer includes a one-dimensional material.

13. The electron source according to claim 12, wherein, The diameter of the one-dimensional material is 1 nm to 20 nm.

14. The electron source according to claim 12 or 13, wherein, The electron excitation layer contains a plurality of the one-dimensional materials, and the axes of any two of the one-dimensional materials are parallel to each other.

15. The electron source according to any one of claims 12 - 14, wherein, The electron excitation layer contains a plurality of the one-dimensional materials, and the gap between two adjacent one-dimensional materials along the radial direction of the one-dimensional material is zero.

16. The electron source according to any one of claims 12-15, wherein, The angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is 0 to 90°.

17. The electron source according to claim 16, wherein, The axes of the one-dimensional materials in the electron excitation layer are all the same as the emission direction of the laser, and the length of the one-dimensional material is 0.1 μm to 1 μm.

18. The electron source according to claim 16, wherein, The angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°, and the length of the one-dimensional material is 1 μm to 200 μm.

19. The electron source according to claim 18, wherein, The angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is greater than 0° and less than or equal to 90°, and the length of the one-dimensional material is 10 μm to 30 μm.

20. The electron source according to any one of claims 16, 18, and 19, wherein, The angle between the axis of the one-dimensional material in the electron excitation layer and the emission direction of the laser is 45° to 90°.

21. The electron source according to any one of claims 1 to 20, wherein, The electron excitation layer includes at least one layer of two-dimensional material.

22. The electron source according to claim 21, wherein, The thickness of the two-dimensional material is 0.1 nm to 50 nm.

23. The electron source according to claim 21 or 22, wherein, The electron excitation layer includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction of the optical fiber, and the two-dimensional materials are all two-dimensional materials with conductivity; two adjacent layers of the two-dimensional materials are the same or different.

24. The electron source according to any one of claims 21-23, wherein, The crystal axis angle between two adjacent layers of the two-dimensional materials is 0° to 360°.

25. The electron source according to any one of claims 1 to 20, wherein, The electron excitation layer is formed by splicing at least two two-dimensional materials with different materials, and the laser of the optical fiber irradiates at the splicing position of the adjacent two-dimensional materials.

26. The electron source according to any one of claims 1 to 25, wherein, The materials in the electron excitation layer include one-dimensional materials and zero-dimensional materials arranged at the ends and / or sides of the one-dimensional materials.

27. The electron source according to claim 26, wherein, The diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm.

28. The electron source according to claim 26 or 27, wherein, The average particle size of the zero-dimensional material is 1 nm to 100 nm.

29. The electron source according to any one of claims 1-28, wherein, The electron excitation layer includes a zero-dimensional material and a two-dimensional material, and the zero-dimensional material is arranged on the surface of the two-dimensional material.

30. The electron source according to any one of claims 1-29, wherein, The electron excitation layer includes a one-dimensional material and a two-dimensional material, and the one-dimensional material is arranged on the surface of the two-dimensional material.

31. The electron source according to any one of claims 1 to 30, wherein, The electron source also satisfies at least one of the following conditions: (1) The zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals; (2) The one-dimensional material includes at least one of nanotubes, nanoribbons, and nanowires; (3) The two-dimensional material includes at least one of graphene, black phosphorus, transition metal chalcogenides, and hexagonal boron nitride.

32. The electron source according to any one of claims 1 to 31, wherein, The optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

33. The electron source according to any one of claims 1 to 31, wherein, The optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core, and 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 pulsed laser emitted from the core can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the pulsed laser emitted from the core and emits electrons.

34. The electron source according to any one of claims 1 to 31, wherein, The optical fiber is 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 along the extending direction of the light guiding hole.

35. The electron source according to claim 34, wherein, The electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on one side of the side wall of the electron excitation layer close to the light guiding hole; or, The auxiliary layer is stacked on one side of the side wall of the electron excitation layer far from the light guiding hole.

36. The electron source according to claim 34 or 35, wherein, The electron excitation layer includes a first part that completely covers the side wall of the light guiding hole, and a second part arranged on the end face of the light-emitting end of the perforated optical fiber; The second part is connected to the first part and is electrically connected to the conductive connection layer.

37. The electron source according to any one of claims 34-36, wherein, The conductive connection layer includes a first conductive part arranged on the end face of the light-emitting end of the perforated optical fiber, and a second conductive part arranged on the circumferential side surface of the perforated optical fiber; Wherein, the first conductive part is connected to the second conductive part and overlaps with the second part of the electron excitation layer.

38. The electron source according to any one of claims 1-31, wherein, The optical fiber is a perforated optical fiber, 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 pulsed 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 pulsed laser emitted from the perforated optical fiber and emits electrons.

39. The electron source according to any one of claims 1 to 31, wherein, 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.

40. The electron source according to claim 39, wherein, The electron excitation layer includes a first part; The projection of the first part in a target plane perpendicular to the core extension direction covers the projection of the core in the target plane; The first part is electrically connected to the conductive connection layer.

41. The electron source according to claim 40, wherein, The electron excitation layer further includes a second part connected to the first part; the projection of the second part in the target plane is located on the periphery of the projection of the first part in the target plane; and the second part overlaps with the conductive connection layer.

42. The electron source according to any one of claims 39-41, wherein, The conductive connection layer includes a first conductive part provided at the tip of the optical fiber, and a second conductive part connected to the first conductive part and provided on the circumferential side surface of the optical fiber; the first conductive part overlaps with the second part.

43. The electron source according to any one of claims 39 - 42, wherein, Along the extension direction of the core, the size of the tip is L1, and the size of the electron excitation layer is L2, where L1 is greater than L2.

44. The electron source according to claim 43, wherein, The size of the tip and the size of the electron excitation layer satisfy the following relationship: L2 > 1 / 2 × L1.

45. The electron source according to any one of claims 1-31, wherein, The optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core; A light leakage notch is formed along the radial direction of the light output end of the optical fiber; The electron emission layer is provided 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 further extends to the light output end of the optical fiber.

46. An electron gun, the electron gun includes a housing, a grid, an anode, and the electron source according to any one of claims 1-45; The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

47. An application of the electron source according to any one of claims 1-45, the application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

48. A four-dimensional electron microscope for scanning a sample, the four-dimensional electron microscope includes: A light source assembly for emitting pulsed laser; The electron source according to any one of claims 1-45, including an excitation optical fiber coupled to the light source assembly, and an electron emission layer, the electron emission layer at least includes an electron excitation layer, the electron excitation layer is arranged on the light output path of the pulsed laser emitted by the excitation optical fiber, so that the electron excitation layer can emit an electron beam under the excitation of the pulsed laser; the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material; An electron optical assembly arranged on the electron beam emission side of the electron source, the electron optical assembly is used to adjust the deflection direction of the electron beam so that the electron beam is incident on the sample; And A detector arranged on one side of the sample for collecting the reflected electron signal of the electron beam incident on the sample or the transmitted electron signal of the electron beam penetrating the sample.

49. The four-dimensional electron microscope according to claim 48, wherein, The light source assembly includes a light source and a first optical fiber, the light source is coupled to one end of the first optical fiber, and the excitation optical fiber is connected to the other end of the first optical fiber; The light source is used to emit the pulsed laser, and the first optical fiber is used to transmit the pulsed laser emitted by the light source to the excitation optical fiber.

50. The four-dimensional electron microscope according to claim 49, wherein, The light source assembly further includes a first optical fiber beam splitter, a second optical fiber, and a first optical fiber delay line; The first optical fiber beam splitter has a first input end coupled to the light source and a first output end opposite to the first input end, and the first output end is respectively connected to the first optical fiber and the second optical fiber; One end of the second optical fiber away from the first optical fiber beam splitter extends toward the sample; The first optical fiber delay line is coupled to the second optical fiber to perform time delay on the light beam propagating in the second optical fiber.

51. The four-dimensional electron microscope according to claim 50, wherein, The reflected electron signal includes a secondary electron signal or a backscattered electron signal; The sample has an incident surface disposed opposite to the electron beam exit side of the electron source; The detector includes a backscattered detector or a secondary detector, and the backscattered detector or the secondary detector is used to face the incident surface of the sample so that the secondary detector receives the secondary electron signal or the backscattered detector receives the backscattered electron signal.

52. The four-dimensional electron microscope according to any one of claims 49-51, wherein, The reflected electron signal includes a cathodoluminescence signal; The sample has an incident surface disposed opposite to the electron beam exit side of the electron source; The detector includes a cathodoluminescence analysis system, and the cathodoluminescence analysis system is used to face the incident surface of the sample to receive the cathodoluminescence signal.

53. The four-dimensional electron microscope according to any one of claims 49-52, wherein, The sample has an incident surface disposed opposite to the electron beam exit side of the electron source and an exit surface opposite to the incident surface; The detector includes a receiving screen, and the receiving screen is used to face the exit surface of the sample to receive the electron beam penetrating the sample.

54. The four-dimensional electron microscope according to claim 53, wherein, The light source assembly further includes a second optical fiber beam splitter, a third optical fiber, and a second optical fiber delay line; The second optical fiber beam splitter has a second input end coupled to the light source and a second output end opposite to the second input end, and the second output end is respectively connected to the first optical fiber and the third optical fiber; One end of the third optical fiber away from the second optical fiber beam splitter extends toward the sample; The second optical fiber delay line is coupled to the third optical fiber and is used to perform time delay on the light beam propagating in the third optical fiber.

55. The four-dimensional electron microscope according to any one of claims 48-54, wherein, The four-dimensional electron microscope further includes a housing; The housing has a vacuum chamber, and the electron source and the electron optical assembly are sequentially arranged in the vacuum chamber; An opening communicating with the vacuum chamber is provided on the housing, and the light incident end of the excitation optical fiber of the electron source is exposed through the opening and is coupled to the light source assembly.

56. The four-dimensional electron microscope according to claim 55, wherein, The outer peripheral wall of the excitation optical fiber is sealingly connected to the inner side wall of the opening.

57. The four-dimensional electron microscope according to any one of claims 48-56, wherein, The electron source further includes an anode, the anode has a first electron channel, and the electron optical assembly has a second electron channel communicating with the first electron channel; A preset electric field is provided between the anode and the electron excitation layer, and the electron beam can pass through the first electron channel and the second electron channel under the drive of the preset electric field and be incident on the sample.

58. An electron exposure machine for exposing a sample, the electron exposure machine comprising: A light source for emitting laser light; The electron source according to any one of claims 1-45, including an optical fiber coupled to the light source, and an electron emission layer, the electron emission layer at least including an electron excitation layer, the electron excitation layer being disposed on the light-emitting path of the laser emitted by the optical fiber, so that the electron excitation layer can emit an electron beam under the excitation of the laser; the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material; And An electron optical component disposed on the electron beam emission side of the electron source, the electron optical component being used to adjust the focusing and deflection direction of the electron beam, so that the electron beam is incident on the sample, and a preset exposure pattern is formed on the sample.

59. The electronic exposure machine according to claim 58, wherein, The electron exposure machine further includes a housing; The housing has a vacuum chamber, and the light-emitting end of the optical fiber of the electron source and the electron optical component are spaced apart from each other and disposed in the vacuum chamber; The electron excitation layer is disposed on the light-emitting end of the optical fiber to be located on the light-emitting path of the laser emitted by the optical fiber.

60. The electronic exposure machine according to claim 59, wherein, The housing is provided with an opening communicating with the vacuum chamber, and the light-incident end of the optical fiber of the electron source is exposed through the opening and coupled to the light source; The outer peripheral wall of the optical fiber is hermetically connected to the inner side wall of the opening.

61. The electronic exposure machine according to claim 60, wherein, The light-incident end of the optical fiber of the electron source extends outside the vacuum chamber through the opening to be coupled to the light source; or The end face of the light-incident end of the optical fiber of the electron source is flush with the plane where the opening is located.

62. The electronic exposure machine according to any one of claims 58-61, wherein, The electron source further includes an optical modulation member, the optical modulation member being connected between the light source and the optical fiber and used to control whether the laser propagates to the optical fiber.

63. The electronic exposure machine according to claim 62, wherein, The electron optical component includes a focusing magnetic lens and a deflection coil, and the focusing magnetic lens and the deflection coil are arranged at intervals along the emission direction of the electron beam on the electron beam emission side of the electron source.

64. The electronic exposure machine according to claim 62 or 63, wherein, The optical modulation member includes an electro-optic modulator or an optical switch.

65. The electronic exposure machine according to any one of claims 58-64, wherein, The electron source further includes an anode, the anode having a first electron channel, and the electron optical component having a second electron channel communicating with the first electron channel; A preset electric field is provided between the anode and the electron excitation layer, and the electron beam can pass through the first electron channel and the second electron channel under the drive of the preset electric field and be incident on the sample.

66. A multi-beam fiber electron exposure machine for exposing a sample, the multi-beam fiber electron exposure machine comprising: A light source for emitting laser light; The electron source according to any one of claims 1-45, including an optical fiber assembly coupled to the light source, and an electron emission layer, the electron emission layer at least including an electron excitation layer, the optical fiber assembly including a plurality of cores for transmitting the laser; the electron excitation layer is disposed on the light-emitting path of the laser emitted by the cores, so that the electron excitation layer can emit an electron beam under the excitation of the laser; the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material; The electron source further includes an optical modulator, one end of the optical modulator is connected to the light source, the other end of the optical modulator is respectively and correspondingly connected to a plurality of the cores of the optical fiber assembly, and the optical modulator is configured to control whether the laser emitted by the light source propagates into the corresponding cores respectively; and an electro-optical component, disposed on the electron beam output side of the electron source, the electro-optical component is configured to adjust the focusing and deflection directions of the electron beam, so that the electron beam is incident on the sample, and a preset exposure pattern is formed on the sample.

67. The multi-beam optical fiber electron exposure machine according to claim 66, wherein, The optical fiber assembly includes a plurality of optical fibers arranged in an array, and an electron excitation layer is provided on the end face of one end of the emitted laser of each optical fiber, so that the electron excitation layer is located on the light output path of the laser emitted from the core of the corresponding optical fiber.

68. The multi-beam optical fiber electron exposure machine according to claim 66 or 67, wherein, The optical modulator includes one of a spatial light modulator, an optical switch, and an electro-optic modulator.

69. The multi-beam optical fiber electron exposure machine according to any one of claims 66-68, wherein, The electro-optical component includes a focusing magnetic lens and a deflection coil, and the focusing magnetic lens and the deflection coil are arranged at intervals along the output direction of the electron beam on the electron beam output side of the electron source.

70. The multi-beam optical fiber electron exposure machine according to any one of claims 66-69, wherein, The multi-beam fiber electron exposure machine further includes a housing; The housing has a vacuum chamber, and the electron source and the electro-optical component are sequentially arranged in the vacuum chamber; An opening communicating with the vacuum chamber is provided on the housing, and the light input end of the optical fiber assembly of the electron source is exposed through the opening and is coupled to the light source; The outer peripheral wall of the optical fiber assembly is hermetically connected to the inner side wall of the opening.

71. The multi-beam optical fiber electron exposure machine according to any one of claims 66-70, wherein, The electron source further includes an anode, the anode has a first electron channel, and the electro-optical component has a second electron channel communicating with the first electron channel; A preset electric field is provided between the anode and the electron excitation layer, and the electron beam can pass through the first electron channel and the second electron channel under the drive of the preset electric field and be incident on the sample.

72. An X-ray tube, comprising: a tube body, the tube body has a vacuum chamber therein; The electron source according to any one of claims 1-45, including an optical fiber and an electron emission layer, the light output end of the optical fiber is located in the vacuum chamber, the electron emission layer is arranged at the light output end of the optical fiber, and the electron emission layer at least includes an electron excitation layer, and the electron excitation layer is arranged on the light output 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 an anode target, disposed in the vacuum chamber, and the anode target is opposite to and spaced from the light output end of the optical fiber, and the anode target is configured to receive the electrons emitted by the electron excitation layer to emit X-rays; Wherein, an output window is provided on the tube body facing the anode target, and the output window is configured to be able to guide the X-rays 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.

73. The X-ray tube according to claim 72, wherein, Along the extending direction of the optical fiber, the electron source is spaced from the anode target; The anode target has a reflective target surface facing the light output end, and the reflective target surface is arranged at an angle with the extending direction of the optical fiber; The output window is arranged on the side wall of the tube body and faces the reflective target surface.

74. The X-ray tube according to claim 72 or 73, wherein, 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.

75. The X-ray tube according to any one of claims 72 to 74, wherein, Along the extension direction of the optical fiber, the anode target is spaced apart from the light output 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.

76. The X-ray tube according to any one of claims 72-75, wherein, The tube body is respectively sleeved on the optical fiber and the anode target.

77. The X-ray tube according to any one of claims 72-76, wherein, 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.

78. The X-ray tube according to claim 77, wherein, 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.

79. The X-ray tube according to claim 78, wherein, 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.

80. The X-ray tube according to any one of claims 72-79, wherein, 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.

81. The X-ray tube according to any one of claims 72 - 80, wherein, The tube body comprises an inner tube sleeved on the optical fiber and the anode target, and an outer tube sleeved on the inner tube, the outer tube is provided with an opening, 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 transmitting material, and the material of the outer tube includes an X-ray blocking material.

82. The X-ray tube according to any one of claims 72-81, wherein, The outer diameter of the tube body is 125 μm-2000 μm, and the length of the tube body is 3 cm-9 cm.

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