A gradient diameter microchannel plate and its preparation method and application

Abstract

The application relates to a gradient-diameter micro-channel plate and a preparation method and application thereof, wherein the steps of the preparation method comprise the following: preparing a sheet-shaped base plate from a transparent material; using a femtosecond laser to process a tapered array of micro-holes on the base plate to obtain a gradient-diameter base plate; when the tapered array of micro-holes is processed, the entrance end is first etched to form an opening, and then the diameter is uniformly shrunk step by step to the exit end, and the diameter of the entrance end is larger than that of the exit end; the ratio of the hole depth of the tapered array of micro-holes to the diameter of the exit end is 30-200, and the taper angle is 1-5 DEG; an Al2O3-SiO2-B2O3 sol containing Cs is prepared, is uniformly coated on the inner wall of the tapered array of micro-holes, and is subjected to hydrogen reduction to obtain a micro-channel blank plate; electrodes are plated on both ends of the micro-channel blank plate to obtain the gradient-diameter micro-channel plate. The gradient-diameter micro-channel plate provided by the application has the advantages of high gain and low noise, and is more suitable for practical use.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic devices, and particularly relates to a gradient diameter micro channel plate and a preparation method and application thereof. BACKGROUND

[0002] As a kind of core device for realizing signal amplification relying on secondary electron multiplication effect, micro channel plate (MCP) plays an important role in today's photoelectric detection field. Its unique working principle is based on secondary electron emission phenomenon. When incident particles (such as electrons, photons, ions, etc.) hit the inner wall of the channel of the micro channel plate, secondary electrons will be emitted. These secondary electrons will continuously accelerate along the channel direction under the action of the electric field in the channel and collide with the inner wall of the channel multiple times, thereby generating more secondary electrons to realize signal multiplication and amplification. This excellent signal amplification capability makes the micro channel plate widely used in many fields.

[0003] The traditional uniform diameter micro channel plate has obvious limitations, including position resolution decline, which leads to reduced image clarity and resolution, increased noise signal when increasing diameter to achieve high gain, and long straight channel structure that easily leads to electron scattering and energy loss.

[0004] To solve the above problems of the traditional uniform diameter micro channel plate, researchers have proposed a micro channel plate with a gradient structure diameter. Existing gradient structures mostly rely on external bonding or multi-stage processing to achieve this. These methods are difficult to achieve a continuous diameter integrated micro channel plate. Since the diameter cannot be continuously changed, there is still some discontinuity in the transmission and multiplication process of electrons in the micro channel, which cannot fully utilize the advantages of the gradient diameter and further improve the performance of the micro channel plate to meet the requirements of high gain and low noise performance in the high sensitivity detection field.

[0005] Therefore, it is of great significance to develop a gradient diameter micro channel plate with continuous diameter change to improve the gain and reduce the noise of the device, thereby improving the overall performance of the micro channel plate. SUMMARY

[0006] The main purpose of the present application is to provide a gradient diameter micro channel plate and a preparation method and application thereof, and to solve the technical problem of how to provide a gradient diameter micro channel plate with continuous diameter change, which has the advantages of high gain and low noise, and is more suitable for practical use.

[0007] The purpose of the present application and the solution to its technical problems are realized by using the following technical scheme. According to the preparation method of the gradient diameter micro channel plate proposed by the present application, the steps include:

[0008] A substrate is made of a transparent material in a sheet shape;

[0009] A tapered array of micro-holes is processed on the substrate using a femto-second laser to obtain a gradient-diameter substrate; when the tapered array of micro-holes is processed, an entrance end is first etched to form an opening, and then the diameter is uniformly shrunk step by step to an exit end, the diameter of the entrance end is larger than that of the exit end; the ratio of the depth of the tapered array of micro-holes to the diameter of the exit end is 30-200, and the taper angle is 1-5°;

[0010] An Al2O3-SiO2-B2O3 sol containing Cs is prepared, uniformly coated on the inner wall of the tapered array of micro-holes, and then subjected to hydrogen reduction to obtain a micro-channel blank plate;

[0011] Electrodes are plated on both ends of the micro-channel blank plate to obtain a gradient-diameter micro-channel plate.

[0012] The purposes of the present application and the technical problems thereof can also be further achieved by the following technical measures.

[0013] Preferably, according to the preparation method of the gradient-diameter micro-channel plate, the diameter of the entrance end of the tapered array of micro-holes ranges from 3 to 50 µm, the diameter of the exit end ranges from 2 to 48 µm, and the hole spacing is 5-20 µm.

[0014] Preferably, according to the preparation method of the gradient-diameter micro-channel plate,

[0015] The transparent material is borosilicate glass, and its components include, in terms of mass percentage of oxides:

[0016] SiO2: 40-75 wt%;

[0017] B2O3: 5-18 wt%;

[0018] Na2O: 5-12 wt%;

[0019] Al2O3: 5-13 wt%; and

[0020] TiO2: 0-1.5 wt%.

[0021] Preferably, according to the preparation method of the gradient-diameter micro-channel plate, the components of the Al2O3-SiO2-B2O3 sol containing Cs include, in terms of mass percentage of oxides:

[0022] Al2O3: 10-30 wt%;

[0023] SiO2: 40-80 wt%;

[0024] B2O3: 5-25 wt%; and

[0025] Cs2O: 1-3 wt%.

[0026] Preferably, according to the preparation method of the gradient diameter microchannel plate, the mass of the solutes in the aforementioned Cs-containing Al2O3-SiO2-B2O3 sol is 5-30% based on 100% of the mass of the aforementioned Cs-containing Al2O3-SiO2-B2O3 sol.

[0027] Preferably, according to the preparation method of the gradient diameter microchannel plate, the Cs-containing Al2O3-SiO2-B2O3 sol further comprises polyvinylpyrrolidone in an amount of 0.5-2% based on 100% of the mass of the solvent in the aforementioned Cs-containing Al2O3-SiO2-B2O3 sol.

[0028] Preferably, according to the preparation method of the gradient diameter microchannel plate, the Cs-containing Al2O3-SiO2-B2O3 sol is coated to a thickness of 80-150 nm.

[0029] Preferably, according to the preparation method of the gradient diameter microchannel plate, the hydrogen reduction is performed at a temperature of 300-800°C for 2-8 h, with a hydrogen flow rate of 5-10 L / min and a hydrogen purity of ≥99.99%; and / or,

[0030] Preferably, the femtosecond laser has a pulse width of 300-500 fs, an average power of 150-250 mW, a scanning speed of 3-15 mm / s, and a laser energy of 0.3-1.0 J / cm²; and / or,

[0031] Preferably, the electrode is made of nickel or chromium and has a thickness of 0.1-0.5 μm, with a thickness error controlled within ±0.02 μm.

[0032] The purposes and technical problems of the present application are also achieved by the following technical solutions. According to the present application, a gradient diameter microchannel plate is provided, which comprises:

[0033] a transparent substrate, which is in the form of a sheet;

[0034] a conical array of micro-holes, which penetrates the bottom and top surfaces of the transparent substrate and has an axis perpendicular to the bottom and top surfaces of the transparent substrate; the conical array of micro-holes has an inlet end with a larger diameter than an outlet end, a ratio of a hole depth to the diameter of the outlet end is 30-200, and a conical angle is 1°-5°;

[0035] a high-resistance layer, which covers the inner wall of the conical array of micro-holes and is obtained by hydrogen reduction of a Cs-containing Al2O3-SiO2-B2O3 sol; and

[0036] Electrode, the electrode is arranged at two ends of the transparent substrate.

[0037] The application also adopts the following technical scheme to achieve the purpose and solve the technical problems. The application proposes the application of the gradient-diameter micro-channel plate in the field of photoelectric detection.

[0038] By the above technical scheme, the gradient-diameter micro-channel plate, the preparation method and the application have at least the following advantages:

[0039] 1. The preparation method of the gradient-diameter micro-channel plate has the advantages that the laser etching technology is used to process the tapered array micro-holes on the substrate, the integrated forming preparation of the tapered micro-holes is realized, the cumbersome process of manufacturing the capillary glass tube and mechanical processing preparation and the complex process of preparing the tapered fiber capillary micro-holes are avoided, the production efficiency of the gradient-diameter micro-channel plate is improved, the manufacturing time is shortened, and the production cost is reduced.

[0040] 2、The gradient diameter microchannel plate prepared by the method has the following advantages: (1) the diameter gradually decreases along the electron transmission direction, which optimizes the secondary electron collection efficiency; (2) the electric field distribution in the channel presents a gradient change, and the gradient electric field shortens the electron residence time; the larger diameter of the inlet end forms a lower electric field strength area, allowing the initial electrons to enter the channel at a larger incident angle; with the diameter shrinkage, the electric field strength at the outlet end is significantly enhanced, and the electrons are rapidly accelerated under the strong electric field at the outlet end, thereby shortening the residence time of the electrons in the channel and reducing the probability of thermal electron recombination; (3) the outlet end electric field gradient forms a “funnel effect”, which focuses the divergent secondary electron trajectories to the outlet direction, thereby improving the collection angle efficiency; (4) the diameter of the microchannel plate uniformly decreases along the path, and the electron motion trajectory in the channel presents a spiral acceleration characteristic; (5) the tapered structure can reduce backscattered electrons and keep the gain stable; the larger diameter at the initial stage allows the electrons to collide effectively to a certain extent, and with the diameter shrinkage, the electron energy is gradually released through multiple collisions, thereby avoiding the backscattering caused by excessive energy; (6) the strong electric field at the outlet end of the gradient diameter structure converts the remaining energy into directional kinetic energy, thereby ensuring that the electrons effectively escape instead of being trapped in the channel; (7) the space charge suppression mechanism of the gradient diameter structure solves the problems of shielding effect caused by high-density electron clouds in the traditional straight hole and the reduction of the acceleration efficiency of subsequent electrons; (8) the larger diameter of the inlet end dilutes the initial electron density and delays the accumulation of space charge; the shrinked diameter of the outlet end forms a “bottleneck effect”, which significantly improves the electron beam density and maintains a larger electric field strength, so that the electron beam density is increased by 3-5 times at the outlet, while maintaining sufficient kinetic energy to overcome the space charge repulsion; (9) the gradient electric field focuses the electron trajectory, thereby effectively suppressing scattering; the gradient electric field suppresses the lateral diffusion of the electron cloud in the channel, thereby maintaining the electric field strength required for high gain.

[0041] 3. The Cs-containing Al2O3-SiO2-B2O3 sol is coated on the inner wall of the tapered array micro-holes, and through hydrogen reduction, B2O3 is reduced to elemental B, which is embedded in the coating in an amorphous or nanocrystalline form, has high impedance, and is combined with the glass network to regulate the electrical properties, so that a high-impedance layer is formed on the inner wall of the micro-channel and has a rough surface. The rough surface can change the scattering path of electrons. At the same time, Cs2O is reduced to metallic Cs, which is stably distributed in the glass network, and the surface dipole effect of the metallic Cs reduces the work function, prolongs the interaction time of electrons and Cs, thereby improving the emission probability of secondary electrons, effectively dispersing the local electric field concentration area, suppressing the field emission noise caused by sharp protrusions and guiding the movement of electrons in a specific direction, reducing the energy loss caused by disorder scattering, thereby reducing the gain fluctuation, and making the material have good electron emission performance. The high-impedance property of the glass matrix ensures the insulation of the material during the electron multiplication process.

[0042] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will be described in detail with the preferred embodiments of the present application and with the aid of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0043] Fig. 1 The structure schematic diagram of the first perspective view of the gradient diameter micro-channel plate in some embodiments of the present application is shown in the figure.

[0044] Fig. 2 The structure schematic diagram of another perspective view of the gradient diameter micro-channel plate in some embodiments of the present application is shown in the figure.

[0045] In the figure, 1 is an outlet end, 2 is an inlet end, and 3 is a transparent substrate. DETAILED DESCRIPTION

[0046] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following will be described in detail with the aid of the accompanying drawings and the preferred embodiments, the specific implementation, structure, characteristics and effects of the gradient diameter micro-channel plate, the preparation method thereof and the application thereof according to the present application. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0047] It should also be understood that the terms used in the present application specification herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification, unless otherwise clear from the context, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0048] It should also be further understood that the term "and / or" as used in this specification refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0049] It should be noted that all directional descriptions (e.g., input, output, etc.) in this invention are only used to describe the movement of electrons in a specific orientation. If the specific orientation changes, the corresponding directional description will also change. Furthermore, the term "connection" as used herein includes both direct and indirect connections, both of which fall within the scope of this application.

[0050] The present invention proposes a method for preparing a gradient diameter microchannel plate, the steps of which include:

[0051] Transparent materials are made into sheet-like substrates;

[0052] A femtosecond laser is used to process a tapered array of micro-holes on the aforementioned substrate to obtain a gradient diameter substrate. When processing the aforementioned tapered array of micro-holes, the inlet end 2 is first etched to form an opening, and then the diameter is gradually and uniformly reduced to the outlet end 1. The diameter of the aforementioned inlet end is larger than the diameter of the aforementioned outlet end. The ratio of the depth of the aforementioned tapered array of micro-holes to the diameter of the aforementioned outlet end 1 is 30~200, and the cone angle is 1°~5°.

[0053] Prepare an Al2O3-SiO2-B2O3 sol containing Cs, coat it uniformly on the inner wall of the aforementioned conical array micropores, and then perform hydrogen reduction to obtain a microchannel preform.

[0054] Electrodes are deposited at both ends of the aforementioned microchannel preform to obtain a gradient diameter microchannel plate, such as... Figs. 1-2 As shown.

[0055] Specifically, transparent glass is selected as the material of the substrate. Preferably, the glass is borosilicate glass, and the components of the borosilicate glass include, in terms of mass percentage of oxides, SiO2: 40-75 wt%; B2O3: 5-18 wt%; Na2O: 5-12 wt%; Al2O3: 5-13 wt%; and TiO2: 0-1.5 wt%. As the substrate material, the SiO2 content in the borosilicate glass is 40-75 wt%, which forms a glass network to make the substrate glass have good chemical stability and mechanical strength, and too high or too low will destroy the stability of the glass. The B2O3 content is 5-18 wt%, which can reduce the melting point and viscosity of the glass, improve the thermal expansion performance of the glass, and improve the thermal stability of the glass. The Na2O content is 5-15 wt%, which is mainly as an external network to reduce the melting temperature and viscosity of the glass, increase the flowability of the glass, and facilitate the forming processing of the glass. The Al2O3 content is 5-13 wt%, which improves the chemical stability, mechanical strength and hardness of the glass, and at the same time improves the crystallization performance of the glass, and too much will make the glass brittle. The TiO2 content is 0-1.5 wt%, which improves the refractive index and chemical stability of the glass. The glass is cut into a certain specification of thin sheet to make the substrate, and the size thereof can be adjusted according to actual needs, for example, the size thereof is 30 mm x 30 mm x 0.5 mm.

[0056] The tapered array micro-holes are processed on the substrate using a femtosecond laser. Since the femtosecond laser has an extremely short pulse width and an extremely high peak power, it can realize accurate processing of the base material, and further prepare high-precision array micro-holes. Preferably, the pulse width of the femtosecond laser is 300-500 fs, the average power is 150-250 mW, and the scanning speed is 3-15 mm / s. In order to ensure sufficient etching, a laser with an energy of 0.3-1.0 J / cm2 can be selected.

[0057] The inlet end 2 is first etched to form an opening, and then the diameter is gradually reduced to the outlet end 1. The diameter of the inlet end is greater than that of the outlet end. The inlet diameter, outlet diameter, hole spacing and aspect ratio can be adjusted according to actual needs, but the gradient structure must be ensured, that is, the inlet diameter is greater than the outlet diameter, so that when the electron enters the micro-channel from the inlet, the larger diameter can increase the incidence probability of the electron; and the smaller diameter at the outlet can limit the diffusion of the electron, thereby improving the position resolution of the micro-channel plate. In this application, the ratio of the hole depth of the tapered array micro-hole to the diameter of the outlet end 1 is 30-200, and the taper angle is 1°-5°. Within this range, the number of collisions between the electron and the inner wall in the micro-channel can be increased, thereby improving the emission and multiplication efficiency of the secondary electron. The size of the taper angle of the micro-hole is half of the size of the vertex angle of the cone formed after the extension of the side wall of the micro-hole.

[0058] Preferably, the inlet end 2 has a diameter in the range of 3-50 pm, the outlet end 1 has a diameter in the range of 2-48 pm, and the distance between adjacent micro-holes is in the range of 5-20 pm. The distance between adjacent micro-holes is the minimum distance between the edges of the inlet ends of adjacent micro-holes. It is ensured that there is sufficient distance between adjacent micro-holes to avoid crosstalk of electrons during multiplication.

[0059] The Cs-containing Al2O3-SiO2-B2O3 sol is prepared. Preferably, the components of the Cs-containing Al2O3-SiO2-B2O3 sol include, in terms of mass percentage of oxides: Al2O3: 10-30 wt%; SiO2: 40-80 wt%; B2O3: 5-25 wt%; and Cs2O: 1-3 wt%. Preferably, the mass of the solutes in the Cs-containing Al2O3-SiO2-B2O3 sol is 5-30% based on 100% of the mass of the Cs-containing Al2O3-SiO2-B2O3 sol. The sol can be uniformly dispersed by ultrasonic dispersion to optimize the dispersion effect and form a uniform sol. The sol can be uniformly coated on the inner wall of the conical array micro-holes by dip coating. Preferably, the coating thickness is 80-150 nm to reduce the work function. After coating, hydrogen reduction is performed to obtain a micro-channel blank. The hydrogen reduction treatment forms a high-resistance layer on the inner wall of the micro-channel and has a rough surface. The rough surface can change the scattering path of electrons, prolong the interaction time of electrons and the coating, thereby increasing the emission probability of secondary electrons; effectively disperse the local electric field concentration area, inhibit the field emission noise caused by sharp protrusions, and guide the movement of electrons in a specific direction; reduce the energy loss caused by disorder scattering, thereby reducing the gain fluctuation and making the electron emission performance good. Preferably, the hydrogen reduction temperature is 300-800°C, the time is 2-8 h, the hydrogen flow rate is 5-10 L / min, and the hydrogen purity is ≥99.99%.

[0060] Preferably, the Cs-containing Al2O3-SiO2-B2O3 sol further includes polyvinylpyrrolidone in an amount of 0.5-2% based on 100% of the mass of the solvent in the Cs-containing Al2O3-SiO2-B2O3 sol. The polyvinylpyrrolidone (PVP) acts as a dispersant to prevent particle settling; and has high-temperature reduction compatibility, which can be pyrolyzed into CO2 and H2O at 300-500°C, leaving little residue and not affecting the subsequent reduction process; the low-foaming property of PVP helps to uniformly coat the inner wall of the micro-holes, ensures the uniformity of the coating, and avoids blockage of the pores due to bubbles. At the same time, the PVP has adaptability with the solutes of the sol. The coating slurry containing Cs2O has a certain weak alkalinity, and the stability of PVP is better than that of general ionic dispersants in the pH range of 5-10, and has excellent pH adaptability.

[0061] The electrode plating process can be physical vapor deposition or electroless plating, etc. Preferably, the electrode material is selected from nickel (Ni) or chromium (Cr), and the electrode thickness is 0.1-0.5 μm, with a thickness error controlled within ±0.02 μm.

[0062] The gradient diameter microchannel plate according to the present application, as shown in Figs. 1-2 includes:

[0063] a transparent substrate 3, which is in a sheet shape;

[0064] a tapered array of micro-holes, which penetrates the bottom and top surfaces of the transparent substrate 3, and the axis of which is perpendicular to the bottom and top surfaces of the transparent substrate 3; the inlet end 2 of the tapered array of micro-holes has a larger diameter than the outlet end 1, and the ratio of the hole depth to the diameter of the outlet end 1 is 30-200, and the taper is 1°-5°;

[0065] a high-resistance layer, which covers the inner wall of the tapered array of micro-holes, and is obtained by hydrogen reduction of an Al2O3-SiO2-B2O3 sol containing Cs; and

[0066] an electrode, which is arranged at both ends of the transparent substrate 3.

[0067] The present application also provides the use of the gradient diameter microchannel plate in the field of photoelectric detection. The gradient diameter microchannel plate has the advantages of high gain and low noise, and can be widely used in the field of photoelectric detection. For example, in the field of low-light-level night vision equipment, the gradient diameter microchannel plate can help the equipment to realize clear imaging in an extremely low light environment. In night combat, field reconnaissance and other scenarios, the low-light-level night vision instrument can effectively amplify the weak light signal by virtue of the powerful function of the microchannel plate, so that the user can also obtain a clear image of the surrounding environment in the dark, greatly improving the safety and efficiency of action. The gradient diameter microchannel plate can efficiently capture X-ray signals and can be applied to medical diagnosis and industrial detection. For example, in industrial detection, it can detect defects, cracks and other problems in metal materials, and ensure the quality and safety of industrial products. In addition, the gradient diameter microchannel plate can also be applied to high-energy physics experiments and astronomical observations. In high-energy physics experiments, it can detect extremely weak particle signals for the study of the microscopic world. In astronomical observations, it can amplify and detect the weak light emitted by distant celestial bodies, allowing humans to gain a deeper understanding of the mysteries of the universe.

[0068] The application will be further described in conjunction with the specific embodiments. It should be understood that these embodiments are only used to explain the application and should not be construed as limiting the scope of the application. Any non-essential improvement and adjustment made by the person skilled in the art based on the content of the application still falls within the protection scope of the application.

[0069] Unless otherwise specified, the materials and reagents involved in the following are commercially available and well known to those skilled in the art; unless otherwise specified, the methods are well known in the art. Unless otherwise defined, the technical terms or scientific terms used should be understood as the common meaning understood by the person skilled in the art in the field to which the application belongs.

[0070] In the following, the aspect ratio is the ratio of the hole depth to the diameter of the outlet end, and the hole spacing is the minimum distance between the edges of the adjacent micro-holes at the inlet end. The size of the cone angle of the micro-hole is half the size of the vertex angle of the pyramid formed by the extension of the side wall of the micro-hole.

[0071] In the following, the Cs-containing Al2O3-SiO2-B2O3 sol includes solute, solvent and dispersant. The components of the solute include Al2O3 20wt%, SiO2 65wt%, B2O3 14wt% and Cs2O 1.0wt% in terms of mass percentage of solute oxide, and the mass of the solute is 10g in terms of mass of oxide; the solvent is 90g of high-purity ethanol with a purity of more than 99.9%; and the dispersant is 1g of polyvinylpyrrolidone. The specific preparation method is as follows: the oxide powder of the solute is added to high-purity ethanol, and then the dispersant is added. The particles are initially wetted by magnetic stirring (speed 500rpm, time 10min). Then water tank ultrasonic is performed, with a single ultrasonic time of 3min, an interval cooling time of 1min, a repetition of 3 times, a total time of 12min, an ultrasonic frequency of 20kHz, a power of 50W, and the system temperature is maintained at room temperature by ice bath or circulating water cooling during ultrasonic. Mechanical low-speed stirring is provided throughout the ultrasonic process to assist the uniform dispersion of the particles.

[0072] Example 1

[0073] This embodiment provides a gradient diameter micro-channel plate and a preparation method thereof, as shown in Figs. 1-2 .

[0074] A borosilicate glass is cut into a thin sheet with a size of 30mm×30mm×0.5mm to obtain a substrate. The components of the borosilicate glass include SiO2 70wt%, B2O3 14.5wt%, Na2O 10wt%, Al2O3 5wt% and TiO2 0.5wt% in terms of mass percentage of oxide.

[0075] A tapered array of micro-holes is machined on a substrate using a femtosecond laser to obtain a substrate with a gradient diameter. The laser used has a pulse width of 500 fs, an average power of 200 mW, a scanning speed of 10 mm / s, and an energy of 0.5 J / cm². The entrance end 2 is first etched to form an opening with a diameter of 20 µm, and then the diameter is uniformly reduced step by step to the exit end 1, which has a diameter of 10 µm. The hole spacing at the entrance end 2 is 12 µm, and the aspect ratio is 50:1.

[0076] An Al2O3-SiO2-B2O3 sol containing Cs is prepared, and the sol is uniformly coated on the inner wall of the channel of the substrate with a gradient diameter by dip coating, followed by hydrogen reduction to obtain a micro-channel blank. The sol coating thickness is 100 nm, the hydrogen reduction temperature is 500°C, the time is 3 h, the hydrogen flow rate is 5 L / min, and the hydrogen purity is ≥99.99%.

[0077] An electrode is plated on both ends of the micro-channel blank by physical vapor deposition to obtain a micro-channel plate with a gradient diameter. The electrode material is selected as metal nickel. During the electrode plating process, the thickness and uniformity of the plated film are controlled, the electrode thickness is 0.5 µm, and the thickness error is controlled within ±0.02 µm.

[0078] The photon collection efficiency, dark current noise, and secondary electron yield of the micro-channel plate with a gradient diameter are tested, and the test results are shown in Example 1 in Table 1.

[0079] Example 2

[0080] The difference between this example and Example 1 is that the entrance end 2 is first etched to form an opening with a diameter of 30 µm, and then the diameter is uniformly reduced step by step to the exit end 1, which has a diameter of 10 µm. The hole spacing at the entrance end 2 is 12 µm, and the aspect ratio is 50:1. The remaining steps are consistent with Example 1.

[0081] The photon collection efficiency, dark current noise, and secondary electron yield of the micro-channel plate with a gradient diameter are tested, and the test results are shown in Example 2 in Table 1.

[0082] Example 3

[0083] The difference between this example and Example 1 is that a borosilicate glass is cut into a thin sheet with dimensions of 30 mm x 30 mm x 0.4 mm to obtain a substrate. The entrance end 2 is first etched to form an opening with a diameter of 20 µm, and then the diameter is uniformly reduced step by step to the exit end 1, which has a diameter of 10 µm. The hole spacing at the entrance end 2 is 12 µm, and the aspect ratio is 40:1. The remaining steps are consistent with Example 1.

[0084] The photon collection efficiency, dark current noise, and secondary electron yield of the micro-channel plate with a gradient diameter are tested, and the test results are shown in Example 3 in Table 1.

[0085] Example 4

[0086] The difference between this example and Example 1 is that the composition of the borosilicate glass comprises SiO265wt%, B2O318wt%, Na2O8wt%, Al2O38wt%, and TiO21wt%. The glass of Example 4 has a higher hardness, and when a tapered array of micro-holes is processed on the substrate using a femtosecond laser, the energy is 0.6 J / cm2with a properly reduced laser spot. The remaining preparation steps are consistent with Example 1.

[0087] The photon collection efficiency, dark current noise, and secondary electron yield of the gradient-diameter micro-channel plate were tested, and the test results are shown in Example 4 in Table 1.

[0088] Example 5

[0089] The difference between this example and Example 4 is that the inlet end 2 is first etched to form an opening with a diameter of 30 pm, and then the diameter is gradually and uniformly reduced to the outlet end 1, which has a diameter of 10 pm. The inter-hole spacing of the inlet end 2 is 12 pm, and the aspect ratio is 50:1. The remaining steps are consistent with Example 4.

[0090] The photon collection efficiency, dark current noise, and secondary electron yield of the gradient-diameter micro-channel plate were tested, and the test results are shown in Example 5 in Table 1.

[0091] Example 6

[0092] The difference between this example and Example 4 is that the borosilicate glass is cut into a thin sheet with a size of 30 mm x 30 mm x 0.4 mm to obtain the substrate. The inlet end 2 is first etched to form an opening with a diameter of 20 pm, and then the diameter is gradually and uniformly reduced to the outlet end 1, which has a diameter of 10 pm. The inter-hole spacing of the inlet end 2 is 12 pm, and the aspect ratio is 40:1. The remaining steps are consistent with Example 4.

[0093] The photon collection efficiency, dark current noise, and secondary electron yield of the gradient-diameter micro-channel plate were tested, and the test results are shown in Example 6 in Table 1.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that a straight hole array with uniform diameter is processed on the substrate using a femtosecond laser. The diameter is 10 pm, the inter-hole spacing is 12 pm, and the aspect ratio is 50:1. Finally, a uniform-diameter micro-channel plate is obtained. The remaining steps are consistent with Example 1.

[0096] The photon collection efficiency, dark current noise, and secondary electron yield of the uniform-diameter micro-channel plate were tested, and the test results are shown in Comparative Example 1 in Table 1.

[0097] Comparative Example 2

[0098] Comparative Example 2 differs from Example 1 in that the borosilicate glass is cut into a thin sheet with dimensions of 30 mm x 30 mm x 0.2 mm to obtain the substrate. The inlet end 2 is first etched to form an opening with a diameter of 20 µm, and then gradually and uniformly shrunk in diameter to the outlet end 1 with a diameter of 10 µm. The spacing between the inlet end holes is 12 µm, and the aspect ratio is 20:1. Finally, a microchannel plate is obtained. The remaining steps are consistent with Example 1.

[0099] The photon collection efficiency, dark current noise, and secondary electron yield of the microchannel plate are tested, and the test results are shown in Comparative Example 2 in Table 1.

[0100] Table 1. Data summary table of Examples 1-6 and Comparative Examples 1-2

[0101]

[0102] The technical features in the specification of the present application can be combined, and the combination manner is not limited to the combination obtained by reference in the specification. The technical solutions obtained by combining the technical features in the specification are also within the protection scope of the present application.

[0103] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application are still within the scope of the technical solutions of the present application.

Claims

1. A method for preparing a gradient diameter microchannel plate, characterized in that, The steps include: Transparent materials are made into sheet-like substrates; A femtosecond laser is used to fabricate a tapered array of micro-holes on the substrate to obtain a gradient diameter substrate. During the fabrication of the tapered array of micro-holes, the inlet end is first etched to form a larger diameter opening, and then the diameter is gradually and uniformly reduced to the outlet end. The ratio of the hole depth to the outlet diameter of the tapered array of micro-holes is 30–200, and the cone angle is 1°–5°. The pulse width of the femtosecond laser is 300–500 fs, the average power is 150–250 mW, the scanning speed is 3–15 mm / s, and the laser energy is 0.3–1.0 J / cm². 2 ; A Cs-containing Al2O3-SiO2-B2O3 sol was prepared and uniformly coated onto the inner wall of the conical array micropores. Hydrogen reduction was then performed to obtain a microchannel preform. The solute in the Cs-containing Al2O3-SiO2-B2O3 sol, by mass percentage of oxides, comprises the following components: Al2O3: 10-30 wt%; SiO2: 40-80 wt%; B2O3: 5–25 wt%; and, Cs2O: 1-3 wt%; Electrodes are plated at both ends of the microchannel blank to obtain a gradient diameter microchannel plate; The thickness of the Cs-containing Al2O3-SiO2-B2O3 sol coating is 80-150 nm; the hydrogen reduction temperature is 300-800℃, the time is 2-8 h, and the hydrogen flow rate is 5-10 L / min.

2. The method for preparing a gradient diameter microchannel plate according to claim 1, characterized in that, The diameter of the inlet end of the conical array micropores ranges from 3 to 50 μm, the diameter of the outlet end ranges from 2 to 48 μm, and the spacing between the pores ranges from 5 to 20 μm.

3. The method for preparing a gradient diameter microchannel plate according to claim 1, characterized in that, The transparent material is borosilicate glass, and its components, by mass percentage of oxides, include: SiO2: 40-75 wt%; B2O3: 5–18 wt%; Na2O: 5-12 wt%; Al2O3: 5–13 wt%; and, TiO2: 0–1.5 wt%.

4. The method for preparing a gradient diameter microchannel plate according to claim 1, characterized in that, Based on the mass of the Cs-containing Al2O3-SiO2-B2O3 sol being 100%, the mass of the solute is 5% to 30%.

5. The method for preparing a gradient diameter microchannel plate according to claim 1, characterized in that, Based on the solvent mass of the Cs-containing Al2O3-SiO2-B2O3 sol being 100%, the Cs-containing Al2O3-SiO2-B2O3 sol also includes 0.5% to 2% polyvinylpyrrolidone by mass.

6. The method for preparing a gradient diameter microchannel plate according to claim 1, characterized in that, Hydrogen purity ≥ 99.99%; and / or, The electrode is made of nickel or chromium and has a thickness of 0.1 to 0.5 μm, with the thickness error controlled within ±0.02 μm.

7. A gradient diameter microchannel plate, characterized in that, It includes: A transparent substrate, wherein the transparent substrate is sheet-like; A conical array of micropores, wherein the conical array of micropores penetrates the bottom and top surfaces of the transparent substrate, and its axis is perpendicular to the bottom and top surfaces of the transparent substrate; the inlet diameter of the conical array of micropores is larger than the outlet diameter, the ratio of the hole depth to the outlet diameter is 30 to 200, and the cone angle is 1° to 5°; A high-resistance layer, which covers the inner wall of the conical array micropores, is obtained by hydrogen reduction of a Cs-containing Al2O3-SiO2-B2O3 sol; the solute in the Cs-containing Al2O3-SiO2-B2O3 sol, by mass percentage of oxides, comprises the following components: Al2O3: 10-30 wt%; SiO2: 40-80 wt%; B2O3: 5–25 wt%; and, Cs2O: 1-3 wt%; The thickness of the Cs-containing Al₂O₃-SiO₂-B₂O₃ sol coating is 80–150 nm; the hydrogen reduction temperature is 300–800 °C, the time is 2–8 h, and the hydrogen flow rate is 5–10 L / min; and, Electrodes, which are disposed at both ends of the transparent substrate.

8. The application of the gradient diameter microchannel plate according to claim 7 in the field of photoelectric detection.

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