Gain-free microchannel plate two-dimensional framing imaging system

Abstract

A gain-free microchannel plate two-dimensional framing imaging system, comprising a vacuum drift tube, combined-type long and short magnetic lenses, a gain-free electron beam time amplifier, a gated microchannel plate detector, and a pulse generator, wherein the combined-type long and short magnetic lenses surround the outer side of the vacuum drift tube, the gain-free electron beam time amplifier is located at the incident end of the vacuum drift tube, the gated microchannel plate detector is located at the emergent end of the vacuum drift tube, and the area in the vacuum drift tube between the incident end thereof and the emergent end thereof is an electron drift region.

Description

A two-dimensional framing imaging system using a gain-free microchannel plate Technical Field

[0001] The present invention relates to the field of ultrafast diagnosis technology, and more particularly to a two-dimensional framing imaging system of a non-gain microchannel plate. Background Art

[0002] Ultrafast diagnostic technology is primarily used in basic frontier science, national major scientific projects, national defense science and technology, and strategic high-tech. It is an important and unique two-dimensional ultrafast diagnostic device. For example, it is used in laser inertial confinement fusion (ICF) research to detect X-ray emission processes within 1-2 nanoseconds. X-ray framing cameras can obtain the two-dimensional spatial distribution and temporal characteristics of ICF plasma X-ray emission. Improving temporal resolution is a constant pursuit in the industry. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a two-dimensional framing imaging system using a gain-free microchannel plate.

[0004] The technical solution adopted by the present invention to solve the technical problem is as follows: constructing a gain-free microchannel plate two-dimensional framing imaging system, comprising a vacuum drift tube, a long-short magnetic combined lens, a gain-free electron beam time amplifier, a gated microchannel plate detector and a pulse generator, wherein the long-short magnetic combined lens surrounds the outside of the vacuum drift tube, the gain-free electron beam time amplifier is located at the incident end of the vacuum drift tube, the gated microchannel plate detector is located at the exit end of the vacuum drift tube, and the area between the incident end and the exit end of the vacuum drift tube is an electron drift region;

[0005] The gain-free electron beam time amplifier includes a microstrip cathode, a gain-free microchannel plate and a grounded anode. The gain-free microchannel plate includes a first input surface, a first output surface and a plurality of gain-free channels. The first input surface and the first output surface of the gain-free microchannel plate are parallel, and the gain-free channels run through the gain-free microchannel plate. The microstrip cathode is evaporated on the first input surface of the gain-free microchannel plate, and the grounded anode is evaporated on the entire first output surface of the gain-free microchannel plate. A negative DC voltage and a stretched pulse generated by the pulse generator are superimposed on the microstrip cathode, and two ends of the microstrip cathode are respectively transmitted in opposite directions by two stretched pulses at the same time, and the two stretched pulses have the same waveform. The grounded anode is grounded.

[0006] The gated microchannel plate detector includes an impedance gradient line, a microstrip line, a gain microchannel plate, a fluorescent screen, and a CCD camera. The gain microchannel plate includes a second input surface, a second output surface, and multiple gain channels, and the gain channels run through the gain microchannel plate. The microstrip line is evaporated in a strip shape on the second input surface of the gain microchannel plate, and a preset metal layer is evaporated on the entire second output surface of the gain microchannel plate. The pulse generator is connected to the microstrip line through the impedance gradient line, and the pulse generator samples and multiplies the electron beam on the microstrip line through a gated pulse. The first surface of the fluorescent screen is parallel to and spaced apart from the second output surface of the gain microchannel plate, and the second surface of the fluorescent screen is in close contact with the CCD camera.

[0007] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of the present invention, the outer diameter of the non-gain microchannel plate is 106 mm and the thickness is 1 mm; the diameter of the non-gain channel is 35 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent non-gain channels is 39 μm;

[0008] Three microstrip cathodes are evaporated on the first input surface of the non-gain microchannel plate, each microstrip cathode has a width of 12 mm, and the interval between adjacent microstrip cathodes is 10 mm.

[0009] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of the present invention, the outer diameter of the gain microchannel plate is 106 mm and the thickness is 0.5 mm; the channel diameter of each gain channel is 12 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent gain channels is 14 μm;

[0010] Three microstrip lines are evaporated on the second input surface of the gain microchannel plate, the width of each microstrip line is 12 mm, and the interval between adjacent microstrip lines is 10 mm.

[0011] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system described in the present invention, the input and output ports of each gain channel are evaporated into a copper layer and a gold layer of a preset depth, the copper layer is located at the bottom layer, and the gold layer is located at the surface layer.

[0012] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of the present invention, the microstrip cathode of the non-gain microchannel plate includes a copper layer at the bottom layer and a gold layer at the surface layer;

[0013] The grounded anode of the non-gain microchannel plate comprises a copper layer at the bottom layer and a gold layer at the surface layer;

[0014] The microstrip line of the gated microchannel plate detector includes a copper layer at the bottom layer and a gold layer at the surface layer;

[0015] The entire second output surface of the gain microchannel plate is deposited with a preset metal layer including a copper layer at the bottom layer and a gold layer at the surface layer.

[0016] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of the present invention, the thickness of the copper layer is 500 nm, and the thickness of the gold layer is 100 nm.

[0017] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system described in the present invention, the long-short magnetic combined lens includes a long magnetic lens, a first short magnetic lens and a second short magnetic lens, the first short magnetic lens surrounds the incident end of the vacuum drift tube, the second short magnetic lens surrounds the exit end of the vacuum drift tube, and the long magnetic lens surrounds between the incident end and the exit end of the vacuum drift tube.

[0018] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system of the present invention, the first short magnetic lens is composed of a circular soft iron and a copper coil, the copper wire is located inside the soft iron, and a gap with a width of 4 mm is formed inside the first short magnetic lens; the first short magnetic lens has an outer diameter of 410 mm, an inner diameter of 360 mm, and an axial length of 100 mm;

[0019] The second short magnetic lens is composed of a circular soft iron and a copper coil. The copper wire is located inside the soft iron. There is a gap with a width of 4 mm on the inside of the second short magnetic lens. The outer diameter of the second short magnetic lens is 410 mm, the inner diameter is 360 mm, and the axial length is 100 mm.

[0020] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system of the present invention, the long magnetic lens is composed of a copper enameled wire wound between the incident end and the output end of the vacuum drift tube.

[0021] Furthermore, the gain-free microchannel plate two-dimensional framing imaging system described in the present invention also includes an imaging pinhole array located on the input side of the gain-free electron beam time amplifier, and the captured X-ray image generates photoelectron images at different positions of the microstrip cathode after passing through the imaging pinhole array.

[0022] A gain-free microchannel plate two-dimensional framing imaging system embodying the present invention has the following beneficial effects: the present invention uses electron beam time magnification technology to improve the temporal resolution of the framing imaging camera, uses a gain-free microchannel plate electron beam time amplifier to improve temporal resolution uniformity and gain uniformity, utilizes a long-short magnetic combination lens to improve spatial resolution and its uniformity, and adopts a two-way stretched pulse counter-transmission method to increase the effective frame size, thereby improving various performance indicators of the framing imaging camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] 1 is a schematic structural diagram of a two-dimensional framing imaging system of a gain-free microchannel plate according to an embodiment of the present invention;

[0025] FIG2 a is a schematic structural diagram of a gain-free microchannel plate provided in an embodiment of the present invention;

[0026] FIG2 b is a schematic structural diagram of a gain-free channel provided by an embodiment of the present invention;

[0027] 3 is a schematic diagram of gated pulse transmission and gating of a gated microchannel plate detector provided by an embodiment of the present invention;

[0028] FIG4 is a schematic structural diagram of a first short magnetic lens and a second short magnetic lens provided in an embodiment of the present invention;

[0029] FIG5 is a schematic structural diagram of a long magnetic lens provided in an embodiment of the present invention;

[0030] FIG6 a is a schematic diagram of unidirectional transmission of a microstrip cathode single-path stretched pulse according to an embodiment of the present invention;

[0031] FIG6 b is a schematic diagram of two stretched pulses simultaneously transmitted in opposite directions on a microstrip cathode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0033] The ICF fusion burn phase requires a camera with a temporal resolution better than 30 ps, ​​while the current practical camera has a temporal resolution of 60-100 ps. To improve temporal resolution, a gain-free microchannel plate (MCP) two-dimensional framing imaging system was proposed by combining electron beam time magnification with microchannel plate (MCP) gated framing imaging. The electron beam time magnification system is used to stretch the temporal width of the electron beam, achieving temporal amplification. The stretched electron beam is then measured using a gated microchannel plate detector, thereby improving temporal resolution. Theoretical studies have shown that electron beam time magnification can improve camera temporal resolution to less than 10 ps.

[0034] High-precision time-amplified ultrafast two-dimensional framing imaging technology was developed to meet the urgent needs of ICF research in my country. It improves temporal resolution and enables framing imaging cameras to meet engineering and precision requirements, addressing the needs of national ICF research. This technology has significant scientific significance and application value. Furthermore, electron beam time-amplification technology also has application value in ultrafast X-ray diodes and picosecond CMOS.

[0035] This embodiment will be described in detail with reference to FIG. 1 to FIG. 6 b .

[0036] Referring to Figure 1, this embodiment provides a gain-free microchannel plate two-dimensional framing imaging system. The system includes a vacuum drift tube 10, a long-short magnetic combination lens 20, a gain-free electron beam time amplifier 30, a gated microchannel plate detector 40, and a pulse generator 50. The vacuum drift tube 10 is a closed vacuum tube, preferably a cylindrical vacuum tube in this embodiment. The long-short magnetic combination lens 20 surrounds the outside of the vacuum drift tube 10 to generate the magnetic field required by the system. The gain-free electron beam time amplifier 30 is located at the incident end of the vacuum drift tube 10, and the gated microchannel plate detector 40 is located at the exit end of the vacuum drift tube 10. The area between the incident and exit ends of the vacuum drift tube 10 constitutes the electron drift region. It will be appreciated that the gain-free electron beam time amplifier 30 and the gated microchannel plate detector 40 are both located on the longitudinal axis of the vacuum drift tube 10 to facilitate electron propagation and detection.

[0037] Referring to Figures 1 and 2, a gain-free electron beam time amplifier 30 includes a microstrip cathode 301, a gain-free microchannel plate 302, and a grounded anode 303. The microstrip cathode 301 has two functions: first, converting incident light into photoelectrons; and second, transmitting stretched pulses, creating a time-varying electric field between the microstrip cathode and anode to achieve electron beam time amplification. Prior art electron beam time amplifiers consist of a microstrip cathode and an anode grid. A gold layer is evaporated onto polyimide to form a transmissive microstrip cathode. Due to the need to balance quantum efficiency, the gold layer is relatively thin, approximately 80 nm. The thin microstrip cathode significantly attenuates the stretched pulse, causing the stretched pulse slope to gradually decrease. This results in inconsistent electron beam time amplification at different locations on the microstrip cathode, resulting in poor temporal resolution and gain uniformity. Furthermore, the polyimide and grid thicknesses are both tens of micrometers, resulting in poor flatness when fabricated into large surfaces. This makes it difficult to apply high voltage between the cathode and anode grids, which can improve spatial resolution, reduce electron transit time dispersion, and enhance ultimate temporal resolution.

[0038] To address the problems in the prior art, this embodiment utilizes a non-gain microchannel plate 302 to replace the polyimide and grid used in the prior art to develop an electron beam time amplifier. A reflective cathode structure is utilized to increase the thickness of the microstrip cathode conductive layer, thereby reducing attenuation of the stretched pulse while maintaining a high quantum efficiency. Furthermore, the two end faces of the non-gain microchannel plate 302 are very flat, allowing for the application of a relatively high voltage. Therefore, this structure can simultaneously achieve high quantum efficiency, high anode-cathode voltage, high temporal resolution uniformity, and gain uniformity. The non-gain microchannel plate 302 is a semi-finished product of a gain microchannel plate, which becomes a gain microchannel plate after undergoing hydrogen reduction treatment. Prior to hydrogen reduction treatment, the channel walls of the non-gain microchannel plate 302 lack a secondary electron emission layer, as shown in Figures 2a and 2b. Therefore, the non-gain microchannel plate 302 serves solely as a channel and does not provide a gain function.

[0039] Specifically, the zero-gain microchannel plate 302 of this embodiment includes a first input surface 3021, a first output surface 3022, and a plurality of zero-gain channels 3023. The first input surface 3021 and the first output surface 3022 of the zero-gain microchannel plate 302 are parallel, with the first input surface 3021 facing the exterior of the vacuum drift tube 10, and the first output surface 3022 facing the interior of the vacuum drift tube 10. The zero-gain channels 3023 extend through the zero-gain microchannel plate 302, that is, the zero-gain channels 3023 extend through both the first input surface 3021 and the first output surface 3022. A microstrip cathode 301 is evaporated on the first input surface 3021 of the zero-gain microchannel plate 302, and a grounded anode 303 is evaporated across the entire first output surface 3022 of the zero-gain microchannel plate 302.

[0040] The gated microchannel plate detector 40 is the core component of the gain-free microchannel plate 2D framing imaging system. The ratio of its temporal resolution to the electron beam temporal magnification is the temporal resolution of the gain-free microchannel plate 2D framing imaging system. The gated microchannel plate detector 40 comprises an impedance gradient line 401, a microstrip line 402, a gain microchannel plate 403, a phosphor screen 404, and a CCD camera. The gain microchannel plate 403 is a high-spatial-resolution, high-gain electron multiplying device. It is a thin glass sheet composed of numerous tiny through-holes (gain channels 4033). Each through-hole acts as an independent electron multiplier, multiplying the electron signal. Approximately 12μm long copper and gold layers are deposited at the input and output ports of each gain channel 4033. The copper layer is located on the bottom layer, and the gold layer is located on the top layer. When a photon or electron signal enters the wall of a gain channel 4033, it ejects primary electrons. When a high voltage is applied between the two end faces of the gain microchannel plate 403 via electrodes, an electric field is generated within each microchannel. This electric field accelerates primary electrons, causing them to travel along the channel and collide with the inner wall of the channel to generate new secondary electrons. These secondary electrons are in turn accelerated and collide with the channel wall, repeating this process until they are emitted from the channel outlet, thus achieving electron multiplication. Electrons are accelerated by the electric field between the output surface of the gain microchannel plate 403 and the fluorescent screen 404. The high-speed electrons bombard the phosphor on the fluorescent screen 404, emitting light, achieving electro-optical spatial and intensity conversion, and producing a visible light image output. When there is no voltage between the two end faces of the gain microchannel plate 403, or the voltage is too low to generate differential gain, all input signals to the gain microchannel plate 403 are absorbed, and no image is output.

[0041] At a certain moment, the gated microchannel plate detector 40 uses a gated pulse to sample and multiply the time-amplified electron beam imaging a certain area of ​​the gain microchannel plate 403, and transmits it in a traveling wave manner on the microstrip line 402. At another moment, the electron beam of another area is sampled and multiplied, as shown in Figure 3, thereby obtaining multiple images at different times.

[0042] Specifically, the gain microchannel plate 403 includes a second input surface 4031, a second output surface 4032, and multiple gain channels 4033, which extend through the gain microchannel plate 403. A microstrip line 402 is deposited in a strip shape on the second input surface 4031 of the gain microchannel plate 403, and a predetermined metal layer is deposited across the entire second output surface 4032 of the gain microchannel plate 403. A pulse generator 50 is connected to the microstrip line 402 via an impedance gradient line 401. The pulse generator 50 samples and multiplies the electron beam on the microstrip line 402 using gated pulses. The first surface of the fluorescent screen 404 is parallel to and spaced from the second output surface 4032 of the gain microchannel plate 403, and the second surface of the fluorescent screen 404 is in close contact with the CCD camera.

[0043] Furthermore, in the non-gain microchannel plate 2D framing imaging system of this embodiment, the non-gain microchannel plate 302 has an outer diameter of 106 mm and a thickness of 1 mm. The diameter of the non-gain channels 3023 is 35 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent non-gain channels 3023 is 39 μm.

[0044] Three microstrip cathodes 301 are evaporated on the first input surface 3021 of the non-gain microchannel plate 302 . The width of each microstrip cathode 301 is 12 mm, and the interval between adjacent microstrip cathodes 301 is 10 mm.

[0045] Furthermore, in this embodiment of the non-gain microchannel plate 2D framing imaging system, the gain microchannel plate 403 has an outer diameter of 106 mm and a thickness of 0.5 mm. Each gain channel 4033 has a channel diameter of 12 μm, a channel bevel angle ranging from 6° to 8°, and a spacing of 14 μm between adjacent gain channels 4033.

[0046] Three microstrip lines 402 are evaporated on the second input surface 4031 of the gain microchannel plate 403 . The width of each microstrip line 402 is 12 mm, and the interval between adjacent microstrip lines 402 is 10 mm.

[0047] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of this embodiment, the input and output ports of each gain channel 4033 are evaporated into a copper layer and a gold layer of a preset depth, with the copper layer at the bottom layer and the gold layer at the surface layer.

[0048] Furthermore, in the two-dimensional framing imaging system of the non-gain microchannel plate of this embodiment, the microstrip cathode 301 of the non-gain microchannel plate 302 includes a copper layer at the bottom layer and a gold layer at the surface layer.

[0049] The grounded anode 303 of the non-gain microchannel plate 302 includes a copper layer at the bottom layer and a gold layer at the surface layer.

[0050] The microstrip line 402 of the gated microchannel plate detector 40 includes a copper layer at the bottom layer and a gold layer at the surface layer.

[0051] The entire second output surface 4032 of the gain microchannel plate 403 is deposited with a predetermined metal layer including a copper layer at the bottom layer and a gold layer at the surface layer.

[0052] Furthermore, in the non-gain microchannel plate two-dimensional framing imaging system of this embodiment, the thickness of the copper layer is 500 nm, and the thickness of the gold layer is 100 nm.

[0053] Referring to Figures 1, 4, and 5, in the gain-free microchannel plate two-dimensional framing imaging system of this embodiment, the advantages of the long magnetic lens lie in good spatial resolution uniformity, while the advantages of the short magnetic lens lie in high spatial resolution. To improve spatial resolution and uniformity, the two lenses are combined to form a long-short magnetic combined lens 20. This forms an equal-sized image of the electron beam from the microstrip cathode 301 onto the gain microchannel plate 403, with an imaging magnification of 1:1. Alternatively, the long-short magnetic combined lens 20 of this embodiment includes a long magnetic lens 201, a first short magnetic lens 202, and a second short magnetic lens 203. The first short magnetic lens 202 surrounds the incident end of the vacuum drift tube 10, that is, the first short magnetic lens 202 surrounds the gain-free electron beam time amplifier 30. The second short magnetic lens 203 surrounds the exit end of the vacuum drift tube 10, that is, the second short magnetic lens 203 surrounds the gated microchannel plate detector 40. The long magnetic lens 201 surrounds the incident end and the exit end of the vacuum drift tube 10.

[0054] In this embodiment of the gain-free microchannel plate 2D framing imaging system, the first short magnetic lens 202 consists of a circular soft iron ring and a copper coil, with the copper wire located inside the soft iron ring. A 4mm-wide gap is located inside the first short magnetic lens 202, through which the magnetic field enters the electron drift region. The first short magnetic lens 202 has an outer diameter of 410mm, an inner diameter of 360mm, and an axial length of 100mm.

[0055] The second short magnetic lens 203 consists of a circular soft iron ring and a copper coil, with the copper wire located inside the soft iron. A 4mm-wide gap is located inside the second short magnetic lens 203, through which the magnetic field enters the electron drift region. The second short magnetic lens 203 has an outer diameter of 410mm, an inner diameter of 360mm, and an axial length of 100mm.

[0056] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system of this embodiment, the long magnetic lens 201 is composed of a copper enameled wire wound between the incident end and the output end of the vacuum drift tube 10 .

[0057] Furthermore, in the gain-free microchannel plate two-dimensional framing imaging system of this embodiment, an imaging pinhole array 60 is also included on the input side of the gain-free electron beam time amplifier 30. After the captured X-ray image passes through the imaging pinhole array 60, photoelectron images are generated at different positions of the microstrip cathode 301.

[0058] Furthermore, a negative DC voltage and a stretched pulse generated by the pulse generator 50 are superimposed on the microstrip cathode 301, and two stretched pulses are simultaneously transmitted in opposite directions at both ends of the microstrip cathode 301, and the two stretched pulses have the same waveform. The grounded anode 303 is grounded.

[0059] As shown in Figure 6a, the stretched pulse (cathode pulse 1) is transmitted from left to right in the microstrip cathode 301, and the transmission speed v≈2×10 8 m / s. At a certain moment, at points A and B of the microstrip cathode 301, point A is synchronized with the stretched pulse point A1, and point B is synchronized with point B1. The voltage difference between points A1 and B1 is t·G, where t is the time required for the stretched pulse to transmit from point B to point A, and G is the slope of the stretched pulse. The photoelectrons emitted at points A and B at the same moment have different transit times from the microstrip cathode 301 to the gain microchannel plate 403 due to the different acceleration voltages. If the two photoelectrons are to be in the same image, the transit time difference must be less than or equal to the time resolution T of the gain microchannel plate 403. MCP , then t≤T MCP / M, M is the electron beam time magnification, the camera time resolution T≈T MCP / M, so the distance between points A and B is L = v·t ≤ v·T, and the maximum frame size is v·T. If the time resolution is 10ps, the frame size is within 2mm.

[0060] In order to increase the image size, two-way stretched pulse counter-transmission mode is adopted to make the voltage of the entire microstrip cathode 301 consistent.

[0061] As shown in Figure 6b, two stretched pulses (cathode pulse 1 and cathode pulse 2) are transmitted simultaneously in opposite directions from the two ends of microstrip cathode 301. At a given moment, the voltage at point C on microstrip cathode 301 is the sum of the voltage at point C1 of stretched pulse 1 and the voltage at point C2 of stretched pulse 2. As shown in Figure 6b, since the two stretched pulses are transmitted simultaneously in opposite directions from the two ends of microstrip cathode 301, the voltage across the entire microstrip cathode 301 is consistent. This results in a consistent photoelectron transit time from microstrip cathode 301 to gain microchannel plate 403, increasing the image size without being limited by the camera's temporal resolution. It is important to note that when synchronized with the optical pulses, the starting points O1 and O2 of the stretched pulses have already passed the end points of the microstrip cathode 301 in their respective transmission directions.

[0062] Alternatively, the gain-free microchannel plate two-dimensional framing imaging system further includes an oscilloscope, an attenuator and a capacitor, wherein the oscilloscope is connected to one end of the capacitor via the attenuator, and the other end of the capacitor is connected to the microstrip cathode 301, so as to collect and display the waveform of the microstrip cathode 301.

[0063] Furthermore, the working principle of the gain-free microchannel plate two-dimensional framing imaging system is as follows:

[0064] The plasma X-rays radiate X-rays as the captured X-ray image. After passing through the imaging pinhole array 60, the captured X-ray image generates photoelectron images at different locations on the microstrip cathode 301. A negative DC high voltage is applied to the microstrip cathode 301 and superimposed with a stretched pulse. The grounded anode 303 is grounded, synchronizing the X-rays with the rising edge of the stretched pulse. This allows the first photoelectrons emitted to have greater energy than the later photoelectrons, thereby increasing the velocity of the earlier electrons.

[0065] After the photoelectrons pass through the grounded anode 303 and transmit to the drift region of the gain microchannel plate 403, the temporal width of the electron beam is widened. The widened electron beam is imaged on the microstrip line 402 corresponding to the input surface of the gain microchannel plate 403 by the long-short magnetic combined lens 20. If the electron beam is not synchronized with the gate pulse, the electron image will be absorbed by the gain microchannel plate 403, and no image will be output. When a very narrow gate pulse is transmitted along the microstrip line, at a certain moment, only one microstrip region has voltage. The electron image imaged in this region by the long-short magnetic combined lens 20 will be enhanced by the gain microchannel plate 403 and projected onto the fluorescent screen 404 to form a visible light image. After a period of transmission time, the gate pulse reaches another electron image region, at which point the image is output again. In this way, these electron images will be gated one by one, and the output image will be recorded by a CCD camera. Because the electron beam is amplified in time, by using a gated microchannel plate detector 40 with a lower temporal resolution, a very high camera temporal resolution can be achieved.

[0066] This embodiment uses electron beam time magnification technology to improve the temporal resolution of a framing imaging camera, and uses a gain-free microchannel plate electron beam time amplifier to improve temporal resolution uniformity and gain uniformity. It also uses a long-short magnetic combination lens to improve spatial resolution and its uniformity, and adopts a two-way stretched pulse counter-transmission method to increase the effective frame size, thereby improving various performance indicators of the framing imaging camera.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0068] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0069] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0070] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. All equivalent variations and modifications within the scope of the claims of the present invention are intended to be covered by the claims of the present invention.

Claims

1. A two-dimensional framing imaging system with no gain microchannel plate, characterized in that: The invention comprises a vacuum drift tube (10), a long-short magnetic combination lens (20), a gain-free electron beam time amplifier (30), a gated microchannel plate detector (40) and a pulse generator (50), wherein the long-short magnetic combination lens (20) surrounds the outside of the vacuum drift tube (10), the gain-free electron beam time amplifier (30) is located at the incident end of the vacuum drift tube (10), the gated microchannel plate detector (40) is located at the exit end of the vacuum drift tube (10), and the area between the incident end and the exit end of the vacuum drift tube (10) is an electron drift area; The gain-free electron beam time amplifier (30) comprises a microstrip cathode (301), a gain-free microchannel plate (302) and a grounded anode (303); the gain-free microchannel plate (302) comprises a first input surface (3021), a first output surface (3022) and a plurality of gain-free channels (3023); the first input surface (3021) and the first output surface (3022) of the gain-free microchannel plate (302) are parallel, and the gain-free channels (3023) run through the gain-free microchannel plate (302); The microstrip cathode (301) is evaporated on the first input surface (3021) of the gain-free microchannel plate (302), and the grounded anode (303) is evaporated on the entire first output surface (3022) of the gain-free microchannel plate (302); a negative DC voltage and a stretching pulse generated by the pulse generator (50) are superimposed on the microstrip cathode (301), and two ends of the microstrip cathode (301) are respectively transmitted in opposite directions by two stretching pulses at the same time, and the two stretching pulses have the same waveform; the grounded anode (303) is grounded; The gated microchannel plate detector (40) comprises an impedance gradient line (401), a microstrip line (402), a gain microchannel plate (403), a fluorescent screen (404) and a CCD camera; the gain microchannel plate (403) comprises a second input surface (4031), a second output surface (4032) and a plurality of gain channels (4033); the gain channels (4033) penetrate the gain microchannel plate (403); the microstrip line (402) is strip-shaped and vapor-deposited on the second input surface (4031) of the gain microchannel plate (403). , the entire second output surface (4032) of the gain microchannel plate (403) is evaporated with a preset metal layer; the pulse generator (50) is connected to the microstrip line (402) via the impedance gradient line (401), and the pulse generator (50) samples and multiplies the electron beam on the microstrip line (402) via a gated pulse; the first surface of the fluorescent screen (404) is parallel to and spaced from the second output surface (4032) of the gain microchannel plate (403), and the second surface of the fluorescent screen (404) is in close contact with the CCD camera.

2. The gain-free microchannel plate two-dimensional framing imaging system according to claim 1, characterized in that: The outer diameter of the non-gain microchannel plate (302) is 106 mm, and the thickness is 1 mm; the diameter of the non-gain channel (3023) is 35 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent non-gain channels (3023) is 39 μm; Three microstrip cathodes (301) are evaporated on the first input surface (3021) of the non-gain microchannel plate (302), the width of each microstrip cathode (301) is 12 mm, and the interval between adjacent microstrip cathodes (301) is 10 mm.

3. The gain-free microchannel plate two-dimensional framing imaging system according to claim 1, characterized in that: The gain microchannel plate (403) has an outer diameter of 106 mm and a thickness of 0.5 mm; the channel diameter of each gain channel (4033) is 12 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent gain channels (4033) is 14 μm; Three microstrip lines (402) are evaporated on the second input surface (4031) of the gain microchannel plate (403), the width of each microstrip line (402) is 12 mm, and the interval between adjacent microstrip lines (402) is 10 mm.

4. The gain-free microchannel plate two-dimensional framing imaging system according to claim 3, characterized in that: The input port and the output port of each gain channel (4033) are evaporated into a copper layer and a gold layer of a preset depth, wherein the copper layer is located at the bottom layer and the gold layer is located at the surface layer.

5. The gain-free microchannel plate two-dimensional framing imaging system according to claim 1, characterized in that: The microstrip cathode (301) of the gain-free microchannel plate (302) comprises a copper layer located at the bottom layer and a gold layer located at the surface layer; The grounded anode (303) of the non-gain microchannel plate (302) comprises a copper layer at the bottom layer and a gold layer at the surface layer; The microstrip line (402) of the gated microchannel plate detector (40) comprises a copper layer at the bottom layer and a gold layer at the surface layer; The entire second output surface (4032) of the gain microchannel plate (403) is vapor-deposited with a preset metal layer, a copper layer located at the bottom layer, and a gold layer located at the surface layer.

6. The gain-free microchannel plate two-dimensional framing imaging system according to claim 5, characterized in that: The thickness of the copper layer is 500 nm, and the thickness of the gold layer is 100 nm.

7. The gain-free microchannel plate two-dimensional framing imaging system according to claim 1, characterized in that: The long-short magnetic combined lens (20) comprises a long magnetic lens (201), a first short magnetic lens (202) and a second short magnetic lens (203), wherein the first short magnetic lens (202) surrounds the incident end of the vacuum drift tube (10), the second short magnetic lens (203) surrounds the exit end of the vacuum drift tube (10), and the long magnetic lens (201) surrounds between the incident end and the exit end of the vacuum drift tube (10).

8. The gain-free microchannel plate two-dimensional framing imaging system according to claim 7, characterized in that: The first short magnetic lens (202) is composed of a circular soft iron and a copper coil, the copper wire is located inside the soft iron, and the first short magnetic lens (202) has a gap with a width of 4 mm on the inner side; the first short magnetic lens (202) has an outer diameter of 410 mm, an inner diameter of 360 mm, and an axial length of 100 mm; The second short magnetic lens (203) is composed of a circular soft iron and a copper coil, the copper wire is located inside the soft iron, and the inner side of the second short magnetic lens (203) has a gap with a width of 4 mm; the outer diameter of the second short magnetic lens (203) is 410 mm, the inner diameter is 360 mm, and the length in the axial direction is 100 mm.

9. The gain-free microchannel plate two-dimensional framing imaging system according to claim 7, characterized in that: The long magnetic lens (201) is composed of a copper enameled wire wound between the incident end and the output end of the vacuum drift tube (10).

10. The gain-free microchannel plate two-dimensional framing imaging system according to claim 1, characterized in that: It also includes an imaging pinhole array (60) located at the input side of the gain-free electron beam time amplifier (30), and the captured X-ray image generates photoelectron images at different positions of the microstrip cathode (301) after passing through the imaging pinhole array (60).

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