No-gain microchannel plate two-dimensional framing imaging system

Abstract

The invention relates to a gain-free microchannel plate two-dimensional framing imaging system. The system comprises a vacuum drift tube, a long and short magnetic combined lens, a no-gain electron beam time amplifier, a gating micro-channel plate detector and a pulse generator, the long and short magnetic combined lens surrounds the outer side of the vacuum drift tube, and the no-gain electron beam time amplifier is located at the incident end of the vacuum drift tube; the gating micro-channel plate detector is located at the emergent end of the vacuum drift tube, and the area between the incident end and the emergent end in the vacuum drift tube is an electron drift area. According to the invention, the electron beam time amplification technology is adopted to improve the time resolution of the framing imaging camera, the gain-free micro-channel plate electron beam time amplifier is adopted to improve the time resolution uniformity and gain uniformity, and the long and short magnetic combined lens is adopted to improve the spatial resolution and uniformity thereof. And the effective picture size is increased by adopting a two-path broadening pulse opposite transmission mode, so that various performance indexes of the framing imaging camera are improved.

Description

Technical Field

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

[0002] Ultrafast diagnostic technology is mainly used in basic frontier science, national major scientific projects, national defense science and technology, strategic high technology, etc. It is an important and unique two-dimensional ultrafast diagnostic equipment. For example, it is used in laser inertial confinement fusion (ICF) research to detect the 1-2ns X-ray radiation process. The X-ray framing imaging camera can obtain the two-dimensional spatial distribution and time characteristics of ICF plasma X-ray radiation. How to improve the time resolution is the constant pursuit of 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 of a gain-free microchannel plate.

[0004] The technical solution adopted by the present invention to solve the technical problem is: construct 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 in the vacuum drift tube is an electron drift area;

[0005] The gain-free electron beam time amplifier comprises a microstrip cathode, a gain-free microchannel plate and a grounded anode, wherein the gain-free microchannel plate comprises a first input surface, a first output surface and a plurality of gain-free channels, wherein the first input surface of the gain-free microchannel plate is parallel to the first output surface, and the gain-free channels penetrate 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 stretching 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 stretching pulses at the same time, and the two stretching pulses have the same waveform; the grounded anode is grounded;

[0006] The gated microchannel plate detector comprises an impedance gradient line, a microstrip line, a gain microchannel plate, a fluorescent screen and a CCD camera. The gain microchannel plate comprises a second input surface, a second output surface and a plurality of 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 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] Further, in the gain-free microchannel plate two-dimensional framing imaging system of the present invention, the outer diameter of the gain-free microchannel plate is 106 mm and the thickness is 1 mm; the diameter of the gain-free channel is 35 μm, the channel bevel angle ranges from 6° to 8°, and the spacing between adjacent gain-free channels is 39 μm;

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

[0009] Further, 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 with 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] Further, 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 located at the bottom layer and a gold layer located 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, a copper layer located at the bottom layer, and a gold layer located at the surface layer.

[0016] Furthermore, in the gain-free 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] Further, 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] Further, 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 there is a gap with a width of 4 mm on the inner side of the first short magnetic lens; the outer diameter of the first short magnetic lens is 410 mm, the inner diameter is 360 mm, and the length in the axial direction is 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, and there is a gap with a width of 4mm on the inner side of the second short magnetic lens; the outer diameter of the second short magnetic lens is 410mm, the inner diameter is 360mm, and the axial length is 100mm.

[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 implementing the present invention has the following beneficial effects: the present invention adopts electron beam time magnification technology to improve the time resolution of the framing imaging camera, adopts a gain-free microchannel plate electron beam time amplifier to improve the uniformity of time resolution and gain uniformity, uses a long and short magnetic combined lens to improve the spatial resolution and its uniformity, and adopts a two-way widened pulse opposite 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] Figure 1 is a schematic structural diagram of a two-dimensional framing imaging system of a gain-free microchannel plate provided in an embodiment of the present invention;

[0025] Figure 2a is a schematic structural diagram of a gain-free microchannel plate provided in an embodiment of the present invention;

[0026] Figure 2b is a schematic structural diagram of a gain-free channel provided by an embodiment of the present invention;

[0027] Figure 3 It 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] Figure 4 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] Figure 5 is a schematic diagram of the structure of a long magnetic lens provided by an embodiment of the present invention;

[0030] Figure 6a Schematic diagram of unidirectional transmission of microstrip cathode single-path stretched pulses provided by an embodiment of the present invention;

[0031] Figure 6b It is a schematic diagram of the simultaneous opposite transmission of two-way stretched pulses in a microstrip cathode provided by 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 combustion stage requires the camera time resolution to be better than 30ps, while the current practical camera time resolution is 60-100ps. In order to improve the time resolution, the electron beam time magnification technology and microchannel plate (MCP) gated framing imaging technology are combined to propose a gain-free microchannel plate two-dimensional framing imaging system. The electron beam time magnification system is used to broaden the time width of the electron beam to achieve time magnification of the electron beam, and then the gated microchannel plate detector is used to measure the broadened electron beam to improve the time resolution. Theoretical studies have shown that the electron beam time magnification technology can improve the camera time resolution to less than 10ps.

[0034] High-precision time-amplified ultrafast two-dimensional framing imaging technology was proposed based on the urgent needs of my country's ICF research. It can improve the time resolution and make the framing imaging camera meet the engineering and precision requirements, solve the needs of national ICF research, and has important scientific significance and application value. In addition, electron beam time-amplification technology also has application value in ultrafast X-ray diodes, picosecond CMOS, etc.

[0035] refer to Figures 1 to 6b , this embodiment is described in detail.

[0036] refer to Figure 1 The present embodiment provides a two-dimensional framing imaging system of a gain-free microchannel plate, which 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, and a cylindrical vacuum tube is preferably used in the present 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 end and the exit end in the vacuum drift tube 10 is an electron drift region. It can be understood 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 the propagation and detection of electrons.

[0037] refer to Figure 1 As shown in FIG2 , the non-gain electron beam time amplifier 30 includes a microstrip cathode 301, a non-gain microchannel plate 302 and a grounded anode 303, wherein the microstrip cathode 301 has two functions: one is to convert the incident light into photoelectrons; the other is to transmit the stretched pulse, so that there is a time-varying electric field between the microstrip cathode and the anode to achieve electron beam time amplification. The electron beam time amplifier in the prior art is composed of a microstrip cathode and an anode grid. A gold layer is evaporated on polyimide to form a transmission microstrip cathode. Due to the need to take into account quantum efficiency, the thickness of the gold layer is relatively small, about 80nm. The thin microstrip cathode causes a large attenuation of the stretched pulse, so that the slope of the stretched pulse gradually decreases, resulting in inconsistent electron beam time magnification at different positions of the microstrip cathode, and poor time resolution and gain uniformity. In addition, the thickness of polyimide and the grid is tens of micrometers. When they are used to make a large plane, the flatness is poor, which is not conducive to loading a high voltage between the cathode grids, and the high voltage of the cathode grid can improve the spatial resolution, reduce the dispersion of the electron transit time, and improve the ultimate time resolution.

[0038] In order to solve the problems in the prior art, the present embodiment adopts a gain-free microchannel plate 302 to replace the polyimide and grid in the prior art to develop an electron beam time amplifier, and uses a reflective cathode structure to increase the thickness of the microstrip cathode conductive layer, reduce the attenuation of the broadened pulse, and maintain a high quantum efficiency. In addition, the two end faces of the gain-free microchannel plate 302 are very flat and can be loaded with a higher voltage. Therefore, the structure can simultaneously obtain high quantum efficiency, high anode-cathode voltage, high time resolution uniformity and gain uniformity. The gain-free microchannel plate 302 is a semi-finished product of a gain microchannel plate, which becomes a gain microchannel plate after hydrogen reduction treatment. Before the hydrogen reduction treatment, the channel wall of the gain-free microchannel plate 302 has no secondary electron emission layer, and its structural schematic diagram is shown as follows. Figure 2a and Figure 2b Therefore, the non-gain microchannel plate 302 is only used as a channel and has no gain effect.

[0039] Specifically, the gain-free microchannel plate 302 of this embodiment includes 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, the first input surface 3021 faces the outside of the vacuum drift tube 10, and the first output surface 3022 faces the inside of the vacuum drift tube 10; the gain-free channels 3023 penetrate the gain-free microchannel plate 302, that is, the gain-free channels 3023 penetrate the first input surface 3021 and the first output surface 3022. 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.

[0040] The gated microchannel plate detector 40 is the core component of the two-dimensional framing imaging system of the gain-free microchannel plate. The ratio of its time resolution to the electron beam time magnification is the time resolution of the two-dimensional framing imaging system of the gain-free microchannel plate. The gated microchannel plate detector 40 includes an impedance gradient line 401, a microstrip line 402, a gain microchannel plate 403, a fluorescent screen 404 and a CCD camera, wherein the gain microchannel plate 403 is a high spatial resolution, high gain electron multiplier device, which is a glass sheet composed of many tiny through holes (gain channels 4033), each through hole is equivalent to an independent electron multiplier, and the electronic signal is multiplied. A copper layer and a gold layer with a length of about 12 μm will be evaporated at the input and output ports of each gain channel 4033, the copper layer is located at the bottom layer, and the gold layer is located at the surface layer. Photons or electronic signals are input into the channel wall surface of the gain channel 4033 to knock out primary electrons. When a large voltage is applied between the two end faces of the gain microchannel plate 403 through the electrodes, an electric field is generated in each tiny channel, which accelerates the primary electrons, causing them to propagate forward along the channel and collide with the inner wall of the channel to generate new secondary electrons, which are then accelerated and collide with the channel wall, and the process is repeated until they are ejected from the channel outlet, thereby forming electron multiplication. The electrons are accelerated under the action of the electric field between the output surface of the gain microchannel plate 403 and the fluorescent screen 404, and the high-speed electrons bombard the fluorescent screen 404 to emit light to achieve the conversion of electro-optical space and intensity, and generate 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 small to generate differential gain, all signals input to the gain microchannel plate 403 will be absorbed, and no image will be output.

[0041] At a certain moment, the gated microchannel plate detector 40 samples and multiplies the time-amplified electron beam imaging a certain area of ​​the gain microchannel plate 403 through a gated pulse, 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, such as Figure 3 As shown, multiple images at different times are obtained.

[0042] Specifically, the gain microchannel plate 403 includes a second input surface 4031, a second output surface 4032 and a plurality of gain channels 4033, and the gain channels 4033 penetrate the gain microchannel plate 403. The microstrip line 402 is strip-shaped and evaporated on the second input surface 4031 of the gain microchannel plate 403, and a preset metal layer is evaporated on the entire second output surface 4032 of the gain microchannel plate 403. The pulse generator 50 is connected to the microstrip line 402 through the impedance gradient line 401, and the pulse generator 50 samples and multiplies the electron beam on the microstrip line 402 through the gated pulse. The first surface of the fluorescent screen 404 is parallel to the second output surface 4032 of the gain microchannel plate 403 and is spaced apart, and the second surface of the fluorescent screen 404 is close to the CCD camera.

[0043] Further, in the non-gain microchannel plate two-dimensional framing imaging system of this embodiment, 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.

[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] Further, in the non-gain microchannel plate two-dimensional framing imaging system of this embodiment, the outer diameter of the gain microchannel plate 403 is 106 mm and the thickness is 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.

[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 non-gain microchannel plate two-dimensional framing imaging system of the present 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 preset 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] refer to Figure 1 , Figure 4 and Figure 5In the gain-free microchannel plate two-dimensional framing imaging system of this embodiment, it is considered that the advantage of the long magnetic lens is good uniformity of spatial resolution, and the advantage of the short magnetic lens is high spatial resolution. In order to improve the spatial resolution and its uniformity, the two lenses are combined together to form a long and short magnetic combined lens 20, and the electron beam is formed into an equal-sized image from the microstrip cathode 301 on the gain microchannel plate 403, and the imaging magnification is 1:1. As an option, the long and 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, and 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 between the incident end and the exit end of the vacuum drift tube 10.

[0054] In the gain-free microchannel plate two-dimensional framing imaging system of this embodiment, the first short magnetic lens 202 is composed of a circular soft iron and copper coil, the copper wire is located inside the soft iron, and there is a gap with a width of 4mm inside the first short magnetic lens 202, and the magnetic field enters the electron drift region through the gap. The outer diameter of the first short magnetic lens 202 is 410mm, the inner diameter is 360mm, and the length in the axial direction is 100mm.

[0055] The second short magnetic lens 203 is composed of a circular soft iron and copper coil, the copper wire is located inside the soft iron, and there is a gap with a width of 4 mm inside the second short magnetic lens 203, through which the magnetic field enters the electron drift region. 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.

[0056] Furthermore, in the non-gain 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 at 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, a photoelectron image is generated at different positions of the microstrip cathode 301.

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

[0059] like Figure 6aAs shown, 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. For points A and B of the microstrip cathode 301 at a certain moment, point A is synchronized at point A1 of the stretched pulse, and point B is synchronized at point B1. The voltage difference between points A1 and B1 is t·G, where t is the time required for the stretched pulse to be transmitted 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 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] like Figure 6b As shown, two stretched pulses (cathode pulse 1 and cathode pulse 2) are transmitted simultaneously from both ends of the microstrip cathode 301 in opposite directions. At a certain moment, the voltage at point C on the microstrip cathode 301 is the voltage at point C1 of stretched pulse 1 plus the voltage at point C2 of stretched pulse 2. Figure 6b It can be seen that, since the two stretching pulses are transmitted from both ends of the microstrip cathode 301 in opposite directions at the same time, the voltage of the entire microstrip cathode 301 is consistent, and the photoelectron transit time from the microstrip cathode 301 to the gain microchannel plate 403 is the same, and the frame size is not limited by the camera time resolution, which increases the frame size. It should be noted that when synchronized with the light pulse, the stretching pulse starting points O1 and O2 have 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 also 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-ray radiates X-rays as the captured X-ray images, which generate photoelectron images at different positions of the microstrip cathode 301 after passing through the imaging pinhole array 60. Negative DC high voltage is applied to the microstrip cathode 301 and a stretch pulse is superimposed, and the grounded anode 303 is grounded, so that the X-rays are synchronized with the rising edge of the stretch pulse, so that the photoelectrons emitted first obtain greater energy than the photoelectrons emitted later, thereby making the speed of the electrons in front faster.

[0065] After the transmission of the photoelectron to the drift region of the gain microchannel plate 403 through the grounded anode 303, the time 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 through the long and short magnetic combined lens 20. If the electron beam is not synchronously gated pulse, the electronic image will be absorbed by the gain microchannel plate 403, and no image is output. When the gated pulse with a very narrow width is transmitted along the microstrip line, only one section of the microstrip area has voltage at a certain moment, and the electronic image imaged in this area through the long and short magnetic combined lens 20 will be enhanced by the gain microchannel plate 403, and hit the fluorescent screen 404 to form a visible light image. After a period of transmission time, the gated pulse arrives at another electronic image area, and the image is output again at this moment, so that these electronic images will be gated one by one in turn, and the output image is recorded with a CCD camera. Because the electron beam is amplified in time, by using a gated microchannel plate detector 40 with a lower time resolution, a very high camera time resolution can be obtained.

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

[0067] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[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 composition and steps of each example have been generally described in the above description according to function. 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 to be beyond the scope of the present invention.

[0069] The steps of the method or algorithm 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 a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, 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 only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot limit the scope of protection of the present invention. All equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of 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 combined 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 combined 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 in 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 evaporated 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) through the impedance gradient line (401), and the pulse generator (50) samples and multiplies the electron beam on the microstrip line (402) through 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 at the bottom layer and a gold layer 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 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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