WO2022021140A1

WO2022021140A1 - Visible light streak tube and electron-optical imaging system

Info

Publication number: WO2022021140A1
Application number: PCT/CN2020/105496
Authority: WO
Inventors: 张敬金; 宗方轲; 杨勤劳
Original assignee: 深圳大学
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2022-02-03

Abstract

A visible light streak tube and an electron-optical imaging system. The visible light streak tube comprises a spherical cathode (1), a focusing electrode assembly (2), an anode diaphragm (3) and a planar fluorescent screen (4). The focusing electrode assembly (2) comprises at least two focusing electrodes (21, 22). The focusing electrodes (21, 22) are used to adjust a position of an image plane of an electron beam. The focusing electrode assembly (2) and the anode diaphragm (3) are both cylindrical structures. The spherical cathode (1), the focusing electrode assembly (2) and the anode diaphragm (3) are sequentially arranged and spaced apart from each other. The spherical cathode (1) is configured to fit with an electrostatic focusing structure resembling a concentric sphere. The planar fluorescent screen (4) is connected to one end of the anode diaphragm (3) away from the focusing electrode assembly (2) by means of a metal sleeve (5), and is used to receive an electron beam to form an image.

Description

Visible light streak tube and electron optical imaging system

technical field

The embodiments of the present application relate to the technical field of electron beam imaging, for example, to a visible light streak tube and an electron optical imaging system.

Background technique

Laser 3D imaging technology has been a very active branch of laser application technology in recent years. The distance gating characteristics of lasers make laser 3D imaging methods have advantages that other 2D imaging methods do not have. However, laser imaging in related technologies has limitations. That is, the field of view of laser imaging is small and the imaging frame rate is low. To overcome these shortcomings, streak tube imaging lidar (STIL) technology has been proposed in recent years. The streak tube used in STIL should meet the requirements of the cathode effective working area as large as possible and high reliability. For example, the streak tube used in space laser imaging radar should meet the requirements of small size, light weight, high reliability and strong anti-interference ability, etc. Require.

In the related art, an ultra-small stripe tube with a length of only 100 mm and a spherical cathode and a spherical phosphor screen has been designed. The theoretical design value of the imaging area diameter is greater than 28 mm, which is a better design in the related art. The fluorescent screen makes the streak tube have very high requirements on the coaxiality of the electrodes during the assembly process, and is also greatly affected by the field curvature, thus affecting the imaging performance of the electronic optical imaging system using the streak tube.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a visible light streak tube and an electron optical imaging system, so as to reduce the assembly difficulty of the streak tube and the influence of field curvature during imaging.

In a first aspect, an embodiment of the present application provides a visible light streak tube, comprising: a spherical cathode, a focusing pole assembly, an anode diaphragm, and a flat phosphor screen; wherein,

the focusing pole assembly includes at least two focusing poles, the focusing poles are configured to adjust the image plane position of the electron beam;

The focusing electrode assembly and the anode diaphragm are all cylindrical structures, the spherical cathode, the focusing electrode assembly and the anode diaphragm are arranged at intervals in sequence, and the spherical cathode and the focusing electrode assembly are configured to fit Concentric ball-like electrostatic focusing structure;

The flat screen is connected to one end of the anode diaphragm away from the focusing pole assembly through a metal sleeve, and the flat screen is configured to receive electron beam imaging.

In a second aspect, an embodiment of the present application further provides an electron optical imaging system, including the visible light streak tube provided by any embodiment of the present application.

Description of drawings

1 is a schematic structural diagram of a visible light stripe tube provided in Embodiment 1 of the present application;

2 is a schematic structural diagram of a metal grid in an anode aperture provided in Embodiment 1 of the present application;

3 is a schematic structural diagram of a visible light stripe tube provided in Embodiment 2 of the present application;

4 is a schematic structural diagram of another visible light stripe tube provided in Embodiment 2 of the present application;

FIG. 5 is a schematic structural diagram of another visible light stripe tube provided in Embodiment 2 of the present application.

detailed description

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all the structures related to the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Furthermore, the terms "first," "second," etc. may be used herein to describe various directions, acts, steps or elements, etc., but are not limited by these terms. These terms are only used to distinguish a first direction, act, step or element from another direction, act, step or element. The terms "first", "second" and the like should not be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature.

Example 1

FIG. 1 is a schematic structural diagram of a visible light stripe tube provided in Embodiment 1 of the present application. As shown in FIG. 1 , the visible light streak tube includes: a spherical cathode 1, a focusing electrode assembly 2, an anode diaphragm 3 and a flat phosphor screen 4; wherein, the focusing electrode assembly 2 includes at least two focusing electrodes for adjusting the image of the electron beam The focusing electrode assembly 2 and the anode diaphragm 3 are all cylindrical structures, and the spherical cathode 1, the focusing electrode assembly 2 and the anode diaphragm 3 are arranged at intervals in order to fit the concentric spherical electrostatic focusing structure; the flat fluorescent screen 4 passes through The metal sleeve 5 is connected to one end of the anode diaphragm 3 away from the focusing pole assembly 2 for receiving electron beam imaging.

In one embodiment, FIG. 1 shows the cross-sectional structure of the visible light stripe tube in the embodiment of the present application, wherein the spherical cathode 1 can be made of materials such as bi-alkali or multi-alkali A large number of electrons are generated that can be pulled towards the anode diaphragm 3. Optionally, as shown in FIG. 1 , the spherical cathode 1 may extend from the edge 11 of the spherical structure to a plane structure 12 at a certain distance, and be connected to the inner wall of a metal cylindrical structure 13, so as to facilitate the passage of the metal cylindrical structure. It is stably fixed at the relative position of other electrodes, such as the focusing electrode assembly 2.

The focusing pole assembly 2 includes at least two focusing poles, as shown in FIG. 1 , may include two focusing poles arranged at intervals, namely a first focusing pole 21 and a second focusing pole 22 , and the first focusing pole 21 and the second focusing pole The size of the pole 22 can be different, so as to realize the rough adjustment and fine adjustment of the image plane position of the electron beam respectively. The position of the image plane of the electron beam is first adjusted roughly, and then sent to the anode diaphragm 3 after fine adjustment. Since the electron beam moves in the direction perpendicular to the electric field, when the intensity of the electric field changes, the moving direction of the electron beam can change. The denser the electric field, the more obvious the change in the direction of the electron beam. Therefore, by adjusting the focusing The voltage on the pole assembly 2 can adjust the distribution density of the electric field, thereby realizing the adjustment of the position of the electron beam image plane. At the same time, the denser the electric field, the smaller the curvature of the corresponding electric field. By adjusting the voltage on the focusing pole assembly 2, the curvature of the electric field can also be adjusted indirectly. In an imaging system, the larger the detection area is, the more serious the field curvature is, and the imaged positions of the points on the detection plane are not on the same plane, that is, the existence of the field curvature will make the image surface appear curved. A spherical phosphor screen that is closer to the actual image surface shape can reduce the influence of field curvature. In this embodiment, the voltage on the focusing pole assembly 2 can be adjusted to adjust the distribution of the electric field in the streak tube to achieve a small field curvature image surface. , so that the flat screen 4 can be directly used for imaging.

The focusing electrode assembly 2 and the anode diaphragm 3 are both cylindrical structures, and the spherical cathode 1, the focusing electrode assembly 2 and the anode diaphragm 3 are arranged at intervals in order, that is, they are not in contact with each other. At the same time, the spherical cathode 1, the focusing electrode assembly 2 and the adjacent two anode diaphragms 3 can be different in size to fit a concentric sphere-like electrostatic focusing structure, so that the equipotential surface of the electric field distribution in the stripe tube can be kept curved through the matching of the shapes of the electrodes. , and close to the spherical surface, that is, a concentric spherical electrostatic focusing structure can be fitted by changing the number and size of each electrode, so that the imaging process is less affected by aberrations such as field curvature, especially the field curvature. Although the image plane is not completely flat, it can be directly imaged with the flat phosphor screen 4 .

The flat screen 4 is connected to the end of the anode diaphragm 3 away from the focusing pole assembly 2 through a metal sleeve 5. In one embodiment, as shown in FIG. 1, the size of the metal sleeve 5 may be larger than the size of the anode diaphragm 3 for connection. The size of one end, the end of the metal sleeve 5 used for connection with the anode aperture 3 can extend a certain distance to the central axis of the concentric spherical electrostatic focusing structure to be connected with the end of the anode aperture 3 for connection. The other end of the sleeve 5 can be connected with a flat screen 4 of matching size. Optionally, the metal sleeve 5 is hermetically connected with the anode aperture 3 and the flat screen 4, so as to form a vacuum environment in the metal sleeve 5, so as to keep the electron beam in the vacuum environment and prevent air ionization.

On the basis of the above technical solution, optionally, as shown in FIG. 1 , the anode diaphragm 3 includes: a cylindrical section 31 and a cone section 32 that are connected to each other, wherein the cone section 32 is closer to the flat screen 4 , and The inner diameter of the conical cylindrical section 32 gradually increases as it moves away from the cylindrical section 31 . In some embodiments, that is, the electron beam first passes through the cylindrical section 31 of the anode aperture 3, and then passes through the cone section 32 of the anode aperture 3, by setting the tail end of the anode aperture 3 as a cone with a certain taper , it can further ensure that the equipotential surface of the electric field distribution at the tail end of the focusing pole assembly 2 is not restricted and continues to maintain a shape similar to a spherical surface.

On the basis of the above technical solution, optionally, as shown in FIG. 2 , the anode diaphragm 3 includes: a metal grid 33 , and the metal grid 33 is located at the connection between the cylindrical section 31 and the cone section 32 for isolation out of focus and drift regions. In one embodiment, the metal grid 33 is arranged at the exit of the cylindrical section 31 of the anode diaphragm 3, on the one hand, the electron beam can pass through, and on the other hand, it can isolate the front and rear regions to form focusing respectively. zone and drift zone to prevent the field distribution of the deflection yoke from penetrating into the focal zone and affecting the dynamic imaging characteristics. The focusing area starts from the spherical cathode 1 and ends at the metal grid 33 of the anode diaphragm 3 , and the drift area can be a space formed in the cone section 32 and the metal sleeve 5 .

On the basis of the above technical solution, optionally, the visible light stripe tube further includes: an insulating casing, which wraps the spherical cathode 1, the focusing electrode assembly 2 and the anode diaphragm 3, for shielding the electric field inside and outside the insulating casing from each other . In one embodiment, the material of the insulating shell can be ceramic, so as to achieve good high temperature resistance on the basis of insulation, so as to avoid damage due to a large amount of heat generated when the striped tube is working, the insulating shell can also be damaged. The shape can be set according to the shape and structure of the spherical cathode 1, the focusing electrode assembly 2 and the sunlight diaphragm 3 wrapped inside. In this embodiment, the inside of the insulating casing is also a vacuum environment, so as to keep the electron beam in the vacuum environment all the time, and further prevent the air from being ionized. In the actual use process of the striped tube, the voltages on each electrode are different. During the assembly process, each electrode can be fixed on the insulating shell and pressurized through the connected lead wires. By setting the insulating shell, it is possible to The electric field inside the stripe tube is shielded from the external electric field, thereby enhancing the anti-interference of the stripe tube.

The visible light streak tube provided by the embodiment of the present application eliminates the bending phenomenon of the scanned image by selecting the spherical cathode, thereby reducing the time distortion of the image, and at the same time, the spherical cathode, the focusing electrode assembly and the anode diaphragm are fitted as concentric spheres Electrostatic focusing structure, and by adjusting the electrode voltage on the focusing pole assembly to adjust the distribution of the electric field in the stripe tube, so that the shape of the equipotential surface of the electric field distribution in the stripe tube is maintained as a spherical surface, thereby reducing the influence of field curvature and other aberrations, especially The influence of field curvature is reduced. Although the shape of the image surface is not completely flat, it can be directly imaged with a flat phosphor screen. By using a flat phosphor screen instead of a spherical phosphor screen for imaging, the requirements for the accuracy of the structure are greatly reduced, and the fringes are also reduced. Tube assembly difficulty.

Embodiment 2

FIG. 3 is a schematic structural diagram of the visible light stripe tube provided in the second embodiment of the present application. The technical solution of this embodiment is modified on the basis of the technical solution of the above-mentioned embodiment. Optionally, as shown in FIG. 3 , the visible light stripe tube further includes: a grid 6 , and the grid 6 is arranged at intervals between the spherical cathode 1 and the focusing electrode assembly Between 2, it is used to control the speed and direction of the electron beam movement.

In one embodiment, the grid 6 can be a cylindrical structure, and can fit together with the spherical cathode 1, the focusing electrode assembly 2 and the anode diaphragm 3 to form a concentric spherical electrostatic focusing structure, so as to ensure that each The coaxiality of the electrodes makes the distribution of the electric field in the stripe tube fit the effect of concentric spherical surfaces as much as possible. The grid 6 is arranged between the spherical cathode 1 and the focusing electrode assembly 2. In the normal working state of the streak tube, the potential of the grid 6 should be greater than that of the spherical cathode 1, and there is an acceleration field between the two. At this time, the electron beam can pass through. , when the voltage of the grid 6 is adjusted so that its potential is lower than that of the spherical cathode 1, there is a deceleration field between the two. At this time, the energy of the electron beam gradually decreases during the flight of the electron beam in the field. When it decreases to 0, it stops moving, or even Can be reduced to negative to start the reverse movement. If the electron beam can no longer move forward, no electron beam will bombard the flat screen 4, and no image can be produced. Therefore, by adjusting the voltage of the grid 6, the speed and direction of the electron beam movement can be controlled, so as to realize the function of the streak tube imaging gate switch.

Optionally, as shown in FIG. 4 , one end of the grid 6 away from the spherical cathode 1 extends a first preset distance toward the central axis 7 of the concentric spherical electrostatic focusing structure, which can be extended perpendicular to the central axis 7, so that the The aperture of the simulated electron optical lens at the exit at the end of the grid 6 is smaller. At the same time, optionally, the extended end of the grid 6 extends toward the spherical cathode 1 by a second preset distance, which can further adjust the curvature of the electric field equipotential line at the exit of the grid 6, thereby realizing a small focal length and facilitating the miniaturization of the stripe tube. .

On the basis of the above technical solution, optionally, as shown in FIG. 5 , the focusing electrode assembly 2 includes: a first focusing electrode 21 and a second focusing electrode 22 arranged at intervals, and the first focusing electrode 21 and the grid 6 are inserted into each other. It is assumed that the second focusing electrode 22, the first focusing electrode 21 and the cylindrical section 31 of the anode diaphragm 3 are inserted into each other. In one embodiment, the dimensions of the first focusing electrode 21, the second focusing electrode 22, the grid 6 and the cylindrical segment 31 of the anode diaphragm 3 can be different from each other, so that two adjacent ones can be inserted into each other. Design, that is to use electrodes with larger diameters to cover electrodes with smaller diameters, making the structure more compact, effectively reducing the spacing between electrodes, shielding each electrode from each other, improving anti-interference, and more conducive to stripes Miniaturization of tubes. Wherein, more second focusing electrodes 22 can be inserted into the first focusing electrodes 21, so as to make the distribution of the electric field more dense, so as to further adjust the curvature.

Optionally, as shown in FIG. 5 , the inner diameter of the end of the grid 6 away from the spherical cathode 1 is larger than the outer diameter of the first focusing electrode 21 , the inner diameter of the first focusing electrode 21 is larger than the outer diameter of the second focusing electrode 22 , and the second The inner diameter of the focusing electrode 22 is larger than the outer diameter of the end of the anode diaphragm 3 away from the flat phosphor screen 4, so that the aperture shows a decreasing trend, and the curvature of the electric field equipotential line at the outlet of each electrode is continuously adjusted to reduce the focal length, which is further conducive to the miniaturization of the streak tube. change.

In the visible light streak tube provided in this embodiment, a grid is added between the spherical cathode and the focusing electrode assembly, so as to realize the function of the streak tube imaging gate switch. At the same time, by inserting the electrodes into each other, the distance between the electrodes is reduced, so that the electrodes are shielded from each other, the anti-interference performance of the stripe tube is improved, and the miniaturization of the stripe tube is more favorable.

Embodiment 3

The third embodiment of the present application provides an electron-optical imaging system, including the visible light stripe tube provided by any of the above embodiments of the present application, and has the corresponding functional structure and beneficial effects of the visible light stripe tube.

Claims

A visible light streak tube, comprising: a spherical cathode, a focusing electrode assembly, an anode diaphragm and a flat phosphor screen; wherein,

the focusing pole assembly includes at least two focusing poles, the focusing poles are configured to adjust the image plane position of the electron beam;

The focusing electrode assembly and the anode diaphragm are all cylindrical structures, the spherical cathode, the focusing electrode assembly and the anode diaphragm are arranged at intervals in sequence, and the spherical cathode and the focusing electrode assembly are configured to fit Concentric ball-like electrostatic focusing structure;

The flat screen is connected to one end of the anode diaphragm away from the focusing pole assembly through a metal sleeve, and the flat screen is configured to receive electron beam imaging.
The visible light streak tube according to claim 1, wherein the visible light streak tube further comprises: a grid, the grid is disposed between the spherical cathode and the focusing electrode assembly, and the grid is configured To control the speed and direction of electron beam movement.
The visible light streak tube according to claim 2, wherein an end of the grid away from the spherical cathode extends a first preset distance toward the central axis of the concentric ball-like electrostatic focusing structure.
The visible light stripe tube of claim 3, wherein the extended end of the grid extends toward the spherical cathode by a second preset distance.
The visible light streak tube according to claim 2, wherein the focusing electrode assembly comprises: a first focusing electrode and a second focusing electrode arranged at intervals, the first focusing electrode and the grid are interposed with each other, the The second focusing electrode is interposed with the first focusing electrode and the anode diaphragm.
The visible light streak tube according to claim 5, wherein the inner diameter of one end of the grid away from the spherical cathode is larger than the outer diameter of the first focusing electrode, and the inner diameter of the first focusing electrode is larger than the second focusing electrode. The outer diameter of the focusing electrode and the inner diameter of the second focusing electrode are larger than the outer diameter of the end of the anode diaphragm away from the flat phosphor screen.
The visible light streak tube of any one of claims 1-6, wherein the anode diaphragm comprises: a cylindrical section and a cone section that are connected to each other, wherein the cone section is closer to the flat screen, and The inner diameter of the conical cylindrical section gradually increases as it moves away from the cylindrical section.
The visible light streak tube according to claim 7, wherein the anode diaphragm comprises: a metal grid, the metal grid is located at the connection of the cylindrical section and the cone section, the metal grid is set to isolate the focus region from the drift region.
The visible light streak tube according to any one of claims 1-6, further comprising: an insulating shell, the insulating shell wraps the spherical cathode, the focusing electrode assembly and the anode diaphragm, the The insulating housing is arranged to mutually shield the electric field inside and outside the insulating housing.
An electron optical imaging system, comprising the visible light streak tube according to any one of claims 1-9.