Focal point measuring tool for X-ray tube
By using a split-type X-ray tube focal spot measurement fixture, which utilizes a detachable structure and an insulating oil environment, the high cost, long cycle, and distortion problems of traditional testing methods are solved, achieving efficient and low-cost focal spot measurement and improving positioning stability and measurement accuracy.
Patent Information
- Application Number
- CN202511162375.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-11-25
AI Technical Summary
Traditional X-ray tube focus testing methods are costly, time-consuming, and prone to distortion. They are also not recyclable and have inaccuracies in simulating electron scattering effects.
The X-ray tube focal spot measurement fixture adopts a split design, including a base, an outer cylinder, and a top cover. It utilizes a detachable structure and an insulating oil environment for measurement, and exhausts air through an exhaust port, enabling rapid measurement and reusability.
It shortens the focal measurement time, reduces material costs, improves positioning stability and measurement accuracy, reduces repeatability errors, and ensures equipment safety and measurement efficiency.
Smart Images
Figure CN121013237A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of X-ray tubes, and more specifically, to a tooling for measuring the focal spot of an X-ray tube. Background Technology
[0002] Portable X-ray equipment, characterized by its lightweight and flexibility, plays a vital role in various fields such as medicine, industry, and security inspection. Its imaging quality significantly impacts medical diagnostic results and industrial quality control. As the core component of portable X-ray equipment, the end-window transmission miniature X-ray tube's focal spot size is one of the key factors determining imaging quality. Maintaining the focal spot size within a reasonable range of 0.6mm-2mm ensures that the image formed after the X-rays emitted from the source irradiate the object being inspected has sufficient clarity. If the focal spot size does not meet the standard, it will lead to unclear imaging, affecting medical diagnostic results or product quality control outcomes. Therefore, focal spot testing of the X-ray tube is essential to ensure that the focal spot size meets the standards and to prevent various accidents.
[0003] In traditional focal testing methods, the X-ray tube core and high-voltage power supply are typically sealed together with a gel (e.g., epoxy resin potting) before testing. This method is costly, partly because a single sealing requires a large amount of specialized gel material (e.g., 500-1000g of silicone or epoxy resin), which can account for 35%-40% of the total testing cost; and partly because the sealed X-ray tube core and power supply form a permanent bond, making them non-recyclable. This method also suffers from long testing cycles; for example, the gel curing time is typically 48-72 hours, resulting in a single testing cycle of 3-4 days and high labor costs. Furthermore, the testing environment in traditional focal testing methods suffers from distortion because the dielectric constant of the sealing gel (3.5-4.5) differs significantly from that of the insulating oil under actual operating conditions (2.1-2.3), leading to deviations in the simulation of electron scattering effects. Currently, there is an urgent need to overcome the various problems existing in focal testing to ensure the development efficiency and mass production consistency of end-window transmission-type miniature X-ray tubes. Summary of the Invention
[0004] The purpose of this application is to provide an X-ray tube focal spot measuring fixture, the components of which are designed in a split manner, which can easily clamp the X-ray tube, so that the X-ray tube can maintain the stability of position and orientation in an insulating oil environment, and can effectively compensate for thermal expansion, thereby greatly improving positioning stability.
[0005] This application provides an X-ray tube focal spot measurement fixture, including a base, an outer cylinder, and a top cover. The base includes a cylindrical first support portion and a second support portion disposed above the first support portion. The top of the second support portion is recessed downwards to form a first receiving groove. A form-fitting clamp is also disposed within the first receiving groove, with a clamping hole extending vertically through its center for fixing the X-ray tube. The outer cylinder is a cylindrical structure with openings at both ends, disposed on the upper surface of the first support portion. A vent hole is provided through its surface. The top cover is cylindrical and its shape matches the upper opening of the outer cylinder. A second receiving groove is formed by a downward recess in the central region of the upper surface of the top cover. A light-transmitting window for X-rays is provided through its center in the second receiving groove. A form-fitting focal spot test block is disposed within the second receiving groove, with a light-transmitting slit on the lower surface of the focal spot test block for transmitting X-rays emitted from the light-transmitting window.
[0006] In one feasible embodiment, the upper surface of the first support portion is provided with a positioning boss that matches the shape of the inner side of the outer cylinder. A positioning strip is provided between the positioning boss and the edge of the first support portion, and a positioning groove is provided at the lower edge of the outer cylinder that matches the shape of the positioning strip. In use, the outer cylinder is sleeved on the outside of the positioning boss, and the positioning groove and the positioning strip are nested together to limit the position of the outer cylinder.
[0007] In one feasible embodiment, the first support portion is provided with multiple positioning protrusions, and the lower edge of the outer cylinder has positioning holes that mate with the positions and shapes of the positioning protrusions. In use, the positioning holes and positioning protrusions nest together to limit the movement of the outer cylinder.
[0008] In one feasible solution, the second support is provided with multiple guide channels running vertically through it, and the guide channels are distributed in a centrally symmetrical manner around the center line of the second support.
[0009] In one feasible embodiment, the X-ray tube focal spot measuring fixture also includes a height adjustment screw, a height adjustment groove extending through the side of the outer cylinder, and a screw fixing groove on the side of the top cover. The height adjustment screw passes through the height adjustment groove and is fixedly connected to the screw fixing groove to secure the top cover.
[0010] In one feasible embodiment, a raised guide strip is provided on the inner side of the outer cylinder along the vertical direction, and a corresponding guide groove is provided on the outer side of the top cover. In use, the guide strip and the guide groove cooperate to allow the outer cylinder and the top cover to slide relative to each other in the vertical direction.
[0011] In one feasible solution, the inner side of the outer cylinder is provided with internal threads, and the outer side of the top cover is provided with external threads. In use, the top cover and the inner side of the outer cylinder are engaged by the threads to achieve relative vertical movement.
[0012] In one feasible embodiment, the side of the first receiving groove is provided with an internal thread, and the outside of the clamp is provided with an external thread. In use, the clamp and the first receiving groove are fixedly connected through the threaded engagement.
[0013] In one feasible embodiment, the side of the top cover is provided with a scale for indicating the distance the top cover can be raised or lowered.
[0014] In one feasible solution, the base, outer cylinder, and top cover are made of plexiglass.
[0015] Compared with the prior art, the beneficial effects of this application include at least the following:
[0016] The X-ray tube focus measuring fixture of this application features a detachable design for all components, allowing for easy clamping of the X-ray tube and maintaining its position and orientation stability within an insulating oil environment. Since the top cover and outer cylinder can move relative to each other in the vertical direction, the distance between the X-ray emission source and the focus test block is adjustable, enabling the measurement of the focus size of X-rays at different emission distances. Furthermore, the X-ray tube focus measuring fixture of this application has vent holes on the outer cylinder, allowing for rapid expulsion of air from the fixture and ensuring the insulating oil fills the internal space, preventing high-voltage breakdown. Therefore, unlike traditional focus measurement methods that involve potting adhesive within the fixture, the X-ray tube focus measuring fixture of this application can be immersed in insulating oil for focus measurement, eliminating the lengthy adhesive curing process, effectively shortening the focus measurement time, reducing the labor costs required for this process, and consequently shortening the overall product development cycle. Furthermore, since the insulating oil can be reused repeatedly after purification, eliminating the need for consuming a certain amount of insulating material each time, and only requiring cleaning of the X-ray tube focus measurement fixture and X-ray tube after use, the fixture and X-ray tube can be recycled and reused, thus effectively reducing the material cost of X-ray tube focus measurement. Because insulating oil is also used for electrical isolation of the X-ray tube in actual operating conditions, the X-ray tube focus measurement fixture of this application can accurately reproduce the scattering characteristics of the electron beam in the insulating oil, thereby greatly reducing the repeatability error of the final focus size measurement. Compared to traditional integrated focus measurement fixtures, the X-ray tube focus measurement fixture of this application, through its split design, can effectively compensate for thermal expansion, thereby significantly improving positioning stability.
[0017] Furthermore, all components of the X-ray tube focal spot measuring fixture of this application are made of PMMA (polymethyl methacrylate), which, in conjunction with an insulating oil environment, achieves excellent insulation and effectively prevents breakdown accidents. Moreover, the transparent PMMA material facilitates technicians' observation of the internal structure of the X-ray tube focal spot measuring fixture, thereby better ensuring the normal operation of the measurement process and improving work efficiency. Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of an X-ray tube focal spot measuring fixture according to an embodiment of this application;
[0020] Figure 2 This is a schematic diagram of the base;
[0021] Figure 3 A schematic diagram of a base equipped with a clamp;
[0022] Figure 4 This is a schematic diagram of the outer cylinder;
[0023] Figure 5 This is a schematic diagram of the top cover.
[0024] In the diagram: 1. Base; 2. Outer cylinder; 3. Top cover; 4. Clamp; 5. Focal point test block; 6. Height adjustment screw; 101. First support part; 102. Second support part; 111. Positioning boss; 112. Positioning strip; 121. First receiving groove; 122. Guide groove; 201. Exhaust hole; 202. Height adjustment groove; 203. Positioning groove; 301. Second receiving groove; 302. Light transmission window; 303. Screw fixing groove; 401. Clamping hole. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0027] like Figure 1 As shown, this application provides an X-ray tube focal spot measuring fixture, including a base 1, an outer cylinder 2, and a top cover 3. Wherein, as... Figure 2 As shown, the base 1 includes a cylindrical first support portion 101 and a second support portion 102 disposed above the first support portion 101. The top of the second support portion 102 is recessed downward to form a first receiving groove 121. Figure 3 As shown, a shape-fitting clamp 4 is also provided in the first receiving groove 121. A clamping hole 401 is vertically through the center of the clamp 4 for fixing the X-ray tube. Figure 4 As shown, the outer cylinder 2 is a cylindrical structure with openings at the top and bottom, and is disposed on the upper surface of the first support portion 101. A vent hole 201 is provided through the surface of the outer cylinder 2. Figure 1 and Figure 5 As shown, the top cover 3 is cylindrical, and its shape matches the upper opening of the outer cylinder 2. A second receiving groove 301 is formed by a downward indentation in the central area of the upper surface of the top cover 3. A light-transmitting window 302 for X-ray transmission is provided through the center of the second receiving groove 301. A form-fitting focal block 5 is disposed within the second receiving groove 301. A light-transmitting slit is provided on the lower surface of the focal block 5 to allow X-rays emitted from the light-transmitting window 302 to pass through. The width of the light-transmitting window 302 can be set to 10-20 mm, and the width of the light-transmitting slit in the focal block 5 can be set to 10-50 μm. The focal block is made of a material that can block X-rays, such as a tungsten alloy.
[0028] Preferably, the base 1, outer cylinder 2, and top cover 3 can all be made of PMMA (polymethyl methacrylate). Preferably, the wall thickness of the base 1, outer cylinder 2, and top cover 3 can be set to 5mm. Because PMMA has excellent insulation properties, the leakage current of the X-ray tube focus measurement fixture under 50kV high voltage can be less than 1μA. Furthermore, by using PMMA, technicians can directly observe the internal structure of the X-ray tube focus measurement fixture through the transparent base 1, outer cylinder 2, and top cover 3, ensuring the accuracy of the X-ray tube's position and orientation, and whether the gas inside the fixture has been completely purged, thus ensuring the smooth operation of the focus measurement process.
[0029] In use, first place the clamp 4 in the first receiving groove 121 and insert the X-ray tube into the clamping hole 401. Then, place the focal spot test block 5 in the second receiving groove 301 and place the outer cylinder 2 on the first support part 101 to form a complete X-ray tube focal spot measurement fixture. Immerse the entire X-ray tube focal spot measurement fixture in insulating oil and wait for the gas inside to be discharged through the vent hole 201 and other openings or gaps before starting the X-ray tube and focal spot test block 5 to begin the focal spot measurement process. Because air has relatively poor insulation properties, the high voltage generated by the X-ray tube during operation can easily break down the air, causing equipment damage. Therefore, it is necessary to completely purge the air from the insulating oil to minimize the occurrence of breakdown and protect the safe operation of the equipment. In addition, residual gas in the insulating oil may cause unexpected scattering of X-rays, affecting the accuracy of the measurement results. Therefore, it is essential to purge the gas from the insulating oil. In addition to setting an exhaust hole 201 on the surface of the outer cylinder 2, measures such as setting a liquid flow pump inside the tooling can also be taken. The liquid flow pump can drive the insulating oil to flow, thereby promoting the discharge of gas.
[0030] Preferably, a limiting device can be provided between the base 1 and the outer cylinder 2 to limit the outer cylinder 2 from multiple dimensions, preventing unnecessary relative movement between the outer cylinder 2 and the base 1 during use. Specifically, such as... Figure 2 and Figure 3 As shown, a positioning boss 111 that matches the shape of the inner side of the outer cylinder 2 can be provided on the upper surface of the first support part 101. A positioning strip 112 is provided between the positioning boss 111 and the edge of the first support part 101, and a positioning groove 203 that matches the shape of the positioning strip 112 is provided on the lower edge of the outer cylinder 2. In use, as... Figure 1 As shown, the outer cylinder 2 is sleeved on the outside of the positioning boss 111, thereby limiting the outer cylinder 2 in the radial direction; the positioning groove 203 and the positioning strip 112 are nested together, limiting the outer cylinder 2 in the circumferential direction; the outer cylinder 2 can be fixed relative to the base 1 in the vertical direction by its own weight. Alternatively, a special device can be provided to limit the outer cylinder 2 in the vertical direction (for example, through holes can be provided on the sides of the outer cylinder 2 and the positioning boss 111 respectively, and a pin can be inserted into the two through holes in sequence). No further restrictions are made here. In addition, multiple positioning protrusions can be provided on the first support part 101, and the lower edge of the outer cylinder 2 has positioning holes that match the position and shape of the positioning protrusions. In use, the positioning holes and positioning protrusions are nested together to limit the outer cylinder 2 in the radial and circumferential directions.
[0031] The X-ray tube focus measuring fixture of this application features a detachable design for all components, allowing for easy clamping of the X-ray tube and maintaining its position and orientation stability within an insulating oil environment. Since the top cover and outer cylinder can move relative to each other in the vertical direction, the distance between the X-ray emission source and the focus test block is adjustable, enabling the measurement of the focus size of X-rays at different emission distances. Furthermore, the X-ray tube focus measuring fixture of this application has vent holes on the outer cylinder, allowing for rapid expulsion of air from the fixture and ensuring the insulating oil fills the internal space, preventing high-voltage breakdown. Therefore, unlike traditional focus measurement methods that involve potting adhesive within the fixture, the X-ray tube focus measuring fixture of this application can be immersed in insulating oil for focus measurement, eliminating the lengthy adhesive curing process, effectively shortening the focus measurement time, reducing the labor costs required for this process, and consequently shortening the overall product development cycle. Furthermore, since the insulating oil can be reused repeatedly after purification, eliminating the need for consuming a certain amount of insulating material each time, and only requiring cleaning of the X-ray tube focus measurement fixture and X-ray tube after use, the fixture and X-ray tube can be recycled and reused. This effectively reduces the material cost of X-ray tube focus measurement (specifically, performance deviation <2% after 5 repeated tests). Because insulating oil is also used for electrical isolation of the X-ray tube in actual operating conditions, the X-ray tube focus measurement fixture of this application can accurately reproduce the scattering characteristics of the electron beam in the insulating oil, thereby greatly reducing the repeatability error of the final focus size measurement. Specifically, in actual production, the X-ray tube focus measurement fixture of this application can reduce the testing cycle from 72 hours to within 2 hours, while reducing material costs by 60%-70%, and compressing the repeatability error of the final focus size measurement from 15%-20% to no more than 3%. Compared to traditional integrated focal spot measurement fixtures, the X-ray tube focal spot measurement fixture of this application adopts a split design, which can effectively compensate for thermal expansion, thereby significantly improving positioning stability. Specifically, when the temperature changes, it can ensure that the relative position error between the X-ray tube and the focal spot test block is <50μm.
[0032] Furthermore, all components of the X-ray tube focal spot measuring fixture of this application are made of PMMA (polymethyl methacrylate), which, in conjunction with an insulating oil environment, achieves excellent insulation and effectively prevents breakdown accidents. Moreover, the transparent PMMA material facilitates technicians' observation of the internal structure of the X-ray tube focal spot measuring fixture, thereby better ensuring the normal operation of the measurement process and improving work efficiency.
[0033] In one embodiment, such as Figure 2 and Figure 3As shown, the second support 102 is vertically permeated with multiple guide grooves 122, which are centrally symmetrically distributed around the center line of the second support 102. After the X-ray tube focal point measuring fixture is immersed in insulating oil, the guide grooves 122 help to accelerate the flow of insulating oil, promote gas discharge, and, since both the upper and lower ends of the X-ray tube are in an open environment, it can also better prevent gas accumulation caused by the opening in the upper part of the second support 102 for placing the X-ray tube.
[0034] In one embodiment, such as Figure 1 As shown, the X-ray tube focal point measuring fixture of this application also includes a height adjustment screw 6. A height adjustment groove 202 is provided through the side of the outer cylinder 2, and a screw fixing groove 303 is provided on the side of the top cover 3. In use, the top cover 3 is first placed into the outer cylinder 2 to ensure that the height of the top cover 3 meets the requirements. Then, the height adjustment screw 6 passes through the height adjustment groove 202 from the outside and is fixedly connected to the screw fixing groove 303, thereby providing support for the top cover 3. Preferably, two height adjustment screws 6 can be provided and symmetrically installed on the outside of the outer cylinder 3.
[0035] In one embodiment, a raised guide strip can be provided on the inner side of the outer cylinder 2 along the vertical direction, and a corresponding guide groove (not shown in the figure) can be provided on the outer side of the top cover 3. In use, the guide strip and the guide groove cooperate to form a guiding effect on the outer cylinder 2, so that the outer cylinder 2 and the top cover 3 can slide relatively smoothly in the vertical direction, reducing the occurrence of jamming and deflection.
[0036] In one embodiment, an internal thread can be provided on the inner side of the outer cylinder 2, and an external thread can be provided on the outer side of the top cover 3. During use, the outer side of the top cover 3 and the inner side of the outer cylinder 2 are connected by threads to achieve relative vertical movement. Through the threaded connection, technicians can more easily adjust the relative position of the top cover 3 and the outer cylinder 2, and after adjustment, there is no need for additional devices to lock their positions, effectively simplifying the overall operation and structure. Furthermore, an internal thread can be provided on the side of the first receiving groove 121, and an external thread can be provided on the outer side of the clamp 4. During use, the clamp 4 and the first receiving groove 121 are fixedly connected through a threaded connection. Similarly, an internal thread can be provided on the inner side of the clamping hole 401, and an external thread can be provided on the outer side of the X-ray tube, allowing the X-ray tube to be more stably fixed within the X-ray tube focal point measurement fixture through a threaded connection.
[0037] In one embodiment, a scale for indicating the lifting distance of the top cover 3 can be provided on the side of the top cover 3. In use, the lifting distance of the top cover 3 can be obtained through the scale, and then the actual distance between the X-ray emitting end and the receiving end can be calculated. This allows technicians to easily and accurately grasp the focal size corresponding to different emission distances of the X-ray tube, facilitating subsequent analysis.
[0038] In one embodiment, a vertically oriented electric push rod can be provided above the first support portion 101 or inside the outer cylinder 2. The top end of the electric push rod provides support to the lower end of the top cover 3 (not shown in the figure). An external controller can also be provided for the electric push rod. In use, the X-ray tube focal spot measuring fixture is immersed in insulating oil, and the controller is located outside the insulating oil. By using the controller to control the up-and-down movement of the electric push rod, the height of the top cover 3 can be adjusted without removing the X-ray tube focal spot measuring fixture from the insulating oil, thereby effectively improving work efficiency.
[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. An X-ray tube focal spot measurement tool, characterized by, The utility model relates to a kind of X-ray tube fixing device, including: Base (1), including cylindrical first support part (101) and second support part (102) being arranged on the first support part (101), the top of the second support part (102) is concave and forms first accommodating groove (121) downwards;The first accommodating groove (121) is also provided with the clamping device (4) of shape cooperation, the center of the clamping device (4) is vertically provided with clamping hole (401) through, for X-ray tube is fixed; Outer cylinder (2), it is the open cylinder structure of top and bottom, the outer cylinder (2) is arranged on the upper surface of the first support part (101);The surface of the outer cylinder (2) is vertically provided with exhaust hole (201); Top cover (3), it is cylindrical, the top cover (3) is with the upper opening shape cooperation of the outer cylinder (2);The central region of the top surface of the top cover (3) is concave and forms second accommodating groove (301) downwards, the center of the second accommodating groove (301) is vertically provided for the light transmission window (302) for transmitting X-ray;The second accommodating groove (301) is provided with the focal point test block (5) of shape cooperation, the lower surface of the focal point test block (5) is provided with light transmission slit, for transmitting the X-ray that is emitted from the light transmission window (302).
2. The X-ray tube focal spot measurement fixture of claim 1, wherein, The upper surface of the first support part (101) is provided with the positioning boss (111) of shape cooperation with the inner side of the outer cylinder (2), the positioning boss (111) and the edge between the first support part (101) are provided with positioning strip (112), the lower edge of the outer cylinder (2) is provided with the positioning groove (203) of shape cooperation with the positioning strip (112); When using, the outer cylinder (2) is set on the outer side of the positioning boss (111), the positioning groove (203) and the positioning strip (112) are nested with each other, and the outer cylinder (2) is limited.
3. The X-ray tube focal spot measurement fixture of claim 1, wherein, The upper surface of the first support part (101) is provided with a plurality of positioning bosses, and the lower edge of the outer cylinder (2) is provided with a plurality of positioning holes matched with the positions and shapes of the positioning bosses. When using, the positioning holes and the positioning bosses are nested with each other, and the outer cylinder (2) is limited.
4. The X-ray tube focal spot measurement fixture of claim 1, wherein, The second support part (102) is vertically provided with a plurality of flow guide grooves (122), and the flow guide grooves (122) are distributed in a central symmetric manner around the center line of the second support part (102).
5. The X-ray tube focal spot measurement fixture of claim 1, wherein, Further comprising height-adjusting screw (6), the side of the outer cylinder (2) is vertically provided with height-adjusting groove (202), and the side of the top cover (3) is provided with screw fixing groove (303); The height-adjusting screw (6) is fixedly connected with the screw fixing groove (303) after passing through the height-adjusting groove (202), and is used for fixing the top cover (3).
6. The X-ray tube focal spot measurement fixture of claim 1, wherein, The inner side of the outer cylinder (2) is vertically provided with a protruding guide strip, and the outer side of the top cover (3) is correspondingly provided with a guide groove. When using, the guide strip and the guide groove are matched, so that the outer cylinder (2) and the top cover (3) realize relative sliding in the vertical direction.
7. The X-ray tube focal spot measurement fixture of claim 1, wherein, The inner side of the outer cylinder (2) is provided with an internal thread, and the outer side of the top cover (3) is provided with an external thread. In use, the top cover (3) is threadedly connected to the inner side of the outer cylinder (2) to realize relative movement in the vertical direction.
8. The X-ray tube focal spot measurement fixture of claim 1, wherein, The side of the first accommodating groove (121) is provided with an internal thread, and the outer side of the holder (4) is provided with an external thread. In use, the holder (4) is fixedly connected to the first accommodating groove (121) through thread connection.
9. The X-ray tube focal spot measurement fixture of claim 1, wherein, The side of the top cover (3) is provided with a scale for indicating the lifting distance of the top cover (3).
10. The X-ray tube focal spot measurement fixture of claim 1, wherein, The base (1), the outer cylinder (2) and the top cover (3) are made of organic glass.