阅读说明：本技术 一种硬x射线灵敏的分幅相机 (Hard X-ray sensitive framing camera ) 是由 刘慎业 杨志文 谢旭飞 李晋 车兴森 张兴 陈黎 于 2021-06-18 设计创作，主要内容包括：本发明公开了一种硬X射线灵敏的分幅相机,包括光学CCD相机主体和设置于光学CCD相机主体上的变象管,变象管外表面设有窄带滤光片,窄带滤光片外表面设有闪烁体,闪烁体外表面设有一层铝膜,变象管两侧还通过选通脉冲馈入组件连接有光电子倍增组件。本发明采用高速阵列式闪烁体将X射线图像转换为荧光图像,灵敏碱阴极对荧光进行光电转换,提高了相机灵敏度,光纤面板吸收硬X射线,降低了X射线直穿产生的干扰,提高了信噪比。本发明可对硬X射线进行高时空分辨诊断,在脉冲X射线辐射探测领域具有广泛的应用前景。(The invention discloses a hard X-ray sensitive framing camera which comprises an optical CCD camera body and a zoom lens arranged on the optical CCD camera body, wherein a narrow-band optical filter is arranged on the outer surface of the zoom lens, a scintillator is arranged on the outer surface of the narrow-band optical filter, an aluminum film is arranged on the outer surface of the scintillator, and photoelectron multiplication assemblies are connected to two sides of the zoom lens through gating pulse feed-in assemblies. The invention adopts the high-speed array type scintillator to convert the X-ray image into the fluorescence image, the sensitive alkali cathode performs photoelectric conversion on the fluorescence, the sensitivity of the camera is improved, the optical fiber panel absorbs the hard X-ray, the interference generated by the direct penetration of the X-ray is reduced, and the signal-to-noise ratio is improved. The invention can carry out high-time-space resolution diagnosis on the hard X-ray and has wide application prospect in the field of pulse X-ray radiation detection.)

1. A hard X-ray sensitive framing camera, comprising: the imaging device comprises an optical CCD camera body and an image converter tube arranged on the optical CCD camera body, wherein a narrow-band filter is arranged on the outer surface of the image converter tube, a scintillator is arranged on the outer surface of the narrow-band filter, a layer of aluminum film is arranged on the outer surface of the scintillator, one side of the image converter tube is connected with a photoelectron multiplication assembly through a gating pulse feed-in assembly, and the scintillator receives X rays imaged by the imaging assembly and converts the X rays into a fluorescent image.

2. A hard X-ray sensitive framing camera as claimed in claim 1 wherein the scintillator is an arrayed ultrafast scintillator.

3. The hard X-ray sensitive framing camera of claim 2 wherein the arrayed ultrafast scintillator is a short persistence, medium high Z elemental inorganic scintillator with ultrafast response speed, the persistence time being less than 1 ns.

4. A hard X-ray sensitive framing camera as claimed in claim 1 wherein the photomultiplier assembly includes a strobe generator connected to a strobe feed assembly by a broadband radio frequency cable.

5. A hard X-ray sensitive framing camera as claimed in claim 1 wherein the zoom tube includes a fiber optic faceplate, an alkali cathode, a grid, Au micro-strips, an MCP plate and a phosphor screen; the optical fiber panel is positioned on one side close to the scintillator and is tightly attached to the alkali cathode, the other side of the alkali cathode is adjacent to the grid, the other side of the grid is adjacent to the MCP plate, the surface of one side, facing the grid, of the MCP plate is provided with an AU micro-strip, and the other side of the MCP plate is adjacent to the fluorescent screen.

6. A hard X-ray sensitive framing camera according to claim 5 wherein the base cathode is a double or multiple base cathode sensitive to ultrafast scintillator radiation fluorescence.

7. A hard X-ray sensitive framing camera according to claim 1 wherein the image converter tube is high vacuum seal welded using indium seal technology.

8. A hard X-ray sensitive framing camera as claimed in claim 1 wherein the narrow band filter has a long wavelength cut-off of 400nm, a bandwidth of 100nm, a thickness of less than 0.2mm, a diameter of less than 50mm and an ultraviolet fluorescence transmittance of greater than 50% for ultrafast scintillator radiation.

9. A hard X-ray sensitive framing camera as claimed in claim 1 wherein the image pick-up tube is further connected to a high voltage power supply by a high voltage coaxial cable.

10. The hard X-ray sensitive framing camera of claim 1 wherein the gated pulse feed assembly comprises a PCB board, a transmission impedance grading line and a microstrip transmission line.

Technical Field

The invention belongs to the technical field of radiation detection, and particularly relates to a hard X-ray sensitive framing camera.

Background

In the prior art, the X-Ray emitted from the target is directly imaged on the microstrip cathode of the MCP plate to generate photoelectrons, and the short-pulse-width high-voltage pulse traveling at high speed on the microstrip performs high-speed gating on the gain of the photoelectrons in the MCP microchannel, thereby realizing high-speed photography with short exposure time (j.a. insert et al, "Gated X-Ray Detector for the National Ignition Facility," rev.sci.instrum.,77,10E308 (2006)).

In the above technology, the gold microstrip on the front surface of the MCP board is not only a high-voltage gate pulse transmission line, but also a photocathode, the thickness of which is generally about 100nm, the photoelectric conversion efficiency for hard X-rays is very low, and the framing camera with such a structure is insensitive to X-rays above 6 keV. In addition, in this technique, the hard X-rays pass through the microchannels of the MCP plate, generate photoelectrons on the inner walls of the microchannels, and are multiplied, which may reduce the spatial resolution of the camera. The hard X-ray also passes through the MCP plate to directly excite the fluorescent screen to emit light, so that a uniform direct current background signal is generated, and the time resolution and the space resolution of the camera are further reduced.

There is also a technique of using a microchannel cathode whose inner wall is plated with an alkali metal as a photoelectric conversion material to improve the sensitivity of the camera to hard X-rays, and then switching on a gating type framing camera for realizing space-time resolution imaging (a hard X-ray framing camera and a hard X-ray detection method thereof CN 107765506 a and a hard X-ray framing camera CN 207440514U).

The alkali cathode adopted by the hard X-ray framing camera is still insensitive to hard X-rays, photoelectrons cause time dispersion in the multiplication process in a cathode channel, the time resolution of the camera can be greatly reduced, and the scheme can not avoid direct penetration light interference formed by exciting a fluorescent screen after the hard X-rays penetrate through the cathode and the MCP plate.

In the spread type framing photography technology, Au and CsI cathodes are used as photoelectric conversion devices, a magnetic drift tube spreads electronic pulses, the spread electronic pulses are recorded by a framing camera, and the exposure time of the camera can be reduced to be less than 10ps (S.R. Nagel et al, "relationship X-Ray Imager a New/fast Gated X-Ray Imager for the NIF," Rev.Sci. Instrum.).

In the spread-type framing photographic technology, the thickness of the adopted Au and CsI transmission type cathode is generally about 100nm, the photoelectric efficiency of hard X-rays is still very low, the adopted magnetic focusing electronic optical system has no focus in front of the MCP plate, the straight-through X-rays cannot be shielded, and the interference of the straight-through light is difficult to avoid.

Another technique has recently emerged, which employs hydrothermal growth of ZnO: ga Single Crystal is used as a scintillator, hard X-rays are converted into fluorescence images, the fluorescence images are imaged on a gated ICCD camera through a lens, and the hard X-rays are measured in a time-space resolution manner (Transmission Radiation Imaging Based on a ZnO: Ga Single-Crystal Image Converter, Mengxan Xu, Liang Chen, Zhiming Yao, et al. scientific Reports 8,4178 (2018)).

In the fourth technique, using a single crystal scintillator with a diameter of 40mm and a thickness of 1mm as a conversion device, the fluorescence emitted from the X-ray energy deposition site is transmitted to the adjacent region, causing crosstalk, and thus the spatial resolution is insufficient, only 1.5 lp/mm. The nanosecond gated ICCD camera is used for image recording, the exposure time can only reach 5ns, and the time resolution is not high. The technology adopts a deflection light path, avoids the interference caused by that the direct light penetrates through the scintillator and reaches the image intensifier, reduces the utilization efficiency of fluorescence and increases the space occupied by a detection system. In a laser fusion physical experiment, in order to improve signal intensity and spatial resolution of an imaging system, an amplitude division camera should be as close to an observation target as possible, and the camera is often required to be designed into an air chamber type so as to work in a high-vacuum environment. The folded optical path is not suitable for such an air chamber type framing camera.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a hard X-ray sensitive framing camera, wherein a high-speed array type scintillator is adopted to convert an X-ray image into a fluorescent image, a sensitive alkali cathode performs photoelectric conversion on the fluorescent image, the sensitivity of the camera is improved, an optical fiber panel absorbs hard X-rays, the interference generated by the direct penetration of the X-rays is reduced, and the signal-to-noise ratio is improved. The invention can carry out high-time-space resolution diagnosis on the hard X-ray and has wide application prospect in the field of pulse X-ray radiation detection.

The purpose of the invention is realized by the following technical scheme:

a hard X-ray sensitive framing camera comprising: the imaging device comprises an optical CCD camera body and an image converter tube arranged on the optical CCD camera body, wherein a narrow-band filter is arranged on the outer surface of the image converter tube, a scintillator is arranged on the outer surface of the narrow-band filter, a layer of aluminum film is arranged on the outer surface of the scintillator, one side of the image converter tube is connected with a photoelectron multiplication assembly through a gating pulse feed-in assembly, and the scintillator receives X rays imaged by the imaging assembly and converts the X rays into a fluorescent image.

Further, the scintillator adopts an array type ultrafast scintillator.

Furthermore, the array type ultrafast scintillator adopts a short afterglow and medium-high Z element inorganic scintillator with ultrafast response speed, and the afterglow time is less than 1 ns.

Further, the photomultiplier assembly includes a strobe generator connected to the strobe feed assembly by a broadband radio frequency cable.

Furthermore, the image converter comprises an optical fiber panel, an alkali cathode, a grid, an Au microstrip, an MCP plate and a fluorescent screen; the optical fiber panel is positioned on one side close to the scintillator and is tightly attached to the alkali cathode, the other side of the alkali cathode is adjacent to the grid, the other side of the grid is adjacent to the MCP plate, the surface of one side, facing the grid, of the MCP plate is provided with an AU micro-strip, and the other side of the MCP plate is adjacent to the fluorescent screen.

Further, the alkali cathode is a double-alkali cathode or a multi-alkali cathode sensitive to the radiation fluorescence of the ultrafast scintillator.

Further, the image converter tube adopts an indium sealing technology to carry out high vacuum sealing welding.

Furthermore, the long-wave cut-off wavelength of the narrow-band filter is 400nm, the bandwidth is 100nm, the thickness is less than 0.2mm, the diameter is less than 50mm, and the ultraviolet fluorescence transmittance to the radiation of the ultrafast scintillator is higher than 50%.

Furthermore, the image converter tube is also connected with a high-voltage power supply through a high-voltage coaxial cable.

Further, the gating pulse feed-in assembly comprises a PCB board, a transmission impedance gradient line and a microstrip transmission line.

The invention has the beneficial effects that:

(1) the X-ray image can be converted into a fluorescent image, so that the fluorescence emitted from the hard X-ray energy deposition position is localized, the phenomenon that the fluorescence is transmitted to an adjacent region to form crosstalk is avoided, and the spatial resolution capability of the scintillator on the display of the hard X-ray image is improved.

(2) The inorganic high-speed scintillator prepared by the medium-high Z elements has strong absorption and fluorescence conversion capability on hard X rays, and is combined with the alkali cathode sensitive to fluorescence, so that the photoelectric conversion efficiency is increased, and the camera is sensitive to the hard X rays.

(3) The optical fiber panel adopted by the invention has stronger absorption to hard X-rays, greatly reduces the interference of background signals formed by the direct penetration of the hard X-rays and improves the signal-to-noise ratio.

(4) The image converter tube adopts the indium sealing technology to carry out high vacuum sealing welding, reduces the influence of the environment on sensitive elements such as a cathode, an electrode, an MCP plate and the like, and improves the working stability of the camera.

(5) The invention can perform space-time resolution measurement on the hard X-ray and has wide application prospect in the field of pulse radiation detection.

Drawings

Fig. 1 is a schematic structural diagram of a hard X-ray sensitive framing camera provided in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a hard X-ray sensitive framing camera strobe feed-in component according to embodiment 1 of the present invention;

fig. 3 is a partially enlarged schematic view of a hard X-ray sensitive framing camera provided in embodiment 1 of the present invention.

Reference numerals: the device comprises a target to be detected 1, an imaging component 2, an aluminum film 3, an array type ultrafast scintillator 4, a narrow-band optical filter 5, an image converter 6, an optical fiber panel 7, an alkali cathode 8, a grid 9, an Au micro-strip 10, an MCP plate 11, an MCP electrode 12, a fluorescent screen 13, a gated pulse feed-in component 14, a broadband radio frequency cable 15, a gated pulse generator 16, an optical CCD camera body 17, a high-voltage coaxial cable 18, a direct current high-voltage power supply 19, a PCB 20, a transmission impedance gradient line 21, a micro-strip transmission line 22, a gated pulse feed-in component Au micro-strip 23 and a micro-channel plate 24.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that, in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments.

Thus, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

As shown in fig. 1, the framing camera provided in this embodiment is a schematic structural diagram of a hard X-ray sensitive framing camera, and specifically includes an optical CCD camera body 17 and an image converter 6 disposed on the optical CCD camera body 17, a narrowband optical filter 5 is disposed on an outer surface of the image converter 6, an array-type ultrafast scintillator 3 is disposed on an outer surface of the narrowband optical filter 5, a layer of aluminum film 3 is disposed on an outer surface of the array-type ultrafast scintillator 3, a strobe feeding component 14 is disposed on one side of the image converter 6, the strobe feeding component 14 is connected to a strobe generator 16 through a broadband radio frequency cable 15, and the other side of the image converter 6 is connected to a high voltage power supply 19 through a high voltage coaxial cable 18.

The image converter comprises a fiber panel 7, an alkaline cathode 8, a grid 9, an Au microstrip 10, an MCP plate 11 and a fluorescent screen 13.

As shown in fig. 3, the hard X-ray sensitive framing camera provided in this embodiment is a partially enlarged schematic view. The image converter 6 comprises an optical fiber panel 7, an alkaline cathode 8, a grid 9, an Au microstrip 10, an MCP plate 11 and a fluorescent screen 13; the optical fiber panel 7 is positioned on one side close to the scintillator, the optical fiber panel 7 is tightly attached to the alkali cathode 8, the other side of the alkali cathode 8 is adjacent to the grid 9, the other side of the grid 9 is adjacent to the MCP plate 11, the surface of one side, facing the grid 9, of the MCP plate 11 is provided with an AU microstrip 10, and the other side of the MCP plate 11 is adjacent to the fluorescent screen 13. The distance between the grid 9 and the cathode is 1-2mm, the Au microstrip 10 is positioned on the front surface of the MCP plate 11, the MCP plate 11 is positioned 2mm behind the grid 9, and the fluorescent screen 13 is positioned behind the MCP and is about 3mm away from the MCP.

Fig. 2 is a schematic structural diagram of a hard X-ray sensitive framing camera strobe feed-in component 14 according to this embodiment. The gate pulse feed-in assembly 14 comprises a PCB 20, an MCP microchannel plate 24, a transmission impedance gradient line 21 and a microstrip transmission line 22, wherein an Au microstrip 23 of the gate pulse feed-in assembly 14 is arranged on the surface of the MCP microchannel plate 24.

Hard X-rays emitted by a measured target 1 are imaged by an imaging component 2 and then enter an array type ultrafast scintillator 3 to be converted into a fluorescent image, the fluorescent image is coupled to an alkali cathode 8 through a narrow-band filter 5 and an optical fiber panel 7 to generate photoelectrons, an electric field generated by high voltage between the alkali cathode 8 and an applied grid 9 accelerates the photoelectrons and images the photoelectrons on an Au micro-strip 10 on the front surface of an MCP plate 11, a short-pulse-width high-voltage pulse output by a pulse high-voltage generator is coupled to a gating pulse feed-in component 14 through a broadband radio frequency cable 15 and then is transmitted to the Au micro-strip 10 on the surface of the MCP, the high-voltage gating pulse advancing on the Au micro-strip 10 only multiplies the photoelectrons at the position where the high-pulse-width high-voltage pulse reaches the position synchronously, gain high-speed gating of the photoelectrons in a micro-channel of the MCP plate 11 is realized, the photoelectrons can be multiplied and emit from the rear end of the MCP plate 11 within the time when the high-speed high-voltage pulse advancing at the position exists, an MCP electrode 12 is arranged between the MCP plate 11 and the fluorescent screen 13, emitted photoelectrons are accelerated by an electric field between the MCP plate 11 and the fluorescent screen 13, bombard the fluorescent screen 13 to generate fluorescent images, and are finally recorded by a CCD (charge coupled device) camera, so that high-time-space-resolution diagnosis of the hard X-ray source is realized.

The imaging assembly 2 is a 16-channel array KB microscope, producing multiple X-ray source images on an array ultrafast scintillator 3. The imaging component 2 adopts a KB microscope, and has high spatial resolution and high light receiving efficiency.

The scintillator adopts ZnO doped with Ga, the time resolution is not high and is generally 200ps, but the conversion efficiency of converting X-rays into detection light is high. The afterglow time is particularly related to the Ga doping concentration, and has high concentration, short afterglow time, low concentration and long afterglow time.

The array-type ultrafast scintillator 3 provided by this embodiment is a transparent ZnO material doped with Ga uniformly, and the Ga doping concentration is 3 × 10¹⁸atom/mol, thickness of 20 μm, afterglow time of less than 100 ps.

The array type ultrafast scintillator 3 is a micron needle-shaped or thread-shaped array type scintillator which is uniformly and densely distributed and is grown on a quartz substrate by adopting a hydrothermal method, a magnetron sputtering method or a template method. Specifically, ZnO crystal seeds are grown on the quartz optical fiber panel 7 by adopting a magnetron sputtering method, then array ZnO crystals with the thickness of 10-20 microns are grown on the seed crystals by adopting a hydrothermal method, and then the sample is placed in a hydrogen or oxygen environment for high-temperature annealing.

The narrow-band filter 54 is ZWB2 glass, the long-wave cut-off wavelength is 400nm, the bandwidth is 100nm, the thickness is 0.2mm, the diameter is 50mm, and the ultraviolet fluorescence transmittance of the radiation of the array type ultrafast scintillator 3 is higher than 50%.

The optical fiber panel 75 has the spatial resolution better than 60lp/mm, the thickness of 5mm and the diameter of 50mm, the fluorescent transmittance to the radiation of the array type ultrafast scintillator 3 is higher than 80 percent, and the optical fiber panel 7 has strong absorption effect on hard X rays and can effectively prevent the interference of directly penetrating the hard X rays.

The alkaline cathode 8 is an S20 photocathode sensitive to the radiation fluorescence of the array type ultrafast scintillator 3, and the peak sensitivity of the fluorescence spectrum is 40mA/W (@390 nm).

The MCP plate 11 is a microchannel plate with long service life, high gain and stable performance, and Al is prepared in microchannels by adopting an atomic deposition method₂O₃The secondary electron emission layer of (1).

The image converter tube adopts indiumHigh vacuum sealing welding with vacuum degree of 1.0 × 10^-6Pa, reducing the influence of the environment on sensitive elements such as the alkali cathode 8, the electrode, the MCP plate 11 and the like, and improving the working stability of the camera.

The distance between the alkali cathode 8 and the grid 9 is 2mm, and a high voltage of 5-10kV is applied therebetween, so that the photoelectron image generated by the alkali cathode 8 is transmitted to the front surface of the MCP plate 11 with high fidelity.

The hard X-ray sensitive framing camera provided by the embodiment can convert an X-ray image into a fluorescence image, localizes fluorescence emitted by a hard X-ray energy deposition position, avoids crosstalk caused by transmission of the fluorescence to an adjacent area, and improves the spatial resolution capability of a scintillator on the display of the hard X-ray image. The inorganic high-speed scintillator prepared by the medium-high Z elements has strong absorption and fluorescence conversion capability on hard X rays, and is combined with an alkali cathode sensitive to fluorescence, so that the photoelectric conversion efficiency is increased, and the camera is sensitive to the hard X rays. The adopted optical fiber panel has stronger absorption to hard X-rays, greatly reduces the interference of background signals formed by the direct penetration of the hard X-rays and improves the signal-to-noise ratio. The high vacuum sealing welding is carried out by adopting the indium sealing technology, so that the influence of the environment on sensitive elements such as the cathode, the electrode, the MCP plate and the like is reduced, and the working stability of the camera is improved. In addition, the hard X-ray sensitive framing camera provided by the embodiment can be used for measuring the hard X-ray in a space-time resolution manner, and has a wide application prospect in the field of pulse radiation detection.

Example 2

The same structure as that of embodiment 1 is not repeated, and the imaging component 2 of this embodiment is a 16-channel array pinhole with a diameter of 5mm, and generates a plurality of images of the X-ray source on the array ultrafast scintillator 3.

Compared with the hard X-ray sensitive framing camera in the embodiment 1, the hard X-ray sensitive framing camera has the advantages that the imaging assembly adopts the array pinholes, the structure is simple, and the cost is low.

Example 3

The same structure as that of embodiment 1 is not repeated, and the array-type ultrafast scintillator 3 of this embodiment uses a transparent ZnO material doped with In uniformly, and the In concentration is 2 × 10¹⁸atom/mol, thickness of 20mm, afterglow time of less than 100 ps.

In the hard X-ray sensitive framing camera provided by the embodiment, the scintillator adopts the In-doped scintillator, and the time resolution can reach 10 ps.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.