CN-122018225-A - X-ray gating imaging method and system based on cascading microchannel plate and hCMOS

CN122018225ACN 122018225 ACN122018225 ACN 122018225ACN-122018225-A

Abstract

The invention relates to the technical field of gating imaging, and provides an X-ray gating imaging method and system based on a cascading micro-channel plate and hCMOS, which sequentially comprise a photoelectric cathode, a photoelectric imaging device and a photoelectric imaging device, wherein the photoelectric cathode is used for converting an incident X-ray image into an optoelectronic image; the photoelectric image sensor comprises a first-stage electron transmission microchannel plate, a second-stage gain microchannel plate MCP, a hCMOS image sensor and a second-stage gain microchannel plate, wherein the first-stage electron transmission microchannel plate is coupled with a photoelectric cathode and is used for carrying out time slicing on the photoelectric image and outputting an electron beam slice carrying time information, the second-stage gain microchannel plate MCP is coupled with the first-stage electron transmission microchannel plate and is used for carrying out electron multiplication on the electron beam slice and outputting an amplified electron image, and the hCMOS image sensor is coupled with the second-stage gain microchannel plate and is used for directly receiving and detecting the amplified electron image, converting the amplified electron image into an electric signal and reading the electric signal. The invention can preferably perform X-ray gated imaging.

Inventors

XIANG LIJUAN
Fu Gun
CAI HOUZHI

Assignees

深圳大学

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (8)

1. An X-ray gating imaging system based on a cascading microchannel plate and hCMOS is characterized by comprising the following components in sequence along the light incidence direction: A photocathode for converting an incident X-ray image into a photoelectron image; The first-stage electron transmission microchannel plate is coupled with the photocathode and is used for carrying out time slicing on the photoelectronic image and outputting an electron beam slice carrying time information; the second-stage high-gain micro-channel plate MCP is coupled with the first-stage electron transmission micro-channel plate and is used for carrying out electron multiplication on the electron beam slice and outputting an amplified electron image; hCMOS the image sensor is coupled with the second-stage high-gain micro-channel plate and is used for directly receiving and detecting the amplified electronic image, converting the electronic image into an electric signal and reading the electric signal.
2. The X-ray gating imaging system based on the cascading micro-channel plate and hCMOS as claimed in claim 1, wherein the photocathode is made into a micro-strip transmission line structure, and the port of the micro-strip line is an exponential impedance gradient structure; the photocathode gates the optical signals based on microstrip transmission lines and traveling wave gating pulses, and establishes a space-time mapping relation, namely, the time distribution of the input signals is converted into the space distribution along the microstrip lines.
3. The X-ray gating imaging system based on the cascade microchannel plate and hCMOS is characterized in that the first-stage electron transmission microchannel plate and the photocathode form an ultrafast electron optical shutter together, the channel wall of the ultrafast electron optical shutter has no secondary electron emission layer and no gain effect, and the time slicing of an electron image is completed in a window; first-stage electron transfer microchannel plate channel the axis having a chamfer angle with respect to the normal to the substrate The setting of the chamfer angle satisfies the cut-off condition based on the channel geometry, as shown in the following formula: ; In the middle of For the aperture of the channel it is, Is the channel length.
4. An X-ray gated imaging system based on cascaded microchannel plates and hCMOS as claimed in claim 3 wherein the second stage high gain microchannel plate operates in a long pulse bias mode with the channel walls having secondary electron emitting layers which transfer some kinetic energy to electrons within the material when high energy electrons bombard the channel walls, allowing them to escape against the surface barrier; Secondary electron emission coefficient Defined as the average number of secondary electrons excited per incident electron, which is the incident electron energy And angle of incidence Is described by an empirical formula: ; Wherein, the Reflecting the quantum efficiency of the secondary electrons excited by the material, The ratio relation of the average range of electrons in the material to the average escape depth of secondary electrons is that as the electrons are continuously penetrated deep in a channel, the collision times n are increased cumulatively, and the total electron gain G in a single channel is expressed as the geometric progression increase of the single collision emission coefficient: ; By integrating the physical process in the non-saturated linear working area, the macroscopic electronic gain G and the applied voltage are deduced Following a significant power law: ; In the middle of As a characteristic of the turn-on voltage, The gain factor determined by the length-diameter ratio and the material property of the channel, and the electron multiplication factor can be controlled by adjusting the pulse bias voltage of the second-stage high-gain microchannel plate, so as to ensure that the weak signal is amplified above the response threshold of the detector.
5. The X-ray gated imaging system based on cascaded microchannel plates and hCMOS of claim 4, further comprising a timing control module configured to: and inputting a nanosecond-level half-width wide pulse into the second-level high-gain microchannel plate, establishing a stable electric field environment for electron avalanche and covering an expected occurrence window of events, and inputting a picosecond-level half-width ultra-short traveling wave pulse into the micro-strip cathode within the effective coverage range of the window to finish gating the transient physical image.
6. The X-ray gated imaging system based on cascaded microchannel plates and hCMOS as set forth in claim 5, wherein a vacuum drift region is disposed between the second stage high gain microchannel plate and the hCMOS image sensor, and a post-acceleration voltage is applied to the vacuum drift region for causing the amplified electron image to bombard the hCMOS image sensor at a higher energy to produce an electron bombardment gain.
7. The X-ray gating imaging system based on the cascading micro-channel plate and hCMOS, as set forth in claim 6, wherein the hCMOS image sensor is a radiation-resistant reinforced sensor, and has a pixel memory function for ensuring data integrity in a strong radiation background environment.
8. An X-ray gating imaging method based on a cascading micro-channel plate and hCMOS is characterized in that an X-ray gating imaging system based on the cascading micro-channel plate and hCMOS is adopted according to any one of claims 1 to 7.

Description

X-ray gating imaging method and system based on cascading microchannel plate and hCMOS Technical Field The invention relates to the technical field of gating imaging, in particular to an X-ray gating imaging method and system based on a cascading micro-channel plate and hCMOS. Background In the research of high-energy density physical experiments, the evolution of the physical process often occurs in nanosecond or picosecond time scale, and is accompanied by strong X-ray radiation, neutron flux and electromagnetic pulse interference, for example, in the implosion stagnation stage of laser inertial confinement nuclear fusion (inertial confinement fusion, ICF), high-temperature and high-density plasmas evolve in a very short time and generate a large amount of radiation. In order to analyze the evolution process of the plasma, the diagnostic system needs to perform multi-frame and short-interval two-dimensional imaging on radiation information in a strong interference environment, and keeps stable performance parameters such as time resolution capability, sensitivity, dynamic range and the like. A single stage microchannel plate (microchannel plate, MCP) frame camera is the core two-dimensional spatially resolved diagnostic device for transient physical processes. The framing camera has the capability of acquiring a plurality of two-dimensional images in a single exposure, and is an important tool for researching an ultrafast physical process. With the development of ICF experiments toward higher energy and faster ignition, more stringent requirements are put forward on diagnostic equipment, not only requiring a time resolution breakthrough of 30 ps, but also requiring high detection sensitivity and high signal-to-noise ratio under extremely strong radiation interference environments. Particularly in experiments where neutron yields may exceed 10 16, the diagnostic equipment is required to have radiation-resistant reinforcement. The radiation-resistant modification work of a learner aiming at NIF shows that under the strong neutron environment, the traditional circuit is extremely easy to damage, and radiation resistance improvement is needed to ensure the integrity of data. The traditional MCP framing camera is mature in application, but the time resolution and the signal intensity are contradictory, the high-gain working mode of the MCP with the thickness of 0.5 mm is adopted to improve the transit time dispersion and the gain non-uniformity, and the low-gain working mode of the MCP with the thickness of 0.2 mm is adopted to shorten the transit time dispersion, but the signal to noise ratio of the signal read out by the fluorescent screen and the rear-end optical imaging equipment is poor, so that the sampling process needs to be decoupled structurally. And the sampling mode of imaging the fluorescent screen electronic image through the optical imaging equipment has obvious signal coupling loss, so unnecessary conversion links are required to be reduced to enhance the output signal-to-noise ratio. In recent years, with the progress of the radiation-resistant semiconductor process, the electron direct detection technology based on hCMOS is a new research hot spot. The technology eliminates a fluorescent screen and an optical lens, places a sensor chip without a protective window in vacuum, directly receives electron bombardment, and realizes high-sensitivity detection by utilizing the principle that electrons deposit energy in silicon to generate a large number of electron-hole pairs. Although the direct detection technique has great potential, the above contradiction needs to be solved, if the microchannel plate is operated in a low gain state in pursuit of high time resolution, the front-end signal is weaker, and the signal-to-noise ratio under the strong radiation substrate is still limited although the electron bombardment gain is supplemented. If the microchannel plate gain is increased in pursuit of a high signal, the time resolution is reduced. Disclosure of Invention The single-stage microchannel plate MCP framing camera is difficult to simultaneously consider time resolution and detection sensitivity. Increasing the MCP thickness increases the gain factor, but the multiplication times and the transit time dispersion of electrons in the channel are increased, so that the time resolution is reduced, and decreasing the MCP thickness shortens the transit time dispersion, but the gain is insufficient, so that the sensitivity requirement cannot be met. The traditional indirect imaging mode utilizes optical equipment to image the fluorescent screen electronic image, has signal coupling loss, and results in poor signal-to-noise ratio of output signals. The invention provides an X-ray gating imaging method and system based on a cascading micro-channel plate and hCMOS, which can solve the problems and achieve the imaging effect of considering time resolution and signal-to-noise ratio under a strong radiation