Remote X-ray imaging system and method based on photon counting

Abstract

The invention relates to a remote X-ray imaging system and method based on photon counting, and the system comprises a pulse X-ray source which is used for generating narrow pulse cone beam X-rays and recording an emission timestamp; the large-area array photon counting detector is used for receiving back scattering photons and recording photon energy and arrival timestamps; and the control data processing subsystem is used for calculating longitudinal distance information according to the time difference, generating a target three-dimensional structure image in combination with the two-dimensional image, and obtaining material information through a photon energy matching energy spectrum database. According to the invention, X-ray direct three-dimensional imaging can be realized, movable parts such as a vertical scanning mechanism control part and a transverse scanning platform translation mechanism in a flying spot scanning system are removed, and the reliability of in-orbit operation of an imaging system is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of spacecraft imaging detection, and particularly to a long-distance X-ray imaging system and method based on photon counting. Background Art

[0002] Spacecraft have many remarkable characteristics in terms of system composition and technology, and belong to technology-intensive and complex high-tech products. However, when operating in orbit, spacecraft are affected by various disturbing forces in the space environment and operate in a harsh space environment of vacuum, weightlessness, high and low temperatures, strong radiation, and full of unknown interference factors, which greatly shortens their designed service life and accelerates the occurrence of aging failures. For example, the Earth observation satellite "Optical 2" launched by Japan in September 2006 malfunctioned after 8 months of operation and lost contact with the ground, ultimately turning this reconnaissance satellite worth 587 million US dollars into space debris.

[0003] Therefore, for spacecraft operating in orbit for a long time, in order to avoid the paralysis of the entire system caused by the failure of certain components, it is necessary to conduct regular on-orbit inspections, timely detect and handle possible failures of the spacecraft, so as to ensure its safe and reliable completion of tasks and avoid huge losses caused by scrapping due to failures. However, traditional satellite fault detection mainly relies on ground telemetry, which has poor reliability and cannot guarantee real-time fault detection.

[0004] Currently, traditional ground three-dimensional X-ray imaging systems usually adopt large cone angle scanning imaging technology, where the X-ray source and detector are fixed, and the detected object is placed on a turntable and rotated at a constant speed, such as the Chinese invention patent with the publication number CN104510485A; or adopt flying spot scanning backscatter imaging technology, where the light source and detector are integrated. This technology uses a chopper wheel rotating at high speed and a platform translating at a constant speed to achieve vertical and horizontal scanning respectively, such as the Chinese invention patent with the publication number CN113835129A, collects two-dimensional projection images of the detected object through different angles, and uses a reconstruction algorithm to obtain a three-dimensional internal structure image, thereby realizing three-dimensional non-destructive detection.

[0005] Therefore, the former requires the satellite itself to control the rotation around the axis and cannot achieve on-orbit detection of non-cooperative faulty satellites. The latter, due to the flying spot scanning device including motors, rotating components, and a constant speed translation mechanism, has many intermediate transmission links and fault points and cannot achieve high-reliability on-orbit operation.

[0006] Therefore, there is an urgent need to design a long-distance X-ray imaging system and method based on photon counting to achieve high-reliability on-orbit operation. Summary of the Invention

[0007] To solve the above technical problems existing in the prior art, the object of the present invention is to provide a long-distance X-ray imaging system and method based on photon counting, which can achieve direct three-dimensional X-ray imaging, remove moving parts such as the vertical scanning mechanism control component and the horizontal scanning platform translation mechanism in the flying spot scanning system, and is more conducive to the reliability of the imaging system during on-orbit operation.

[0008] To achieve the above object of the invention, the present invention provides a long-distance X-ray imaging system based on photon counting, comprising:

[0009] A pulsed X-ray source for generating narrow pulsed cone-beam X-rays and recording the emission timestamp;

[0010] A large-area array photon counting detector for receiving backscattered photons and recording the photon energy and arrival timestamp;

[0011] A control data processing subsystem for calculating the longitudinal distance information according to the time difference, generating a target three-dimensional structure image by combining two-dimensional images, and obtaining material information by matching the photon energy with the pre-stored energy spectrum database.

[0012] According to a technical solution of the present invention, the pulsed X-ray source comprises:

[0013] A pulsed signal generation module for generating a periodic narrow pulsed electrical signal;

[0014] A gated X-ray radiation module for generating pulsed X-rays by regulating the electron beam flux through the gate, and forming a cone beam with a 60° divergence angle after collimation.

[0015] According to a technical solution of the present invention, the large-area array photon counting detector comprises:

[0016] An array-type scintillator for converting X-ray photons into fluorescent photons;

[0017] An avalanche photodiode array for converting fluorescent photons into electrical pulse signals and recording the photon energy and arrival timestamp.

[0018] According to a technical solution of the present invention, the control processing subsystem comprises:

[0019] A time-frequency control module for synchronizing the timestamps of the light source and the detector;

[0020] A data processing module for calculating the longitudinal dimension distance information according to the time difference;

[0021] A material analysis module for matching the photon energy spectrum with the pre-stored database to identify the material.

[0022] According to one aspect of the present invention, there is provided an on-orbit fault detection system for a spacecraft, including a photon-counting based long-distance X-ray imaging system and a fault diagnosis module as described in any one of the above technical solutions. The fault diagnosis module is used to determine the faulty components of the spacecraft, their positions and materials, and identify the categories and degrees of faults based on the target three-dimensional structure image and material information.

[0023] According to one aspect of the present invention, there is provided a photon-counting based long-distance X-ray imaging method, including the following steps:

[0024] Step S1, generating narrow pulse cone-beam X-rays and recording the emission timestamp;

[0025] Step S2, receiving backscattered photons and recording the photon energy and arrival timestamp;

[0026] Step S3, calculating the longitudinal distance information based on the time difference, generating a target three-dimensional structure image in combination with a two-dimensional image, and obtaining material information by matching the photon energy with an energy spectrum database.

[0027] According to one technical solution of the present invention, in step S1, it specifically includes:

[0028] Step S11, based on the imaging instruction sent by the main satellite to the target spacecraft, starting the imaging;

[0029] Step S12, the pulse signal generation module generates a periodic narrow pulse electrical signal;

[0030] Step S13, loading the electrical signal onto the X-ray source grid control circuit, regulating the electron beam flux in real time, and generating pulsed X-rays;

[0031] Step S14, collimating and outputting cone-beam X-rays with a 60° divergence angle through a collimating aperture to cover the target detection area;

[0032] Step S15, using the time-frequency module to add a high-precision timestamp to the periodic narrow pulse electrical signal to mark the pulse signal emission time.

[0033] According to one technical solution of the present invention, in step S2, it specifically includes:

[0034] Step S21, the cone-beam X-rays penetrate the surface covering of the spacecraft and undergo Compton scattering with the skin and internal structure;

[0035] Step S22, the backscattered photons return along the original path and are received by a large area photon counting detector;

[0036] Step S23, the large area photon counting detector converts X-ray photons into fluorescent photons through an array-type scintillator and converts them into electrical pulse signals by an avalanche photodiode array;

[0037] Step S24: Record the energy information and arrival timestamp of each photon.

[0038] According to one technical solution of the present invention, in the step S3, it specifically includes:

[0039] Step S31: The time-frequency control module synchronizes the time of the X-ray source, the large-area array photon counting detector, and the control data processing subsystem.

[0040] Step S32: Calculate the difference between the photon arrival timestamp and the pulse emission timestamp to obtain the longitudinal dimension distance information.

[0041] Step S33: Combine the transverse position data of the two-dimensional array of the large-area array photon counting detector to directly synthesize the target three-dimensional structure image.

[0042] Step S34: Extract the energy spectrum information of the photons received by each pixel to generate an energy spectrum curve.

[0043] Step S35: Call the pre-stored standard material energy spectrum database.

[0044] Step S36: Through the energy spectrum matching algorithm, invert the material distribution of the internal structure of the target to obtain the material information.

[0045] According to one aspect of the present invention, there is provided a method for on-orbit fault detection of a spacecraft implemented by using the photon counting-based long-distance X-ray imaging method described in any one of the above technical solutions, including the following steps:

[0046] Based on the target three-dimensional structure image and the material information, determine the faulty components of the spacecraft, their positions and materials, and identify the category and degree of the fault.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention proposes a photon counting-based long-distance X-ray imaging system and method. By using a time counter to mark the X-ray pulse emission time and the photon arrival time, the time difference of the scattered photons traveling back and forth at different internal structure positions of the spacecraft is directly calculated, so as to obtain the longitudinal dimension distance information of different spatial positions. At the same time, combined with the two-dimensional image of the area array detector, the three-dimensional internal structure image of the target spacecraft is directly obtained. With the assistance of the three-dimensional image, the fault location of the spacecraft can be quickly located, making the on-orbit maintenance process more accurate, reducing unnecessary disassembly of the spacecraft, saving time and cost, and improving the safety of on-orbit maintenance. At the same time, this direct three-dimensional imaging method based on photon counting removes movable components such as the vertical scanning mechanism control component and the horizontal scanning platform translation mechanism in the flying spot scanning system, which is more conducive to the reliability of the imaging system during on-orbit operation.

[0049] In the present invention, by using a large area photon counting detector, the energy information of scattered photons received can be directly obtained, so as to obtain the energy spectrum information of each position point in the three-dimensional image. By comparing the energy spectrum diagrams of different materials in the database, the material information of each part in the image can be obtained, so as to quickly identify the faulty parts of the spacecraft, determine the cause of the fault, and take corresponding maintenance measures to ensure that the machine can resume normal operation as soon as possible.

[0050] In the present invention, since the number of returned photons in X-ray backscatter imaging is extremely small, the flying spot scanning X-ray backscatter imaging system must be closely attached to the target for measurement. In this embodiment, by using X-ray single photon detection technology to receive the modulated optical signal and eliminating the influence of the detector background noise, it can respond to a single photon at the quantum limit, with the sensitivity being 2-3 orders of magnitude higher than that of the traditional X-ray detection system. It can realize three-dimensional imaging of extremely weak X-ray light at a long distance, thus ensuring a safe distance during the in-orbit detection process and avoiding collision accidents with the target spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0052] Figure 1 Schematically showing the structural diagram of a long-distance X-ray imaging system based on photon counting in an embodiment of the present invention;

[0053] Figure 2 Schematically showing the flow diagram of a long-distance X-ray imaging method based on photon counting in an embodiment of the present invention;

[0054] Figure 3 Schematically showing the flow diagram of a method for on-orbit fault detection of a spacecraft implemented by a long-distance X-ray imaging method based on photon counting in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0056] Such asFigure 1 As shown in the figure, the present invention provides a long-distance X-ray imaging system based on photon counting, which mainly includes a pulsed X-ray source, a large-area photon counting detector, and a control data processing subsystem, and can reduce the difficulty of three-dimensional reconstruction and improve the quality of three-dimensional images.

[0057] Among them, the pulsed X-ray source is used to generate narrow-pulse cone-beam X-rays and record the emission timestamp.

[0058] The large-area photon counting detector is used to receive backscattered photons and record the photon energy and arrival timestamp.

[0059] The control data processing subsystem is used to calculate the longitudinal distance information according to the time difference, generate a target three-dimensional structure image in combination with the two-dimensional image, and obtain the material information by matching the photon energy with the energy spectrum database.

[0060] By generating narrow-pulse cone-beam X-rays with the pulsed X-ray source and recording the emission timestamp, receiving backscattered photons with the large-area photon counting detector and recording the photon energy and arrival timestamp, calculating the longitudinal distance information according to the time difference by the control data processing subsystem, generating a target three-dimensional structure image in combination with the two-dimensional image, and obtaining the material information by matching the photon energy with the energy spectrum database, three-dimensional structure imaging of the target and acquisition of the material information are realized.

[0061] In some embodiments of the present invention, the pulsed X-ray source includes a pulse signal generation module and a grid-controlled X-ray radiation module. The narrow-pulse electrical signal is mainly generated by the pulse signal generation module, the electron beam is modulated through the grid, and the pulsed ray radiation signal is radiated. After collimation, the cone beam is output with a 60° divergence angle to cover the detected area of the spacecraft. At the same time, the emission time of the pulse signal is recorded and sent to the control data processing module. The pulse width of the emitted X-rays determines the longitudinal resolution of the three-dimensional image.

[0062] In some embodiments of the present invention, the large-area photon counting detector is a large-area photon counting detector, which is composed of a large-area array-type scintillator and an avalanche photodiode single-photon detection array. It is mainly responsible for converting the received scattered X-ray photons into fluorescent photons through the scintillator, and finally converting them into pulse signals by the avalanche diode and reading them out. According to the intensity and timestamp of the electrical pulse signal, the X-ray photon energy and the photon arrival time are obtained.

[0063] In some embodiments of the present invention, the control data processing subsystem is composed of a time-frequency control module, a data processing module, and a material discrimination module, and is mainly responsible for performing time synchronization control on the light source and the detector, obtaining the longitudinal dimension distance information of different pixel positions through the time difference between the transmitted signal and the signals received by different pixels of the area array detector, and directly obtaining the three-dimensional internal structure image of the target spacecraft in combination with the two-dimensional image of the area array detector. At the same time, by receiving the photon energy information and the energy spectrum information of each position point in the three-dimensional image, and using the energy spectrum matching module, a three-dimensional map of the target spacecraft carrying material information is finally obtained.

[0064] According to one aspect of the present invention, there is provided a spacecraft on-orbit fault detection system, including a photon-counting based long-distance X-ray imaging system as described in any one of the above technical solutions and a fault diagnosis module, where the fault diagnosis module is used to determine the faulty components of the spacecraft, their positions and materials, and identify the types and degrees of faults based on the target three-dimensional structure image and material information.

[0065] As Figure 2 shown, according to one aspect of the present invention, there is provided a photon-counting based long-distance X-ray imaging method, including the following steps:

[0066] Step S1, generating narrow pulse cone-beam X-rays and recording the emission timestamp, specifically including:

[0067] Step S11, based on the imaging instruction of the main satellite for the target spacecraft, starting the imaging;

[0068] Step S12, the pulse signal generation module generates a periodic narrow pulse electrical signal;

[0069] Step S13, loading the electrical signal onto the X-ray source grid control circuit, regulating the electron beam flux in real time, and generating pulsed X-rays;

[0070] Step S14, collimating and outputting cone-beam X-rays with a 60° divergence angle through a collimator hole to cover the target detection area;

[0071] Step S15, using the time-frequency module to add a high-precision timestamp to the periodic narrow pulse electrical signal to mark the pulse signal emission time.

[0072] Step S2, receiving backscattered photons and recording the photon energy and arrival timestamp, specifically including:

[0073] Step S21, the cone-beam X-rays penetrate the spacecraft surface covering and undergo Compton scattering with the skin and internal structure;

[0074] Step S22, the backscattered photons return along the original path and are received by the large area array photon counting detector;

[0075] Step S23: The large-area array photon counting detector converts X-ray photons into fluorescent photons through an array-type scintillator, and converts them into electrical pulse signals by an avalanche photodiode array;

[0076] Step S24: Record the energy information and arrival timestamp of each photon.

[0077] Step S3: Calculate the longitudinal distance information based on the time difference, generate a target three-dimensional structure image by combining with a two-dimensional image, and obtain material information by matching the photon energy with a spectral database, specifically including:

[0078] Step S31: The time-frequency control module synchronizes the time of the X-ray source, the large-area array photon counting detector, and the control data processing subsystem;

[0079] Step S32: Calculate the difference between the photon arrival timestamp and the pulse emission timestamp to obtain the longitudinal dimension distance information;

[0080] Step S33: Combine the lateral position data of the two-dimensional array of the large-area array photon counting detector to directly synthesize a target three-dimensional structure image;

[0081] Step S34: Extract the spectral information of photons received by each pixel to generate a spectral curve;

[0082] Step S35: Call the pre-stored standard material spectral database;

[0083] Step S36: Through a spectral matching algorithm, invert the material distribution of the internal structure of the target to obtain material information.

[0084] According to one aspect of the present invention, there is provided a method for on-orbit fault detection of a spacecraft implemented by using the photon counting-based long-distance X-ray imaging method described in any one of the above technical solutions, including the following steps:

[0085] Based on the target three-dimensional structure image and material information, determine the faulty components of the spacecraft, their positions and materials, and identify the type and degree of the fault.

[0086] As Figure 3 shown, the imaging method and the fault detection method of the present invention are described in detail as follows, and the steps are as follows:

[0087] (1) Power on the device, initialize the system, and enter the waiting state after completion; the sub-satellite platform receives the detection instruction for the target spacecraft sent by the main satellite, and the imaging system determines whether the beam conditions are met. If so, start the detection task.

[0088] (2) The X-ray light source calls the pulse signal generation module to generate a periodic narrow pulse electrical signal, which is loaded onto the gate control circuit of the X-ray radiation module. At the same time, the built-in time-frequency module adds a high-precision timestamp to this signal, marks the emission time of the pulse signal, and sends it to the control data processing subsystem.

[0089] (3) The gated X-ray radiation module receives the pulse electrical signal through the gate control circuit, and in real-time controls the flux of the electron beam in the X-ray tube, enabling the electron beam to strike the target in a pulsed form to generate a pulsed X-ray radiation signal. The radiation signal is collimated by a collimator hole and output as a cone beam X-ray with a 60° divergence angle, covering the area of the spacecraft that needs to be detected.

[0090] (4) The emitted cone beam X-ray penetrates into the interior of the spacecraft detection area. During this process, the X-ray undergoes Compton scattering with components of different depths and materials such as the outer skin and internal structure. A small portion of the photons exhibit the backscattering effect, that is, they are reflected back to the imaging system along the incident path direction and are received by the large area array photon counting detector.

[0091] (5) In the large area array photon counting detector, the large area array type scintillator module converts the received scattered X-ray photons into fluorescent photons through the scintillator, and finally converts them into single photon electrical signals by avalanche diodes for reading, obtaining the two-dimensional backscattered color image of the target spacecraft, and sending it to the control data processing subsystem. At the same time, the intensity of the single photon electrical signal and the timestamp of the photon arrival are recorded, thereby obtaining the X-ray photon energy and the photon arrival time of the received signal, and sending them to the control data processing subsystem.

[0092] (6) Call the time-frequency control module to synchronize the time-frequency modules in the X-ray light source, the large area photon counting detector, and the control data processing subsystem, thereby ensuring the longitudinal distance measurement accuracy.

[0093] (7) Call the data processing module to calculate the time difference between the emission time of the pulse electrical signal of the light source and the photon arrival time of the signals received by different pixels of the area array detector, obtaining the longitudinal dimension distance information of different pixel positions. At the same time, combined with the two-dimensional image of the area array detector, directly obtain the three-dimensional internal structure image of the target spacecraft.

[0094] (8) Call the material analysis module. By analyzing the photon energy information received by each pixel, obtain the energy spectrum curve of the pixel position. Call the prefabricated standard material energy spectrum database for energy spectrum correlation matching, thereby obtaining the material information of the target spacecraft at this part.

[0095] (9) Call the fault diagnosis software module, and based on the three-dimensional imaging data map of the spacecraft, further accurately locate the fault position within the fault area, determine the components of the spacecraft that have failed and their corresponding positions and materials; identify the category and degree of the fault.

[0096] (10) Send the fault component position, fault category and fault degree, as well as the three-dimensional scan image to the main satellite, so as to ensure timely handling of the spacecraft fault. Finally, stop the X-ray source beam and prepare for the next detection.

[0097] In summary, the present invention proposes a long-distance X-ray imaging system and method based on photon counting. By using the three-dimensional imaging technology based on X-ray photon counting, it eliminates the limitation of the traditional flying spot scanning backscatter imaging that multiple projection images at different angles need to be obtained for three-dimensional image reconstruction, directly obtains the three-dimensional imaging information of the internal structure of the target, thereby reducing the difficulty of three-dimensional reconstruction and improving the quality of the three-dimensional image, and further improving the detection efficiency. At the same time, this method removes the moving components such as the vertical scanning mechanism control component and the horizontal scanning platform translation mechanism in the flying spot scanning system, which is more conducive to the reliability of the imaging system in orbit operation and has important significance for on-orbit fault detection and maintenance, etc.

[0098] The parts not elaborated in detail in the present invention belong to the well-known technologies in the art.

[0099] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0100] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0101] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A long-distance X-ray imaging system based on photon counting, characterized in that, Comprising: A pulsed X-ray source for generating narrow pulsed cone-beam X-rays and recording the emission timestamp; A large-area photon-counting detector for receiving backscattered photons and recording the photon energy and arrival timestamp; A control data processing subsystem for calculating the longitudinal distance information based on the time difference, generating a target three-dimensional structure image by combining two-dimensional images, and obtaining material information by matching the photon energy with the energy spectrum database.

2. The long-distance X-ray imaging system based on photon counting according to claim 1, characterized in that, The pulsed X-ray source includes: A pulse signal generation module that generates a periodic narrow pulsed electrical signal; A gated X-ray radiation module that generates pulsed X-rays by regulating the electron beam flux through the gate, and forms a cone beam with a 60° divergence angle after collimation.

3. The long-distance X-ray imaging system based on photon counting according to claim 1, wherein The large-area photon-counting detector includes: An array-type scintillator that converts X-ray photons into fluorescent photons; An avalanche photodiode array that converts fluorescent photons into electrical pulse signals and records the photon energy and arrival timestamp.

4. The long-distance X-ray imaging system based on photon counting according to claim 1, characterized in that, The control processing subsystem includes: A time-frequency control module for synchronizing the timestamps of the light source and the detector; A data processing module for calculating the longitudinal dimension distance information based on the time difference; A material analysis module for matching the photon energy spectrum with a pre-stored database to identify the material.

5. A space vehicle on-orbit fault detection system, characterized in that, Comprising the photon-counting based long-distance X-ray imaging system as described in any one of claims 1 to 4 and a fault diagnosis module, the fault diagnosis module being used to determine the faulty components of the spacecraft, their positions and materials, and identify the types and degrees of faults based on the target three-dimensional structure image and material information.

6. A long-distance X-ray imaging method based on photon counting, characterized in that, Including the following steps: Step S1, generating narrow pulsed cone-beam X-rays and recording the emission timestamp; Step S2, receiving backscattered photons and recording the photon energy and arrival timestamp; Step S3, calculating the longitudinal distance information based on the time difference, generating a target three-dimensional structure image by combining two-dimensional images, and obtaining material information by matching the photon energy with the energy spectrum database.

7. The method for long-distance X-ray imaging based on photon counting according to claim 6, characterized in that, In the said step S1, specifically including: Step S11, starting imaging based on the imaging instruction sent by the main satellite to the target spacecraft; Step S12, the pulse signal generation module generates a periodic narrow pulsed electrical signal; Step S13, loading the electrical signal to the gated circuit of the X-ray source, regulating the electron beam flux in real time, and generating pulsed X-rays; Step S14, collimating and outputting a cone beam with a 60° divergence angle through a collimator hole to cover the target detection area; Step S15, using the time-frequency module to add a high-precision timestamp to the periodic narrow pulsed electrical signal to mark the pulse signal emission time.

8. The photon-counting based long-distance X-ray imaging method according to claim 6, wherein In the said step S2, specifically including: Step S21, the cone-beam X-rays penetrate the spacecraft surface covering, and Compton scattering occurs with the skin and internal structure; Step S22, the backscattered photons return along the original path and are received by the large-area photon-counting detector; Step S23, the large-area photon-counting detector converts X-ray photons into fluorescent photons through the array-type scintillator and converts them into electrical pulse signals by the avalanche photodiode array; Step S24, recording the energy information and arrival timestamp of each photon.

9. The photon-counting based long-distance X-ray imaging method according to claim 6, wherein In the said step S3, specifically including: Step S31, the time-frequency control module synchronizes the time of the X-ray source, the large-area photon-counting detector and the control data processing subsystem; Step S32: Calculate the difference between the photon arrival timestamp and the pulse emission timestamp to obtain the longitudinal dimension distance information; Step S33: Combine the transverse position data of the two-dimensional array of the large area array photon counting detector to directly synthesize the target three-dimensional structure image; Step S34: Extract the energy spectrum information of the photons received by each pixel to generate an energy spectrum curve; Step S35: Call the pre-stored standard material energy spectrum database; Step S36: Through the energy spectrum matching algorithm, invert the material distribution of the internal structure of the target to obtain the material information.

10. A method for on-orbit fault detection of a spacecraft implemented by using the long-distance X-ray imaging method based on photon counting according to any one of claims 6 to 9, characterized in that, The steps include: Based on the target three-dimensional structure image and the material information, determine the faulty components of the spacecraft, their positions and materials, and identify the category and degree of the fault.

Images