X-ray Ultrafast Imaging System and Method Based on Radiation Conversion and Aperture Encoding

Abstract

The present invention provides an X-ray ultrafast imaging system and method based on radiation conversion and aperture coding, addressing existing ultrafast X-ray imaging technologies, such as poor versatility, time resolution in the hundreds of picoseconds, or a limited number of framing techniques. The system includes an X-ray coupling module that couples target X-ray signals and images them onto a semiconductor chip module; a semiconductor chip module that converts the spatiotemporal distribution of X-ray intensity into the spatiotemporal distribution of the chip's refractive index; a chirped pulse light generation module; a chirped pulse light coupling module that irradiates the semiconductor chip module with linear chirped pulse light generated by the chirped pulse light generation module and couples the pulse light reflected by the semiconductor chip module into a phase extraction module; a phase extraction module; an aperture-coded framing reading module that projects the spatiotemporal distribution information signal of the linear chirped light intensity output by the phase extraction module onto a data acquisition module; the data acquisition module; and an image processing module that processes the image output by the data acquisition module.

Description

Technical Field

[0001] The present invention belongs to the field of ultrafast imaging, and in particular relates to an X-ray ultrafast imaging system and method based on radiation conversion and aperture coding. Background Art

[0002] Ultrafast X-ray imaging technology is widely used in fields such as high-energy physics. For example, in laser-driven inertial confinement fusion experiments, a laser drives a deuterium-tritium target pellet, causing it to implode and compress, leading to fusion. The high-temperature, high-density material produced when the implosion reaches its maximum compression level forms the core. The symmetry of the core's hot spot influences fusion efficiency. Because the core hot spot evolves on the order of hundreds of picoseconds and emits spontaneous X-rays ranging from hard X-rays, ultrafast X-ray imaging with picosecond time resolution is essential for studying the evolution of the core hot spot and is crucial for improving fusion efficiency.

[0003] Traditional ultrafast X-ray imaging techniques include active pump-probe, traveling-wave gating and framing, and solid-state framing. The active pump-probe method uses a sub-picosecond free-electron laser to illuminate a target and uses the target's ultrafast diffraction pattern to invert the target's structure. However, this active imaging approach limits its application in experiments such as inertial confinement fusion, preventing it from capturing the spontaneous X-ray evolution of high-temperature, high-density plasmas. The time resolution of traveling-wave gating and framing is in the hundreds of picoseconds, making it inadequate for capturing dynamic events with timescales shorter than these. Solid-state framing technology was proposed by KL Baker et al. at Lawrence Livermore National Laboratory (KL Baker, R Stewart, P T Steele, S P Vernon, W W H Sing, and B A Remington, “Solid-state framing camera with multiple timeframes,” Appl. Phys. Lett., vol. 103, p. 151111, Oct. 2013. KL Baker, P T Steele, R Stewart, S P Vernon, W W H Sing, and B A Remington, “Solid-state framing camera operating in interferometric mode,” Rev. Sci. Instrum., vol. 89, no. 10, p. 10G107, 2018.). It uses a semiconductor chip to achieve radiation conversion, converting X-ray signals into short-wave infrared probe light. By imaging the multiple frames of the probe light, passive ultrafast X-ray imaging with a time resolution of 5 ps is achieved. However, multi-frame imaging of probe light in solid-state framing technology is achieved through polarization delay and polarization splitting, and the number of frames is limited to two, which makes it impossible to finely and continuously freeze the dynamic information of the target. Summary of the Invention

[0004] In order to solve the technical problems of existing ultrafast X-ray imaging technology, such as poor versatility, time resolution of hundreds of picoseconds, inability to capture dynamic events with time scales shorter than hundreds of picoseconds, or limited number of frames, the present invention provides an X-ray ultrafast imaging system and method based on radiation conversion and aperture coding.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] In a first aspect, the present invention provides an X-ray ultrafast imaging system based on radiation conversion and aperture coding, which is special in that it includes an X-ray coupling module, a semiconductor chip module, a chirped pulse light generation module, a chirped pulse light coupling module, a phase extraction module, an aperture coding frame reading module, a data acquisition module, an image processing module, and a synchronization control module;

[0007] The X-ray coupling module is used to couple the target's X-ray signal to form an image on the semiconductor chip module;

[0008] The semiconductor chip module is used to detect the X-ray signal of the target and convert the spatiotemporal distribution of the X-ray intensity into the spatiotemporal distribution of the chip refractive index;

[0009] The chirped pulse light generating module is used to generate linear chirped pulse light;

[0010] The chirped pulse light coupling module is used to expand and collimate the linear chirped pulse light generated by the chirped pulse light generating module and then irradiate the semiconductor chip module, and is used to couple the linear chirped pulse light carrying the spatiotemporal distribution of the chip refractive index reflected by the semiconductor chip module into the phase extraction module;

[0011] The phase extraction module is used to extract the spatiotemporal distribution of the chip refractive index carried by the linear chirped pulse light into the spatiotemporal distribution information of the linear chirped light intensity;

[0012] The aperture coding and framing reading module is used to disperse, encode, and dispersion compensate the linear chirped light intensity spatiotemporal distribution signal output by the phase extraction module and project it onto the data acquisition module. The aperture coding and framing reading module includes a first convex lens, a first dispersive element, a second convex lens, an aperture coding plate, a third convex lens, a second dispersive element, and a fourth convex lens, which are sequentially arranged along the light beam transmission direction.

[0013] The data acquisition module is used to collect the image output by the coded aperture framing reading module within a single exposure and transmit it to the image processing module;

[0014] The image processing module is used to process the image output by the data acquisition module, reconstruct the multi-frame images of the signals at different moments carried by the linear chirped light using a multi-frame image reconstruction algorithm, and invert the multi-frame images of the time-varying X-ray signal of the target using an X-ray signal inversion algorithm;

[0015] The synchronization control module is used for picosecond synchronization between the target, the chirped pulse light generation module and the data acquisition module.

[0016] Furthermore, the chirped pulse light coupling module is a beam splitter;

[0017] The beam splitter reflects the linear chirped pulse light generated by the chirped pulse light generating module and transmits the linear chirped pulse light carrying the spatiotemporal distribution of the chip refractive index reflected by the semiconductor chip module.

[0018] Furthermore, an optical fiber is provided between the beam splitter and the chirped pulse light generating module, one end of the optical fiber is connected to the chirped pulse light generating module, and the other end is coupled to the beam splitter.

[0019] Furthermore, a reflecting mirror is provided between the beam splitter and the chirped pulse light generating module.

[0020] Furthermore, the response time of the semiconductor chip module is in the order of picoseconds;

[0021] The linear chirped pulse light has a pulse width of nanosecond to picosecond order, and a central wavelength of 700nm to 850nm.

[0022] In a second aspect, the present invention further provides an X-ray ultrafast imaging method based on radiation conversion and aperture coding, which is special in that it includes the following steps:

[0023] 1) The X-ray coupling module couples the target's X-ray signal to form an image on the semiconductor chip module. At the same time, the target transmits a trigger signal to the synchronization control module, and the synchronization control module transmits a first control signal and a second control signal according to the trigger signal.

[0024] 2) The semiconductor chip module converts the spatiotemporal distribution of X-ray intensity into the spatiotemporal distribution of chip refractive index;

[0025] 3) The chirped pulse light generation module receives the first control signal sent by the synchronization control module, generates a linear chirped pulse light with a pulse width in the nanosecond to picosecond range and a central wavelength in the range of 700nm to 850nm, and then the linear chirped pulse light is expanded and collimated by the chirped pulse light coupling module, irradiated to the semiconductor chip module, and reflected by the semiconductor chip module, and then enters the phase extraction module after passing through the chirped pulse light coupling module;

[0026] 4) The phase extraction module extracts the spatiotemporal distribution of the chip refractive index carried by the linear chirped pulse light into the spatiotemporal distribution information of the linear chirped light intensity;

[0027] 5) The temporal and spatial distribution information of the linear chirped light intensity enters the aperture-coded frame reading module, is transmitted through the first convex lens, and is dispersed by the first dispersive element. The dispersed signal is coupled to the aperture-coded plate through the second convex lens and imaged. The encoded signal is transmitted through the third convex lens and is dispersion-compensated by the second dispersive element. The dispersion-compensated signal is coupled to the data acquisition module through the fourth convex lens and imaged.

[0028] 6) The data acquisition module receives the second control signal from the synchronization control module, acquires the signal output by the aperture coding framing reading module within a single exposure, transmits the acquired data to the image processing module, uses a multi-framing image reconstruction algorithm to reconstruct multi-framing images of the signals at different moments carried by the linear chirped light, and uses an X-ray signal inversion algorithm to invert multi-framing images of the time-varying X-ray signal of the target.

[0029] Furthermore, in step 6), the multi-frame image reconstruction algorithm is a compressed sensing algorithm or a deep learning algorithm.

[0030] Furthermore, in step 6), the X-ray signal inversion algorithm uses the correspondence between X-ray intensity-semiconductor chip refractive index change-chirped pulse light phase change-phase extraction system intensity change-image intensity change for inversion.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] 1. The imaging system and method of the present invention use semiconductor chips to achieve the radiation conversion of X-ray time-varying signals into short-wave infrared chirped pulse probe light signals, and perform aperture-coded frame reading of the chirped pulse probe light. Based on the theory of compressed sensing, while ensuring picosecond time resolution, the number of reconstructed frames can be increased to hundreds, and the requirements for the effective detection area of the detector are low. It has the advantages of high spatial resolution and a large field of view, and is expected to achieve continuous and refined X-ray imaging of complex dynamic phenomena.

[0033] 2. The imaging system and method of the present invention can achieve ultrafast X-ray imaging with a time resolution of the order of picoseconds and a number of frames of the order of hundreds. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the principle structure of the X-ray ultrafast imaging system based on radiation conversion and aperture coding of the present invention;

[0035] Figure 2 This is a working principle diagram of the aperture-coded framing reading module in an embodiment of the present invention;

[0036] The accompanying drawings are numerals as follows:

[0037] 101-target, 102-X-ray coupling module, 103-semiconductor chip module, 104-chirped pulse light generation module, 105-chirped pulse light coupling module, 106-reflector, 108-phase extraction module, 109-aperture coding frame reading module, 110-first convex lens, 111-first dispersion element, 112-second convex lens, 113-aperture coding plate, 114-third convex lens, 115-second dispersion element, 116-fourth convex lens, 117-data acquisition module, 118-image processing module, 119-synchronization control module. DETAILED DESCRIPTION

[0038] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0039] like Figure 1 As shown, the present invention is an X-ray ultrafast imaging system based on radiation conversion and aperture coding, characterized by including an X-ray coupling module 102, a semiconductor chip module 103, a chirped pulse light generation module 104, a chirped pulse light coupling module 105, a phase extraction module 108, an aperture coding frame reading module 109, a data acquisition module 117, an image processing module 118 and a synchronization control module 119.

[0040] The X-ray coupling module 102 is used to couple the X-ray signal of the target 101 to form an image on the semiconductor chip module 103 .

[0041] The semiconductor chip module 103 is used to detect the X-ray signal of the target 101 and convert the spatiotemporal distribution of the X-ray intensity into the spatiotemporal distribution of the chip refractive index; the response time of the semiconductor chip module 103 is in the order of picoseconds.

[0042] The chirped pulse light generating module 104 is used to generate linear chirped pulse light with a pulse width in the nanosecond to picosecond range and a central wavelength in the range of 700 nm to 850 nm.

[0043] The chirped pulse light coupling module 105 is used to expand and collimate the linear chirped pulse light generated by the chirped pulse light generating module 104 and then irradiate it onto the semiconductor chip module 103, and is also used to couple the linear chirped pulse light carrying the spatiotemporal distribution of the chip refractive index reflected by the semiconductor chip module 103 into the phase extraction module 108.

[0044] The phase extraction module 108 is used to extract the spatiotemporal distribution of the chip refractive index carried by the linearly chirped pulse light into spatiotemporal distribution information of the linearly chirped light intensity.

[0045] The aperture-coded frame reading module 109 is used to disperse, encode, and dispersion compensate the spatiotemporal distribution information of the linear chirp light intensity output by the phase extraction module 108 and project it onto the data acquisition module 117. The aperture-coded frame reading module 109 includes a first convex lens 110, a first dispersive element 111, a second convex lens 112, an aperture-coded plate 113, a third convex lens 114, a second dispersive element 115, and a fourth convex lens 116, which are arranged in sequence along the light beam transmission direction.

[0046] The data acquisition module 117 is used to acquire the image output by the coded aperture framing reading module within a single exposure and transmit the image to the image processing module 118 .

[0047] The image processing module 118 is used to process the images output by the data acquisition module 117, reconstruct multi-frame images of the signals carried by the linear chirped light at different times using a multi-frame image reconstruction algorithm, and invert the multi-frame images of the time-varying X-ray signal of the target 101 using an X-ray signal inversion algorithm. The multi-frame image reconstruction algorithm can be a compressed sensing algorithm, a deep learning algorithm, or the like; and the X-ray signal inversion algorithm uses the corresponding relationship between X-ray intensity, semiconductor chip refractive index change, chirped pulse light phase change, phase extraction system intensity change, and image intensity change for inversion.

[0048] The synchronization control module 119 is used for picosecond synchronization among the target 101 , the chirped pulse light generating module 104 and the data acquisition module 117 .

[0049] In this embodiment, the chirped pulse light coupling module 105 is a beam splitter, which reflects the linear chirped pulse light generated by the chirped pulse light generating module 104 to the semiconductor chip module 103, and transmits and couples the linear chirped pulse light carrying the spatiotemporal distribution of the chip's refractive index reflected by the semiconductor chip module 103 to the phase extraction module 108. In this embodiment, the chirped pulse light coupling module 105 is provided with a reflector 106 between the beam splitter and the chirped pulse light generating module 104, which is used to fold the linear chirped pulse light generated by the chirped pulse light generating module 104 to achieve miniaturization of the system. In other embodiments, an optical fiber is provided between the beam splitter and the chirped pulse light generating module 104, the incident end of the optical fiber is connected to the chirped pulse light generating module 104, and the outlet end faces the beam splitter. The light beam emitted from the outlet end of the optical fiber is incident on the beam splitter and emitted to the semiconductor chip module 103 through the beam splitter.

[0050] Based on the above-mentioned X-ray ultrafast imaging system, this embodiment provides an X-ray ultrafast imaging method based on radiation conversion and aperture coding, including the following steps:

[0051] 1) The X-ray coupling module 102 couples the X-ray signal of the target 101 to form an image on the semiconductor chip module 103. At the same time, the X-ray generating device of the target 101 transmits a trigger signal to the synchronization control module 119. The synchronization control module 119 performs clock delay according to the trigger signal and transmits a first control signal to the chirped pulse light generating module 104 and a second control signal to the data acquisition module 117 to achieve synchronization between the target 101, the chirped pulse light generating module 104, and the data acquisition module 117.

[0052] 2) The semiconductor chip module 103 converts the spatiotemporal distribution of X-ray intensity into the spatiotemporal distribution of chip refractive index;

[0053] 3) The chirped pulse light generating module 104 receives the first control signal from the synchronization control module 119 and generates linear chirped pulse light with a pulse width in the nanosecond to picosecond range and a central wavelength in the range of 700nm to 850nm. The linear chirped pulse light is then expanded and collimated by the chirped pulse light coupling module 105 and irradiated onto the semiconductor chip module 103. The semiconductor chip module 103 reflects the linear chirped pulse light and then passes through the chirped pulse light coupling module 105 and enters the phase extraction module 108.

[0054] 4) The phase extraction module 108 extracts the spatiotemporal distribution of the chip refractive index carried by the linear chirped pulse light into the spatiotemporal distribution information of the linear chirped light intensity;

[0055] 5) The spatial and temporal distribution information of the linear chirped light intensity enters the aperture-coded frame reading module 109, is transmitted through the first convex lens 110, and is dispersed by the first dispersive element 111. The dispersed signal is coupled by the second convex lens 112 and imaged onto the aperture-coded plate 113. The signal encoded by the aperture-coded plate 113 is transmitted through the third convex lens 114, and then dispersion-compensated by the second dispersive element 115. The dispersion-compensated signal is coupled by the fourth convex lens 116 and imaged onto the data acquisition module 117.

[0056] 6) The data acquisition module 117 receives the second control signal from the synchronization control module 119, acquires the signal output by the aperture coding frame reading module 109 within a single exposure, and transmits the acquired data to the image processing module 118. The multi-frame image reconstruction algorithm is used to reconstruct multi-frame images of the signals at different moments carried by the linear chirped light, and the X-ray signal inversion algorithm is used to invert multi-frame images of the time-varying X-ray signal of the target 101.

[0057] Among them, in step 5), the working principle of the aperture coding frame reading module 109 is as follows Figure 2As shown. The first dispersive element 111 disperses the linear chirped light; the dispersed linear chirped light is imaged on the aperture coding plate 113. Since different wavelength information is imaged at different spatial positions of the aperture coding plate 113, images of different wavelengths are modulated by different spatial patterns; the modulated linear chirped light signal is dispersed and compensated by the second dispersive element 115, restoring the spatial positions of the different wavelength images to their initial states; finally, the data acquisition module 117 captures a two-dimensional space-time integral image and reconstructs a three-dimensional data set (xy-λ). Since the linear chirped light has different wavelengths λ1,…,λ N The intensity distribution information carried by t1, ..., t N The instantaneous information of the target 101 at moment t, therefore, the N reconstructed images in the spectral dimension will be used to invert the N ultrafast images of the target 101.

[0058] In step 6), the multi-frame image reconstruction algorithm is a compressed sensing algorithm or a deep learning algorithm; the X-ray signal inversion algorithm uses the correspondence between X-ray intensity-semiconductor chip refractive index change-chirped pulse light phase change-phase extraction system intensity change-image intensity change for inversion.

[0059] This embodiment uses a semiconductor chip to realize the radiation conversion of X-ray time-varying signals into short-wave infrared chirped pulse probe light signals, and performs aperture-coded frame reading of the chirped pulse probe light. Based on the theory of compressed sensing, while ensuring picosecond time resolution, the number of reconstructed frames can be increased to hundreds, and the requirements for the effective detection area of the detector are low. It has the advantages of high spatial resolution and large field of view, and is expected to achieve continuous and refined X-ray imaging of complex dynamic phenomena.

[0060] The above is only a description of the preferred embodiment of the present invention, and does not limit the technical solution of the present invention to this. Any modifications made by those skilled in the art based on the main technical concept of the present invention fall within the technical scope to be protected by the present invention.

Claims

1. An X-ray ultrafast imaging system based on radiation conversion and aperture coding, characterized by: It comprises an X-ray coupling module (102), a semiconductor chip module (103), a chirped pulse light generating module (104), a chirped pulse light coupling module (105), a phase extraction module (108), an aperture coding framing reading module (109), a data acquisition module (117), an image processing module (118), and a synchronization control module (119); The X-ray coupling module (102) is used to couple the X-ray signal of the target (101) to form an image on the semiconductor chip module (103); The semiconductor chip module (103) is used to detect X-ray signals of the target (101) and convert the spatiotemporal distribution of X-ray intensity into the spatiotemporal distribution of chip refractive index; The chirped pulse light generating module (104) is used to generate linear chirped pulse light; The chirped pulse light coupling module (105) is used to expand and collimate the linear chirped pulse light generated by the chirped pulse light generating module (104) and then irradiate the semiconductor chip module (103), and is also used to couple the linear chirped pulse light carrying the spatiotemporal distribution of the chip refractive index reflected by the semiconductor chip module (103) into the phase extraction module (108); The phase extraction module (108) is used to extract the spatiotemporal distribution of the chip refractive index carried by the linear chirped pulse light into spatiotemporal distribution information of the linear chirped light intensity; The aperture coding frame reading module (109) is used to disperse, encode, and dispersion compensate the linear chirped light intensity spatiotemporal distribution signal output by the phase extraction module (108) and project it onto the data acquisition module (117). The aperture coding frame reading module (109) comprises a first convex lens (110), a first dispersion element (111), a second convex lens (112), an aperture coding plate (113), a third convex lens (114), a second dispersion element (115), and a fourth convex lens (116) sequentially arranged along the light beam transmission direction. The data acquisition module (117) is used to acquire the image output by the coded aperture framing reading module within a single exposure, and transmit it to the image processing module (118); The image processing module (118) is used to process the image output by the data acquisition module (117), reconstruct the multi-frame images of the signals at different moments carried by the linear chirped light using a multi-frame image reconstruction algorithm, and invert the multi-frame images of the time-varying X-ray signal of the target (101) using an X-ray signal inversion algorithm; The synchronization control module (119) is used for picosecond-level synchronization between the target (101), the chirped pulse light generation module (104) and the data acquisition module (117).

2. The X-ray ultrafast imaging system based on radiation conversion and aperture coding according to claim 1, characterized in that: The chirped pulse light coupling module (105) is a beam splitter; The beam splitter reflects the linear chirped pulse light generated by the chirped pulse light generating module (104), and transmits the linear chirped pulse light carrying the spatiotemporal distribution of the chip refractive index reflected by the semiconductor chip module (103).

3. The X-ray ultrafast imaging system based on radiation conversion and aperture coding according to claim 2, characterized in that: An optical fiber is provided between the beam splitter and the chirped pulse light generating module (104), one end of the optical fiber is connected to the chirped pulse light generating module (104), and the other end is coupled to the beam splitter.

4. The X-ray ultrafast imaging system based on radiation conversion and aperture coding according to claim 2, characterized in that: A reflecting mirror (106) is provided between the beam splitter and the chirped pulse light generating module (104).

5. The X-ray ultrafast imaging system based on radiation conversion and aperture coding according to any one of claims 1 to 4, characterized in that: The response time of the semiconductor chip module (103) is in the order of picoseconds; The linear chirped pulse light has a pulse width of nanosecond to picosecond order, and a central wavelength of 700nm to 850nm.

6. A method for ultrafast X-ray imaging based on radiation conversion and aperture coding, characterized in that: The following steps are involved: 1) The X-ray coupling module (102) couples the X-ray signal of the target (101) to form an image on the semiconductor chip module (103), and at the same time, the target (101) transmits a trigger signal to the synchronization control module (119), and the synchronization control module (119) transmits a first control signal and a second control signal according to the trigger signal; 2) The semiconductor chip module (103) converts the spatiotemporal distribution of X-ray intensity into the spatiotemporal distribution of chip refractive index; 3) The chirped pulse light generating module (104) receives a first control signal sent by the synchronization control module (119) and generates linear chirped pulse light with a pulse width in the nanosecond to picosecond range and a central wavelength in the range of 700nm to 850nm. The linear chirped pulse light is then expanded and collimated by the chirped pulse light coupling module (105) and then irradiated onto the semiconductor chip module (103). The semiconductor chip module (103) reflects the linear chirped pulse light and then enters the phase extraction module (108) after passing through the chirped pulse light coupling module (105). 4) The phase extraction module (108) extracts the spatiotemporal distribution of the chip refractive index carried by the linear chirped pulse light into spatiotemporal distribution information of the linear chirped light intensity; 5) The spatial and temporal distribution information of the linear chirped light intensity enters the aperture coding frame reading module (109), is transmitted through the first convex lens (110), and is dispersed by the first dispersive element (111). The dispersed signal is coupled to the aperture coding plate (113) through the second convex lens (112). The encoded signal is transmitted through the third convex lens (114), and is dispersion compensated by the second dispersive element (115). The dispersion compensated signal is coupled to the data acquisition module (117) through the fourth convex lens (116). 6) The data acquisition module (117) receives the second control signal sent by the synchronization control module (119), acquires the signal output by the aperture coding frame reading module (109) within a single exposure, transmits the acquired data to the image processing module (118), uses a multi-frame image reconstruction algorithm to reconstruct multi-frame images of signals at different moments carried by the linear chirped light, and uses an X-ray signal inversion algorithm to invert multi-frame images of the time-varying X-ray signal of the target (101).

7. The X-ray ultrafast imaging method based on radiation conversion and aperture coding according to claim 6, characterized in that: In step 6), the multi-frame image reconstruction algorithm is a compressed sensing algorithm or a deep learning algorithm.

8. The X-ray ultrafast imaging method based on radiation conversion and aperture coding according to claim 6 or 7, characterized in that: In step 6), the X-ray signal inversion algorithm uses the corresponding relationship between X-ray intensity-semiconductor chip refractive index change-chirped pulse light phase change-phase extraction system intensity change-image intensity change for inversion.

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