阅读说明：本技术 适用于x射线诊断的高时空分辨光学系统 (High space-time resolution optical system suitable for X-ray diagnosis ) 是由 刘祥明 刘永刚 徐涛 理玉龙 彭晓世 魏惠月 关赞洋 任宽 王峰 于 2021-06-22 设计创作，主要内容包括：本发明公开了一种适用于X射线诊断的高时空分辨光学系统,探测光产生模块、X射线响应模块、成像模块和分幅记录模块。采用以上技术方案,以超连续光谱为探测光,探测光产生模块选择性输出探测光,再利用透射光栅进行空间分光,最后采用高性能CCD成像,利用光学方法实现了分幅,具有抗干扰能力强、时间和空间分辨高等优点；并且,记录的时间窗口可调,时间分辨率可调,空间分辨率高；同时,该系统结构极为紧凑,能够用于极小空间、极短时间尺度条件下X射线时空演化过程的测量,服务于高能量密度相关物理过程的研究；另外,该系统还可以作为主动测量设备,用于材料荧光性质测量、器件结构测量等。(The invention discloses a high-space-time resolution optical system suitable for X-ray diagnosis, which comprises a detection light generation module, an X-ray response module, an imaging module and a framing recording module. By adopting the technical scheme, the supercontinuum is taken as the detection light, the detection light generating module selectively outputs the detection light, the transmission grating is used for spatial light splitting, and finally high-performance CCD imaging is adopted, and the framing is realized by an optical method, so that the method has the advantages of strong anti-interference capability, high time and spatial resolution and the like; moreover, the recorded time window is adjustable, the time resolution is adjustable, and the spatial resolution is high; meanwhile, the system has extremely compact structure, can be used for measuring the space-time evolution process of the X-ray under the conditions of extremely small space and extremely short time scale, and is used for researching the related physical process of high energy density; in addition, the system can also be used as an active measuring device for measuring the fluorescence property of the material, measuring the structure of the device and the like.)

1. A high spatial and temporal resolution optical system suitable for X-ray diagnostics, comprising:

the detection light generation module can convert incident short pulse laser into supercontinuum chirped pulses and generate two beams of detection light which are separated in time and have different wavelengths, wherein the polarization directions of the two beams of detection light are respectively in the horizontal direction and the vertical direction;

the X-ray response module can enable each beam of detection light emitted from the detection light generation module to carry the spatial-temporal evolution process information of the X-ray generated by the interaction of the target shooting laser and the target (13);

the imaging module comprises a first 4f system (15), a beam shifter (16), a Fresnel biprism (17) and a second 4f system (18) which are sequentially arranged along the light propagation direction, wherein the beam shifter (16) is positioned on an image plane of the first 4f system (15), and the imaging module can spatially divide two beams of detection light emitted by the X-ray response module into two beams;

the framing recording module at least comprises a transmission grating (19) and a CCD (21) which are sequentially arranged along the light propagation direction, wherein the transmission grating (19) can divide two beams of detection light which are emitted from the imaging module and are spatially separated from each other and have mutually vertical polarization directions into a plurality of beams of light respectively and image the beams of light to different positions of the CCD (21).

2. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 1, characterized in that: the detection light generation module comprises a focusing lens (2), a nonlinear medium (3), a parabolic mirror (4), an adjustable attenuation plate (5), a multi-band-pass filter (6), a dispersion medium (7), a polarizing plate (8), a broadband half-wave plate (9) and a delay crystal (10) which are sequentially arranged along the light propagation direction;

the incident short pulse laser is focused on a nonlinear medium (3) through a focusing lens (2) to generate a super-continuous spectrum with different spectral ranges and different spectral intensities, the super-continuous spectrum is collimated through a parabolic mirror (4) and adjusted in light intensity through an adjustable attenuator (5) in sequence, then is emitted to a multi-band-pass filter (6), is divided into a plurality of independent wave bands through the multi-band-pass filter (6), is expanded into detection light with a plurality of temporally separated wave bands through a dispersion medium (7), the detection light with the plurality of wave bands is divided into two detection light beams with polarization directions respectively in the horizontal direction and the vertical direction after sequentially passing through a polarizer (8), a broadband half-wave plate (9) and a delay crystal (10), and the two detection light beams emitted to an X-ray response module have time intervals.

3. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 2, characterized in that: the nonlinear medium (3) is calcium fluoride.

4. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 2, characterized in that: the dispersive medium (7) is a glass rod.

5. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 1, characterized in that: the X-ray response module comprises a half-mirror (11), a semiconductor response medium (12) arranged between the half-mirror (11) and a target (13) and a metal aperture (14) arranged between the target (13) and the semiconductor response medium (12), wherein one side, close to the metal aperture (14), of the semiconductor response medium (12) is plated with a layer of detection light reflection film (14 a);

x-rays generated by interaction of the target hitting laser and the target (13) are imaged on a semiconductor response medium (12) through a metal small hole (14), meanwhile, two beams of detection light emitted from the detection light generation module are emitted into the semiconductor response medium (12) through the half-transmitting mirror (11), carry the information of the space-time evolution process of the X-rays and then are reflected back to the half-transmitting mirror (11) from the semiconductor response medium (12), and finally are emitted to a first 4f system (15) through the half-transmitting mirror (11).

6. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 5, characterized in that: the half-transmitting and half-reflecting mirror (11), the semiconductor response medium (12), the metal small hole (14) and the target (13) are all arranged in the light shield.

7. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 5, characterized in that: the probe light reflection film (14a) is copper with a thickness of 100 nm.

8. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 5, characterized in that: the semi-transparent semi-reflecting mirror (11) is a non-polarization wide-spectrum semi-transparent semi-reflecting mirror.

9. The high space-time resolution optical system suitable for X-ray diagnosis according to claim 1, characterized in that: a reflecting mirror (20) is arranged between the transmission grating (19) and the CCD (21), and multiple beams of detection light emitted by the transmission grating (19) are reflected by the reflecting mirror (20) and then are imaged on different positions of the CCD (21) respectively.

Technical Field

The invention relates to the technical field of ultrafast process detection, in particular to a high-space-time resolution optical system suitable for X-ray diagnosis.

Background

In laser fusion and high energy density physical research, X-ray space-time diagnosis is a very important technical means. Important properties of the plasma, including important physical parameters such as electron temperature, electron density and temperature gradient, can be obtained by measuring an X-ray energy spectrum and an X-ray space-time evolution process. Therefore, the time-space evolution process of the X-ray becomes key data for understanding the processes of interaction between laser and substances, plasma heating and compression, target pellet implosion dynamics and even combustion and the like.

The two-dimensional images of the X-ray emission regions at different moments are the basis for understanding and researching the plasma state and dynamics of the black cavity, are important bases for researching the energy coupling efficiency of the laser and the black cavity, the transmission and energy deposition position of the targeted laser, and the conversion and transportation of the X-ray, and play an important role in grasping physical processes such as the instability growth of a hydrodynamic interface, the propagation of shock waves and the like.

At present, the X-ray diagnostic techniques mainly include a fringe technique, a framing technique, a drift tube technique, and the like, and these techniques all mainly rely on electronic methods to achieve higher time or higher spatial resolution recording. Conventional fringe cameras can provide temporal resolution on the order of ps and even higher, but do not have two-dimensional spatial resolution capability. The time resolution of the traditional framing camera is in the range of 30-70ps, and the space resolution can reach more than 30 line pairs. The DIXI type framing camera based on the drift tube technology can achieve 5ps of time resolution and 3 line pairs of space resolution, and the framing camera with the structure has high time resolution capability but does not have high space resolution capability. Moreover, the electronic diagnosis system formed by the technology is complex in structure and is easily affected by interference of strong neutrons, gamma rays, electromagnetic noise and the like, so that measurement is inaccurate and even parts are damaged. For this purpose, anti-tamper devices are usually additionally designed to protect the diagnostic system. However, with the deepening of laser fusion and high energy density physical experiments, various interferences become stronger and stronger, so that the complexity of an anti-interference device is obviously increased, and the protection effect cannot be completely guaranteed, thereby becoming a main factor for limiting the further development of the current X-ray diagnosis technology.

Converting the spatial-temporal evolution process of X-rays into the detection of visible light signals is a very efficient method. However, the time resolution of the CCD and CMOS of the ultrafast two-dimensional imaging of the optical band is only 100ns, and the corresponding reading speed is only 10⁷And the technology at present stage cannot fundamentally break through the limitations of chip storage technology and electronic reading speed. Therefore, it is not sufficient to realize ultrafast two-dimensional imaging only with an electronics-based detection technique, and other non-electronics detection techniques need to be developed. The related method measurement comprises a frequency-resolved optical shutter (FROG for short), self-reference spectrum phase coherent electric field reconstruction (SIPDER for short) and an improved pump detection technology. These methods, although having a very high time resolution (depending on the width of the probe pulse), can only measure repetitive phenomena. In 2014, "Nature" published an optical compression high-speed imaging technology (referred to as CUP for short), and a conventional streak camera was used to capture non-repetitive events. In this process, no mechanical or optical scanning technique is used, with the aid of spatially coded digital micromirrors. With the further extension of research, the detection spectral range of the CUP is expanded from visible and near infrared bands to ultraviolet bands. However, the cpu has extremely high requirements on the algorithm, which results in extremely high application difficulty.

Therefore, after a series of theoretical and experimental researches, the applicant believes that the high-space-time resolution measurement realized by the optical method has natural advantages, and the high-space-time resolution X-ray diagnosis system which realizes strong anti-interference capability by the optical method is urgently needed to be designed.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a high spatial and temporal resolution optical system suitable for X-ray diagnosis.

The technical scheme is as follows:

a high space-time resolution optical system suitable for X-ray diagnosis is characterized by comprising:

the detection light generation module can convert incident short pulse laser into supercontinuum chirped pulses and generate two beams of detection light which are separated in time and have different wavelengths, wherein the polarization directions of the two beams of detection light are respectively in the horizontal direction and the vertical direction;

the X-ray response module can enable each beam of detection light emitted from the detection light generation module to carry the spatial-temporal evolution process information of the X-ray generated by the interaction of the target hitting laser and the target material;

the imaging module comprises a first 4f system, a beam shifter, a Fresnel biprism and a second 4f system which are sequentially arranged along the light propagation direction, wherein the beam shifter is positioned on an image plane of the first 4f system, and the imaging module can divide two beams of detection light emitted by the X-ray response module into two beams of detection light on the space;

the framing recording module at least comprises a transmission grating and a CCD (charge coupled device) which are sequentially arranged along the light propagation direction, wherein the transmission grating can divide two beams of detection light which are emitted from the imaging module and are spatially separated from each other and have mutually vertical polarization directions into a plurality of beams of light respectively and image the light to different positions of the CCD respectively.

By adopting the structure, the supercontinuum is taken as the detection light, the detection light generating module selectively outputs the detection light, the transmission grating is utilized for spatial light splitting, finally, the high-performance CCD imaging is adopted, the framing is realized by an optical method, and the system has the advantages of strong anti-interference capability (not influenced by complex environments such as neutrons and the like), high time and spatial resolution and the like unlike the traditional X-ray framing camera; moreover, the recorded time window is adjustable, the time resolution is adjustable, and the spatial resolution is high; meanwhile, the system has extremely compact structure, can be used for measuring the space-time evolution process of the X-ray under the conditions of extremely small space and extremely short time scale, and is used for researching the related physical process of high energy density; in addition, the system can also be used as an active measuring device for measuring the fluorescence property of the material, measuring the structure of the device and the like.

Preferably, the method comprises the following steps: the detection light generation module comprises a focusing lens, a nonlinear medium, a parabolic mirror, an adjustable attenuation plate, a multi-band-pass optical filter, a dispersion medium, a polarizing plate, a broadband half-wave plate and a delay crystal which are sequentially arranged along the light propagation direction;

the incident short pulse laser is focused on a nonlinear medium through a focusing lens to generate a super-continuous spectrum with different spectral ranges and different spectral intensities, the super-continuous spectrum sequentially passes through a parabolic mirror collimation plate and an adjustable attenuation plate to adjust the light intensity and then emits to a multi-band-pass filter, the multi-band-pass filter is divided into a plurality of independent wave bands, the wave bands are widened into detection lights with a plurality of temporally separated wave bands through a dispersion medium, the detection lights with the plurality of wave bands sequentially pass through a polarizing plate, a broadband half-wave plate and a delay crystal and then are divided into two detection lights with polarization directions respectively in the horizontal direction and the vertical direction, and two detection lights emitted to an X-ray response module have a time interval.

By adopting the structure, the nonlinear medium is selected according to the requirement and is used for generating the super-continuum spectrum with different spectral ranges and different spectral intensities, the multi-band-pass filter is used as a detection light selection device, and the dispersion medium is also selected according to the requirement, so that two beams of detection light with set time intervals and mutually vertical polarization directions can be stably and reliably output.

Preferably, the method comprises the following steps: the nonlinear medium is calcium fluoride. By adopting the structure, the generated super-continuum spectrum probe can be stable in light intensity distribution.

Preferably, the method comprises the following steps: the dispersive medium is a glass rod. By adopting the structure, the detection light of a plurality of wave bands separated in time can be obtained by selecting the glass rods with different lengths and flexibly selecting the corresponding time windows.

Preferably, the method comprises the following steps: the X-ray response module comprises a semi-transparent semi-reflecting mirror, a semiconductor response medium arranged between the semi-transparent semi-reflecting mirror and the target material and a metal small hole arranged between the target material and the semiconductor response medium, and one side of the semiconductor response medium, which is close to the metal small hole, is plated with a layer of detection light reflection film;

x-rays generated by interaction of the target hitting laser and the target are imaged on the semiconductor response medium through the metal small holes, meanwhile, two beams of detection light emitted from the detection light generation module are emitted into the semiconductor response medium through the semi-transparent semi-reflecting mirror, carry information of the X-ray spatial and temporal evolution process, are reflected back to the semi-transparent semi-reflecting mirror from the semiconductor response medium, and are finally emitted to the first 4f system through the semi-transparent semi-reflecting mirror.

By adopting the structure, the X-ray and the detection light reach the semiconductor response medium at the same time, wherein the X-ray and the semiconductor response medium interact with each other to convert the time-space evolution process of the X-ray into the change of the concentration of carriers in the semiconductor response medium, the carriers can obviously absorb the detection light, and the emergent detection light carries the information of the time-space evolution process of the X-ray.

Preferably, the method comprises the following steps: the semi-transparent semi-reflecting mirror, the semiconductor response medium, the metal small hole and the target are all arranged in the light shield. By adopting the structure, stray light can be effectively isolated, and the influence on a diagnostic system is reduced.

Preferably, the method comprises the following steps: the detection light reflection film is copper with the thickness of 100 nm. By adopting the structure, the copper film plated on the surface can effectively reflect the detection light, and compared with the traditional gold plating mode, copper plating is more beneficial to transmission of high-energy X rays, the influence on the strength of the X rays is further reduced, and meanwhile, the cost is lower.

Preferably, the method comprises the following steps: the semi-transparent semi-reflecting mirror is a non-polarization wide-spectrum semi-transparent semi-reflecting mirror. By adopting the structure, the polarization state of the detection light is not influenced, and the spectrum width is adapted.

Preferably, the method comprises the following steps: and a reflector is arranged between the transmission grating and the CCD, and a plurality of beams of detection light emitted by the transmission grating are reflected by the reflector and then are respectively imaged on different positions of the CCD. By adopting the structure, not only can the propagation path of light be accurately controlled, but also the whole structure is more compact.

Compared with the prior art, the invention has the beneficial effects that:

the high-space-time resolution optical system suitable for X-ray diagnosis adopts the technical scheme, takes a super-continuous spectrum as detection light, the detection light generation module selectively outputs the detection light, then utilizes a transmission grating to perform space light splitting, and finally adopts high-performance CCD imaging to realize framing by an optical method, which is different from the traditional X-ray framing camera; moreover, the recorded time window is adjustable, the time resolution is adjustable, and the spatial resolution is high; meanwhile, the system has extremely compact structure, can be used for measuring the space-time evolution process of the X-ray under the conditions of extremely small space and extremely short time scale, and is used for researching the related physical process of high energy density; in addition, the system can also be used as an active measuring device for measuring the fluorescence property of the material, measuring the structure of the device and the like.

Drawings

Fig. 1 is a light path diagram of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples and the accompanying drawings.

As shown in fig. 1, a high spatial and temporal resolution optical system suitable for X-ray diagnosis mainly includes a probe light generation module, an X-ray response module, an imaging module and a framing recording module. The detection light generation module can convert incident short pulse laser into super-continuum spectrum chirped pulse and generate two beams of detection light which are separated in time and have different wavelengths, and the polarization directions of the two beams of detection light are respectively in the horizontal direction and the vertical direction. The X-ray response module can enable each beam of detection light emitted from the detection light generation module to carry the spatial-temporal evolution process information of the targeted X-ray. The imaging module can divide two beams of detection light emitted by the X-ray response module into two in space. The framing recording module can divide two beams of detection light which are emitted from the imaging module and are spatially separated from each other, and the polarization directions of the detection light are perpendicular to each other into a plurality of beams of light, and the beams of light are imaged on different positions of the CCD21 respectively.

The detection light generation module comprises focusing lenses arranged in sequence along the light propagation direction2. A nonlinear medium 3, a parabolic mirror 4, a tunable attenuator 5, a multi-band pass filter 6, a dispersive medium 7, a polarizer 8, a broadband half-wave plate 9 and a retardation crystal 10. The nonlinear medium 3 is preferably calcium fluoride, and the nonlinear medium is replaceable and can be used for generating supercontinuum with different spectral ranges and different spectral intensities, and the wavelength range is 400-850 nm. A parabolic mirror 4 is used to collimate the supercontinuum. The adjustable attenuation sheet 5 can change the detection light intensity according to requirements. The multi-band pass filter 6 is used to divide the supercontinuum into several bands, each band having a bandwidth of about 25nm, and in this embodiment, the multi-band pass filter 6 may be the FF01-378/474/554/635/735 of semrock. The dispersive medium 7 is preferably a glass rod in this embodiment, corresponding to a time window of typically 10ps to 200ps, so that probe light in multiple wavelength bands separated in time can be obtained. The retardation crystal 10 is a birefringent crystal, such as YVO₄The crystal can generate two beams of light with horizontal polarization and vertical polarization with certain time delay.

The incident short pulse laser is focused on a nonlinear medium 3 through a focusing lens 2 to generate a super-continuum spectrum with different spectral ranges and different spectral intensities, the super-continuum spectrum is collimated by a parabolic mirror 4 and adjusted in light intensity by an adjustable attenuator 5, then emitted to a multi-band-pass filter 6, and divided into a plurality of independent wave bands by the multi-band-pass filter 6, and then widened into detection lights with a plurality of wave bands separated in time through a dispersion medium 7, the detection lights with the plurality of wave bands are sequentially separated into two detection lights with polarization directions respectively in a horizontal direction and a vertical direction after passing through a polarizer 8, a broadband half-wave plate 9 and a delay crystal 10, and the two detection lights emitted to an X-ray response module have a time interval which can be set as required, and the time interval is 5 ps.

The X-ray response module comprises a half-mirror 11, a semiconductor response medium 12 arranged between the half-mirror 11 and a target 13, and a metal aperture 14 arranged between the target 13 and the semiconductor response medium 12, wherein one side of the semiconductor response medium 12 close to the metal aperture 14 is plated with a detection light reflection film 14 a. Wherein, the semiconductor response medium 12 is a doped III-V semiconductor, such as AlGaAs layered structure, and the carrier lifetime is short, which is beneficial to ultra-fast process detection. The detection light reflection film 14a is copper with a thickness of 100nm, which not only can effectively reflect detection light, but also is more beneficial for transmission of high-energy X rays by copper plating compared with the traditional gold plating mode, further reduces the influence on the X ray intensity, and is lower in cost. . In this embodiment, the half mirror 11 is a non-polarization wide-spectrum half mirror, which not only does not affect the polarization state of the probe light, but also adapts to the spectrum width. In addition, the half-mirror 11, the semiconductor response medium 12, the metal small hole 14 and the target 13 are all arranged in the light shield, so that stray light can be effectively isolated, and the influence on a diagnostic system is reduced.

X-rays generated by interaction of the target laser and the target 13 are imaged on the semiconductor response medium 12 through the metal small holes 14, carriers are firstly generated in the semiconductor response medium 12 by the X-rays, and the spatial distribution of the X-rays causes the carrier concentration to be not uniform in space. Meanwhile, two probe lights emitted from the probe light generating module are emitted into the semiconductor response medium 12 through the half-mirror 11, the carrier can obviously absorb the probe light, and the region with high carrier concentration has large absorption. Therefore, the probe light reflected from the semiconductor response medium 12 will carry the information of the X-ray spatial and temporal evolution process, and finally exit to the first 4f system 15 through the half mirror 11.

And the imaging module comprises a first 4f system 15, a beam shifter 16, a Fresnel biprism 17 and a second 4f system 18 which are arranged in sequence along the light propagation direction. Wherein the first 4f system 15 comprises a first lens 15-1 and a second lens 15-2 and the second 4f system 18 comprises a third lens 18-1 and a fourth lens 18-2. Meanwhile, a beam shifter 16 is located on the image plane of the first 4f system 15, and spatially separates two probe lights whose polarization directions are horizontal and vertical. The two beams then pass through a fresnel biprism 17, which in this case is equivalent to two virtual images each emitting two beams, which are imaged into a framing recording module via a second 4f system 18.

And the framing recording module at least comprises a transmission grating 19 and a CCD21 which are sequentially arranged along the light propagation direction, wherein a reflecting mirror 20 is arranged between the transmission grating 19 and the CCD 21.

Two beams of detection light which are spatially separated and have mutually vertical polarization directions are emitted from the imaging module, are respectively split into a plurality of beams of light by the transmission grating 19, and are respectively imaged on different positions of the CCD21 after being reflected by the reflecting mirror 20. Specifically, one of the probe lights emitted from the imaging module is split into a plurality of beams by the transmission grating 19 and arranged in a row at the CCD21, and the other probe light emitted from the imaging module is split into a plurality of beams by the transmission grating 19 and arranged in a row at the CCD 21. Because the detection light wave bands are completely separated, two rows of images on the CCD21 are separated, because the detection light is chirp pulse, different wavelengths correspond to different time, the function of framing is realized by utilizing optics, and a plurality of two-dimensional images with certain time intervals are recorded on the same CCD 21. It is also noted that the time interval between different images of the same row is determined by the time interval between the bands, while the time interval between the two rows is determined by the delay crystal 10.

In the absence of X-rays, a stable background signal is first obtained using CCD 21; then, comparing the signal with an image collected by the CCD21 after the X-ray irradiation to obtain an X-ray spatial and temporal evolution signal; by data processing optimization, the spatial and temporal evolution process of the X-ray can be obtained.

The time resolution (namely the time interval between two images) of the high-space-time resolution X-ray optical diagnostic system is adjustable, and the high-space-time resolution X-ray optical diagnostic system comprises the following two modes: 1. changing the length of the glass rod to generate chirp pulses with different time widths; 2. varying lengths of time delay crystal 10. The high time resolution can reach 500fs, the time window is several ps, the low time resolution can reach 10ps, and the time window is more than 100 ps. The spatial resolution of the system can reach more than 30 um.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.