JP2021110538A - X-ray imaging device and X-ray imaging method - Google Patents

Abstract

To provide an X-ray imaging apparatus capable of performing measurement with high time resolution without increasing time resolution of the X-ray detector.SOLUTION: An X-ray imaging apparatus for observing an X-ray with which a sample P is irradiated comprises a first optical system provided with a first crystal plate having a plurality of crystal plates 1a, 2a and 3a arranged in an incident direction of X-rays containing a plurality of wavelengths, and a second crystal plate group having a plurality of crystal plates which is a plurality of crystal plates 1b, 2b and 3b arranged apart at a predetermined distance x from the first crystal plate group, on which the X-rays separated into a plurality of wavelengths by each crystal plate and constituting the first crystal plate group are made incident and an X-ray group containing each of the separated X-rays makes incident on the sample.SELECTED DRAWING: Figure 1

Description

The present invention relates to an imaging device and an imaging method using X-rays.

In general, physical phenomena at the atomic level occur in an extremely short time, so measurement techniques that can achieve a time resolution of the current picoseconds are important for research in a wide range of fields such as solid materials and biological materials. For example, it is a technology that can be used in various fields such as electrical / electronic engineering and medical treatment.

For example, Non-Patent Document 1 describes a method of capturing a change in a material at a time interval as short as picoseconds by a high-speed imaging technique using visible light. Further, Patent Document 1 describes a method that enables high-speed observation using curved crystals.

Japanese Unexamined Patent Publication No. 2014-103857 Japanese Unexamined Patent Publication No. 2008-26098

Nature Photonics volume 8, pages 695-700 (2014)

Conventionally, in order to understand the dynamics of phonons, which are one of the thermal carriers, it is necessary to measure the dynamics on the order of picoseconds. Therefore, the pump-and-probe method has been used in the measurement. Since the pump-and-probe method is a method that can be applied only to experiments with good reproducibility, it is not desirable to use it for instantaneous dynamics measurement such as picosecond order. For a more detailed understanding of the phenomenon, dynamics measurement using a single pulse is desired.

The present inventor makes it possible to observe atomic structural changes with high time resolution of nanoseconds and picoseconds using X-rays, and has high time resolution of about millisecond by a conventional detector and high time resolution like the pump and probe method. Those that could not be observed by measurement methods other than those with reproducibility were made observable. One aspect of the present invention is to provide an X-ray imaging apparatus and an X-ray imaging method capable of performing measurement with high time resolution without increasing the time resolution of the X-ray detector.

The X-ray measuring device according to one embodiment is an X-ray imaging device for observing X-rays applied to a sample, and has a plurality of crystal plates arranged in an incident direction of X-rays including a plurality of wavelengths. The first crystal plate group and the first crystal plate group are arranged at a predetermined distance from each other, and X-rays separated into a plurality of wavelengths by each crystal plate constituting the first crystal plate group are incident. A first optical group having a plurality of crystal plates, and a second crystal plate group having the plurality of crystal plates in which an X-ray group containing each of the separated X-rays is incident on the sample. It is configured as an X-ray imaging apparatus, which comprises a system.

According to one embodiment, it is possible to perform measurement with high time resolution without increasing the time resolution of the X-ray detector.

It is a figure which shows the configuration example of the X-ray image pickup apparatus which added the optical path difference to the X-ray of three different wavelengths. It is a figure which shows the other configuration example of the X-ray image pickup apparatus which added the optical path difference to the X-ray of three different wavelengths. It is a figure which shows the further other configuration example of the X-ray image pickup apparatus which added the optical path difference to the X-ray of three different wavelengths. It is a figure which shows the structural example of a crystal plate. It is a figure for demonstrating the diffraction condition using the crystal plate shown in FIG. It is a figure which shows the modification of the crystal plate shown in FIG. It is a figure for demonstrating the method of adjusting the irradiation position of the incident light using the crystal plate shown in FIG. It is a figure which shows the further other configuration example of the X-ray image pickup apparatus which added the optical path difference to the X-ray of three different wavelengths.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the members having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted. Further, in the following embodiments, the description of the same or similar parts is not repeated in principle unless it is particularly necessary.

(Consideration)
<About X-ray imaging device>
Hereinafter, matters examined by the present inventor will be described before the embodiments are described.
As described above, a measurement method having a high time resolution of nanoseconds or picoseconds is a technique that can be used in various fields, but it is difficult to realize this. As an example of study, the present inventor has studied an X-ray having a plurality of wavelengths and a mechanism for changing the optical path difference depending on the wavelength. In the X-ray imaging apparatus of the study example, the optical path of X-rays having a plurality of wavelengths can be changed according to each wavelength, and the timing at which the sample is irradiated with X-rays can be changed. Further, by observing the X-rays after irradiation with the same or different X-ray detectors, it is possible to obtain information at different times depending on the region of the detector regardless of the time resolution on the detector side.

In order to realize such an X-ray measuring device, a mechanism for changing the optical path of X-rays is required. In the case of visible light, the optical path can be changed by using a simple optical mirror, but for X-rays with a short wavelength, optical path control using a diffraction phenomenon is required. Therefore, in order to control the optical path, it is extremely important to arrange the single crystal crystal plates in consideration of the X-ray diffraction conditions and to control the angle thereof. Further, in order to divide the optical path difference of about picoseconds into a plurality of X-rays having a plurality of wavelengths, it is necessary to precisely control the angle of the crystal with respect to the relative position between the crystal plates.

From the above, it is desired to provide a time-decomposable device by devising a configuration for dividing an optical path of short pulses of X-rays having a plurality of wavelengths according to each wavelength.

<About X-ray imaging device>
As described above, according to the technique described in Patent Document 1, it is possible to create an optical path difference even with X-rays having a single wavelength by using a curved crystal. However, it is extremely difficult to bend a general solid material (particularly a single crystal). Therefore, a structure that does not require a special distortion structure is desirable.

From the above, it is desired to provide an X-ray imaging apparatus in which a plurality of optical paths are irradiated to a single sample with a time lag without using a curved single crystal by devising the configuration.

(Embodiment)
[Heating device]
<Structure of the X-ray imaging apparatus of this embodiment>
Hereinafter, the X-ray imaging apparatus of this embodiment will be described with reference to FIGS. 1 to XX. FIG. 1 is a schematic view showing an X-ray imaging apparatus 100 according to the present embodiment. FIG. 1 is an example of an X-ray imaging apparatus and an imaging method in which X-rays having three different wavelengths have optical path differences.

As shown in FIG. 1, in the X-ray imaging apparatus 100, a plurality of crystal plates are arranged in a direction in which white X-rays containing a plurality of different wavelengths are incident. As shown below, the X-ray imaging apparatus 100 is directed from the crystal plates 1a, 2a, 3a and the central axis of these crystal plates in a direction perpendicular to the incident direction of white X-rays (that is, crystal plates 1a, 2a). The first optical system 101 having crystal plates 1b, 2b, and 3b arranged at a distance x (parallel to 3a) and the same central axis as the crystal plates 1b, 2b, and 3b and in the incident direction. Second optics having crystal plates 1b, 2b, 3b arranged on the downstream side in the above, and X-ray cameras 10, 20, 30 for measuring X-rays having a wavelength diffracted by the crystal plates 1b, 2b, 3b. It has a system 102.

In FIG. 1, the crystal plates 1a, 2a, and 3a arranged on the same line axis are arranged at angles _{θ 1} , θ ₂ , and θ _{3 with respect to the incident axis of white X-rays, respectively.} In general, X-rays having a wavelength of λ are diffracted in the direction θ of the diffraction conditions represented by λ = 2ds in θ with respect to the interplanar spacing d of the crystal planes of the crystal plate. If this diffraction condition is not satisfied, X-rays are transmitted and travel straight. Therefore, X-rays containing different wavelengths are diffracted only at a specific wavelength in each crystal plate (see the bottom of FIG. 1), and the course of some X-rays is changed in the direction of a specific angle.

In FIG. 1, X-rays having wavelengths of _{λ 1} , λ ₂ , and λ ₃ corresponding to the respective diffraction conditions are arranged by arranging the same crystal plates of the same material at angles θ ₁ , θ ₂ , and θ _3. You can change the course of some of the. _{The X-rays of wavelengths λ 1} , λ ₂ , and λ ₃ diffracted by the crystal plates 1a, 2a, and 3a are then diffracted by the crystal plates 1b, 2b, and 3b and irradiated to the sample P. At this time, if the X-ray is a pulse with a short time, the optical paths of the X-rays having wavelengths of _{λ 1} , λ ₂ , and λ _{3 pass through different optical paths and irradiate the sample P.} , The timing of the X-ray pulse applied to the sample P changes with time. By devising the angle and arrangement of the crystal plates in this way, it is possible to create a time difference of about nanoseconds or picoseconds with respect to the timing of irradiation of the X-ray pulse applied to the sample.

Therefore, in FIG. 1, as an example, in the X-ray imaging apparatus 100 for observing the X-rays applied to the sample (sample P), in the incident direction of X-rays (for example, incident white X-rays) containing a plurality of wavelengths. A first crystal plate group having a plurality of arranged crystal plates (for example, crystal plates 1a, 2b, 3c) and the first crystal plate group are arranged at a predetermined distance x apart from the first crystal plate group. A plurality of crystal plates to which X-rays (for example, _{monochromatic X-rays having wavelengths λ 1} , λ ₂ , and λ ₃ ) separated into a plurality of wavelengths by each crystal plate constituting the plate group are incident, and the above separation A first optical system having a second crystal plate group having a plurality of crystal plates (for example, crystal plates 1b, 2b, 3b) in which an X-ray group containing each of the X-rays is incident on the sample. The configuration provided with 101 is adopted.

The X-rays irradiated to the sample P are the crystal plates 1c, 2c, and 3c constituting the second optical system 102 arranged on the same line axis as the crystal plates 1b, 2b, and 3b, and have different paths in different directions. By changing, it is possible to observe with different X-ray cameras 10, 20, and 30. Since the measured values measured by each different X-ray camera are information about the X-rays applied to the sample P at different timings, it is possible to measure information about the dynamics of nanoseconds and picoseconds. Become. Therefore, in FIG. 1, as an example, in the X-ray imaging apparatus 100, a plurality of crystal plates for separating X-rays of each wavelength included in the X-ray group incident on the sample are separated X-rays. A third crystal plate group having a plurality of crystal plates (for example, crystal plates 1c, 2c, 3c) in which each of the lines is incident on an X-ray detector (for example, X-ray cameras 10, 20, 30) at different positions. The configuration including the second optical system 102 having the above is adopted.

The crystal plate shown in FIG. 1 is a single crystal, and a semiconductor single crystal such as Si or Ge can be used. Further, a single crystal of an insulator such as an oxide or a single crystal of a metal material may be used. By using materials having different crystal lattice constants, the plane spacing d of λ = 2ds in θ can be changed, so that the angle of X-ray diffraction can be modulated by the material of the crystal plate. In the present embodiment, the crystal plates may be crystals having the same interplanar spacing, or a plurality of crystals having different interplanar spacing may be used.

In the example of FIG. 1, X-rays containing three different wavelengths are illustrated, but many kinds of optical paths can be created by increasing the wavelength range of incident white X-rays and the number of crystal plates to be arranged. It is possible to obtain information with different time differences.

In FIG. 1, an X-ray camera is used as an example of the X-ray detector. However, as shown in FIG. 2, the X-ray cameras 10, 20, and 30 are arranged by arranging the large field detector 40 instead of the crystal plates 1b, 2b, and 3b and the X-ray cameras 10, 20, and 30. May be good. When the X-ray imaging apparatus 200 having such an optical system 103 is used, the wavelength of the X-rays irradiated to the sample P differs at each timing, but the detection information at all timings is the large field detector 40. Observed at. In the case of the X-ray detection method shown in FIG. 1, X-ray transmission information can be obtained, but evaluation by X-ray diffraction cannot be performed. As shown in FIG. 2, by adopting the optical system 103 in which the large-field detector 40 is arranged instead of the X-ray cameras 10, 20, and 30 of the second optical system 102, the timing of irradiation to the sample P can be adjusted. Although different X-rays cannot be separated by each detector, since the X-ray diffraction spot position depends on the wavelength of the X-ray, the information of each diffraction peak includes information having different irradiation timings. Therefore, it is possible to evaluate the dynamics by analyzing each diffraction peak including the irradiation time information.

In the present embodiment, as shown in FIG. 3, a configuration using the X-ray interference effect can be adopted. In FIG. 3, in addition to the arrangement of each element in the first optical system 101 and the second optical system 102 shown in FIG. 1, reference X-rays (reference waves) are further used as the third optical system 104. An X-ray imaging apparatus 300 having crystal plates 1d, 2d, and 3d for obtaining is used. As shown in FIG. 3, the X-rays passing through the crystal plates 1d, 2d, and 3d are not irradiated to the sample P, but the optical path lengths of the crystal plates 1c, 2c, and 3c and the X-ray cameras 10, 20, and 30 are samples. The positions and angles of the crystal plates 1d, 2d, and 3d are adjusted and arranged so that the distance is the same as the X-rays irradiated to P.

Therefore, the reference wave and the X-ray irradiating the sample P cause interference at the positions of the X-ray cameras 10, 20, and 30. When two waves interfere with each other, it becomes possible to observe a change in the phase of X-rays instead of observing a change in the absorption intensity of X-rays. As described in Patent Document 2, the change in the phase of X-rays can be measured with higher sensitivity than the change in absorption intensity. Therefore, according to the present embodiment, time-resolvable X-ray phase imaging becomes possible. Therefore, in FIG. 3, as an example, there are a plurality of crystal plates to which X-rays transmitted through the first crystal plate group are incident, and each of the X-rays having a plurality of wavelengths included in the transmitted X-rays is captured. , A plurality of crystal plates (for example, crystal plates 1d, 2d, 3d) incident on each crystal plate (for example, crystal plates 1c, 2c, 3c) constituting the third crystal plate group of the second optical system 102. ) Is included in the fourth crystal plate group, and the third optical system 104 is provided.

<Preparation of Crystal Plate of Example>
In this embodiment, single crystal Si is used as the crystal plate whose X-ray optical path is changed. By processing a single single crystal Si, it is possible to form a structure in which the crystal plates 1a and the crystal plates 1b shown in FIGS. 4 (a) and 4 (b) are connected. In FIG. 4, it can be seen that the crystal plate 1a and the crystal plate 1b have a concave shape in which they are integrated with each other via the base 401. By processing Si into such a structure, it is possible to prepare two crystal plates having parallel crystal plane orientations, and it is possible to construct crystal plates having uniform angles with extremely high accuracy. As shown in FIGS. 4 and 5, the distance L between the crystal plate 1a and the crystal plate 1b has the following relationship (Equation 1), where the distance x between the two optical paths is defined.

Here, the angle θ is determined by the X-ray diffraction condition (λ = 2dsin2θ _B). As shown in the lower part of FIG. 5, the X-ray diffraction condition of the Laue case is determined by the same formula as the ordinary Bragg diffraction condition. When using the (220) plane of Si, d = 1.92 Å. If the _{crystal plate is designed so that θ B} = 4.0 ° and x = 30 mm, the optical path of the X-ray with an energy of 23.2 keV can be changed by processing it to L = 215.0 mm. Table 1 shows the relationship between the energy of each X-ray and the arrangement of the angle between the crystal plate and the X-ray.

By arranging the X-ray energies shown in Table 1 in relation to the inclination of the crystal plate, it is possible to control the irradiation time difference as in the time difference in Table 1. The relationships shown in Table 1 are merely examples, and in the present embodiment, the design can be changed by the X-ray energy desirable for measurement. Further, although the (220) plane of single crystal Si is taken as an example, different crystal planes of Si may be used, or diffraction of different single crystal materials may be used. When different surface spacings d are used, the optical paths can be appropriately separated by designing based on the above description.

In the present embodiment, a structure may be formed in which the distance between the crystal plates 1a and the crystal plates 1b shown in FIG. 6 is slightly different by processing a single single crystal Si. That is, as shown in FIG. 6, the distance L between the crystal plate 1a and the crystal plate 1b is set, and one end of one of these crystal plates (for example, the crystal plate 1b) in the width direction is set as described above. The crystal plate 1a and the crystal plate 1b are tilted toward another crystal plate (for example, the crystal plate 1a), and the distance L at the center of the width direction between the crystal plates 1a and the crystal plate 1b is brought closer to a narrower distance L'. May be. In FIG. 6, the crystal plate 1b is configured to be close to the crystal plate 1a, but the crystal plate 1a may be configured to be close to the crystal plate 1b.

By using a crystal plate as shown in FIG. 6, when the irradiation position of the incident light is changed as shown in FIG. 7, the distance x between the X-rays when the optical path difference is made and the transmitted X-rays can be changed. can. In FIG. 7A, the crystal plates 1a and 1b are arranged at a distance x, but in FIG. 7B, these are moved in the downward direction D in the figure to move the crystal plates 1a and 1b. It can be seen that the distance from and is a distance x'shorter than the distance x.

In order to irradiate the sample position with X-rays of different wavelengths, it is necessary to adjust the distance x. However, using a single crystal having the structure shown in FIG. 6, the position of the crystal plate should be adjusted as shown in FIG. Therefore, the spacing between the crystal plates can be easily adjusted.

In the present embodiment, two crystal plates processed from the same single crystal are used, but the positions and angles of the two single crystal plates may be adjusted. For example, the position and angle of a part or all of the crystal plates constituting each crystal plate group may be adjusted by a general drive mechanism (adjustment mechanism) such as a motor (not shown).

The X-ray imaging apparatus according to the present embodiment has been described above. Further, as shown below, X-rays containing a plurality of wavelengths incident on the first crystal plate group (for example, incident white X-rays) A modification may be made by providing a fourth optical system 105 having a plurality of crystal plates (for example, crystal plates 1e and 2e) for adjusting the incident direction.

FIG. 8 is a diagram showing a configuration example of the X-ray imaging apparatus 400. As shown in FIG. 8, in the X-ray imaging apparatus 400, in addition to the first optical system 101 and the second optical system 102 shown in FIG. 1, two focusing mirrors (for example, a KB mirror) 1e, It includes a fourth optical system 105 having 2e. By using such a fourth optical system 105, it becomes easy to incident the incident white X-rays at the target position. FIG. 8 illustrates a case where the fourth optical system 105 is applied to the X-ray apparatus 100 shown in FIG. 1, but the X-ray apparatus 200 shown in FIG. 2 and the X-ray apparatus 300 shown in FIG. Can be applied in the same way.

As described above, according to the present embodiment, X-rays having a plurality of wavelengths are irradiated with the sample by separating the optical paths using an X-ray interferometer and changing the optical path difference to the sample. The configuration is such that the time during which different X-rays are applied to the sample is different. Then, by changing the optical path of the X-rays scattered from the sample and measuring in different regions with an X-ray camera, time resolution is not required on the measuring instrument side, and dynamics on the order of picoseconds can be measured. As a result, it becomes possible to capture changes in material properties at different times using a single X-ray pulse. In addition, the use of X-rays makes it possible to measure the dynamics of information inside a substance.

100, 200, 300, 400 X-ray imager 101 First optical system 102, 103 Second optical system 104 Third optical system 105 Fourth optical system 1a to 3a, 1b to 3b Crystal plate (first Optical system)
1c to 3c crystal plate (second optical system)
1d to 3d crystal plate (third optical system)
1e, 2e crystal plate (fourth optical system)
10, 20, 30 X-ray camera 40 large field of view detector

Claims (10)

An X-ray imaging device that observes the X-rays applied to the sample.
A first crystal plate group having a plurality of crystal plates arranged in the incident direction of X-rays including a plurality of wavelengths, and
A plurality of crystal plates that are arranged at a predetermined distance from the first crystal plate group and are incident with X-rays separated into a plurality of wavelengths by each crystal plate constituting the first crystal plate group. A first optical system having a second crystal plate group having the plurality of crystal plates, and an X-ray group containing each of the separated X-rays incident on the sample.
An X-ray imaging apparatus comprising. The X-ray imaging apparatus according to claim 1.
A plurality of crystal plates that separate X-rays of each wavelength included in the X-ray group incident on the sample, and the plurality of separated X-rays are incident on X-ray detectors at different positions. A second optical system having a third crystal plate group, which has a crystal plate of
An X-ray imaging apparatus comprising. The X-ray imaging apparatus according to claim 1.
An angle adjustment mechanism that can adjust the position and angle of a part or all of each crystal plate that constitutes each crystal plate group,
An X-ray imaging apparatus comprising. The X-ray imaging apparatus according to claim 2.
A plurality of crystal plates to which X-rays transmitted through the first crystal plate group are incident, and each of the X-rays having a plurality of wavelengths contained in the transmitted X-rays can be transferred to the second optical system. A third optical system having a fourth crystal plate group having the plurality of crystal plates incident on each crystal plate constituting the third crystal plate group,
An X-ray imaging apparatus comprising. The X-ray imaging apparatus according to claim 1.
A fourth optical system having a plurality of crystal plates for adjusting the incident direction of X-rays including the plurality of wavelengths incident on the first crystal plate group.
An X-ray imaging apparatus comprising. This is an X-ray imaging method for observing X-rays applied to a sample.
In the first optical system
X-rays containing a plurality of wavelengths are applied to a first crystal plate group having a plurality of crystal plates arranged in the incident direction of the X-rays.
The X-rays are separated into a plurality of wavelengths by each crystal plate which is arranged at a predetermined distance from the first crystal plate group and constitutes the first crystal plate group.
Separated X-rays are incident on each of the plurality of crystal plates constituting the second crystal plate group, and the separated X-rays are incident on each of the plurality of crystal plates constituting the second crystal plate group.
A group of X-rays including each of the incident X-rays is incident on the sample.
An X-ray imaging method characterized by this. The X-ray imaging method according to claim 6.
In the second optical system
X-rays of each wavelength included in the X-ray group incident on the sample are separated by a plurality of crystal plates constituting the third crystal plate group.
Each of the X-rays separated by the plurality of crystal plates is incident on the X-ray detectors at different positions.
An X-ray imaging method characterized by this. The X-ray imaging method according to claim 1.
The angle adjustment mechanism adjusts the position and angle of a part or all of the crystal plates constituting each crystal plate group, and incidents the X-ray group on the sample.
An X-ray imaging method characterized by this. The X-ray imaging method according to claim 7.
In the third optical system
X-rays transmitted through the first crystal plate group are incident on a plurality of crystal plates constituting the fourth crystal plate group.
With the plurality of crystal plates, each of the X-rays having a plurality of wavelengths contained in the transmitted X-rays is incident on each crystal plate constituting the third crystal plate group of the second optical system.
An X-ray imaging method characterized by this. The X-ray imaging method according to claim 6.
In the fourth optical system
The plurality of crystal plates adjust the incident direction of the X-rays including the plurality of wavelengths incident on the first crystal plate group.
An X-ray imaging method characterized by this.

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