JPH0519680B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The invention of this application is directed to
It converges a linear beam onto a position where a analysis sample is placed, for example, and relates to a large diameter and bright X-ray lens.

(b) Prior Art In the wavelength region of X-rays having wavelengths on the order of angstroms, it is extremely difficult to obtain optical elements with good transmission or reflection efficiency equivalent to lenses and mirrors in general optical systems.

Although the purpose of use is different, a curved crystal like a mirror for performing spectroscopy has the same light focusing effect as a mirror, but the X-ray beam enters the curved crystal, is reflected, and then turned back. Sometimes, most of the X-ray beam is absorbed by the curved crystal, and only about 1/1000 of the incident X-ray beam can be irradiated onto the analysis sample, which is extremely inefficient.

As a very recent new technology, a technology has been proposed that attempts to converge the X-ray beam using a lens with a concentric lattice called a zone plate, which has the same effect as a convex lens, but it is still in the realm of practical application. has not been reached.

According to this proposal, an X-ray beam diverging from an X-ray light source is incident on a zone plate, and when it passes through the zone plate, it is diffracted in a certain direction, and an X-ray beam of a certain specific wavelength is converged to one point. This is what we are trying to do.

This will be explained with reference to FIGS. 1a and 1b.

FIG. 1A schematically shows the zone plate 1 viewed from the side into which the X-ray beam is incident, and the white portion is a grating through which the X-ray beam passes. Same figure b
, a position P at a distance a from the zone plate 1
An X-ray beam diverged from an X-ray light source located at is diffracted by the zone plate 1 in a certain specific direction and converged at a point Q at a distance b from the zone plate 1.

At the current technological level, the aperture that can be manufactured for a single zone plate as described above is determined by the wavelength of the X-ray beam, and at a wavelength of about 100 Å, the aperture is at most about 3 mm, and about 10 Å. The wavelength is about 1 mm. As described above, since the aperture of the zone plate that can be manufactured is small, the lens is very dark, and has the disadvantage that it cannot provide a level of brightness worthy of practical use.

(C) Purpose The invention of this application solves the drawbacks of the prior art described above, and the first invention is to make a parallel X-ray beam generated from an X-ray light source enter a group of diffraction gratings, By making the transmitted X-ray beam incident on a group of zone plates arranged at positions on the circumference of the focal length and converging it to one point, we can provide a bright and large-diameter X-ray lens and produce X-rays with high wavelength purity. The purpose is to obtain the second
In the invention, an X-ray beam diverging from an X-ray light source is made incident on a first zone plate group arranged at positions on the circumference of the focal length, and an X-ray beam passing through this is made incident on a diffraction grating group. , the X-ray beam that has passed through this is incident on a second zone plate arranged at positions on the circumference of the focal length, and is converged to one point, thereby providing a bright and large-diameter X-ray lens, and The purpose is to obtain X-rays with high wavelength purity.

(D) Structure The first invention of this application allows only the X-ray beam of a certain wavelength to pass through a parallel X-ray beam diverging from an X-ray light source through a group of diffraction gratings, and then passes through a group of multiple zone plates. The second invention makes the X-ray beam diverged from the X-ray light source enter the first zone plate group, and the X-ray beam that has passed through it is focused on the focal point of the zone plate group. The X-ray beam is made incident on a group of diffraction gratings, and only an X-ray beam of a certain specific wavelength is allowed to pass therethrough, and is made incident on a second group of zone plates where it is converged at its focal point.

(e) Examples The first invention and the second invention of this application will be explained below using examples.

Figure 2 shows something related to the first invention of this application, in which figure a is a side view of an embodiment of the X-ray lens of the first invention, and figure b is a view from the side into which the X-ray beam is incident. Figure c shows a schematic diagram of a diffraction grating in which the incident X-ray beam is diffracted and only the X-ray beam of a specific wavelength is allowed to pass through.

In Figure 2a, B is a parallel X-ray beam generated from an X-ray light source (not shown), 2 is a transmission type diffraction grating group, and this diffraction grating group 2 shields unnecessary diffracted light and scattered light. Shield plates 21 _a , 21
Diffraction gratings 2 ₁ , 2 ₂ , sandwiched by _b , ...21 _o
...2 _o-1 , and are arranged in a direction perpendicular to the X-ray beam B. 1 indicates a large number of zone plate groups, including shield plates 11 _a , 11 _b ,...11
Zone plates 1 ₁ , 1 ₂ ,... held by _o
1 _o-1 , focal length ₁ centered at focal point F ₁
They are arranged at positions on the circumference of the circle. In addition,
Zone plates 1 ₁ , 1 ₂ , ...1 _o-1 are diffraction gratings 2 ₁ ,
2 ₂ ,...2 _o-1 are arranged in a direction perpendicular to the traveling direction of the main beam passing through them.

To explain the action of the X-ray lens with such a configuration, a parallel X-ray beam B generated from an X-ray light source (not shown) travels toward the right in the drawing, and unnecessary diffracted light and scattered light are transmitted to the diffraction grating group 2. shield plate _21a ,
21 _b ,...21 _o , and the diffraction grating 2
₁ , 2 ₂ , ...2 _o-1 .

As shown in FIGS. 2b and 2c, a parallel X-ray beam B from an X-ray light source (not shown) enters a diffraction grating ₂₁ schematically shown by black lines, and an X-ray beam of a certain wavelength is generated. Only B is subjected to β angle diffraction and is made incident on the next stage zone plate ₁₁ . Other diffraction gratings 2 ₂ , 2 ₃ ,...
2 _o-1 similarly allows only the X-ray beam B of a certain wavelength to pass in the direction of the focal point F ₁ , and the zo plates 1 ₂ ,
1 ₃ ,...1 _o-1 . X-ray beam B passing through each zone plate 1 ₁ , 1 ₂ , ...1 _o-1
Due to the focusing effect of the zone plate, the principal beam of light is focused, for example, at a focal point F ₁ where an analysis sample (not shown) is placed.

Next, an example of the X-ray lens according to the second invention of this application will be described. FIG. 3a is a side view of the embodiment, and FIG. 3b is a diagram illustrating the principle by which the X-ray beam diverged from the X-ray light source is converged to a convergence point.

In FIG. 3a, F ₁ is a focal point where an X-ray light source (not shown) is placed, and the X-ray beam B diverged from this focal point advances toward the right in the drawing. 1
is a large number of zone plates 1 ₁ , 1 ₂ , at a position on the circumference centered on the focal point F ₁ and having a focal length ₁ in a direction perpendicular to the X-ray beam B that advances while diverging.
...1 _o-1 , and shield plates 11 _a , 11 _b , ... 11 _o that sandwich these zone plates. 2 is a group of diffraction gratings, including diffraction gratings 2 ₁ , 2 ₂ , ...2 _o-1 and shield plates 21 _a , 21 _b , ... 2 that sandwich these diffraction gratings.
It consists of 1 _o . 3 is a second zone plate group, which is arranged in a direction perpendicular to the traveling direction of the X-ray beam B that has passed through the diffraction grating group 2;
and zone plates 3 ₁ , 3 ₂ , ... 3 _o- arranged at positions on the circumference of a focal length ₂ centered on the focal point F ₂ .
₁ and shield plates 31 _a , 31 _b , . . . 31 _o that sandwich these zone plates.

The operation of the X-ray lens having such a configuration will be explained.

An X-ray beam B diverging from an X-ray light source (not shown) placed at a focal point F ₁ travels toward the right side of the drawing while diverging, and _the X-ray beam B diverges from the is incident on zone plate group 1 of .
The first zone plate group 1 allows only the X-ray beam B having a certain specific wavelength to pass through the respective corresponding diffraction gratings 2 in parallel, and travels toward the diffraction grating group 2. Shield plate 21 _a of diffraction grating group 2,
21 _b ,...21 _o shield unnecessary diffracted light and scattered light, and the remaining X-ray beam B is transmitted to the diffraction grating 2.
₁ , 2 ₂ , ...2 _o-1 . Diffraction grating 2 ₁ , 2
₂ ,...2 _o-1 , of the X-ray beam B incident thereon, only the X-ray beam B having a specific wavelength is diffracted in the direction of the corresponding second zone plate group 3,
The light is incident on the second zone plate group 3 arranged at positions on the circumference of a focal length ₂ centered on the focal point _F2 . The second zone plate group 3 converges the incident X-ray beam B to, for example, a focal point F ₂ where an analysis sample is placed.

In Figure 3b, the X emitted from the X-ray source
The linear beam B is incident on the zone plate of the first zone plate group ₁ , and this zone plate ₁
The X-ray beam B ₁ that has passed through the shield plates 21 _a and 21 _b
The beam is incident on the diffraction grating 2 _1-1 held between the two at an incident angle θ ₁ , is diffracted by an exit angle θ ₂ , and is emitted toward the zone plate 3 ₁ of the second zone plate group 3 . Let the incident angle θ ₁ to the diffraction grating 2 ₁ , the exit angle θ ₂ , the wavelength of the emitted X-ray beam B be λ, the interval between the diffraction gratings 2 _1-1 and 2 _1-2 , and the diffraction order P. As is well known as the basic form of diffraction, the relationship is sinθ ₂ −sinθ ₁ = (λ/d), (P
=0, ±1, ±2, ...).

In order to diffract the X-ray beam B ₁ diverged from the focal point F ₁ in the direction of the focal point F ₂ , the incident angle θ ₁ , the exit angle θ ₂ , and the lattice spacing d must satisfy the above formula. It becomes necessary. As a first means, the spacing of the diffraction gratings 2 _1-1 , 2 _1-2 , 2 _1-3 , ... may be made different from d ₁ , d ₂ , ..., respectively, or as a second means, the grating spacing d may be changed. The diffraction gratings 2 _1-1 and 2 are arranged so that the incident angle θ ₁ and the exit angle θ ₂ are different when they are constant.
_1-2 ,... must be tilted respectively.

In the description of the embodiments of the first invention and the second invention of this application, a case is described in which a zone plate is also provided on the central axis connecting the focal point and the diffraction grating. Only the zone plate that is used may be omitted.

As described above, the X-ray lenses of the first invention and the second invention of this application have a large aperture, are bright, and can thereby obtain an X-ray beam with high wavelength purity. High analysis results can be obtained.

(F) Effect As explained above, according to the first invention of this application, parallel X-ray beams are made incident on the diffraction grating group, and only X-ray beams of a specific wavelength are made incident on the zone plate group and converged. Because there is, the caliber is large,
According to the second invention, a bright X-ray lens can be provided, and an X-ray beam with high wavelength purity can be obtained. The X-ray beam that has passed through the plate group is made to enter the diffraction grating group, and only the X-ray beam of a specific wavelength is made to enter the second zone plate group for convergence. , a bright X-ray lens can be provided, and an X-ray beam with high wavelength purity can be obtained.

[Brief explanation of the drawing]

Figure 1 shows a conventional zone plate, Figure a is a schematic diagram of the zone plate, Figure b is a diagram showing an optical system using the zone plate, and Figure 2 is related to the first invention of this application. Figure a is a side view of the example, Figure b is a schematic view of the diffraction grating viewed from the front, and Figure c is a diagram of the X passing through the diffraction grating.
FIG. 3 is a diagram illustrating the state in which a linear beam is diffracted, and FIG. 3 shows something related to the second invention of this application, FIG. 3A is a side view of the embodiment, and FIG. It is. In the figure, 1 is a zone plate group in the first invention, a first zone plate group in the second invention, 2 is a diffraction grating group, 3 is a second zone plate group, 11 _a , 11 _b , ...11 _o is the shield plate of the zone plate, 1 ₁ , 1 ₂ , ...1 _o-1 is the zone plate, 21 _a , 21 _b , ... 21 _o is the shield plate of the diffraction grating, 2 ₁ , 2 ₂ , ... 2 _{o -1} is a diffraction grating, 31 _a ,
31 _b ,...31 _o are the shield plates of the zone plate,
3 ₁ , 3 ₂ , ...3 _o-1 indicates the zone plate.

Claims (1)

[Claims] 1. A diffraction grating group that allows an X-ray beam having a specific wavelength to pass from a parallel X-ray beam emitted from an X-ray light source, and a diffraction grating group through which an An X-ray lens comprising a group of zone plates arranged at circumferential positions with a focal length of ₁ . 2. A first zone plate group arranged at a circumferential position with a focal length of ₁ around the X-ray light source, and only an X-ray beam of a specific wavelength from the X-ray beam passing through the first zone plate group. a group of diffraction gratings that pass through the group of diffraction gratings, and a group of second zone plates that receive the X-ray beam of a specific wavelength that has passed through the group of diffraction gratings and are arranged at positions on a circumference centered on the focal length ₂ . X-ray lens.