JP2993147B2 - X-ray high-order light removal filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectroscopic technique for light in the wavelength range of soft X-rays, and more particularly to a filter device capable of removing higher-order diffracted light generated from a spectroscope.

[0002]

2. Description of the Related Art In recent years, with the development of a high-luminance light source such as a radiation light or a laser plasma X-ray source, the importance of a technique of dispersing light having a wavelength in a soft X-ray region and selecting a desired wavelength has increased. doing. In general, a spectroscope using a concave diffraction grating is used for wavelength selection in this wavelength range. For example, as shown in FIG. 5, the concave diffraction grating 3 is placed on a circle (Roland circle) 6 whose diameter is the radius of curvature R of the concave diffraction grating 3.
Are provided with an entrance slit 4 and an exit slit 5 sandwiching them.

[0003] The wavelength resolution of a spectroscope as shown in this figure is given by the following equation if the influence of aberration is ignored.

[0004]

(Equation 1)

Here, λ is the wavelength of the soft X-ray, R is the radius of curvature of the concave diffraction grating (diameter of the Rowland circle), d is the pitch of the diffraction grating, and a is the exit slit width. Accordingly, in this spectroscope, for example, for an X-ray having a wavelength of 20 °, the radius of curvature R is set to 2 m, and a
When zero diffraction gratings are used, λ / △ λ is 192 in the equation (1), and {λ is 0.1Å resolution.

[0006]

As described above, a spectroscope using a concave diffraction grating as shown in FIG. 5 can obtain a sufficient resolution for soft X-rays. In addition to the wavelength to be obtained (hereinafter referred to as the selected wavelength), there is a problem that higher-order light of the selected wavelength is always mixed.

That is, the dispersion condition by the concave diffraction grating and the basic formula of the Rowland circle image are given by the following equations, as is well known. d (sin α + sin β) = mλ (m = 0, ± 1, ± 2...) (2) where r ₁ = R · cos α, r ₂ = R · cos β, and α is incident on the concave diffraction grating. Angle, β is also the reflection angle,
r ₁ is the distance between the entrance slit and the concave diffraction grating, and r ₂ is the distance between the exit slit and the concave diffraction grating (see FIG. 5).

As is apparent from the equation (2), when light of the selected wavelength λ is to be obtained by spectroscopy, in addition to the light of the selected wavelength λ (m = 1), a fraction of the integer is used. Wavelength, ie λ /
Light having a wavelength of 2, λ / 3, λ / 4 (m = 2, 3, 4,...) (Hereinafter referred to as higher-order light) also satisfies the dispersion condition. come. Therefore, when using a light source such as synchrotron radiation that has a continuous spectrum over a wide range, such high-order light contamination is a serious problem because it makes the equipment using the selected wavelength malfunction and complicates the interpretation of the experimental results. Points.

Therefore, as a method of removing such higher-order light, light is incident on a mirror coated with platinum or the like at a very small oblique incidence angle in front of the spectroscope, and a high energy component (ie, a high energy component (ie, a high energy component) is obtained by total reflection of X-rays. Generally, a method of removing a high-order light wavelength region) and a method of using as a filter a thin film made of a substance that transmits only light of a desired wavelength and absorbs high-order light are generally used.

However, in the former method using the total reflection, all the X-rays having a wavelength longer than a certain wavelength value determined by the mirror surface material and the oblique incident angle are reflected. When trying to use lines, it has little effect on the removal of higher order light.

A filter utilizing the latter absorption can only reduce the secondary light, and has little effect on third- or higher-order light. Further, there is a problem that if the removal rate of the secondary light is increased, the transmittance of the primary light necessarily decreases. In addition, there is a problem that it is necessary to change the material of the filter every time the selected wavelength is changed, and there is a case where an appropriate filter material does not exist depending on the selected wavelength.

As described above, there is no effective means for completely removing high-order light emitted from the spectroscope at a wavelength in the soft X-ray region, and there is no significant means for conducting an experiment using the separated soft X-rays. Was an obstacle. The present invention has been made in view of such conventional problems, and has as its object to provide a high-order light removing filter based on a new concept that can completely remove high-order light from dispersed soft X-rays.

[0013]

According to the first aspect of the present invention, there is provided an X-ray high-order light for performing wavelength scanning by rotating a multilayer film plane reflecting mirror around an axis perpendicular to an incident surface. The removal filter is characterized in that the multilayer film is composed of a multilayer film in which two different substances are alternately laminated, and the thickness of each material layer is equal to each other.

Further, according to the second aspect of the present invention, two multilayer planar reflecting mirrors according to the first aspect are used, and the multilayer planar reflecting mirrors are opposed to each other in parallel, and each of the mirrors is maintained in a parallel state. A rotating means for rotating the multilayer planar reflecting mirror by the same angle.

[0015]

According to the first aspect of the present invention, as described above, two different materials A and B are alternately laminated, and the thicknesses d _A and d of the respective materials A and B are further increased. _B
Are used, and wavelength scanning is performed by rotating the mirrors about an axis perpendicular to the incident surface.

The incident light is X-ray diffracted light emitted from a spectroscope as shown in FIG. 5, and includes a selected wavelength separated by such a spectroscope and its higher-order light. Then, the angle of incidence is changed by rotating the multilayer film plane reflecting mirror around an axis perpendicular to the incident optical axis, thereby changing the selected wavelength and the wavelength of the higher-order light to be removed.

Further, according to the invention described in claim 2, according to claim 1
By using two multilayer planar reflecting mirrors described above and facing each other in parallel, the light reflected by one multilayer planar reflecting mirror is made incident again on the other multilayer planar reflecting mirror, and the above-described spectral separation is performed. X-ray diffracted light emitted from the vessel is reflected twice. Here, since the two multilayer film plane reflecting mirrors are opposed to each other in parallel, they are incident on the multilayer film plane reflecting mirror at the same incident angle.

Further, by rotating each multilayer film plane reflecting mirror by the same angle while maintaining the parallel state by the rotating means, the selected wavelength can be selected while the incident angles to the multilayer film plane reflecting mirrors are equal. In addition, the wavelength of the higher-order light to be removed is changed.

Here, the action of removing higher-order light in the present invention will be described. First, by making the thicknesses of the two substance layers constituting the multilayer film equal to each other, the reflected light intensity of the high-order light, particularly the secondary light, becomes weak.

That is, in the reflection at the multilayer film, the wavelength λ of the incident light, the oblique incident angle θ, and the period d of the multilayer film are as follows.
X-rays are reflected only when the following Bragg condition is satisfied, and hardly reflected where the condition is not satisfied. 2d sin θ = nλ (n is a positive integer) (3) where n is a positive integer and the order of reflection. Therefore, if the incident angle is constant, discrete wavelengths (n = 1, 2, 3)
... Have respective peaks.

Expression (3) is a diffraction condition when crystal planes having a thickness that can be neglected in X-ray diffraction are originally arranged at a period d. In the present invention, this is applied to a multilayer film that reflects X-rays, and a periodic structure is artificially created by alternately stacking two different substances with the same thickness.

An example of a thin film layer made of each material constituting this laminated structure is shown below. For example, a heavy atomic layer having large X-ray scattering and a light atomic layer having small scattering are combined and alternately laminated to form a crystal. A reflection state almost similar to that of the periodic structure of the surface is shown. Here, the combination of the heavy atomic layer and the light atomic layer is an example showing a material having high reflection efficiency as a selection criterion for different substances, and is not limited thereto.
Any substance can be used as long as it has a different scattering to X-rays.

Then, Br in the multilayer film according to the present invention is
The agg condition is satisfied when X-rays scattered by a layer made of a substance having higher scattering (for example, each of the heavy atom layers described above) interfere with each other with a phase shift of an integral multiple of 2π. .

Here, the point that the multilayer film reflection of the present invention differs from diffraction by a crystal is that a layer that scatters X-rays (hereinafter referred to as a “reflection layer”)
That. ) Cannot be ignored, and the incident light may not be reflected even if the Bragg condition is satisfied. That is, since the X-rays incident on the multilayer film are reflected by scattering inside the reflection layer (a difference occurs in the scattering position inside the reflection layer), the X-rays reflected by the scattering on one reflection layer are reflected. Has a phase width corresponding to the thickness of the substrate.

When the amplitude of the scattered light is represented by a sine wave, the amplitude of the X-ray scattered by the one reflection layer is proportional to the following equation.

[0026]

(Equation 2)

Here, α is the phase of the scattered light, P is the width of the phase corresponding to the thickness of the heavy atom layer, k is the wave number, and x is the coordinate taken in the traveling direction of the light. As is clear from the equation (4), even if the Bragg condition is satisfied,
When P = 2mπ (m: integer), the peak intensity of the reflected light is 0.

On the other hand, assuming that the period of the multilayer film of the present invention is d and the thickness of the reflection layer is d _H , the n-order reflected waves are shifted in phase by 2nπ in one layer, so that the scattered light The width of the phase is P = 2nπd _H / d. Therefore, when n = md / d _H (n, m: integer) is satisfied, the peak intensity of the reflected light becomes zero. For example, when d / d _H = 2, the peak intensity of even-order reflected light is 0, and when d / d _H = 3, the peak intensity of reflected light of a multiple of 3 is 0. The above discussion corresponds to the extinction theory in X-ray diffraction. Here, since the absorption is not taken into consideration, the peak intensity does not actually become exactly 0, but the peak intensity is much lower than the reflections of other orders.

In the present invention, since the thicknesses of the two layers constituting the multilayer film are equal to each other, it is possible to keep the secondary peak reflectance extremely low while maintaining the primary peak reflectance of the multilayer film high. I have. That is, according to the X-ray high-order optical filter according to the present invention, of the incident light including the high-order light from the spectroscope, the primary light is strongly reflected and the secondary light is hardly reflected, so that the secondary high-order light is removed. be able to.

In the reflection by the multilayer film, the center wavelength of the higher-order reflection peak is strictly a fraction of the center wavelength of the first-order reflection peak due to refraction of light and dispersion of the refractive index. (The wavelength of the higher order light of the incident light) and slightly deviates, and if the reflection peak of the primary light of the incident light is combined, the higher order light of the incident light (particularly, the third order light or more) is not reflected.

That is, in the above Bragg's equation, the influence of X-ray refraction is ignored. In the wavelength region of X-rays, the refractive index of the substance is close to 1 so that the refraction of X-rays is very slight, but the effect cannot be ignored when obliquely incident. Bragg's equation considering this refraction is given by the following equation. 2d sin θ (1−δ (λ) / sin ² θ) = mλ (5) where δ represents the real part of the refractive index of the material constituting the multilayer film (in the present invention, the average value of the two materials) ).

Since δ generally varies depending on the wavelength of the incident light (refractive index dispersion), in the reflection by the multilayer film, the central wavelength of the higher-order peak of the reflection intensity is exactly an integer fraction of the central wavelength of the primary peak. Not be. On the other hand, the wavelength of the higher-order light of the diffracted light emitted from the spectroscope is a fraction of the wavelength of the primary light, and the incident light incident on the multilayer film of the present invention includes this higher-order light.

Therefore, as shown in FIG. 3, the oblique incidence on the multilayer mirror is made such that the center wavelength of the primary peak of the reflection on the multilayer and the wavelength of the primary light emitted from the spectroscope coincide with each other. Angle θ
Is adjusted, the center wavelength of the higher-order peak of the multilayer reflection does not coincide with the wavelength of the higher-order light of the diffracted light coming from the spectroscope, and is slightly shifted.

At this time, if the half value width of the reflectance peak in the multilayer film is sufficiently smaller than this deviation amount, the high-order light coming from the spectroscope will not be reflected by the multilayer film, and the high-order light will be removed. The half width of the reflectance peak can be reduced by increasing the number of layers of the multilayer film to some extent. In the X-ray high-order light removing filter according to the present invention, the properties of such a multilayer film are particularly utilized to improve the quality of the filter.
Higher-order light of the second order or higher is also removed.

[0035] That is, in the present invention, when the two substances A, is B, the thickness d _A of each layer, is equal multilayer planar reflector d _B, by reflecting the diffracted light from the spectroscope All higher-order light contained therein is removed. At this time,
The angle of incidence of the diffracted light on the multilayer planar reflecting mirror may be set so that the center wavelength of the peak of the primary reflection by the multilayer film matches the wavelength of the primary light of the diffracted light from the spectroscope. Then, when performing wavelength scanning while changing the wavelength, the multilayer film plane reflecting mirror may be rotated so that the incident angle becomes an appropriate value according to the selected wavelength.

According to the second aspect of the present invention, two such multilayer film plane reflecting mirrors are used, and these are arranged so that the reflecting surfaces face each other in parallel, so that the diffracted light coming from the spectroscope can be used. Reflect twice.

In this case, the reflectivity of the n-th light (I _n ) of the higher-order light with respect to the reflectivity of the primary light (I ₁ ) in the multilayer film reflection.
Assuming that the ratio is I _n / I ₁ , this value becomes (I _n / I ₁ ) ² by reflecting twice as described above. Therefore, the rejection of the n-th order diffracted light is 1- (I _n / I ₁ ) ^2.
Therefore, by reflecting the light twice, the removal rate of high-order light is significantly increased.

When the wavelength scanning is performed by changing the selected wavelength, the two multi-layer reflecting mirrors are rotated by the rotating means while maintaining the parallel state with each other. The angle of incidence on the film reflecting mirror remains the same, and the light emission direction does not change. However, since the output optical axis moves in parallel with the wavelength scanning, one of the multi-layer reflecting mirrors may be translated in the optical axis direction simultaneously with the rotation (see FIG. 4). This makes it possible to keep the output optical axis from moving.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a multilayer planar mirror according to a first embodiment of the present invention. In this example, tungsten and carbon were used as materials for forming each layer. (Less than,
It is called a W / C multilayer film. (2) Tungsten and carbon were alternately laminated on a mirror-polished silicon substrate by rf magnetron sputtering to produce a multilayer planar reflector 1. Then, the thickness of the tungsten layer (d _A) and the equally 30Å Both the thickness of the layer of carbon (d _B), is formed so that the thickness d of one cycle (one-layer) is 60 Å, The number of layers of the multilayer film was set to 50 layers.

The multilayer film plane reflecting mirror 1 constructed as described above
As shown in FIG. 1, a high-order light elimination filter was configured so as to be rotatable about an axis perpendicular to the incident optical axis. Then, light having a continuous spectrum emitted from the radiated light is separated by a spectroscope using a concave diffraction grating as shown in FIG. 5, and the diffracted light 2 is incident on a high-order light removing filter according to this embodiment. Let me.

In this embodiment, the multilayer film flat reflecting mirror 1 is used.
When the angle of oblique incidence on light is fixed to 10 °, the primary peak wavelength of the multilayer reflection is 19.3 °, and the secondary and tertiary peak wavelengths are 10.15 ° and 6.90 °, respectively. Was. The reflectivity of the primary peak is 14.8%,
The reflectance of the next peak is 0.1%.

Therefore, 1
In the second reflection, the ratio of the secondary light reflection of the diffracted light 2 becomes 1/148 as compared with the reflection of the primary light. Therefore, the removal rate of the secondary light with respect to the primary light is 1- (1/14)
8) = 99.32%, and the secondary light is almost completely removed.

Further, the third-order reflectance of the multilayer reflection is 1.
Although it is 4%, the wavelength of the reflection peak is 6.90 ° and the peak half width is 0.04 °. On the other hand, 1
The wavelength of the next light is set to 1
The wavelength of the third order light of the diffracted light at 9.3 ° is 6.43.
Å.

Therefore, since the wavelength of the tertiary light of the diffracted light 2 does not overlap with the position of the tertiary peak of the multilayer film reflection, the tertiary light of the diffracted light 2 is not reflected by this multilayer film. At this time, the tertiary light removal rate of the diffracted light 2 is 99.93% or more,
Secondary light was removed. Then, the same or higher removal rate can be obtained in the same manner with respect to the fourth order or higher order light of the diffracted light 2, so that these are completely removed.

Next, the oblique incident angle on the multilayer flat mirror 1 was fixed at 20 °. At this time, the primary peak wavelength of the multilayer reflection is 39.0 °, and the secondary and tertiary peak wavelengths are:
They are 20.3 ° and 13.5 ° respectively. The reflectance of the primary peak is 3.7%, and the reflectance of the secondary peak is 0.04%.

Therefore, the ratio of the reflection intensity of the secondary light of the diffracted light 2 to the primary light in one reflection by the multilayer film plane reflecting mirror 1 is 4/370. Therefore, the rejection ratio of the secondary light of the diffracted light 2 to the primary light is 1- (4/370) = 98.9.
In this case, the secondary light is almost completely removed.

The third-order reflectivity of the multilayer film reflection is 3.0.
%, The wavelength of the reflection peak is 13.5 ° and the peak half width is 0.13 °. On the other hand, when the wavelength of the primary light from the spectroscope is set to 39.0 ° so as to coincide with the primary peak wavelength of the multilayer reflection in this case, the wavelength of the tertiary light is 1
3.0 °.

Therefore, also in this case, since the wavelength of the tertiary light of the diffracted light does not overlap the tertiary peak position of the multilayer film reflection at all, the tertiary light of the diffracted light is not reflected. At this time, the removal ratio of the third-order light of the diffracted light is 99.08% or more, the third-order light is completely removed, and the same applies to the fourth-order or higher-order light, and the same or higher. Is obtained.

As described above, in the multilayer planar reflecting mirror according to the present embodiment, a W / C multilayer film having one period d of 60 ° is used, and this is used at an oblique incidence angle of 10 ° to 20 °. Thus, a high-order light removing filter capable of efficiently removing the higher-order light in the selected wavelength range of 19 ° to 39 ° was realized.

For comparison, the higher-order light elimination rate in the case of a filter using a normal difference in absorption coefficient was examined. In this case, the linear absorption coefficient mu ₁ of X-rays is given by the following equation. μ ₁ = 4πβ / λ where β is the imaginary part of the refractive index and λ is the wavelength of the X-ray. When X-rays pass through a substance having a thickness of t, the X-rays are attenuated to exp (−μ ₁ t) by absorption. Therefore, the wavelength λ
_The ratio of the transmittance of the light of _{No. 2} to the transmittance of the light of the wavelength λ ₁ is exp (−μ ₂ t) / exp (−μ ₁ t).

[0051] Therefore, the removal rate of m-th order higher light ₁ a linear absorption coefficient at the wavelength of the primary light mu, m order light 1-exp (- [mu] _m linear absorption coefficient at a wavelength as mu _m of t) / exp (−μ ₁ t), and when a material satisfying μ _m > μ _{1 is} used, the higher-order light rejection increases as the thickness t of the filter increases.
The transmittance of the next light decreases.

By the way, as the material of the filter, a material having an absorption edge at a wavelength slightly shorter than the selected wavelength to be used is suitable because the absorption becomes small at a wavelength slightly longer than the absorption edge. Therefore, copper having an absorption edge at 13 ° was used for X-rays having a wavelength of 19.3 °. Then, for comparison with the example, the thickness of the filter was set to 0.55 μm so that the transmittance was the same. At this time, the removal rate of the secondary light was 76.9%. In addition, for tertiary light, 1
The transmittance was higher than that of the secondary light, and there was no effect as a filter.

On the other hand, for X-rays having a wavelength of 39.0 °,
Silver having an absorption edge at 31 ° was used, and the thickness of the filter was set to 0.4 μm so that the transmittance would be the same for comparison with the example. At this time, the secondary light removal rate is 9
It is 7.52%, which is lower than the embodiment of the present invention, and the tertiary light removal rate is 5.1%.

Next, a second embodiment of the present invention will be described. With the same specifications as in the first embodiment, two identical multilayer film plane mirrors 1A and 1B made of a W / C multilayer film are formed, and they are opposed to each other such that the reflection surfaces are parallel to each other as shown in FIG. I let it. Then, while maintaining the parallel state, the filter was held so as to be able to rotate by the same angle at the same time to constitute a high-order light removing filter.

Then, the light having a continuous spectrum emitted from the radiated light is split by a spectroscope using a concave diffraction grating as shown in FIG. 5, and the diffracted light 2 is used in the second embodiment. The light was incident on such a high-order light removal filter.

In this embodiment, the multilayer planar reflecting mirror 1
When the oblique incident angle on A is fixed to 10 °, the oblique incident angle on the multilayer flat-surface reflecting mirror 1B is also 10 °. The peak wavelength of the multilayer film reflection is the same as that of the first embodiment.
The secondary and tertiary peak wavelengths are 19.3 ° and 10.
5 ° and 6.90 °. The reflectance of one multilayer planar mirror is the same as that of the first embodiment. The reflectance of the primary peak is 14.8%, and the reflectance of the secondary peak is 0.1%.

Therefore, in this embodiment, the rejection rate of the secondary light of the diffracted light with respect to the primary light by the two reflections by the multilayer film plane reflecting mirrors 1A and 1B is 1- (1/148).
² = 99.995%, and the secondary light was completely removed. At this time, the filter transmission efficiency of the primary light is 2.
2%.

The tertiary reflectivity and peak wavelength in this embodiment are the same as those in the first embodiment. Therefore, the wavelength of the tertiary light of the diffracted light completely overlaps with the position of the tertiary peak of the multilayer film reflection. Therefore, the tertiary light is not reflected. The removal rate of the tertiary light of the diffracted light by the two reflections in this embodiment is 9
9.999% or more, and the tertiary light is completely removed.
Furthermore, the same removal rate can be obtained in the same manner for higher-order light of fourth order or higher of diffracted light.

Next, when the oblique incident angle of the diffracted light 2 is fixed at 20 °, the rejection ratio of the secondary light to the primary light after being reflected twice in this embodiment is 1- (4 / 370) ² = 9
9.988%, and the secondary light is completely removed. At this time, the transmittance of the primary light through the filter was 0.15%.

On the other hand, also in this embodiment, the tertiary light of the multilayer film does not overlap with the wavelength of the tertiary light of the diffracted light 2 because the tertiary peak of the reflected light does not overlap at all. For this reason, the removal rate of the tertiary light from the primary light after being reflected twice in this embodiment is:
99.99% or more, and the tertiary light was completely removed.
The same removal rate can be obtained in the same manner for the fourth-order or higher-order light.

As described above, in the second embodiment, the W / C multilayer film having a period d of 60 ° is formed by oblique incidence angles of 10 ° to 20 °.
Of the selected wavelength 19 ° to 39 °
A high-order light removal filter capable of completely removing high-order light in the range of Å has been realized.

The two multilayer film plane reflecting mirrors 1A and 1B
When the angle is changed, for example, as shown in FIG. 4, by moving one multilayer film plane reflecting mirror 1B in parallel to the optical axis direction, the optical axis of the emitted light does not move, and this selected wavelength is changed. The configuration of the device to be used can be simplified.

Here, for comparison, a higher-order light removal rate in the case of phytoloo using the above-described ordinary difference in absorption coefficient will be described. For X-rays having a wavelength of 19.3 °, 1
Although copper having an absorption edge at 3 ° was used, for comparison with the second embodiment, the thickness of the filter was set to 1.1 μm so that the transmittance was the same. At this time, the removal rate of the secondary light of the diffracted light was 94.3%. In addition, the transmittance of the third-order light was higher than that of the first-order light, and there was no filter effect.

Next, for X-rays having a wavelength of 39.0 °,
Silver having an absorption edge at 31 ° was used, and for comparison with the second embodiment, the thickness of the filter was set to 0.8 μm so that the transmittance was the same. At this time, the removal rate of the secondary light of the diffracted light is 99.92%, which is lower than the embodiment of the present invention, and the removal rate of the tertiary light is 10.0%, which is almost impossible to remove.

When a normal filter is used, only a substance whose absorption edge wavelength is shorter than the selected wavelength and longer than one half of the selected wavelength can be used. However, as the selected wavelength moves away from the absorption edge wavelength, higher-order light removal is performed. There is a problem that the rate decreases. Therefore, from 19 ° to 39
If an attempt is made to remove high-order light with a filter over the wavelength range of Å, there is a range in which a sufficient high-order light removal rate cannot be obtained.

However, according to the embodiment described above, X
Since the linear high-order light removal filter has nothing to do with the absorption edge of the substance, a high high-order light removal rate can be obtained as described above over the entire range of the wavelength region to be used. Also,
The above wavelength region is not limited to this, and can be used in other wavelength regions by changing the thickness and the incident angle of each layer of the multilayer film.

[0067]

As described above, in the X-ray high-order light removing filter according to the present invention, the secondary light is removed by making the thicknesses of the two materials of the multilayer film equal to each other, thereby reducing the refraction of the X-ray. Since higher order light is removed by using the effect of dispersion of the refractive index, the secondary light can be removed efficiently while maintaining the transmittance of the primary light to a certain extent. Third-order or higher light that cannot be obtained can be completely removed. Also, in conventional filters that use the difference in absorption coefficient, the higher-order light rejection rate decreases significantly as the selected wavelength moves away from the absorption edge wavelength of the filter material to the longer wavelength side, and furthermore, the wavelength range in which higher-order light cannot be removed depending on the selected wavelength. However, according to the present invention, there is an advantage that a high order light rejection can always be obtained over a wide wavelength range.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a high-order light removing filter using a multilayer planar reflecting mirror according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of a high-order light removing filter using two multilayer planar mirrors according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a state where a higher-order peak wavelength of a multilayer film deviates from a higher-order peak wavelength of a spectroscope due to refraction of X-rays and dispersion of a refractive index.

FIG. 4 is a configuration diagram when an optical axis is not moved in an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a spectroscope using a concave diffraction grating.

[Explanation of symbols]

 1, 1A, 1B: multilayer film plane reflecting mirror 2: diffracted light coming from a spectroscope 3: concave diffraction grating 4: entrance slit 5: exit slit 6: Roland circle

Claims (2)

(57) [Claims] 1. An X-ray high-order light removal filter that performs wavelength scanning by rotating a multilayer film plane reflecting mirror around an axis perpendicular to an incident surface, wherein the multilayer film alternately laminates two different substances, An X-ray high-order light removing filter, comprising a multilayer film having the same material layer thickness as each other. 2. Using two multilayer planar mirrors according to claim 1, each multilayer planar mirror is opposed to each other in parallel, and each multilayer planar mirror is identical while maintaining its parallel state. An X-ray high-order light removing filter comprising a rotating means for rotating by an angle.