JPH0511100A - X-ray high-order light elimination filter - Google Patents

Abstract

PURPOSE:To eliminate high-order light effectively and select only desired wave length by layering two different materials by turns and constituting a filter with the multilayer film of the same thickness of each layer. CONSTITUTION:An X-ray high-order light elimination filter utilizes a multilayer flat film reflection mirror formed by layering two different materials A and B by turns in the same thicknesses d1, d2. As the thicknesses of the two layers constituting the multilayer film are the same, the primary peak reflection factor of the multilayer film is kept high and the secondary reflection factor is suppressed very low at the same time. Since the central wave length of high- order peak does not become strictly the reverse of integer time of the central wave length of primary reflection peak and shifts slightly in the reflection in a multilayer film because of refraction of light and the dispersion of refraction factor, the coupling of reflection peak of the primary incidence light delets the reflection of the high-order light of the incidence light. By rotating a reflection mirror around the axis perpendicular to the surface of incidence, the incidence angle is varied and selected wave length and the high-order light wave length to be eliminated are varied. By this, effective elimination of the high- order light and the selection of desired wave length become possible.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, with the development of high-intensity light sources such as synchrotron radiation and laser plasma X-ray sources, the importance of a technique for separating light of a wavelength in the soft X-ray region and selecting a desired wavelength has increased. is doing. A spectroscope using a concave diffraction grating is generally used for wavelength selection in this wavelength range. For example, as shown in FIG. 5, the concave diffraction grating 3 is formed on a circle (Roland circle) 6 having a radius of curvature R of the concave diffraction grating 3.
There is one in which an entrance slit 4 and an exit slit 5 are provided with a space between them.

The wavelength resolution of the spectroscope as shown in this figure is given by the following equation, ignoring the influence of aberration.

[0004]

[Equation 1]

Here, λ is the wavelength of the soft X-ray, R is the radius of curvature of the concave diffraction grating (the diameter of the Rowland circle), d is the pitch of the diffraction grating, and a is the exit slit width. Therefore, in this spectroscope, for example, with respect to X-rays having a wavelength of 20 Å, the radius of curvature R is set to 2 m, and a is set to 50 μm.
If 0 diffraction grating is used, λ / Δλ becomes 192 in the equation (1), and Δλ can obtain a resolution of 0.1Å.

[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 high-order light of the selected wavelength is always mixed.

That is, the dispersion formula by the concave diffraction grating and the basic formula of Rowland circle image formation are given by the following equations as well known. d (sinα + sinβ) = 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 the light of the selected wavelength λ is to be spectrally obtained, in addition to the light of the selected wavelength λ (m = 1), it is Wavelength, λ /
Light having a wavelength of 2, λ / 3, λ / 4 ... (m = 2, 3, 4, ...) (hereinafter referred to as high-order light) also satisfies the dispersion condition, and therefore these are mixed in the diffracted light. come. Therefore, when using a light source with a continuous spectrum over a wide range, such as synchrotron radiation, such a mixture of higher-order light complicates the malfunction of the device using the selected wavelength and the interpretation of the experimental result, which is a serious problem. It becomes a point.

Therefore, as a method of removing such higher-order light, light is made incident on a mirror coated with platinum or the like in front of the spectroscope at a very small oblique incident angle, and high energy components (ie 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.

However, in the former method of utilizing total reflection, all X-rays having a wavelength longer than a certain wavelength value determined by the mirror surface material and the oblique incident angle are reflected, so that X having a relatively long wavelength in the soft X-ray region is reflected. When trying to use lines, it has little effect in removing higher order light.

Further, the latter filter utilizing absorption can reduce the secondary light, but has almost no effect on the tertiary or higher-order light. Further, if the removal rate of the secondary light is increased, the transmittance of the primary light is inevitably reduced. Further, there are also problems that it is necessary to change the material of the filter each 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 has been no effective means for completely removing the high-order light emitted from the spectroscope at the wavelength in the soft X-ray region, and it is a great problem in conducting an experiment using the dispersed soft X-rays. It was an obstacle. The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a high-order light removal filter based on a new concept that can completely remove high-order light from spectral soft X-rays.

[0013]

In order to solve the above-mentioned problems, in the invention according to claim 1, X-ray higher-order light for wavelength scanning by rotating a multilayer film flat reflecting mirror around an axis perpendicular to the incident surface. In the removal filter, the multi-layered film is formed by alternately stacking two different substances, and the layers of the respective substances have the same film thickness.

Further, in the invention described in claim 2, two multilayer film plane reflecting mirrors according to claim 1 are used, and the multilayer film plane reflecting mirrors are opposed to each other in parallel, and each of them is kept in the parallel state. The multi-layered film flat reflecting mirror is provided with a rotating means for rotating the same by the same angle.

[0015]

Since the invention according to claim 1 of the present application is configured as described above, two different substances A and B are alternately laminated, and one layer thickness d _A and d of each substance A and B is formed. _B
Are used to perform wavelength scanning by rotating the mirror about a shaft perpendicular to the incident surface.

This incident light is the diffracted light of the X-ray emitted from the spectroscope as shown in FIG. 5, and includes the selected wavelength and the higher-order light thereof which are spectroscopically separated by such a spectroscope. Then, the incident angle is changed by rotating the multilayer film flat reflecting mirror about an axis perpendicular to the incident optical axis, and the selected wavelength and the wavelength of the higher-order light to be removed are changed.

According to the second aspect of the invention, the first aspect is
By using two described multilayer flat mirrors to face each other in parallel, the reflected light reflected by one of the multilayer flat mirrors is re-incident on the other flat multilayer mirror, and the above-mentioned spectroscopic analysis is performed. The diffracted light of the X-ray emitted from the container 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 the respective multilayer film flat reflecting mirrors by the same angle while maintaining this parallel state by the rotating means, the selected wavelengths are kept in a state where the incident angles are equal to each other. Also, the wavelength of the higher-order light to be removed is changed.

Now, the function of removing high-order light in the present invention will be described. First, by making the thicknesses of the layers of the two substances constituting the multilayer film equal to each other, the reflected light intensity of the secondary light, especially the secondary light, becomes weak.

That is, in the reflection by the multilayer film, the wavelength λ of the incident light, the oblique incident angle θ, and the cycle d of the multilayer film are
X-rays are reflected only when the following Bragg conditions are satisfied, and almost no reflection occurs when these conditions are not satisfied. 2d sin θ = nλ (n is a positive integer) (3) Equation (3) Here, n is a positive integer and is the order of reflection. Therefore, if the incident angle is constant, the discrete wavelengths (n = 1, 2, 3
The reflectance has a peak for each wavelength).

By the way, the expression (3) is a diffraction condition when the crystal planes whose thickness is originally negligible in X-ray diffraction are arranged at the period d. In the present invention, this is applied to a multilayer film that reflects X-rays, and two different substances are alternately laminated with the same thickness to artificially create a periodic structure.

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

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

Here, the point that the multilayer film reflection of the present invention is different from the diffraction by crystals is a layer that scatters X-rays (hereinafter referred to as "reflection layer").
Say. The thickness of () is not negligible, and may not be reflected even if the incident light satisfies the Bragg condition. That is, since X-rays incident on the multilayer film are reflected by scattering inside the reflective layer (differences occur in scattering positions inside the reflective layer), X-rays reflected by scattering at one reflective layer are reflected. The width of the phase depends on the thickness of the.

When the amplitude of scattered light is represented by a sine wave, the amplitude of X-rays scattered by this one reflecting 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 in the traveling direction of the light. As is clear from the equation (4), even if the above Bragg condition is satisfied,
When P = 2mπ (m: integer), the peak intensity of reflected light becomes zero.

On the other hand, when the period of the multilayer film of the present invention is d and the thickness of the reflective layer is d _H , the reflected waves of the nth order are phase-shifted by 2nπ in one pair, and therefore the scattered light in the heavy atom layer is 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 0. For example, when d / d _H = 2, the peak intensity of the even-order reflected light is 0, and when d / d _H = 3, the peak intensity of the reflected light of a multiple of 3 is 0. The above discussion corresponds to the extinction theory in X-ray diffraction. Here, since absorption is not taken into consideration, it does not actually become exactly 0, but the peak intensity is much lower than reflections of other orders.

In the present invention, since the two layers constituting the multilayer film have the same thickness, the secondary peak reflectance of the multilayer film can be kept extremely low while the primary peak reflectance of the multilayer film is kept high. There is. That is, according to the X-ray high-order optical filter of 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.

Next, in the reflection by the multilayer film, the center wavelength of the higher-order reflection peak is exactly an integer 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 incident light is higher than the wavelength of the incident light (the wavelength of the higher-order light of the incident light), and is slightly shifted.

That is, in the above Bragg equation, the influence of X-ray refraction is neglected. In the wavelength range of X-rays, the refractive index of the substance is close to 1, so the refraction of X-rays is very small, but the effect cannot be ignored when it is obliquely incident. The Bragg 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 substance that constitutes the multilayer film (in the present invention, the average value of the two substances). ).

Since this δ generally differs depending on the wavelength of incident light (refractive index dispersion), the center wavelength of the higher-order peak of the reflection intensity is exactly an integral fraction of the center wavelength of the first-order peak in reflection by the multilayer film. Don't 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 first-order light, and the incident light entering the multilayer film of the present invention includes this higher-order light.

Therefore, as shown in FIG. 3, the oblique incidence on the multilayer reflecting mirror is made so that the center wavelength of the primary peak of the reflection on the multilayer film and the wavelength of the primary light emitted from the spectroscope coincide with each other. Angle θ
In addition, the central wavelength of the higher-order peak of the reflection of the multilayer film and the wavelength of the higher-order light of the diffracted light coming from the spectroscope do not match, and there is a slight deviation.

At this time, if the full width at half maximum of the reflectance peak in the multilayer film is sufficiently smaller than this deviation amount, the higher order light coming from the spectroscope will not be reflected by the multilayer film, and the higher order light will be removed. The full width at half maximum of the reflectance peak can be narrowed by increasing the number of layers of the multilayer film to some extent. The X-ray high-order light removal filter according to the present invention utilizes the properties of the multilayer film as described above, and particularly
It is supposed that high-order light higher than the second order will be removed.

That is, in the present invention, assuming that the two substances are A and B, the diffracted light from the spectroscope is reflected by the multilayer film plane reflecting mirror having the same thickness d _A and d _{B of the} respective layers. All high-order light contained therein is removed. At this time,
The incident angle of the diffracted light on this multilayer film plane reflecting mirror may be set so that the central wavelength of the peak of the first-order reflection by the multilayer film matches the wavelength of the primary light of the diffracted light from the spectroscope. Then, when wavelength scanning is performed by 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 they are arranged in parallel with each other so that their reflecting surfaces face each other. Reflect twice.

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

When wavelength scanning is performed by changing the selected wavelength, the rotating means rotates the two multilayer film reflecting mirrors while keeping them in parallel with each other. The incident angle to the film reflecting mirror remains the same, and the light emitting direction does not change. However, since the emission optical axis moves in parallel with the wavelength scanning, one of the multilayer film reflecting mirrors may be moved in parallel in the optical axis direction at the same time as the rotation (see FIG. 4). This makes it possible to prevent the outgoing optical axis from moving.

[0039]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a multilayer-film flat mirror according to the first embodiment of the present invention. In this example, tungsten and carbon were used as the material forming each layer. (Less than,
It is called a W / C multilayer film. ) On the mirror-polished silicon substrate, tungsten and carbon were alternately laminated by the rf magnetron sputtering method to form the multilayer film plane reflecting mirror 1. The thickness of the tungsten layer (d _A ) and the thickness of the carbon layer (d _B ) are both equal to 30Å, and the thickness d of one cycle (one layer) is 60Å, The number of layers of the multilayer film was 50 layers each.

The multi-layered film plane mirror 1 thus constructed
As shown in FIG. 1, a high-order light removal filter was constructed by holding it so that it could rotate around an axis perpendicular to the incident optical axis. Then, the light having a continuous spectrum emitted from the emitted light is dispersed by a spectroscope using a concave diffraction grating as shown in FIG. 5, and the diffracted light 2 is incident on the high-order light removal filter according to this embodiment. I am letting you.

In this embodiment, the multilayer flat mirror 1 is used.
When the oblique incidence angle to is fixed at 10 °, the first-order peak wavelength of the multilayer reflection is 19.3Å, and the second- and third-order peak wavelengths are 10.15Å and 6.90Å, respectively. It was The reflectance of the primary peak is 14.8%, which is 2
The reflectance of the next peak is 0.1%.

Therefore, the multilayer flat mirror 1
The second-order light reflection of the diffracted light 2 after the first reflection is 1/148 in comparison with the first-order light reflection. Therefore, the removal rate of the secondary light from 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 film reflection is 1.
Although it is 4%, the wavelength of the reflection peak is 6.90Å and the peak half width is 0.04Å. On the other hand, 1 from the spectroscope
Match the wavelength of the next light with the primary peak of the multilayer reflection, and
The wavelength of the third-order light of the diffracted light is 6.4 when assuming 9.3Å.
It is Å.

Therefore, since the wavelength of the third-order light of the diffracted light 2 does not overlap with the third-order peak position of the multilayer film reflection, the third-order light of the diffracted light 2 is not reflected by this multilayer film. At this time, the removal rate of the third-order light of the diffracted light 2 is 99.93% or more, which is 3
The next light was removed. Then, the removal rates equal to or higher than those of the diffracted light 2 of the fourth and higher orders are obtained in the same manner, so that these are completely removed.

Next, the oblique incidence angle on the multilayer flat mirror 1 was fixed at 20 °. At this time, the first-order peak wavelength of the multilayer film reflection is 39.0Å, and the second- and third-order peak wavelengths are
They are 20.3Å and 13.5Å 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 is 4/370 by one reflection by the multilayer film plane reflecting mirror 1. Therefore, the removal rate of the secondary light of the diffracted light 2 with respect to the primary light is 1- (4/370) = 98.9.
2%, and in this case as well, the secondary light is almost completely removed.

The third-order reflectance of the multilayer reflection is 3.0.
%, But the wavelength of the reflection peak is 13.5 Å and the peak half width is 0.13 Å. On the other hand, when the wavelength of the primary light from the spectroscope is matched with the primary peak wavelength of the multilayer film reflection in this case to be 39.0Å, the wavelength of the tertiary light is 1
It is 3.0Å.

Therefore, also in this case, the wavelength of the third-order light of the diffracted light does not overlap with the third-order peak position of the reflection in the multilayer film at all, so that the third-order light of the diffracted light is not reflected. At this time, the removal rate of the third-order light of the diffracted light is 99.08% or more, the third-order light is completely removed, and the same is true for the higher-order light of the fourth-order or higher, and the same or higher. The removal rate of is obtained.

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

For comparison, the high-order light removal rate in the case of a filter utilizing the usual difference in absorption coefficient was examined. In this case, the X-ray absorption coefficient μ ₁ 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. Further, when X-rays pass through a substance having a thickness t, the X-rays are attenuated to exp (−μ ₁ t) by absorption. Therefore, the wavelength λ
_The ratio between the transmittance of the light of _{No. 2} and the transmittance of the light of 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 if a material having μ _m > μ _{1 is} used, the higher order light removal rate increases as the filter thickness t increases, but at the same time
The transmittance of the next light is reduced.

By the way, as the material of the filter, since the absorption becomes small at a wavelength slightly longer than the absorption edge, a material having an absorption edge at a wavelength slightly shorter than the selected wavelength to be used is suitable. Therefore, for X-rays having a wavelength of 19.3Å, copper having an absorption edge at 13Å was used. 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%. Also, 1 for 3rd order light
The transmittance was higher than that of the next light and there was no effect as a filter.

On the other hand, for X-rays with a wavelength of 39.0Å,
Silver having an absorption edge at 31 Å was used, and the thickness of the filter was set to 0.4 μm so that the transmittance was the same for comparison with the example. At this time, the removal rate of the secondary light is 9
The ratio is 7.52%, which is lower than that of the embodiments of the present invention, and the removal rate of the third-order light is 5.1%, which is a problem that the removal is hardly possible.

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 these are opposed to each other so that their reflecting surfaces are parallel to each other, as shown in FIG. Let Then, the high-order light removal filter was constructed by holding the parallel state so that they can be rotated by the same angle.

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

In this embodiment, the multilayer flat mirror 1 is used.
When the oblique incident angle on A is fixed at 10 °, the oblique incident angle on the multilayer film flat reflecting mirror 1B is also 10 °. The peak wavelength of the reflection of the multilayer film is similar to that of the first embodiment.
The second and third peak wavelengths are 19.3Å and 10.
They are 5Å and 6.90Å. The reflectance of one multilayer flat mirror is similar to 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 removal rate of the diffracted light from the secondary light reflected by the multilayered film flat reflecting mirrors 1A and 1B with respect to the primary light 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.
It was 2%.

The third-order reflectance and the peak wavelength in this embodiment are the same as those in the first embodiment. Therefore, the wavelength of the third-order light of the diffracted light completely overlaps with the third-order peak position of the multi-layer film reflection. Therefore, the third-order light is not reflected. The removal rate of the third-order light of the diffracted light is 9 due to the twice reflection in this embodiment.
It is 9.999% or more, and the third-order light is completely removed.
Furthermore, a removal rate equivalent to this can be obtained in the same manner for diffracted light of higher than 4th order.

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

On the other hand, also in this embodiment, since the third-order peak of the multilayer film reflection and the wavelength of the third-order light of the diffracted light 2 do not overlap at all, the third-order light is not reflected. Therefore, the removal rate of the third-order light from the first-order light after being reflected twice in this example is
It was 99.99% or more, and the third-order light was completely removed.
Then, a removal rate equivalent to this can be similarly obtained for higher-order light of 4th order or higher.

As described above, in the second embodiment, the W / C multilayer film having the period d of 60Å is used for the oblique incident angle of 10 ° to 20 °.
When used in the range of,
A high-order light removal filter that can completely remove high-order light in the range of Å was realized.

It should be noted that the two multilayer flat mirrors 1A and 1B are
When the angle of is changed, for example, as shown in FIG. 4, by moving one of the multilayer film plane reflecting mirrors 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 used can be simplified.

Here, for comparison, the high-order light removal rate in the case of a filter using the above-mentioned difference in normal absorption coefficient will be described. For X-rays with a wavelength of 19.3Å, 1
Although copper having an absorption edge at 3Å 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%. Further, the transmittance of the third-order light was higher than that of the first-order light, and the effect of the filter was not obtained.

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

When a normal filter is used, only a substance having an absorption edge wavelength shorter than the selected wavelength and longer than half the selected wavelength can be used. There is a problem that the rate decreases. Therefore, from 19Å to 39 as shown in this embodiment.
When trying to remove high-order light with a filter over the wavelength range of Å, there is a range where a sufficient high-order light removal rate cannot be obtained.

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

[0067]

As described above, in the X-ray high-order light removal filter according to the present invention, the secondary light is removed by making the thicknesses of the two substances of the multilayer film equal to each other, and the X-ray refraction is suppressed. Since the higher order light of higher order is removed by using the effect of dispersion of the refractive index, it is possible to efficiently remove the second order light while maintaining the transmittance of the first order light to some extent. It is possible to completely remove the high-order light of the third order or higher, which cannot be performed. Further, in the filter utilizing the conventional difference in absorption coefficient, the higher-order light removal rate is greatly reduced as the selected wavelength is separated from the absorption edge wavelength of the filter material to the longer wavelength side, and further, the higher-order light cannot be removed depending on the selected wavelength. However, according to the present invention, there is an advantage that it is possible to always obtain a high high-order light removal rate over a wide wavelength range.

[Brief description of drawings]

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

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

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

FIG. 4 is a configuration diagram in a case where an optical axis is kept stationary 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 flat mirror 2 ... Diffracted light coming from the spectroscope 3 ... concave diffraction grating 4 incident slit 5: exit slit 6 ... Roland Yen

Claims (2)

[Claims] 1. An X-ray high-order light removal filter that performs wavelength scanning by rotating a multilayer film flat mirror about an axis perpendicular to an incident surface, wherein the multilayer film alternately stacks two different substances, An X-ray high-order light removing filter, wherein the X-ray high-order light removing filter is formed of a multilayer film in which the film thicknesses of the substance layers are the same. 2. The two multilayer film plane reflecting mirrors according to claim 1 are used, each multilayer film plane reflecting mirror is made to face each other in parallel, and each multilayer film plane reflecting mirror is the same while keeping the parallel state. An X-ray high-order light removal filter, which is provided with a rotating means for rotating by an angle.