JPH1151881A - X-ray imaging device and x-ray imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the spatial resolution of a phase contrast X-ray imaging device. SOLUTION: This device is provided with an X-ray generation source 1 generating an X-ray, an X-ray interferometer 3 making the X-ray incident light, and an X-ray detector 7 detecting an X-ray interference image emitted from the X-ray interferometer 3. In this case, a means for positioning the X-ray detector 7 and another means for positioning the X-ray detectors 7 at respective different positions and synthesizing a plurality of the detected interference images by calculation using the shape of a detection element. As a result, the spatial resolution of the X-ray detector 7 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an X-ray imaging apparatus and an X-ray imaging apparatus.
The present invention relates to an apparatus and a method for nondestructively inspecting the inside of an object, which relates to a line imaging method.

[0002]

2. Description of the Related Art As a technique for non-destructively observing the inside of a sample containing a large amount of light elements such as oxygen and carbon, Japanese Patent Application Laid-Open No.
No. 48262, JP-A-8-25
No. 4510, for example. In the above example, the inside of the sample is observed from a phase change generated when X-rays pass through the sample, using a Mach-Zehnder interferometer using a crystal as an optical element. In this interferometer,
The incident beam is split into a beam 1 and a beam 2 by the first half mirror. Then, the beam 1 is reflected by the first mirror and the beam 2 is reflected by the second mirror, and overlaps and interferes again at the second half mirror. When the interferometer is ideally configured and there is no optical path difference between the beam 1 and the beam 2, the spatial intensity distribution of the interference light emitted from the interferometer becomes uniform.

When a sample is placed in one of the optical paths of the beam 1 or the beam 2, the phase of the X-ray transmitted through the sample changes according to the difference in the refractive index in the sample. As a result, the second
The intensity of the interference light emitted from the half mirror depends on the difference in the refractive index in the sample. Therefore, the spatial distribution of the refractive index in the sample can be detected by measuring the spatial intensity distribution of the interference light.

It is known that a phase change of an X-ray transmitted through a light element such as oxygen or carbon is about 1000 times larger than a change in amplitude due to absorption. Therefore, the inside of the sample can be observed with high sensitivity by using the above method. Further, since the refractive index is extremely small in the X-ray region, ordinary optical elements such as a plane mirror used for visible light cannot be used. Therefore, each optical element of the interferometer is
And the like, and utilizes the X-ray diffraction and transmission phenomena caused by the crystal.

[0005]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 4-34826
No. 2, JP-A-8-254510.
In an X-ray imaging apparatus or a non-destructive inspection apparatus as described in Japanese Patent Application Laid-Open Publication No. H10-209, the spatial resolution of the apparatus is limited by the spatial resolution of the X-ray detector used. For example, in a CCD camera generally used, the size of a detection element is at least about 10 microns square, and therefore, the spatial resolution of an X-ray imaging apparatus can be obtained only about several tens microns. An object of the present invention is to improve the spatial resolution of an X-ray imaging device.

[0006]

According to the present invention, there is provided an X-ray source for generating X-rays, an X-ray interferometer using X-rays as incident light, and an X-ray for detecting X-rays emitted from the X-ray interferometer. In an X-ray imaging apparatus equipped with a detector, means for positioning the X-ray detector, and positioning of the X-ray detector at different positions, and combining a plurality of X-ray interference images detecting the same region by calculation. This problem is solved by adding a means for performing the above to a conventional X-ray imaging apparatus, thereby realizing a detection spatial resolution exceeding the spatial resolution of the X-ray detector.

Hereinafter, the calculation used in the present invention will be described for a one-dimensional interference image.

An X-ray having a spatial intensity distribution shown in FIG.
It is assumed that I0 is incident on the X-ray detector. The width of this incident X-ray I0
It is detected by an X-ray detector composed of W detection elements. At this time, the incident X-ray I0 is spatially averaged by the width W of the detection element. Therefore, the signal I1 (j) output from the j-th detection element of the X-ray detector is given when the detection efficiency of the detector is n.

[0009]

(Equation 1)

## EQU1 ## FIG. 2 shows a signal {I1 (j)} = {I1 (1), I1 (2),..., I1 (N)} output from each detection element.

Next, the X-ray detector is moved by an amount dW smaller than the width w of the detection element to detect the same incident X-ray I0.
At this time, the signal I2 (j) output from the j-th detecting element of the X-ray detector is

[0012]

(Equation 2)

## EQU1 ## Hereinafter, this process is repeated m times until the total movement amount of the detector becomes the width w of the detector, and the signal {I3
(Im (j)} is detected from (j)}.

Next, the detected signal {Ii (j)} (i = 1,.
As shown in FIG. 3, synthesis is performed while maintaining the intensity and position of each measurement point to obtain a synthesized signal {I (j)} (j = 1,..., MN). By this combination, the composite signal {I (j)} becomes

[0015]

(Equation 3)

## EQU1 ## FIG. 4 shows the composite signal {I (j)}. As can be seen from Equation 3, {I (j)} is equivalent to the result of measuring the incident X-ray I0 while moving the X-ray detector composed of a single detection element having a width W by dW. Therefore, the detection efficiency n

[0017]

(Equation 4)

When expressed as a function of location

[0019]

(Equation 5)

It can also be described as:

Next, the incident X-ray I0 is converted into discrete data {I'0 (j)}.

[0022]

(Equation 6)

Similarly, the detection efficiency n (x) is similarly calculated by discrete data

[0024]

(Equation 7)

[Mathematical formula-see original document]

[0026]

(Equation 8)

## EQU1 ## This equation is commonly called convolution.

The convolution operation is a reversible operation. Therefore, since n (j) is already known, the spatial distribution {I′0} of the incident X-ray is obtained from the composite signal {I (j)} by performing deconvolution processing which is the inverse operation of convolution on Equation 8. (j)}. FIG. 5 shows the result of deconvolution processing of the synthesized signal {I (j)}.
It can be seen that almost the same spatial distribution as that of the incident X-ray I0 has been reproduced.

As described above, the X-ray detectors are positioned at different positions, a plurality of X-ray interference images that have detected the same area are combined by calculation, and deconvolution processing is performed. To achieve a detection spatial resolution that exceeds the spatial resolution of the detector.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 6 shows a first embodiment of the present invention, and FIG. 7 is a sectional view thereof.
The apparatus mainly comprises an X-ray source 1, a spectroscope 2, an X-ray interferometer 3, an X-ray detector 7, an image processing unit 10, a sample and sample holders 5, 6. The entire apparatus is installed on a vibration isolation mechanism 4 to remove vibrations from the surroundings.

The X-rays emitted from the X-ray source 1 are monochromatized by the spectroscope 2 and incident on the X-ray interferometer 3. The incident X-ray is the first
The beam is split into a first beam and a second beam by the half mirror 31. The first beam penetrates the sample 5 and the second half mirror 3
Partially reflected at 2. The second beam is the second half mirror 3
It is reflected at 2. Then, the first beam and the second beam are combined again on the third half mirror 33 to form an interference image. The X-ray interferometer 3 may be an integral type as shown in this embodiment, or may be a type in which each half mirror is separated. Further, a total reflection mirror may be used as the second half mirror.

The X-ray interference image emitted from the X-ray interferometer 3 is detected by an X-ray detector 7. Since the X-ray detector 7 is installed on the detector moving mechanism 8, the X-ray detector 7 can be moved by the detector moving mechanism 8. The control of the movement of the detector moving mechanism 8 is performed by the control mechanism 10. Further, the control mechanism 10 is linked with the computer 9, and can alternately repeat the movement of the X-ray detector 7 and the measurement of the interference image. At this time, by making the amount of movement of the X-ray detector 7 per one time constant, the spatial resolution of the image obtained as a result of the calculation can be made constant regardless of the location. In addition, the smaller the amount of movement per operation, the higher the spatial resolution by calculation.

The image processing unit 9 performs a deconvolution process on the plurality of X-ray interference images output from the computer 9 using the shape of the detection element, and displays the result. here,
As a method of deconvolution, it may be obtained by dividing the Fourier-transformed X-ray interference image data by the shape of the Fourier-transformed detection element, or may be obtained by repeated calculation in real space.

According to this embodiment, the X-ray detector is moved,
The X-ray detectors can be positioned at different positions to detect X-ray interference images in the same region, and the detected X-ray interference images can be combined by calculation. Therefore, the spatial resolution of the X-ray imaging device can be improved.

Second Embodiment In the first embodiment, the X-ray detector 7 moves only one axis. Therefore, only the spatial resolution in the moving direction of the X-ray detector 7 can be improved. In the second embodiment shown in FIG. 8, a mechanism for two-dimensionally moving the detector moving mechanism 8 is added. For this purpose, the X-ray detector 7 is installed on the horizontal table 101. The horizontal table can be moved in the horizontal direction by the horizontal drive unit 102. Further, the pedestal 103 of the horizontal table is installed on the vertical table 104. Therefore, the X-ray detector 7 can be moved in the vertical direction by the vertical drive unit 105. Here, 101 to 1
06 constitutes the detector moving mechanism 8 of the first embodiment.

According to this embodiment, the X-ray detector 7 can be positioned two-dimensionally. Therefore, the spatial resolution of the X-ray imaging device can be improved two-dimensionally.

[0038]

According to the present invention, the spatial resolution of a detector in an X-ray interferometer can be improved. For this reason,
The spatial resolution of the phase contrast X-ray imaging device can be improved.

[Brief description of the drawings]

FIG. 1 is a spatial intensity distribution diagram of incident X-rays.

FIG. 2 is a diagram showing an interference image measured by a detector.

FIG. 3 is a diagram showing a method of synthesizing a measured interference image.

FIG. 4 is a diagram showing an interference image obtained as a result of synthesis.

FIG. 5 is a diagram showing a result of deconvolution processing of a combined interference image.

FIG. 6 is a diagram showing an overall configuration of an X-ray imaging apparatus according to the present invention.

FIG. 7 is a diagram showing a cross section of the X-ray imaging apparatus of the present invention.

FIG. 8 is a view showing one embodiment of a moving mechanism in the X-ray imaging apparatus of the present invention.

[Explanation of symbols]

1: X-ray source 2: Spectroscope 3: X-ray interferometer 4: Vibration isolation table
5: Sample 6: Sample holder 7: X-ray detector 8: Detector moving mechanism 9: Computer 10: Image processing unit 31: First half mirror 32: Second half mirror 33: Third half mirror 101: Horizontal table 102 : Horizontal drive unit 103: Horizontal table base 104: Vertical table 105: Vertical drive unit 106: Vertical table base.

Claims (5)

[Claims] 1. An X-ray source for generating X-rays, an X-ray interferometer using the X-rays as incident light, and an X-ray emitted from the X-ray interferometer.
An X-ray imaging apparatus provided with an X-ray detector for detecting a X-ray interference image; a means for positioning the X-ray detector;
An X-ray imaging apparatus, comprising: means for positioning a line detector at different positions, and combining a plurality of X-ray interference images that have detected the same region by calculation. 2. The X-ray imaging apparatus according to claim 1, wherein the X-ray detector is positioned two-dimensionally. 3. An X-ray imaging method in which an X-ray interference image emitted from an X-ray interferometer is detected by an X-ray detector. An X-ray imaging method, comprising: repeatedly moving an X-ray detector and detecting the same region of the X-ray interference image; and combining the detected plurality of X-ray interference images by calculation. 4. The X-ray imaging method according to claim 3, wherein the X-ray detector is moved two-dimensionally. 5. An X-ray imaging apparatus comprising: an X-ray source for generating X-rays; a sample stage for holding a sample; and an X-ray detector for detecting X-rays transmitted through the sample. X-ray imaging, comprising: means for positioning an X-ray detector; and means for positioning the X-ray detectors at different positions and synthesizing a plurality of X-ray interference images that have detected the same area by calculation. apparatus.