JP2007218605A - Device for observing back-reflection x-ray diffraction image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for observing a back-reflection X-ray diffraction image that shortens the camera length, can observe many Laue spots, and has high resolution. <P>SOLUTION: The device for observing the back-reflection X-ray diffraction image guides a reflective X-ray diffraction image obtained by projecting X-rays from an X-ray tube 10 to a sample 40 to a CCD element 31 via a camera obscura 20 having a fluorescent screen for converting an X-ray diffraction image into a visible light image, and observes the back-reflection X-ray diffraction image. A collimator 15 is vertically attached to one surface of camera obscura, a transmission type fluorescent screen is disposed on the plane facing it, and a mirror plane for guiding the visible light image formed on the transmission type fluorescent screen to the CCD element attached to the other surface of the camera obscura is arranged inside the fluorescent screen. The collimator has a first pinhole P1 and second pinhole P2, and has a third pinhole P3 (27) disposed on the fluorescent screen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a back reflection X-ray diffraction image observation apparatus that observes an X-ray diffraction image by a back reflection Laue method or a back reflection pinhole method.

  Conventionally, the backside Laue method or the backside pinhole method (so-called backside Debye method) does not place the sample in the X-ray optical path between the X-ray source and the detector, but the X-ray of the sample. Since a line diffraction image can be observed, it is widely used for determining the crystal orientation of a single crystal material. The back reflection pinhole method is used for measuring the crystal grain size of polycrystalline materials, observing textures, and measuring residual stress. For example, Patent Document 1 below discloses an X-ray back diffraction image observation apparatus using a back surface Laue method or a back surface Debye method and a television as a detector (prior art 1). .

Patent Document 2 below discloses a Laue system that is used for crystal orientation determination and operates in a back reflection mode. For this purpose, an X-ray detector is, for example, an airtight chamber filled with a mixed gas obtained by mixing carbon dioxide or methane, which is a quenching gas, and argon gas, and a two-dimensional arrangement inside the airtight chamber to form an electronic grid. This is a so-called multi-wire proportional counter (MWPC) having a wire array. The argon gas in the hermetic chamber is ionized by a diffracted beam, detected by an electronic grid through a gas amplification process, and then the detected information is sent to a signal conditioning module for the processing (prior art 2). ).
Japanese Patent Laid-Open No. 50-150480 (Japanese Patent Publication No. 52-41073) JP 2005-519295 A (International Publication Number WO2003 / 0776699)

  The above-described back surface Laue method or back surface Debye method is a classic method of recording (detecting) on an X-ray film, but in recent years, as an X-ray detection means, for example, an imaging plate These techniques have been revived with the advent of media with relatively high detection sensitivity and capable of obtaining digital images. In particular, recently, a digital image pickup device called CCD has been developed and used.

  By the way, in the prior art mentioned above, especially the prior art 1, a television camera for capturing an X-ray image from a sample is used as a detector. However, the sensitivity is not sufficient, There was no integration function, and the dynamic range was less than 2 digits. For this reason, in practice, even if a powerful X-ray source with an output of 12 kW is used, the ability to finally capture a back-reflected Laue image of a high-quality crystal can be obtained, and observation of the Debye ring of back reflection can be observed. However, in reality, observation was impossible.

  That is, in the structure known from the prior art 1, since the mirror for viewing the back reflection image is obstructive, the distance between the sample and the fluorescent plate (Lc: called the camera length) cannot be set sufficiently small. . Therefore, the size of the fluorescent plate is usually about 100 mm. However, with this mechanism, the Lc cannot be brought close to 50 mm or less. Furthermore, if the crystal has a size, the sample must be further retracted so as not to touch the black paper for shading, and Lc becomes 70 mm, so that it can be obtained on the fluorescent screen. There is a drawback that the number of spots and their positions in the Laue pattern cannot be sufficiently observed.

  In addition, a collimator for obtaining X-ray parallelism cannot be projected in front of the fluorescent screen. This is because when the collimator protrudes to the front of the fluorescent screen, the resulting image is shaded, and the number of observable Laue spots is further reduced. Therefore, as shown in FIG. 1 of Patent Document 1, the structure does not protrude from the phosphor screen of the phosphor plate.

  However, in such a structure, on the other hand, the distance between the two pinholes in the collimator cannot be made sufficiently long. Therefore, there is a drawback that the divergence angle of the X-ray projected onto the sample cannot be made sufficiently small. Note that if a Laue image is captured without sufficiently reducing the X-ray divergence angle, the Laue spots will spread and a clear Laue pattern cannot be obtained. In order to remedy such drawbacks, it is necessary to increase the distance between the pinholes. However, in that case, the X-ray intensity obtained on the fluorescent screen is not enough, but the intensity further decreases. End up.

  Furthermore, in the Laue system disclosed in the above-described prior art 2, because of the structure / principle, the diffracted X-rays obliquely cross the detection gas having a thickness, so that the detection position spreads radially, and therefore, There was a problem that Laue spots could not be clearly observed and the resolution obtained was low.

  Therefore, in the present invention, in view of the above-described problems in the prior art, various single crystals having a short camera length and capable of observing many Laue spots and having excellent resolution are also provided. It is an object of the present invention to provide a back reflection X-ray diffraction image observation apparatus that can be used as an apparatus for determining the crystal orientation of a material.

  According to the present invention, in order to achieve the above object, first, a reflected X-ray diffraction image obtained by projecting X-rays from an X-ray source onto a sample, and an X-ray diffraction image as a part of the visible X-ray diffraction image. A back-reflection X-ray diffraction image observation device for observing a back-reflection X-ray diffraction image by guiding it to a light detection means through a dark box equipped with a fluorescent plate to be converted to A collimator that projects the X-ray from the X-ray source in parallel to the surface of the sample is attached vertically, and an X-ray diffraction image of the reflected X-ray from the sample is displayed on the parallel surface facing the one surface. A transmissive fluorescent plate for converting to an optical image is provided, and a mirror surface for guiding a visible light image formed on the transmissive fluorescent plate to the light detecting means attached to the other surface of the dark box is provided therein. The collimator is placed in a position close to the X-ray source. Back reflection X-ray diffraction image observation comprising: a first pinhole, a second pinhole arranged at a position close to the mirror surface, and a third pinhole provided on the phosphor plate An apparatus is provided.

  In the present invention, in the back reflection X-ray diffraction image observation apparatus described above, the mirror surface is preferably arranged at an inclination angle of about 45 ° with respect to the projection X-ray of the collimator, or It is preferable that the collimator is arranged at an acute inclination angle of less than 45 ° and 37 ° or more with respect to the projected X-ray of the collimator.

  In the present invention, in the back reflection X-ray diffraction image observation apparatus described above, it is preferable that the light detection means is constituted by a CCD element, and further, the CCD element is provided with a cooling device. In addition, in the back reflection X-ray diffraction image observation apparatus described above, the third pinhole of the collimator has a structure extended to the outside, or further, the back reflection X-ray diffraction image It is preferable to attach to the apparatus for changing the attitude | position of an observation apparatus with respect to the said sample.

  As is clear from the above, according to the present invention, it is possible to observe a large number of Laue spots by shortening the camera length and to observe back reflection X-ray diffraction images with excellent resolution. It is possible to provide a device, and the practically excellent effect is exhibited.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
First, FIG. 1 attached herewith shows a back reflection X-ray diffraction image observation apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 in the drawing indicates an X-ray tube that is a source of X-rays. A so-called dark box 20 is provided adjacent to the X-ray tube 10. A detection unit 30 is attached to one surface (in this example, the lower surface in the figure) of the outer periphery that constitutes 20, and a back reflection X-ray diffraction image observation device is configured. Moreover, the code | symbol 40 in a figure has shown the measurement sample which measures the crystal orientation by this back reflection X-ray-diffraction image observation apparatus. As is apparent from the figure, according to this back reflection X-ray diffraction image observation apparatus, an X-ray diffraction image of a sample can be obtained without placing the sample in the X-ray optical path between the X-ray source and the detector. Can be observed.

  Between the X-ray tube 10 and the dark box 20, a collimator 15 provided with a first ponhole P1 and a second ponhole P2 is attached. The collimator 15 is disposed in the center of the surface adjacent to the X-ray tube 10 and is provided so as to protrude into the space in the dark box 20, and the tip thereof is located near the approximate center of the dark box 20. ing. The collimator 15 is fixed by a collimator holder 16 provided on the dark box 20 side, and the X-ray tube S is positioned so that the X-ray source S is positioned on a line connecting the two pinholes P1 and P2 of the collimator 15. The position of 10 is adjusted.

  On the other hand, the dark box 20 is provided with an inclined mirror plate in its internal space, as is apparent from the figure. That is, this mirror surface plate is made of a plate-shaped mirror surface support 21 and a metal formed on one surface of the mirror surface support 21 (that is, the surface of the space opposite to the space from which the collimator 15 protrudes). The mirror surface 22 is formed of a thin film, and is tilted and fixed along the opposing line in the dark box by the mirror fixing portions 23 and 23 (that is, in this example, inclined by 45 ° with respect to the X-ray beam). is doing).

  In addition, a fluorescent plate comprising a fluorescent layer support (plate) 24 and a fluorescent layer 25 formed on the surface thereof is provided on the opposite surface of the dark box 20 opposite to the surface on which the collimator 15 is mounted. A light-shielding body (plate) 26 made of a light-shielding polymer film such as black paper or black kapton is stretched outside the fluorescent plate for light shielding. A member 27 constituting the third pinhole P3 is provided at the central portion of the fluorescent plate and the light shield 26.

  The mirror plate formed on one surface of the mirror support 21 and used for reflection is, for example, aluminum having a thickness of about 5000 angstroms on the surface of the smooth and smooth support 21 such as glass. (Al) The mirror surface 22 is formed by vapor deposition. The mirror plate is fixed in the dark box 20 and has an oblique hole (opening) O in the center thereof to secure an X-ray passage. Note that the arrangement of the mirror plate is not limited to 45 °.

  In the above fluorescent plate, a fluorescent layer is applied to a transparent glass or acrylic support with a certain thickness (for example, about 50 μm). This fluorescent plate is a transmissive fluorescent plate and is arranged perpendicular to the X-ray beam. A circular hole for extracting X-rays is formed in the center of the fluorescent plate, and a third pinhole 27 is fitted in the hole. The center of the third pinhole is positioned so as to be on a line connecting the two pinholes P1 and P2 of the collimator 15.

  In addition, a detection unit 30 is connected to the lower surface of the dark box 20 via, for example, a cylindrical connection unit 28, and an imaging lens 29 is disposed inside the connection unit 28. On the other hand, the detection unit 30 is provided with a CCD element 31 as a detection element for detecting a Laue image, and a cooling device 35 for cooling the CCD element. In addition, this cooling device 35 is for suppressing the dark current (dark current) of the CCD element 31, for example, electronic cooling using a Peltier device or the like, a device using a liquid refrigerant (liquid cooling device), Furthermore, an air-cooled type using fins or the like can be employed.

  Next, the operation of the back reflection X-ray diffraction image observation apparatus whose configuration has been described above will be described. First, X-rays radiated from the X-ray source S of the X-ray tube 10 are collimated and taken out by the double pinhole collimator 15, and further passed through the third pinhole 27 (P3) to obtain a sample to be measured. Projected on the surface. In such a structure, the X-ray divergence angle is substantially determined by the first pinhole P1 and the third pinhole P3 and the distance between them.

  That is, the divergence angle of X-rays can be made sufficiently small. Note that even though the collimation of the double pinhole collimator (that is, the first pinhole P1 and the second pinhole P2 of the collimator 15) is not sufficient, the divergence angle can be limited by the third pinhole P3 described above. At the time of the reflection Laue method, the Laue spot can be clearly observed. In addition, when used as a back-reflection pinhole method applied to polycrystalline materials, Debye observation can be performed with high resolution, and in particular, a sufficient divergence angle can be secured for the separation of specific X-rays of Kα1 and Kα2. . When it is desired to further limit the divergence angle of the X-ray beam, as shown in the attached FIG. 2, the above-described pinhole, particularly the third pinhole P3, penetrates the transmission type fluorescent plate including the light shielding body (plate) 26. Can be extended to the outside. Furthermore, the end face of the extension collimator 27 ′ is subjected to a light shielding process (that is, a light shielding body 26 such as black paper or black Kapton is stretched) so that light does not leak into the dark box 20, that is, the above-mentioned. It is desirable to use the extended collimator and to perform the shading process. In FIG. 2, reference numeral 271 indicates a fixing portion for fixing the extended collimator 27 member 'to the fluorescent plate.

  Further, as described above, according to the collimator provided with the third pinhole P3 on the fluorescent plate, there is nothing between the fluorescent plate and the specular plate as apparent from the structure (that is, the collimator 15). Therefore, the optical path of the light reflected by the mirror plate is not blocked. Therefore, the shadow does not occur in the diffraction image (visible light image) obtained on the CCD element 31 via the lens 29 (in the structure of Patent Document 1, the shadow is generated when the collimator is extended. ), A good diffraction image can be obtained.

  Next, as described above, the X-rays extracted by the collimation mechanism including the collimator 15 and the third pinhole P3 are irradiated onto the sample placed at a predetermined distance from the fluorescent layer 25 of the fluorescent plate, The back reflection X-ray diffraction image generated by the sample is projected by the fluorescent layer 25 of the fluorescent plate. The back-reflection X-ray diffraction image is converted into weak visible light (visible light image) by the fluorescent layer 25 of the fluorescent plate. Further, the X-ray diffraction image (visible light image) by back reflection converted into visible light is reflected by the mirror (mirror surface 22) disposed at an acute angle with respect to the fluorescent plate, for example, 45 °, and then, An image is formed on the sensitive surface of the CCD element 31 by the lens 29 (see the broken line in the figure), converted into an electric signal, and a digital image is obtained by an image processing device (not shown).

Further, it is preferable to use a particularly sensitive back-illuminated CCD as the CCD element 31 as the detector, and further, for example, it is kept at a low temperature of about −50 ° C. by electronic cooling using the Peltier effect. ing. In this way, dark current is suppressed and a long exposure time is enabled. More specifically, the CCD element is driven by a full frame transfer system, the number of pixels is about 512 × 512 pixels, and reading after image storage takes about 5 seconds. Although not shown here, a mechanical shutter is disposed between the lens 29 and the CCD element 31, so that the shutter is opened during image accumulation, and light is incident on the CCD element 31 during reading. It is designed to close so as not to enter. The resulting image in a digital image, a dynamic range 10 about ^4, is sufficient for intensity measurement. In addition, the CCD element 31 provided with a cooling device can cope with exposure for one hour or more, and can open the way to micro-region diffraction with a collimator narrowed down.

  In addition, by employing the CCD element 31 described above as the detector, observation of the back reflection X-ray diffraction image can be easily obtained as a digital image. That is, since it is a digital image, the intensity profile can be easily acquired. This eliminates the need for manual work (development processing, etc.) like conventional photographic methods and imaging plates (IP). For example, image processing operations using a CPU or the like are possible. Application of the back reflection pinhole method can be automated.

  In the back reflection X-ray diffraction image observation apparatus having the above-described configuration, as is apparent from FIG. 1, the distance between the sample and the fluorescent plate (Lc: camera length) is the same as that of the sample 40 and the third pinhole P3. Can be freely changed without any restriction, that is, the camera length can be shortened as much as possible (minimum: 0 mm) as necessary. This makes it possible to observe the number and positions of spots in the Laue pattern obtained on the fluorescent plate sufficiently and accurately, and a device that can be used as a device for determining the crystal orientation of various single crystal materials. Enable realization.

  Here, FIG. 3 attached here shows an example in which the back reflection X-ray diffraction image observation apparatus described above is applied to a residual stress measurement apparatus. That is, the back reflection X-ray diffraction image observation apparatus 100 is a posture for remotely changing the posture of the sample arranged adjacent to the sample 40 (here, an example of a rotational position is shown, but a translational position is also possible). A so-called rotatable arm 250 is attached to the rotary shaft 210 of the control device 200. This makes it possible to set the X-ray incident angle at a desired angle with respect to the surface of the sample 40 and measure the residual stress by the reflected diffraction X-ray.

  According to the configuration of the apparatus described above, when changing the orientation of the sample, the surface of the observation apparatus that is closest to the sample is opposed to the transmission fluorescent plate (fluorescent layer support) perpendicular to the X-ray beam. Since the body 24 and the fluorescent layer 25) are arranged, there is no obstacle between the sample and the fluorescent plate, so that the camera length can be freely set. That is, in the case of the back reflection Laue method, it is possible to observe a sufficiently large number of Laue spots by shortening the camera length. In addition, the dark box and the sample interfere with each other even when the sample posture (rotation position, translational position) is changed remotely (specifically, black paper or black which is a light shielding body (plate) 26 for light shielding). No worries about breaking Kapton). (In the structure of Patent Document 1 described above, there is a risk of breaking not only black paper but also the mirror.)

  In addition, as another application of the back reflection X-ray diffraction image observation apparatus, in addition to the crystal orientation measurement / crystal orientation alignment of the single crystal, observation of the crystal state of the polycrystal, that is, orientation evaluation, crystal grain size observation, It can also be used for residual stress measurement. In FIG. 3, the same reference numerals as those in FIG. 1 indicate the same configuration as described above, and here, an example in which the tip of the third pinhole P3 is further extended is shown.

  Further, in the above-described embodiment, an example is shown in which the mirror plate is disposed at an angle of 45 ° with respect to the X-ray beam (or fluorescent plate) in the dark box 20. Without being limited thereto, as shown in FIG. 4 attached, it is possible to make the angle more acute as long as the optical path (see the broken line in the figure) in consideration of the aperture of the lens is not blocked. In this embodiment, the inclination angle formed by the mirror plate with respect to the X-ray beam can be set up to about 37 °. According to this, the thickness of the dark box 20 can be reduced, and at the same time The effect of improving the strength can be obtained.

  According to the above configuration, as is clear from the above-described embodiment, (1) it is possible to freely set the camera length, and also when changing the orientation of the observation apparatus with respect to the sample, There is no obstacle as in the prior art, and a sufficiently large number of Laue spots can be clearly observed with high resolution.

  In addition, according to the back reflection X-ray diffraction image observation apparatus described in detail above, a practical back reflection X-ray diffraction image can be obtained. As an example, FIG. 5 attached herewith shows an example of photographing a back reflection Laue image obtained by the back reflection X-ray diffraction image observation apparatus according to the present embodiment. Here, the sample is a Si crystal, and the camera length is about 35 mm. Further, a 2 kW sealed X-ray tube was used as the X-ray source, and a clear back reflection Laue image was obtained with an exposure time of 10 seconds.

  In FIG. 5, FIG. 5 (a) is a Laue image obtained by the above apparatus before the orientation adjustment, and FIG. 5 (b) is a state in which the in-plane orientation is adjusted by φ rotation. The Laue statue. Further, FIG. 5 (c) is a Laue image in a state where the [110] crystal zone is coincident with the equator plane by χ rotation (tilt), and FIG. 100) shows a Laue image in a state in which X-rays are vertically incident and a pattern to be rotated four times is obtained. That is, a sufficiently large number of Laue spots can be observed, and the rotation of the three axes orthogonal to φ, χ, ω can be rotated, and the back-reflection X-ray diffraction image observation apparatus according to the present invention can be used to rotate the crystal axis. It will be clear that this can be done easily.

It is sectional drawing which shows the whole structure of the back reflection X-ray-diffraction image observation apparatus which becomes one embodiment of this invention. It is a partially expanded sectional view for showing the modification of a 3rd pinhole in the said back surface reflection X-ray-diffraction image observation apparatus. It is a perspective view which shows the structure at the time of utilizing for a residual stress measurement as an example of the application of the said back surface reflection X-ray-diffraction image observation apparatus. It is sectional drawing which shows the structure used as other embodiment which made the inclination of the mirror plate in the back reflection X-ray-diffraction image observation apparatus of the said FIG. 1 into the acute angle. It is a figure which shows the Laue image actually observed with the said back surface reflection X-ray-diffraction image observation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... X-ray tube 15 ... Collimator 20 ... Dark box 21 ... Mirror surface support 22 ... Mirror surface 24 ... Fluorescent layer support (plate)
25 ... Fluorescent layer 26 ... Shading body (plate)
27, 27 '... collimator member P1 ... first pinhole P2 ... second pinhole P3 (27, 27') ... third pinhole O ... oblique hole (opening)
DESCRIPTION OF SYMBOLS 30 ... Detection part 31 ... CCD element 35 ... Cooling device

Claims (7)

A reflected X-ray diffraction image obtained by projecting X-rays from an X-ray source onto a sample is passed through a dark box having a fluorescent plate for converting the X-ray diffraction image into a visible light image in a part of the reflected X-ray diffraction image. A back reflection X-ray diffraction image observation apparatus for guiding and observing a back reflection X-ray diffraction image,
The dark box is vertically attached with a collimator that projects X-rays from the X-ray source parallel to the surface of the sample and projects the sample onto the surface of the dark box. A transmissive fluorescent plate for converting an X-ray diffraction image by reflected X-rays from the light into an optical image, and further, a visible light image formed on the transmissive fluorescent plate is provided on the other surface of the dark box. A mirror surface for guiding to the attached light detection means is arranged,
The collimator includes a first pinhole disposed at a position close to the X-ray source, a second pinhole disposed at a position close to the mirror surface, and a first pinhole provided on the fluorescent plate. 3. A back reflection X-ray diffraction image observation apparatus, comprising: 3 pinholes.   2. The back reflection X-ray diffraction image observation apparatus according to claim 1, wherein the mirror surface is arranged at an inclination angle of about 45 degrees with respect to the projection X-ray of the collimator. Diffraction image observation device.   2. The back reflection X-ray diffraction image observation device according to claim 1, wherein the mirror surface is arranged with an acute inclination angle of less than 45 ° and 37 ° or more with respect to the projected X-ray of the collimator. A back reflection X-ray diffraction image observation apparatus characterized by the above.   2. The back reflection X-ray diffraction image observation apparatus according to claim 1, wherein the light detection means is constituted by a CCD element.   5. The back reflection X-ray diffraction image observation apparatus according to claim 4, wherein the CCD element includes a cooling device.   2. The back reflection X-ray diffraction image observation apparatus according to claim 1, wherein the third pinhole of the collimator has a structure extending outward. . The back reflection X-ray diffraction image observation apparatus according to any one of claims 1 to 6, further comprising an apparatus for changing the posture of the back reflection X-ray diffraction image observation apparatus with respect to the sample. A back reflection X-ray diffraction image observing apparatus characterized by being attached.

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