EP2194375B1 - X-ray optical element and diffractometer with a Soller slit - Google Patents

Description

The invention relates to an X-ray optical element having a Soller aperture comprising a plurality of lamellae for collimating an X-ray beam with respect to the direction of the axis of the Soller aperture, and having a further aperture for limiting an X-ray beam, wherein the further aperture is rigidly connected to the Soller aperture during operation.

Background of the invention

X-ray diffractometry can be used for a variety of analytical tasks, using different measurement geometries, e.g. Bragg-Brentano or parallel beam geometry. However, this requires different optical elements in the beam path. In order to enable a quick change between the different measuring geometries, it is desirable to keep the necessary rebuilding measures as low as possible.

Out US 6,807,251 B2 is an X-ray diffractometer with a parabolic mirror for using the diffractometer in the parallel beam geometry, and a slit diaphragm for limiting the X-ray beam in the Bragg Brentano geometry known. The mirror and the slit are rigidly connected. A rotatable path selection disc with a slit is disposed behind the diaphragm / mirror unit and can select by rotation the X-ray beam (parallel or divergent) required for the corresponding geometry.

Out US 606650372 B2 An X-ray diffractometer is known in which the X-ray radiation for different tasks can be performed in sections on different beam paths, one of which runs straight from the sample through a diaphragm system with adjustable and / or replaceable diaphragm to the X-ray detector, while the other beam path is bent and first from the sample position to a dispersive or reflective X-ray optical element, and from there to the X-ray detector. By means of a shutter, the bent beam path relative to the detector can be hidden. The diaphragm and the dispersive or reflective X-ray optical element are rigidly adjusted to each other and can be pivoted together relative to the sample.

A disadvantage of these arrangements, however, is that a division of the X-ray beam takes place and accordingly only a part of the radiation emanating from the X-ray source can be used for each application. In addition claim the known arrangements relatively much space to realize the different beam paths can.

In particular for measurements in the parallel-beam geometry, the use of roller blinds with which vertical and / or horizontal divergence of X-rays can be restricted is advantageous. For example, linear rollerblades are in US 6,266,392 B1 . US2005 / 0281382 A1 and US Pat. No. 6,307,917 B1 described in detail.

Bruker Advanced X-ray solutions "Diffraction Solutions D8 Advance" 2002 discloses an X-ray diffractometer for reflection and transmission measurements in parallel beam geometry. The X-ray emanating from the sample runs through a linear or a radial Soller aperture.

US Pat. No. 6,307,917 B1 discloses an X-ray apparatus with Soller aperture for collimating divergent X-rays. The Soller panel is part of a monochromator unit with a monochromator panel that serves to confine the X-ray beam, which is then collimated by the Soller panel.

An X-ray optical element according to the preamble of claim 1 is disclosed in the patent US-A1-2007 / 0086567 disclosed.

Object of the invention

The object of the invention is to propose an X-ray optical element with a Soller aperture and another aperture, which allows automatic switching between the Soller aperture and the further aperture.

Brief description of the invention

This object is achieved in that the X-ray bounded by the further diaphragm intersects the axis of the Soller diaphragm within the Soller diaphragm and the direction of the X-ray bounded by the further diaphragm includes an angle α ≥ 10 ° with the axis of the Soller diaphragm.

An X-ray beam coming from a radiation source can thus be limited either by the Soller diaphragm or by the further diaphragm, as the case may be at which angle the soller axis is aligned with the direction of the incident x-ray beam. If the X-ray beam collapses parallel or at a small angle (<10 °) to the Soller axis, it passes through the Soller aperture. The greater the direction of the incident X-ray differs from the Soller axis, the more radiation passes through the further aperture.

The directions of X-rays limited by the Soller aperture and the wider aperture penetrate within the Soller aperture. For this purpose, the Soller diaphragm has a beam window which allows X-ray radiation to be conducted in one direction, which forms an angle α ≥ 10 ° with the axis of the Soller diaphragm. In this way, a very compact and flexible optical element is realized.

The "Soller Aperture Axis" is to be understood as meaning the axis of symmetry of the Soller Aperture, which runs in the direction of the X-ray beam to be collimated by the Soller Aperture (optical axis), ie. in the case of a linear Soller panel, the Soller axis runs between an inlet opening and an outlet opening parallel to the slats of the Soller panel. In the case of a radial Soller aperture, the Soller axis extends along the mirror plane of the Soller aperture between an inlet opening and an outlet opening.

With the optical element according to the invention, the optical setup of a diffractometer can be adapted to the application required by the sample or the question (for example Bragg-Brentano, powder GID, reflectometry).

Preferred embodiments of the invention

An embodiment of the X-ray optical element according to the invention provides that the Soller aperture is a linear Soller aperture. A linear roller blind includes a plurality of thin laminations (eg, metal foils) arranged parallel to each other and spaced from each other. Linear roller blinds are used in particular when using point detectors.

Another embodiment of the X-ray optical element according to the invention provides that the Soller aperture is a radial Soller aperture. In a radial Sollerblende the slats are not parallel, but within a certain angular range (total opening angle = angle between the first and last lamella) radially aligned with respect to a center. The distance between the individual lamellae defines the divergence angle of the radial Soller aperture. Radial Soller covers are used in particular when using strip detectors.

In a further development of the embodiment with a linear Soller diaphragm, the slats of the linear Soller diaphragm are arranged parallel to the beam direction of the X-ray bounded by the further diaphragm. In this arrangement, both the X-ray beam bounded by the further diaphragm and an X-ray beam extending in the direction of the Soller axis (in different directions) can pass through the Soller diaphragm.

However, it can also be advantageous if the Soller panel has a recess perpendicular to the Soller axis. The X-ray beam bounded by the further diaphragm can thus intersect the axis of the Soller diaphragm within the Soller diaphragm, irrespective of the orientation of the slats of the Soller diaphragm.

Alternatively, the Soller panel may comprise two partial panels, wherein the further panel is at least partially disposed between the two partial panels. However, the two partial panels of the Soller panel must then be precisely adjusted.

Particularly advantageous is an embodiment in which the further diaphragm has at least two diaphragm jaws, wherein the diaphragm jaws are arranged on different sides of the Soller diaphragm. In particular, it is advantageous if a diaphragm jaw is arranged on the side of the Soller diaphragm, which faces the incident on the further diaphragm X-ray, and the other diaphragm jaw is arranged on the side facing away from the incident on the further diaphragm X-ray.

It is particularly advantageous if the diaphragm jaws with the axis of the Soller aperture an angle not equal to 90 °, preferably 45 °, include.

Alternatively, however, the further diaphragm can also be arranged completely on one side of the roller blind, in particular in one piece. In this case, for example, a pinhole can be used.

Preferably, the further diaphragm is made of tantalum.

Moreover, it is advantageous if the geometry of the further diaphragm, in particular the diaphragm opening, can be adjusted in the non-operating state. The beam cross section of the X-ray emerging from the further diaphragm is thus well-defined.

A further embodiment of the X-ray optical element according to the invention provides that the further diaphragm is a linear Soller diaphragm. The X-ray optical element comprises in this embodiment two Soller diaphragms whose axes are arranged at an angle α ≥ 10 °. The two Soller aperture in cross through, so that at least one of the Soller covers has a recess within which the other Soller panel is at least partially arranged.

In an advantageous embodiment of the embodiment with two linear roller blinds, the two linear roller blinds have different divergence angles, i. The distances between the slats are different for the two linear roller blinds.

In addition, the further panel may be a radial Soller panel. This is particularly advantageous in the use of strip detectors.

In a specific development of this embodiment, the optical element according to the invention has two radial blind plates with different opening angles.

The invention also relates to a diffractometer having a source for generating a primary beam, a sample holder for arranging a sample, a detector for registering a secondary beam emanating from the sample and having an X-ray optical element described above.

In a preferred embodiment of the diffractometer according to the invention, the X-ray optical element is rotatably mounted in the diffractometer about an axis of rotation perpendicular to the axis of the Soller aperture. The inlet opening of the Soller aperture can thus be driven by rotation of the beam path and at the same time the beam window of the further aperture in the beam path. Thus, the incident X-ray beam does not have to be divided into two beam paths, but rather the X-ray optical element can be aligned by rotation so that optimum radiation can be realized for each geometry.

Preferably, a motor is provided for rotating the X-ray optical element. The X-ray optical element is mounted on the motor axis for this purpose. According to the setting of the motor, the size of the opening defined by the further aperture can be varied perpendicular to the X-ray beam (clear height of the further diaphragm).

In a particularly preferred embodiment, an automatic control of the rotation of the X-ray optical element is provided, in particular a computer control.

The X-ray optical element is preferably arranged on the secondary beam side, e.g. to switch between Bragg-Brentano (further aperture in the beam) and reflectometry (linear Soller aperture in the beam).

Alternatively or additionally, however, it is also possible for the X-ray optical element to be arranged on the primary beam, for example for switching between Bragg-Brentano on flat powder samples (further aperture in the beam) and reflection measurements on uneven powder samples (linear Soller aperture in the beam).

• Für den Fall, dass das röntgenoptische Element sekundärseitig angeordnet ist, kann es vorteilhaft sein, wenn der Detektor im Kreuzungspunkt der Lammellenrichtungen zumindest einer radialen Sollerblende des röntgenoptischen Elements angeordnet ist. Die Lamellenrichtung verläuft in der durch die entsprechende Lamelle definierten Ebene entlang der Mittellinie der Lamelle (in Ausbreitungsrichtung des kollimierten Röntgenstrahls). Eine Anordnung des Detektors im Kreuzungspunkt der Sollerblendenlamellen ist besonders vorteilhaft für beispielsweise Transmissionsmessungen mit fokussierendem Primärstrahl.

When using an embodiment of the optical element according to the invention with at least one radial Soller aperture, the radial Soller aperture can be aligned differently with respect to the other components of the diffractometer:

• In the event that the X-ray optical element is arranged on the secondary side, it may be advantageous if the detector is arranged at the crossing point of the Lammellenrichtungen of at least one radial Sollerblende of the X-ray optical element. The slat direction runs in the plane defined by the corresponding slat along the center line of the slat (in the propagation direction of the collimated X-ray beam). An arrangement of the detector at the point of intersection of the roller shutter blades is particularly advantageous for example for transmission measurements with a focusing primary beam.

Regardless of the arrangement of the X-ray optical element, it may be advantageous if the sample holder is arranged at the crossing point of the Lammellenrichtungen of at least one radial Soller aperture of the X-ray optical element. An arrangement of the sample holder at the crossing point of the Soller blades is particularly advantageous for transmission measurements on capillary samples with strip detector

In the event that the X-ray optical element is arranged on the primary side, it may also be advantageous if the source is arranged in the center of at least one radial Soller aperture of the X-ray optical element. An arrangement of the source at the crossing point of the Soller blades is particularly advantageous for measurements in Bragg-Brentano arrangement in which special emphasis is placed on scattered beam suppression.

Further advantages of the invention will become apparent from the description and the drawings. Likewise, the features mentioned above and those listed further can be used individually or in any combination. The embodiments shown and described are not exhaustive Enumerating to understand, but rather have exemplary character for the description of the invention.

Drawing and detailed description of the invention

Fig. 1a-c

eine Schnittdarstellung eines erfindungsgemäßen röntgenoptischen Elements in verschiedenen Ausrichtungen bezüglich des einfallenden Röntgenstrahls mit linearer Sollerblende und weiterer Blende mit Blendenbacken;

Fig. 2

eine perspektivische Darstellung des röntgenoptischen Elements aus Fig. 1;

Fig. 3

eine schematische Darstellung eines erfindungsgemäßen Diffraktometers,

Fig. 4

eine Schnittdarstellung eines erfindungsgemäßen röntgenoptischen Elements mit radialer Sollerblende und weiterer Blende mit Blendenbacken; und

Fig. 5

eine Schnittdarstellung eines erfindungsgemäßen röntgenoptischen Elements mit linearer Sollerblende und radialer Sollerblende als weiterer Blende.

Show it:

Fig. 1a-c

a sectional view of an X-ray optical element according to the invention in different orientations with respect to the incident X-ray beam with a linear Soller aperture and another aperture with diaphragm cheeks;

Fig. 2

a perspective view of the X-ray optical element Fig. 1 ;

Fig. 3

a schematic representation of a diffractometer according to the invention,

Fig. 4

a sectional view of an X-ray optical element according to the invention with radial Sollerblende and further aperture with diaphragm jaws; and

Fig. 5

a sectional view of an X-ray optical element according to the invention with a linear Soller aperture and radial Soller aperture as another panel.

Fig. 1a -c and Fig. 2 show a particularly preferred embodiment of an optical element 1 according to the invention with a linear Sollerblende 2 (equatorially arranged Sollerblende) and a further diaphragm, the two diaphragm jaws 3a, 3b, for example in the form of tantalum cutting comprises. The diaphragm jaws 3 a, 3 b, as well as the Soller diaphragm 2 are fastened to a holder 4 , whereby the further diaphragm is rigidly connected to the Soller diaphragm 2. The Soller panel 2 has a Soller axis 5 which extends parallel to the slats of the Soller panel between an inlet opening 6 and an outlet opening 7 . The plane formed by the diaphragm jaws 3 a, 3 b of the further diaphragm closes with the axis 5 of Soller aperture an angle which is not equal to 90 ° and preferably> 10 °, in the case shown 45 °. The distance between the diaphragm jaws 3a, 3b to each other can be changed in the non-operating state by moving the diaphragm jaws 3a, 3b. The Soller panel 2 has a beam window in the form of a recess 8 through which radiation with a propagation direction that does not run along the Soller axis 5 can pass through the X-ray optical element 1 ( Fig. 1b, 1c ). Alternatively, a beam window can also be realized that by appropriate alignment of the slats of the Soller shutter 2 of the beam path during rotation of the X-ray optical element 1 relative to the Soller axis 5 both through the slats of the Soller shutter 2 and through the further aperture extends (not shown). The slats of the Sollerblende 2 off Fig. 1a-c would then be aligned parallel to the drawing plane.

In Fig. 1a is an alignment of the X-ray optical element according to the invention against an incident X-ray 10 ("X-ray 10" will also include radiation bundles hereinafter) shown, in which the Sollerblende 2 is arranged parallel to the X-ray beam 10. The X-ray beam 10 is then collimated by the Soller shutter 2.

By rotation of the X-ray optical element 1 about an axis of rotation 9, the X-ray optical element 1 can be rotated relative to the incident X-ray beam 10. The axis of rotation 9 of the X-ray optical element 1 is in this case in each position of the X-ray optical element 1 perpendicular to the Soller axis 5 and the incident X-ray 10. The X-ray optical element 1 according to the invention allows the choice between a beam path through the Soller aperture 2 or a beam path through the further aperture, without while distracting or dividing the X-ray beam 10. Starting from the reference system of the X-ray optical element 1, the beam path running through the further diaphragm intersects the beam path passing through the Soller diaphragm 2 within the Soller diaphragm 2. As a result, a compact embodiment of the X-ray optical element 1 is realized.

Fig. 1b, 1c show two different positions of the X-ray optical element 1 relative to the incident X-ray beam 10, in which the X-ray beam 10 is limited by the further aperture (dimmed). By different angular positions of the Soller axis 5 to the incident X-ray beam 10, the limited height (with respect to the incident X-ray beam 10) of the further diaphragm can be varied by the diaphragm jaws 3a, 3b. This is done by the Fig. 1b, 1c clear. The maximum passage of the X-ray beam 10 through the further diaphragm takes place in the embodiment shown here in a 90 ° relative to the in Fig. 1a shown position (position with beam parallel to the Soller axis 5).

The use of the X-ray optical element according to the invention in a diffractometer allows an automatic change between a Bragg-Brentano beam path, in which the simple further aperture limits the X-ray beam 10, and a parallel beam path through the Soller aperture 2. Thus, the investigation of various powder samples with a structure and without readjustment of the device allows. In conjunction with a parallel primary beam, reflectometry measurements are also possible in which, for small angles of incidence, that is to say in the region of intense reflexes, a construction with a single diaphragm (for example with diaphragm jaws 3a, 3b) is selected. For large angles of incidence, that is to say in the range of weak intensities, it is then possible to switch automatically to a beam path with the Soller diaphragm 2 in order to increase the intensity yield of the sample. Also, the change between measurements along the specular axis of the sample with high resolution, i. with small opening of the further diaphragm, and measurements of the diffuse and faint scattered signal of the sample under grazing incidence, ie with Soller diaphragm 2, are thus possible with a single structure.

Fig. 3 shows a schematic structure of such a diffractometer according to the invention with an X-ray source 11, a sample holder 12, a detector 13 and two inventive X-ray optical elements 1, wherein one of the X-ray optical elements primary beam side and the other secondary beam side is arranged. The X-ray optical elements 1 are on a goniometer attached and rotatably arranged with respect to the X-ray source 11, the sample holder 12 and the detector 13. Preferably, the rotation of the X-ray optical elements 1 is realized in each case by means of a motor (not shown). The optical axis (direction of the X-ray beam 10) passes through the axis of rotation of the X-ray optical element 1 or the motor. It is also possible to provide only one optical element 1, ie either primary beam side or secondary beam side.

Instead of in Fig. 1a-c and Fig.2 shown X-ray optical element 1, other embodiments of the X-ray optical element according to the invention can be used in the primary beam 10a and / or in the secondary beam 10b .

For example, instead of a linear Soller diaphragm 2, the X-ray optical element 1 ' according to the invention may comprise a radial Soller diaphragm 14 , as in FIG Fig. 4 shown. This embodiment of the X-ray optical element 1 'can be used for a change between, for example, transmission measurements with capillaries and streak detector (use of the radial Soller aperture 14) and Bragg Brentano measurements in reflection geometry (use of the further aperture with diaphragm jaws 3a, 3b). Depending on the application, it may be advantageous to arrange the source 11, the sample holder 12 or the detector 13 in the center of the radial Soller aperture 14, wherein the point of intersection of the slats of the radial Soller aperture 14 with the axis 15 of the radial Soller aperture 14 is the center of the radial Soller aperture 14 is defined.

Fig. 5 shows a further embodiment of the X-ray optical element 1 " according to the invention , in which a linear Sollerblende 2 and a radial Sollerblende 14 are combined.The axis 5 of the linear Sollerblende 2 and the axis 15 of the radial Sollerblende 14 are preferably perpendicular to each other.This embodiment of the X-ray optical Element 1 "is used to adjust the beam path during the automatic change between transmission measurements and reflectance measurements in powder samples. In particular, when switching between capillary samples with strip detector (use the radial Soller aperture 2) and flat samples with point detectors (using the linear Soller aperture 14).

In addition, two linear roller blinds 2 can also be combined (not shown). If the lamellae of the two linear roller blinds 2 are oriented perpendicular to one another and perpendicular to the roller axis 5, such an X-ray optical element can be used for switching between applications in which the one hand is measured in the scattering plane and, on the other hand, measured out of the scattering plane.

It is also possible to combine more than two diaphragms within an X-ray optical element in a corresponding manner.

All embodiments of the diffractometer according to the invention can also be used for neutron beam diffractometry.

With the diffractometer according to the invention, a change between a Soller panel and at least one further panel without user intervention and readjustment can be done automatically.

LIST OF REFERENCE NUMBERS

1

X-ray optical element

2

Soller face (linear)

3a, 3b

Aperture baking of the further aperture

4

bracket

5

Soller axis of the linear Sollerblende

6

Entrance of the Sollerblende

7

Outlet opening of the Sollerblende

8th

Recess in Sollerblende

9

Rotation axis of the X-ray optical element

10

X-ray

10a

primary beam

10b

secondary beam

11

X-ray source

12

sample holder

13

detector

14

radial Soller aperture

15

Axis of the radial roller blind

Claims (15)

1. X-ray optical element (1, 1', 1") comprising a Soller slit having a plurality of lamellas for collimating an X-ray beam with respect to the direction of the axis (5, 15) of the Soller slit, and a further collimator for delimiting an X-ray beam (10), wherein the further collimator is rigidly connected to the Soller slit (2, 14) during operation,
   characterized in that
   the X-ray beam (10) delimited by the further collimator intersects the axis (5, 15) of the Soller slit within the Soller slit and the direction of the X-ray beam (10) subtends an angle α≥10° with respect to the axis (5, 15) of the Soller slit.
2. X-ray optical element (1, 1") according to claim 1, characterized in that the Soller slit is a linear Soller slit (2).
3. X-ray optical element (1', 1") according to claim 1, characterized in that the Soller slit is a radial Soller slit (14).
4. X-ray optical element (1, 1', 1") according to any one of the preceding claims, characterized in that the Soller slit has a recess (8) perpendicular to the axis of the Soller slit (5).
5. X-ray optical element (1, 1') according to any one of the claims 1 to 4, characterized in that the further collimator comprises at least two collimator jaws (3a, 3b), wherein the collimator jaws (3a, 3b) are arranged on different sides of the Soller slit (2, 14).
6. X-ray optical element (1, 1') according to claim 5, characterized in that the collimator jaws (3a, 3b) subtend an angle with respect to the axis (5, 15) of the Soller slit (2, 14) which differs from 90°, preferably an angle of 45°.
7. X-ray optical element (1") according to any one of the claims 1 to 4, characterized in that the further collimator is a linear Soller slit (2).
8. X-ray optical element according to claim 7 and claim 2, characterized in that the two linear Soller slits (2) have different divergence angles.
9. X-ray optical element (1") according to any one of the claims 1 to 4, characterized in that the further collimator is a radial Soller slit (14).
10. X-ray optical element according to claim 3 and claim 9, characterized in that the two radial Soller slits (14) have different opening angles and/or different divergence angles.
11. Diffractometer having a source (11) for generating a primary beam, a sample holder (12) for arranging a sample, a detector (13) for detecting a secondary beam emitted by the sample, and an X-ray optical element (1, 1', 1") according to any one of the preceding claims.
12. Diffractometer according to claim 11, characterized in that the X-ray optical element (1, 1', 1") is installed in the diffractometer in such a fashion that it can be rotated about an axis of rotation (9) which is perpendicular to the axis (5, 15) of the Soller slit (2, 14).
13. Diffractometer according to claim 12, characterized in that automatic control of the rotation of the X-ray optical element (1, 1', 1") is provided, in particular computer control.
14. Diffractometer according to any one of the claims 11 to 13, characterized in that the X-ray optical element (1, 1', 1") is arranged on the side of the primary beam.
15. Diffractometer according to any one of the claims 11 to 13, characterized in that the X-ray optical element (1, 1', 1") is arranged on the side of the secondary beam.

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