X-ray or gamma ray systems or devices – Specific application – Diffraction – reflection – or scattering analysis
Reexamination Certificate
2002-10-04
2004-12-14
Glick, Edward J. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Diffraction, reflection, or scattering analysis
C378S205000
Reexamination Certificate
active
06831962
ABSTRACT:
TECHNICAL FIELD
This invention relates in general to the technical field of the centering of small samples by using standardized geometries; this invention relates in particular to a method for the automatic relative adjusting of the position coordinates of at least
one sample which is on a sample holder or table of a goniometer,
which is to be examined by means of the goniometer,
which is movable in its position in at least one direction of translation and
which is rotatable about at least one tilting axle in its orientation or tilting
with respect to the center coordinates of the goniometer determined by the intersection point of the tilting axles.
This invention furthermore relates to an associated device for the automatic relative adjusting of the position coordinates.
PRIOR ART
A goniometer is a component part of an X-ray diffracting device, for example of a diffraction measuring instrument or of a diffractometer as it is used for the X-ray diffraction analysis. For the X-ray diffraction analysis by means of a diffractometer, for example a crystalline structure of a substance, is analysed by radiation of the substance with an X-ray and by measuring a diffraction angle of the X-ray reflected by the substance or having passed through this substance. A goniometer is used in relation with a diffractometer for measuring a diffraction angle of the X-ray and serves for the exact positioning of the sample inside the diffractometer.
In principle, six spatial degrees of freedom are now to be granted for the positioning of the sample in the goniometer. Here, they are the translational coordinates x, y and z (according to the three spatial directions) and the three rotational coordinates Omega (&ohgr;), Chi (&khgr;) and Phi (&phgr;).
The translational degrees of freedom are used to move the sample to a determined position. This being, by using X-ray diffractometers, the sample should be at any time of the measurement exactly in the X-ray in order to guarantee stable and reliable measuring results. The cross section of the X-ray corresponds in general approximately to the cross section of the sample to be examined. Thus, the translational degrees of freedom allow to adjust the sample at a predetermined location in the X-ray.
On the other hand, the rotational degrees of freedom are used in X-ray diffractometers to vary the orientation or tilting with respect to the X-ray. An eventually dynamic variation of the orientation or of the tiling within the scope of a measurement is at present still a necessary condition for interpretable measuring results.
Mechanical arrangements with these translational as well as rotational degrees of freedom are designated as goniometers. The requirement of a high stability with respect to the position in space (→ translational component) by simultaneous variation of the orientation or tilting (→ rotational component) results in that these systems are mechanically very complicated and also expensive. Nowadays available systems are constructed in such a way that the orientation or the tilting of the sample is realized by interpenetrating circles of revolution, whereby usually the designation Omega (&ohgr;) is associated to the external circle of revolution, the designation Chi (&khgr;) to the middle circle of revolution and the designation Phi (&phgr;) to the internal circle of revolution.
According to the prior art, there is a multitude of alternatives which get along with less than three degrees of freedom with respect to the rotational orientation or tilting. The so-called Kappa (&egr;) arrangements which have a few limitations with respect to the angle of rotation as well as three rotational degrees of freedom belong to these alternatives. Furthermore, so-called two circle arrangements are known which only have two axes, namely Omega (&ohgr;) and Phi (&phgr;). In the course of the last centuries, uniaxial systems (→ only Phi) are also more and more used which, however, have only very limited possibilities with respect to the orientation or tilting of the sample but which are used more and more often because of their simplicity of construction.
If the position of the sample in the goniometer system is to be kept maintained even during a variation of the orientation or tilting, it is absolutely necessary that the centers of the circles of revolution meet in a common point of intersection. The deviation from this common point of intersection, i.e. the offset of the axles at the point of the sample, is also designated as “sphere of confusion”. Slight deviations are more complicated to construct with an increasing number of axles and result in that the costs for such a goniometer system rise strongly overproportionally with the number of the axles.
DESCRIPTION OF THE INVENTION
Aim, Solution, Advatages
Starting from the above stated disadvantages and insufficiencies, the aim of this invention is to develop a method as well as a device for the complex process of the automatic centering which considerably simplifies the construction of the goniometric systems and also considerably reduces the costs for multiple circle systems.
This aim is achieved by a method and apparatus according to the present invention.
According to the instruction of this invention, therefore the centering is no longer executed statically but dynamically. While the above described techniques of conventional type always have the three essential components
translational adjusting of the center of the goniometer in the measuring point,
translational centering of the sample in the center of the goniometer and
rotational orientation or tilting of the sample during the measurement,
according to an inventive further development of the technique of this invention, the static centering of the sample in the center of the goniometer is completely abandoned because, according to the invention, the centering is realized dynamically by translational adjustment.
In this context, the skilled in the art in the field of the goniometric measuring methods will in particular know how to appreciate that, according to the instruction of this invention, the requirement of a coincidence as precise as possible of the axles in the center of the goniometer is superfluous. According to the invention, the position of the sample can be maintained during the measurement dynamically and during any orientation or tilting variation dynamically in the measuring position.
The further advantages which can be achieved with the method as well as with the device according to this invention consist in particular in that goniometers in any configuration can be manufactured considerably smaller and cheaper (the requirement of the precise point of intersection of all orientation or tilting axles is the essential reason for the big structural shape of existing goniometers).
According to the instruction of this invention, the mechanical requirements thus are reduced to
the translational adjusting of the sample in the measuring point, whereby the movements of this translational adjusting dynamically compensate the deviations of the sample position from the measuring position and whereby it does not matter if the dynamic translational adjusting moves the whole goniometer, a part thereof or only the sample, and
the rotational orientation or tilting of the sample during the measurement.
If now the position of the sample is not in the center of one of the axles of rotation of the goniometer, this results, by a rotation about this axle, in a precession or wobbling movement of the sample, this means that the sample describes an orbit about the axle of rotation. If there are several axles of rotation which can eventually also move simultaneously, there can result a complex trajectory. The orientation or the tilting of the sample is however at any time independent from the translational adjusting, i.e. a location in the coordinate system of the goniometer adjustment can be associated to any point of this trajectory.
According to an advantageous embodiment of this invention, an electronic camera system is provided in order to fi
Glick Edward J.
McCormick Paulding & Huber LLP
Thomas Courtney
X-Ray Research GmbH
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