X-ray or gamma ray systems or devices – Specific application – Diffraction – reflection – or scattering analysis
Patent
1993-12-06
1995-10-17
Porta, David P.
X-ray or gamma ray systems or devices
Specific application
Diffraction, reflection, or scattering analysis
378 79, 378 81, 378208, G01N 23207
Patent
active
054597706
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to X-ray diffractometers for use in investigation of sample such as single crystals, thin films and surfaces and the like, using position-sensitive detectors.
In GB patent application no. 8929306.2 (GB-A-2228167) the present inventor describes an X-ray diffractometer which comprises a source of X-rays for producing an incident beam falling on a sample to be investigated, a position-sensitive detector which has a wide aperture to detect the diffracted X-rays over a wide angular coverage, and means for effecting controlled relative rotation between the detector and the incident beam to increase the effective area of detection covered by the detector.
Various embodiments of the diffractometer are described and claimed.
Other prior art of interest comprises the following patent specifications: GB-A-2081440, GB-A-774572; EP-A-0207863; EP-A-0115891; and EP-A-0015475. In each of these prior patent specifications, there is shown relative movement between the X-ray source, the sample under investigation, or the detector. In EP-A-0207863 in particular, the sample is shown to be supported on a three axis stage. The position-sensitive detector is generally arcuate and the X-ray source if movable arcuately about an axis through the sample and lying in the same plane as the arc of the detector. Other art of possible relevance includes U.S. Pat. No. 3,105,901, EP-A-0165877 and Zeitschrift fur Metallkunde Vol. 75, no. 2, February 1984.
The present inventor has now appreciated that significant advantages are to be gained by providing additional freedoms of movement in a diffractometer of the type described and claimed in GB-A-2228167.
In accordance with a first aspect of the present invention therefore an X-ray diffractometer comprising an X-ray source for producing an X-ray beam; a position sensitive detector for detecting diffracted X-rays over a wide angle; and means for effecting controlled relative rotation between the detector and the X-ray source incident beam, is characterised by means for mounting the X-ray source for rotation about the axis of the X-ray Ream emitted therefrom.
By allowing rotation of the X-ray source so that the incident beam (which is much narrower in one dimension of the cross-section than in the other) can be arranged to lie with its longer dimension either in the arcuate plane of the detector (see GB PA 8929306.2) or perpendicular to it. By this means, in the latter orientation of the X-ray source, a thin film sample in particular, having a planar surface disposed perpendicularly to the plane of the incident beam, can be investigated in an optimum way.
According to a second aspect of the present invention, an X-ray diffractometer comprising an X-ray source for producing an X-ray beam; a position sensitive detector for detecting diffracted X-rays over a wide angle; and means for effecting controlled relative rotation between the detector and the X-ray source incident beam, is characterised by;
a sample holder capable of rotation about three mutually perpendicular axis; and means for providing rotation of the sample relative to the sample holder about two perpendicular axes, whereby thin films or substrates under investigation can be individually aligned into selected diffraction geometries.
One example of an X-ray diffractometer according to the present invention will now be described with reference to the accompanying drawings in which:
FIGS. 1 & 2 and 3 & 4 are copies of FIGS. 1 & 2 and 5 & 6 of the drawings from GB-A-2228167;
FIG. 5 is a diagrammatic side view illustrating the application of the second aspect of the present invention to the apparatus shown in GB patent application 8929306.2; and,
FIGS. 6 to 9 illustrate how the first aspect of the present invention is applied to that apparatus.
FIG. 1 illustrates the basic X-ray diffractometer described in GB patent application 8929306.2, the diffractometer comprising an X-ray source 1, a sample support 2 and an arcuate, position-sensitive X-ray detector 3. A sample, often a crystal 4, is mounted on the sample
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patent: 4658411 (1987-04-01), Argoud et al.
patent: 4961210 (1990-10-01), Fatemi
patent: 5181233 (1993-01-01), Rink et al.
Cambridge Surface Analytics Ltd.
Porta David P.
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