Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
  • G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators

Definitions

• the invention relates to an X-ray optical arrangement according to the preamble of claim 1. It can be particularly advantageous in X-ray analysis, e.g. in X-ray diffractometry, reflectometry and / or fluorescence analysis.
• X-rays with high intensity i.e. especially high photon density required. This can be achieved by focusing the X-rays. In many cases, however, it is cheaper to use X-rays with a very small divergence, in the best case, as parallel X-rays.
• the X-rays are preferably grazing, ie with relatively small angles of incidence up to a maximum of a few degrees angles of incidence or a few tenths of a degree of incidence, ie close to the critical angle of total reflection, is directed onto a sample or a corresponding substrate surface and, accordingly, the radiation cross section is projected onto the sample surface in accordance with 1 / sin ⁇ . It is desirable to further increase the photon density per surface on the projection surface or to concentrate on a smaller projection surface.
• the surface intensity and consequently also the photon density can be increased by strongly bundling parallel or approximately parallel X-rays and consequently the locally detectable measurement signal of a sample can also be increased.
• the spatial resolution of the measurement signals ie the most accurate assignment of the measurement signals to the measurement location, places high demands on the measurement setup.
• diaphragms are usually arranged in the beam path of the X-ray radiation, so that only a part of the X-ray radiation can reach the measurement location through the aperture opening and thus a locally defined assignment of the measurement signal to the measurement location is achieved.
• the use of such diaphragms results in loss of intensity of the X-ray radiation, which cannot be used for the measurement.
• the measuring accuracy suffers from this or an increase in the required measuring time has to be accepted, which is undesirable for many applications and also makes measurements impossible.
• the X-ray optical arrangement according to the invention uses conventional X-ray optical elements, such as a suitable X-ray source, an X-ray focusing element and an X-ray reflecting element.
• the X-ray radiation from the X-ray source is directed onto the focusing element, which is an element that achieves a lens effect, but more advantageously an ent speaking shaped reflector can act.
• the X-ray radiation focused by this element is directed to an X-ray reflecting element, the reflecting surfaces of which are convex and parabolic.
• This surface shape of the reflecting element can simultaneously obtain a bundling (compression) of the X-rays and their parallel alignment with negligible divergence, which can be directed onto a correspondingly arranged and aligned surface of a sample or a substrate.
• the convergent X-rays can be generated with a punctiform, elliptical or linear cross-section, the surface contour of the element reflecting the X-rays being naturally also adapted to this geometry.
• the focusing and the reflecting element can have cylinder symmetry.
• the function of the aperture used changes and it serves to suppress stray light.
• diaphragms are still required in individual cases to increase the spatial resolution, a much smaller part of the X-ray intensity is masked out by the diaphragms, since the photon density in the correspondingly compressed X-ray radiation is considerably higher than is the case with known solutions , In this way an increase in intensity greater than 2 can be achieved.
• At least the surface of the reflective element can have a single reflective layer, but in many cases cheaper, a multi-layer system.
• the X-ray radiation from the focusing element can be directed onto the reflective element at an angle dem the critical angle ⁇ c of total reflection and the desired effect can be achieved.
• the individual layers of the multi-layer system taking into account the different angles of incidence of the X-rays, have a correspondingly adapted thickness distribution with which the respective angles of incidence B ir with a predefinable one X-ray wavelength meet Bragg's equation on each surface element of the reflective element.
• the gradient layers have a double layer thickness that changes over the length.
• a further increase in the photon density and also an improved monochromatization of the X-rays can thereby be achieved.
• the adjacent individual layers of a multi-layer system have different X-ray refractive indices.
• the greatest possible compression of the x-ray radiation can be achieved if the focal points F of the focusing and reflecting element with one another match, but are at least arranged in close proximity to each other.
• the focusing element images the X-ray source in a line focus
• a higher spatial resolution of the measurement signals can be achieved with the X-ray optical arrangement according to the invention even with small angles of incidence of the X-rays on the samples, since the projected area on the sample is reduced with approximately the same number of photons.
• the signal-to-noise ratio can also be improved with the invention, since an additional monochromator is arranged in the beam path with the reflecting element.
• the dynamic range of the measurement can also be increased, which e.g. increases the information content of a measured reflectogram, since covert diffraction orders can possibly be detected by background signals.
• the X-rays can be directed to certain small measuring sites / areas.
• the invention will be explained below using an exemplary embodiment.
• FIG. 1 shows schematically an example of an X-ray optical arrangement according to the invention in which divergent X-rays from an X-ray source are directed onto a focusing element and converted into parallel radiation with a smaller beam cross section, and
• Figure 2 in schematic form an example of an arrangement in which parallel X-rays are directed onto a focusing element and converted into parallel radiation with a significantly smaller beam cross-section.
• divergent X-rays from an X-ray source 1 are directed onto a concave surface formed in the shape of an ellipse or parabola, with a surface reflecting the X-rays used, in this case a multilayer system.
• the X-ray radiation is reflected from there and at the same time directed onto the convex, parabolic reflecting surface of the reflecting element, the X-ray radiation reflected from the reflecting element 3 being simultaneously compressed and aligned in parallel.
• the parallel x-ray radiation bundled in this way can then be used for the various x-ray analysis techniques, with x-ray cross sections in the range of less than 200 ⁇ m being readily obtained. are reachable.
• a multilayer system can also be present on the reflecting surface of the reflecting element 3, in which the layer thicknesses of the individual layers are taken into account locally, corresponding to the different angles of incidence of the incident X-rays.
• the parallel, reflected X-ray radiation can not only have a higher intensity, but it is also monochromatized.
• X-ray radiation with little or no divergence is directed in parallel onto the concave, parabolic reflecting surface of a focusing element 2.
• the X-ray radiation is reflected accordingly from this surface and simultaneously focused and directed onto the surface of the reflecting element 3.
• the beam cross section b ', the x-ray radiation reflected in parallel by the reflecting element 3 is substantially smaller than the beam cross section b, the originally used parallel x-ray radiation. It follows from this that with sufficiently high reflectivity of (2) and (3) the photon density in the X-ray radiation reflected by the reflecting element 3 has been increased compared to the original parallel radiation.
• the focused x-ray radiation specifies different angles of incidence ⁇ ⁇ on the reflecting surface of the reflecting element 3, it is consequently also necessary to use a corresponding gradient multilayer system which has a different period thickness ⁇ at the corresponding x-ray radiation wavelength corresponding to the respective angles of incidence.
• the reflecting surface of the focusing element 2 has a parabolic shape (FIG. 2), but an elliptical contour (FIG. 1) can also be used.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Apparatus For Radiation Diagnosis (AREA)

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• 2000
  • 2000-06-05 DE DE10028970A patent/DE10028970C1/de not_active Expired - Fee Related
• 2001
  • 2001-05-18 WO PCT/DE2001/002043 patent/WO2001094987A2/fr active IP Right Grant
  • 2001-05-18 AT AT01943167T patent/ATE301328T1/de not_active IP Right Cessation
  • 2001-05-18 DE DE50106990T patent/DE50106990D1/de not_active Expired - Lifetime
  • 2001-05-18 EP EP01943167A patent/EP1323170B1/fr not_active Expired - Lifetime
  • 2001-05-18 JP JP2002502480A patent/JP2003536081A/ja active Pending
  • 2001-05-18 US US10/048,873 patent/US6724858B2/en not_active Expired - Lifetime

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