Abstract: An apparatus and method for performing rapid, high-resolution polycrystalline crystallographic texture analysis, by calculating an Orientation Distribution Function (ODF) from partial pole figures obtained from x-ray diffraction measurements on large samples, e.g., 200 millimeter diameter wafers. The measurement apparatus includes a 2-D area x-ray detector and a collimated x-ray source arranged in a specific, fixed spatial relationship dependant on the properties of the sample to be measured, and also includes a particular wafer motion assembly. The wafer motion assembly includes three mutually orthogonal rectilinear translation stages, and a &phgr; rotation stage mounted thereon, as an uppermost motion stage, with its range restricted to 180° of rotation.

Abstract: An X-ray micro-diffraction measuring method for detecting X-rays diffracted at a minute portion of a specimen upon irradiating the minute portion with X-rays is disclosed. A cylindrical stimulation type fluorescent member is arranged around the specimen. A sample facet of the specimen is tilted by, for example, 45° with respect to the stimulation type fluorescent member such that the stimulation type fluorescent member can receive both diffracted X-rays passing along a direction tangential to the sample facet and diffracted X-rays passing along a direction perpendicular to the sample facet. Diffracted X-ray images can be obtained on the stimulation type fluorescent by merely rotating the specimen about only the &phgr; axis thereof so as to perform the in-plane rotation without a rotation about the &khgr; axis. By eliminating a rotation about one axis from rotations about two axes for the specimen, it may be possible to avoid a degradation of measurement preciseness due to a crossing error of the two axes.

Abstract: The invention relates to the X-ray crystal structure of the hepatitis C virus helicase domain. More specifically, the invention relates to crystallized complexes of HCV helicase and an oligonucleotide, to crystallizable compositions of HCV helicase and an oligonucleotide and to methods of crystallizing an HCV helicase-oligonucleotide complex. The invention further relates to a computer programmed with the structure coordinates of the HCV helicase oligonucleotide binding pocket or the HCV helicase nucleotide triphosphate pocket wherein said computer is capable of displaying a three-dimensional representation of that binding pocket.

Abstract: A sample changer (2) for the automatic intake of a multitude of samples into the measurement position on the goniometer axis (a) of an X-ray diffractometer (20) in which the individual samples--each showing a surface, which meets the goniometer axis at a tangent in the measurement position--are linearly arranged on an insertable magazine (3). The samples on the magazine (3) can be moved in the direction of the goniometer axis (a) in order to transport each sample translationally into the measurement position. Furthermore the sample changer (2), the magazine (3) and the mountings (10) show recesses, which allow the refracted X-ray beams from the sample in transmission mode to pass through to the detector (14) unimpeded. The sample changer is suitable for reflection mode as well as transmission mode measurements without having to redesign the system.

Abstract: There is disclosed a method for X-ray topography wherein an X-ray topographic image is obtained for an unprocessed single crystal ingot as it is after being produced by Czochralski method to observe crystal dislocations, thereby finding a boundary between a dislocation-appearing area and a dislocation-disappearing area. A scanning stage (34) travels along a direction X to position the observation area of the silicon ingot (22) at the X-ray irradiation site. The silicon ingot (22) is .phi.-rotated on its axis so that the predetermined crystal lattice plane erects vertically. A traveling table (46) travels along a direction Y to align the rotation center (49) of an .omega.-rotation table (48) with the peripheral surface of the ingot (22). The .omega.-rotation and .phi.-rotation are precisely adjusted while observing diffracted X-rays with an X-ray television camera (26). Then, an X-ray recording medium (66) is mounted on the scanning stage (34).

Abstract: An unrestricted motion device (10) has a sample holder (12), a detector holder (14) capable of independent multi-dimensional movement, a radiation source (16) and a radiation source holder (42) also capable of independent, multi-dimensional movement. In a preferred embodiment, the radiation source (16) is an x-ray tube. A controller (18) is connected to the sample holder (12) and detector holder (14) as well as to radiation source (16) so as to enable control of the independent movement of the sample holder (12) and detector holder (14), as well as operation of radiation source (16) and independent movement of radiation source (16). So long as any two of the sample holder (12), detector holder (14) or radiation source holder (42) are capable of multi-dimensional, independent movement, the entire diffraction cone (40) can be observed and analyzed. In a preferred embodiment, the holders are robots.

Abstract: The present invention relates to X-ray devices for the investigation of material structure, density and geometry of reflected surfaces by measuring reflected, diffracted or scattered radiation. These X-ray optical devices are especially useful for measuring polished surfaces with large reflective areas which are used in the electronics and the computer industry (wafers, memory discs), high precision mechanics and optics. The present invention describes a device which increases the accuracy and efficiency in which X-ray reflectometry measurements can be made in different parts of the X-ray spectral region. The main technical advantages of the invention are a two-fold reduction in the ultimate error of angular measurements in different spectral regions, and a decrease in the random errors associated with the intensity measurements that are observed which are due in part to a drift in the electric parameters of the device.

Abstract: A method and apparatus for producing a monochromatic beam. A plurality of beams are generated from a polyenergetic source. The beams are then transmitted through a bent crystal, preferably a bent Laue crystal, having a non-cylindrical shape. A position of the bent crystal is rocked with respect to the polyenergetic source until a plurality of divergent monochromatic beams are emitted from the bent crystal.

Abstract: An x-ray diffractometer has an x-ray detector and an x-ray source mounted on vehicles traveling along an arc-shaped track around a sample. The vehicles move independently. Alternatively, the vehicles can move independently on separate parallel tracks.

Abstract: An x-ray diffractometer has an x-ray detector and an x-ray source mounted on vehicles traveling along an arc-shaped track around a sample. The vehicles move independently. Alternatively, the vehicles can move independently on separate parallel tracks.

Abstract: In an x-ray diffractometer having (i) first and second motors 10, 17 for respectively rotating a sample 4 and an x-ray detector 13 around a rotational axis 7 and (ii) .theta.-2.theta. interlock control means 22 for supplying drive signals to the motors 10, 17, such that a .theta.-2.theta. relationship is always maintained between the angles of the sample 4 and the x-ray detector 13 with respect to irradiated x-rays 2, there is disposed a rotational vibration control unit 23 for supplying, to the first motor for rotating the sample holding member 6, a drive signal for rotationally vibrating the sample, in addition to the drive signal for .theta.-2.theta. interlock. Eliminating an individual drive mechanism for rotationally vibrating the sample 4, this arrangement makes it possible that, with a simple and economical structure, diffracted x-rays are efficiently detected even for a sample having an uneven surface, thereby to obtain an accurate measurement result.

Abstract: An apparatus for making rapid in-situ thermal stress measurements includes a controlled atmosphere test chamber for receiving and holding a test sample, and a heating zone within the test chamber confined to the near vicinity of the test sample. A test sample holder, a test sample heater, an x-y translation stage and a rotating stage are mounted within the test chamber. An X-ray source is positioned for producing an incident X-ray beam directed at the test sample from different inclination angles. The incident X-ray beam passes through a long but narrow X-ray window in the test chamber, diffracts from the test sample back through the same X-ray window and continues outside of the chamber to an X-ray detector. The diffracted X-ray beam is converted to light. The light is transmitted through optical fibers and is detected by a CCD array. The invention uses an advantageous scintillation material and a slow scan, fiber-optic compatible CCD photo-sensor array.

Abstract: A powder sample inspection cell assembly comprising a cell, an aperture being provided in a side wall of the cell; a closure member which can be clamped over the aperture to close it; and means for compacting the contents of the cell, the cell being oriented such that, after compaction, powder in the cell is sufficiently compacted so as not to escape through the aperture when the closure member is removed.

Abstract: The present invention is directed to an automated system for use in the determination of subsurface material properties of a specimen by X-ray diffraction, comprising a specimen support, a rotatable mounting and aligning fixture for mounting the specimen support onto the shaft of a motor driven positioning system, a chemical holding tank having a first half section having a chemical holding chamber for providing a chemical bath for removing surface material from the specimen and a second half section for providing a position for permitting X-ray diffraction measurement of the specimen, a chemical reservoir in fluid communication with the chemical holding chamber of chemical holding tank to provide a steady supply of chemical solution to the chemical holding chamber through a closed loop system, a neutralization tank for receiving contaminated rinse water from the chemical holding tank, and an electronic controller for controlling the cycling of the specimen between the chemical holding chamber and the positio

Abstract: This invention relates to a double open-ended sample holder cell for x-ray spectroscopic analysis including a cell (58) for containing the sample, a first ring (52) mounted to the cell at one open face (48) securing an analytic film (56) to the cell, a second ring (50) mounted to the cell securing a microporous or solid film (54) at the other open face (46); the second ring including a continuous ring wall extending outwardly from the rim o the cell; the continuous ring wall and the microporous film defining a compartment adjoining the second open face that contains any sample material that passes or breaks through the microporous or solid film. A support bar (92) connected to the top securing ring provides a grip for a tool used in the process of remotely raising or lowering the sample holder relative to placement into or removal from an x-ray cassette.

Abstract: A surface processing method effected before the total-reflection X-ray fluorescence analysis is effected is disclosed. The surface processing is to modify all of the contaminants attached at least to the measurement surface of the wafer into particle-shaped residues. For this purpose, the measurement surface of the wafer is first dissolved by hydrofluoric acid to form a large number of droplets on the measurement surface. Next, the thus formed droplets are dried with the position thereof kept unchanged. After the drying, contaminants attached to the measurement surface of the wafer are left as particle-shaped residues. After this, the measurement surface of the wafer is analyzed by the total-reflection X-ray fluorescence analyzing method.

Abstract: An apparatus is disclosed which is used for total reflection fluorescent X-ray analysis on a liquid drop-like sample containing very small amounts of impurities. The apparatus comprises a heat-resistant thin sheet containing an element or elements, as a principal component, not detected on total reflection fluorescent X-ray analysis and an x-ray source directing an X-ray as an incident X-ray at a liquid drop-like sample put on the sheet and containing very small amounts of impurities whereby the liquid drop-like sample is evaporated to a dried solid for the total reflection fluorescent X-ray analysis to be performed there.

Abstract: An apparatus and method for monitoring structural changes of an electrode in a rechargeable battery include an in situ x-ray study electrochemical cell holder (30) comprising top and bottom cell holder members (32, 34) including at least one beryllium window element (36) for transmission of diffractometer x-radiation. A rechargeable battery cell (43) mounted within the x-ray cell holder enclosure comprises an electrolyte/separator element (68) interposed between positive and negative electrodes (64, 66). A current collector element (70) formed of an electrically-conductive open-mesh grid is disposed between the positive electrode and the separator to enable ion-conducting contact of the electrode and separator while maintaining electrical continuity between the electrode and an external x-ray cell holder terminal (54).

Abstract: An X-ray diffractometer has 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. A sample holder is capable of rotation about three mutually perpendicular axes and is also capable of providing rotation of the sample relative to the sample holder about two perpendicular axes. Thin films or substrates under investigation can be individually aligned into selected diffraction geometries by such a diffractometer. The X-ray source itself may be rotatable about the axis of the X-ray beam.

Abstract: For position-sensitive measurements, an X-ray analysis system comprises a one-dimensional position-sensitive detector and a detection Soller slit system in order to achieve position sensitivity in a direction transversely of the dispersion direction of the detector. Different position-sensitive measurement methods can be carried out by adaptation of the Soller slit system and the orientation of the one-dimensional position-sensitive detector.

Abstract: A sample holder for diffraction analysis protects air or moisture sensitive samples and accommodates samples of different sizes, both without contributing to background noise. In particular, a sample holder for beam diffractometery includes a holder body having a substantially flat beam-facing top surface and a through-hole extending through the top surface, a piston fitted in the through-hole so as to travel along an axis of the through-hole, and a cup-shaped cap fitted over at least a portion of the top surface, surrounding the through-hole. To minimize background noise, the top surface of the holder body and a top surface of the piston are made of quartz. For sample loading, a substantially flat plate and a mechanism for removably attaching the plate so as to overlie the top surface of the holder body are provided. The cap may be made of thin plastic so as to not affect the incident X-ray beam.

Abstract: An X-ray diffractometer having a simple yet accurate means for locating the surface of the sample to be examined with respect to the zero point of the X-ray (RS) is disclosed. Briefly stated, a laser (LA) and camera (KA) are positioned at preferably 90.degree. with respect to each other such that the intersection of the optical axis of the camera and the laser passes through the zero point of the diffractometer. In this fashion, the camera will see at its center, the zero point of the X-ray despite the fact that the X-ray is of course invisible to the naked eye. Accordingly, by movement of the sample (P) with respect to this camera image, the true and correct zero point of the X-ray with respect to the surface of the sample to be examined may be determined without the need for experimental and unnecessary X-ray or examination runs being taken.

Abstract: A method and apparatus for use in performing non-contact analytical evaluation of a semiconductor wafer, which needs to be kept clean, to be performed outside of clean room facilities. The apparatus maintains a clean environment surrounding the semiconductor wafer and a portion of the apparatus is substantially transparent to a probe beam of electromagnetic radiation such as X-rays and visible light. The invention substantially overcomes the expenses associated with locating analytical test equipment for testing semi-conductor wafers within clean room facilities.

Abstract: A double open-ended sample holder for sample material for X-ray spectroscopic analysis including a cylindrical body containing the sample material and having top and bottom open faces. An analytic film is mounted tautly across the lower face, and a microporous film positioned across the upper face cell passes gases generated by X-rays striking the sample material but does not pass harmful particle materials contained in the cell. Upper and lower rings mounted to the cylindrical body secure the lower and upper films to the body. A handling support connected to the top securing ring provides a grip for a tool used in the process of remotely raising or lowering the sample holder relative to placement into or removal from an X-ray cassette. The handling support is spaced from the microporous film so that gases generated in the cell are allowed to escape across the microporous film at a maximum rate of evacuation.

Abstract: An X-ray analysis apparatus includes angle encoders for the determination of angular positions of at least two rotary shafts, for example the .theta. shaft for a specimen holder, the 2.theta. shaft of an X-ray detector arm or the rotary shaft of an X-ray source. Because the angles are directly or indirectly measured relative to a fixed point, preferably coupled to a goniometer frame of the apparatus, accurate angle detection is ensured. The encoders can also be used as adjusting mechanisms for exact, flexible angular adjustment.

Abstract: A total reflection X-ray fluorescence apparatus comprises a base material having an optically flat surface for totally reflecting X-rays radiated at a small glancing angle, a first detector such as an SSD for detecting fluorescent X-rays emerging from a specimen located near the optically flat surface of the base material and a second detector such as a scintillation counter for detecting intensity of X-rays coming from the base material.

Abstract: A specimen holder including a housing having a specimen chamber in it. A window defining a wall of the chamber allows transmission of at least a portion of the x-radiation from X-ray diffraction spectometry apparatus on which the holder is mounted, into the chamber. The housing has a passageway in it opening at one end into the specimen chamber and at the opposite end to outside the housing. A cylindrical specimen mount supports the specimen in the housing is constructed for sealing sliding reception in the passageway such that the specimen mount is rotatable about its longitudinal axis and movable lengthwise of the passageway while maintaining a seal with the passageway for positioning the specimen in the specimen chamber.

Abstract: A system for analyzing a metal impurity at the surface of a single crystal semiconductor comprising: an incident device for allowing X-ray to be incident, at an incident angle less than a total reflection angle, onto the surface of a wafer in the form of a thin plate comprised of a single crystal semiconductor (e.g., silicon); a wafer fixing/positioning stage wherein when it is assumed that the wafer surface is partitioned by a lattice having an interval d, and that the wavelength of the X-ray from the incident device is .lambda., an angle that the X-ray and the wafer surface form is .theta., and an arbitrary integer is n, the stage is adapted to fix the crystal orientation of the wafer so as to satisfy the condition of "2d sin .theta..noteq.n.lambda.

Abstract: An oscillation radiography camera, and method for oscillation radiography, is provided with a generator adapted to generate a collimated beam of quantum fields, such as X-ray or gamma ray photons, or neutrons. Two or more motors are constructed and arranged to position a sample for exposure to the collimated beam. Each of the motors rotates the sample about an axis, with the motors providing a precise net rotation of the sample to within a degree. A detector is constructed and arranged to detect the quantum fields scattered from the sample.

Abstract: A sample holder for use with X-ray diffractometers with the capability to rotate the sample, as well as to adjust the position of the sample in the x, y, and z directions. Adjustment in the x direction is accomplished through loosening set screws, moving a platform, and retightening the set screws. Motion translators are used for adjustment in the y and z directions. An electric motor rotates the sample, and receives power from the diffractometer.

Abstract: Procedure based on X-ray diffraction for measuring the stress state of metals, in particular austenitic steels. In the procedure the detector surface (10) is inclined about an axis (A--A) lying on the surface of the sample (20) being examined which is substantially perpendicular to the direction of the stresses (.sigma..sub.xx) being examined. By means of the detector surface (10) the diameters (2S.sub.ax) of the so-called Debye rings in the direction of the surface being examined are recorded at two or several inclination angles (.psi.). The detector surface (10) has arcuate shape, as viewed in the direction (B--B) at right angles against the inclination axis (A--A), and in the procedure is used such as arcuate detector surface (10) elongated in the direction of said inclination axis (A--A) and narrow enough in the opposite direction that an inclination angle (.psi.) of the detector surface (10) large enough in view of the procedure's implementation is feasible.

Abstract: The present invention relates to a sample holder to be used with an x-ray powder diffractometer. One of the novel features resides in the fact that the sample holder is made of single crystal silicon grown in the [100] direction. This sample holder may have a cavity therein for holding a powder sample.

Abstract: A goniometer in an X-ray diffraction device comprises a sample table rotatably provided about a center axis of a sample for holding a sample, an X-ray source rotatably provided about the center axis of the sample for irrdiating first X-ray onto a sample, and an X-ray detector rotatably provided about the center axis of the sample for detecting second X-rays resulting from the irradiation of the first X-rays, the second X-rays being diffracted X-rays depending upon a sample. The sample table, the X-ray source an the X-ray detector are rotatable independently of one another, and a component to be fixed can be freely selected in accordance with a purpose of measurement and sample attachments employed. As such, various kinds of measuring methods are available to perform X-ray diffraction analysis by a single goniometer.

Abstract: Device for measuring the orientation of bulk monocrystalline materials with respect to the crystallographic parameters using the Laue method, consisting, on the one hand, of a Laue chamber including a polychromatic x-ray source, a photographic film support and a collimator placed in the path of the x-rays between the source and the film in the vicinity of the latter defining the optical axis of the Laue chamber, and consisting, on the other hand, of means of support for a bulk specimen, of means of alignment for the chamber and the means of support, and means of determining the orientation of the specimen with respect to the crystallographic axes, characterized in that the means of support comprise at least one specimen-carrier which has a first planar face to receive the specimen, a second planar space perpendicular to the first for immobilizing the specimen, a first reference plane parallel to the first planar face, a second reference face parallel to the second planar face and a third reference plane perpe

Abstract: The invention comprises apparatus for determining the orientation of the crystallographic axes of a single crystal. The crystal is rotated on a turntable while an X-ray beam containing characteristic radiation is directed onto it. A stationary position-sensitive detector, preferably positioned at right angles to the beam detects Bragg reflections from the crystal, and computing means responsive to the signals from the detector, and signals representing the angular position of the turntable determines the crystal orientation.

Abstract: A sample changer for powder X-ray diffractometry includes a cylindrical dispensing container for holding a stack of pre-test sample holders, a cylindrical receiving container for holding a stack of post-test sample holders and a changer arm which automatically picks up the topmost sample disk in the dispensing container and rotatably positions the sample disk on the sample holder stage of an X-ray diffractometer for analysis. After analysis, the changer arm removes the sample holder and releases it into the receving container. The sample holders have a circumferential groove which coacts with semi-circular rotatable cams positioned on the distal end of the changer arm to enable the changer arm to lift and place the sample holders.

Abstract: In an X-ray analysis apparatus, a specimen to be examined is mounted on the circumference of a focusing cylinder, which can be rolled along an auxiliary cylinder arranged concentrically around the beam focus of an X-ray beam. Independently of the movement mechanism used, a fixed part of the specimen then remains continuously in the beam path. Invariably the same surface area of the specimen is irradiated by the X-ray beam. The movement mechanism may have added to it a device by means of which during the movement of the specimen and the detector the detector is continuously optimally directed to the specimen. The specimen holder may have added to it a device for rotating and/or tilting a specimen included therein.

Abstract: A sample cup for use in spectroscopy consists of a cap member having an extending peripheral flange about a closed top surface, with a downwardly extending cylindrical bottom section, the peripheral flange of the cap member has a through aperture located on the inner edge of the flange and extending towards the periphery, a cell body is of a tubular configuration with an opened top and bottom with the opened top surrounded by a flange having an aperture on an inner surface for communicating with the internal hollow of the cell body. The cap member is adapted to coact with the opened top of the cell body and is rotatably supported thereon, whereby in a first mode the through aperture communicates with the cell aperture to create a vent passageway and in a second rotatable position, the apertures do not align to create a closed cell mode.

Abstract: A detector slit for .theta. rotation in an X-ray examination apparatus utilizing the Seemann-Bohlin focusing principle is suspended on a mechanical arm which is capable of rotating about a shaft through the center of the focusing circle. The Seemann-Bohlin system is for .psi. adjustment tiltable about an axis through an irradiated area on an object to be examined. The readjustment of the detector during the .theta. rotation is controlled by a device which provides detector rotation with with a 1:2 gear wheel transmission. For automatic limitation of a .theta. path to be chosen, the detector housing comprises an abutment pin which cooperates with switching elements connected to the mechanical arm. The X-ray tube has a construction reduced length and is connected to a high-voltage source via a rotatable right-angled connector.

Abstract: A beam exposure apparatus is set forth comprising a mechanism for displacing an object being irradiated. This mechanism involves a drive mechanism. The drive mechanism may be rigidly connected to a wall of the apparatus, and a secondary shaft of the drive mechanism is connected by a friction coupling to a part of the object carrier which is to be positioned. The drive mechanism is driven by a direct current drive motor which is powered by a pulsed direct current. The object can be thus positioned with a step accuracy of approximately 0.2 micron. Such positioning can be measured with this accuracy be means of an inductive position detector.

Abstract: A fixture is provided for supporting and aligning small samples of material on a goniometer for X-ray diffraction analysis. A sample-containing capillary is accurately positioned for rotation in the X-ray beam by selectively adjusting the fixture to position the capillary relative to the x and y axes thereof to prevent wobble and position the sample along the z axis or the axis of rotation. By employing the subject fixture relatively small samples of materials can be analyzed in an X-ray diffraction apparatus previously limited to the analysis of much larger samples.

Abstract: In an X-ray analysis apparatus, a moving mechanism is provided by a main guide member along which a main slide device can be displaced. Rotatably connected with the main slide device is a detector guide member along which a detection slide device is displaced. The main slide device, as well as the detection slide device, and an axis of rotation relative to an end of the main guide member are connected to a common central axis by respective arms which can be mutually rotated with them. The main slide device and the detection slide device can each be equipped with a drive motor where the motor for the main slide device is preferably driven first, and the motor for the detector slide device is driven by signals derived from displacing the main slide device.

Abstract: An X-ray goniometer is provided which comprises, a pair of wooden endplates held in a parallel, adjustably spaced relationship by a plurality of connecting dowel rods, a rotatable support mounted to each endplate, each support being rotatable about a common axis perpendicular to the endplates, for supporting each end of the specimen, and means to position the supports in any given angular orientation about the axis. Means may be included to adjust the spacing between endplates and between each support and the axis.

Abstract: A cell for introducing fluid to be examined into a radiation path. The cell is constructed of metallic back and face plates, the back plate has a cavity for the fluid while the face plate presents a cavity with a thin layer of metal defining an aperture for X-rays.

Abstract: A measuring device for X-ray fluorescence analysis, in which a specimen dosed on a carrier is stimulated by glancing incident radiation and examined spectrometrically by a detector which may be arranged above the specimen. On the upper side of an e.g., box-shaped housing in which a vacuum can be created, there is provided a detector extending into the interior of the housing. This detector is connected to the housing by means of a pivotable frame within the housing. The pivot axis of the frame is located in the measuring plane of the detector. Provided on the pivotable frame is a remote controllable specimen exchanger and a remote controllable disengaging device for shifting the specimen carrier out of its operative position, the disengaging device being substantially aligned with the detector axis. The pivotable frame has furthermore provided thereon counter bearings for the specimen carriers; these counter bearings surround the measuring region.

Abstract: Semiconductor crystals for use, for example, in the manufacture of integrated circuits are required to be inspected for crystal lattice perfection before any subsequent circuit processing. This can be done by X-ray diffraction in which the crystal is curved so that a divergent beam irradiates all points of the crystal surface at the same angle and simultaneously. The difficulty is however, in holding the crystal in the appropriately curved form while at the same time not obstructing the passage of X-rays from the front or back of the crystal and so enable topographs to be obtained by both reflection and transmission. According to the invention, in such a system the crystal is attached to a flat, X-ray transparent plate by pneumatic X-ray transparent means, and the plate is deformed to the required curvature, carrying the crystal with it.