Abstract: A detector for a small-angle x-ray diffraction system uses curved readout strips shaped to correspond to the expected intensity distribution of x-rays scattered by the system. This expected intensity distribution may be a series of concentric circles, and each of the strips has a shape that approximates a section of an annulus. The strips may be positioned on a substrate such that a center of curvature of the curved strips is located along an edge of a readout region within which the strips are located or, alternatively, at a geometric center of the readout region. The detector may have a signal readout system that uses a delay line or, alternatively, a multichannel readout system. The detector may make use of electron generation via interaction of the diffracted x-ray beam with a gas in a gas chamber, or through interaction of the diffracted beam with a semiconductor material.

Abstract: In an X-ray detector operating in a rolling shutter read out mode, by precisely synchronizing sample rotation with the detector readout, the effects of timing skew on the image intensities and angular positions caused by the rolling shutter read out can be compensated by interpolation or calculation, thus allowing the data to be accurately integrated with conventional software. In one embodiment, the reflection intensities are interpolated with respect to time to recreate data that is synchronized to a predetermined time. This interpolated data can then be processed by any conventional integration routine to generate a 3D model of the sample. In another embodiment a 3D integration routine is specially adapted to allow the time-skewed data to be processed directly and generate a 3D model of the sample.

Abstract: A detector for a small-angle x-ray diffraction system uses curved readout strips shaped to correspond to the expected intensity distribution of x-rays scattered by the system. This expected intensity distribution may be a series of concentric circles, and each of the strips has a shape that approximates a section of an annulus. The strips may be positioned on a substrate such that a center of curvature of the curved strips is located along an edge of a readout region within which the strips are located or, alternatively, at a geometric center of the readout region. The detector may have a signal readout system that uses a delay line or, alternatively, a multichannel readout system. The detector may make use of electron generation via interaction of the diffracted x-ray beam with a gas in a gas chamber, or through interaction of the diffracted beam with a semiconductor material.

Abstract: An apparatus for examining the surface of a crystalline sample uses in-plane grazing incidence diffraction with a position-sensitive detector. The x-ray source illuminates an extended region of the sample and, for crystal sections having the appropriate lattice orientation, an elongated diffraction signal is produced. The relative position of the sample and the x-ray beam may then be changed to illuminate different regions of the sample so that the diffraction signal corresponds to these other regions. By scanning across the entire sample, a spatial profile of the sample surface may be generated. The system may be used to locate crystal boundaries, defects, or the presence of attenuating materials on the sample surface.

Abstract: Readout noise for each pixel in a CMOS Active Pixel Sensor is reduced by a five step process in which the pixel charge data from the sensor is non-destructively sampled at a plurality of times during a sensor frame time period and corrected for gain variation and nonlinearity. Then fixed pattern and dark current noise is estimated and subtracted from the corrected pixel charge data. Next, reset noise is estimated and subtracted from the pixel charge data. In step four, a model function of charge versus time is fit to the corrected pixel charge data samples. Finally, the fitted model function is evaluated at frame boundary times.

Abstract: An area detector used in a two-dimensional system is used as a point detector in Bragg-Brentano and other geometries by providing the area detector with a mask the limits the area through which X-rays can enter the detector. Secondary X-ray optics and a monochromator that are part of the diffractometer geometry are attached to the area detector mask to allow a fast and easy switch between the two-dimensional detector mode and the point detector mode. A concave detector mask is used with a spherical detector in order to reduce the secondary beam path and increase detector efficiency and the opening in the detector mask can be offset from the mask center to achieve high 2? angle measurements. Single channel bypath electronics are used to disregard the dimensional position of each X-ray count to increase the efficiency and speed of the system.

Abstract: Readout noise for each pixel in a CMOS Active Pixel Sensor is reduced by a five step process in which the pixel charge data from the sensor is non-destructively sampled at a plurality of times during a sensor frame time period and corrected for gain variation and nonlinearity. Then fixed pattern and dark current noise is estimated and subtracted from the corrected pixel charge data. Next, reset noise is estimated and subtracted from the pixel charge data. In step four, a model function of charge versus time is fit to the corrected pixel charge data samples. Finally, the fitted model function is evaluated at frame boundary times.

Abstract: In an X-ray detector operating in a rolling shutter read out mode, by precisely synchronizing sample rotation with the detector readout, the effects of timing skew on the image intensities and angular positions caused by the rolling shutter read out can be compensated by interpolation or calculation, thus allowing the data to be accurately integrated with conventional software. In one embodiment, the reflection intensities are interpolated with respect to time to recreate data that is synchronized to a predetermined time. This interpolated data can then be processed by any conventional integration routine to generate a 3D model of the sample. In another embodiment a 3D integration routine is specially adapted to allow the time-skewed data to be processed directly and generate a 3D model of the sample.

Abstract: An area detector used in a two-dimensional system is used as a point detector in Bragg-Brentano and other geometries by providing the area detector with a mask the limits the area through which X-rays can enter the detector. Secondary X-ray optics and a monochromator that are part of the diffractometer geometry are attached to the area detector mask to allow a fast and easy switch between the two-dimensional detector mode and the point detector mode. A concave detector mask is used with a spherical detector in order to reduce the secondary beam path and increase detector efficiency and the opening in the detector mask can be offset from the mask center to achieve high 2? angle measurements. Single channel bypath electronics are used to disregard the dimensional position of each X-ray count to increase the efficiency and speed of the system.

Abstract: A detection system for wavelength-dispersive and energy-dispersive spectrometry comprises an X-ray detector formed from a solid-state avalanche photodiode with a thin entrance window electrode that permits the efficient detection of X-rays scattered from “light” elements. The detector can be tilted relative to the incident X-rays in order to increase the detection efficiency for X-rays scattered from “heavy” elements. The entrance window may be continuous conductive layer with a thickness in the range of 5 to 10 nanometers or may be a pattern of conductive lines with “windowless” areas between the lines. A signal processing circuit for the avalanche photodiode detector includes an ultra-low noise amplifier, a dual channel discriminator, a scaler and a digital counter. A linear array of avalanche photodiode detectors is used to increase the count rate of the detection system.

Abstract: Crystallite size in a sample is determined by performing a quantitative ?-profile analysis on a diffraction ring in a two-dimensional X-ray diffraction pattern. In particular, a two-dimensional X-ray diffraction system is first calibrated with a sample having a known crystallite size, crystal structure and X-ray absorption coefficient. For a given instrument window, the number of grains contributing to a selected diffraction ring is determined by the effective diffraction volume, grain size and the multiplicity of the diffracting crystal planes. The grain size of an unknown sample can then be determined by a quantitative analysis of the diffraction ring.

Abstract: In an X-ray diffraction apparatus, a high brightness source, such as a rotating anode generator, is combined with demagnification X-ray optics to produce a beam with small image size and high-intensity. In one embodiment, an elliptical X-ray optic is positioned relative to the source and image focal points so that the magnification of the optic is less than one. The combination can produce high-intensity beams with beam images at the sample of less than 0.1 mm.

Abstract: In an X-ray diffraction apparatus, a sample holder has a sample mounted on a pin extending a known distance from a cap that mates with a magnetized base on a goniometer. The sample is mechanically positioned in the center of an X-ray beam by a first movable arm which is located in a precise position relative to the goniometer base by a positioning mechanism and a mechanism that forces the pin into engagement with the first arm. The sample has a known height on the pin with respect to the cap and therefore, the sample can repeatedly be located in the center of the X-ray beam without the use of complex centering arrangements. In order to allow the sample holder to be removed from the goniometer base, a linkage is provided that releases the pin from the first arm.

Abstract: A handheld X-ray diffractometer comprises a miniaturized X-ray source and multiple area detectors to allow the diffractometer to obtain two-dimensional X-ray diffraction images in a large diffraction space without rotating the sample. The source and detectors are located inside of a radio opaque enclosure that protects the operator during use. The handheld diffractometer also comprises a sample monitoring and alignment system that allows an operator to observe the measuring area and to align the diffractometer to the sample from outside of the housing. A specially designed mouthpiece, which mates the diffractometer to the sample area, prevents x-ray leakage and triggers off the data collection. The detectors can be positioned to perform measurements necessary to calculate a mechanical stress in the sample. Linear detectors may also be used in place of the area detectors.

Abstract: A cathode assembly for a rotating anode X-ray source comprises two parts: a focusing part that is mechanically connected to the remainder of the X-ray source and permanently aligned with respect to the anode and a separate emission part that holds the electron source and is removably connected to the focusing part. The electron source is permanently mounted in the emission part and precisely aligned to the focusing part. The focusing part and the emission part are mechanically connected aligned relative to one another at the time of replacement. This arrangement allows the emission part, including the electron source to be quickly removed and replaced by an inexperienced user while maintaining the accuracy of the X-ray source alignment.

Abstract: An X-ray detector is formed with a geometry in the form of a spherical polygon, including an entrance window, a grid and an anode. The spherical polygonal entrance window and the grid form a spherical polygonal drift region between them. The electric field in this region is radial and eliminates parallax broadening. A spherical polygonal amplification region between a resistive anode on an insulating support and the grid allows very high gas amplification and good protection against spark discharges. A readout electrode on the back side of the anode insulator detects induced charges and protects the readout electronics against sparks.

Abstract: A handheld X-ray diffractometer comprises a miniaturized X-ray source and multiple area detectors to allow the diffractometer to obtain two-dimensional X-ray diffraction images in a large diffraction space without rotating the sample. The source and detectors are located inside of a radio opaque enclosure that protects the operator during use. The handheld diffractometer also comprises a sample monitoring and alignment system that allows an operator to observe the measuring area and to align the diffractometer to the sample from outside of the housing. A specially designed mouthpiece, which mates the diffractometer to the sample area, prevents x-ray leakage and triggers off the data collection. The detectors can be positioned to perform measurements necessary to calculate a mechanical stress in the sample. Linear detectors may also be used in place of the area detectors.

Abstract: A rotating anode for x-ray generation uses a heat pipe principle with a heat pipe coolant located in a sealed chamber of a rotating portion of the anode. The rotating portion is positioned relative to a second portion so that relative rotation occurs between the two portions and so that a fluid path exists between the two portions through which an external cooling fluid may flow. The relative motion between the two portions provides a turbulent flow to the cooling fluid. The anode may also include cooling fins that extend into the sealed chamber. The sealed chamber may be under vacuum, and may be sealed by o-rings or by brazing. A closable fill port may be provided via which heat pipe coolant may be added. A balancing mass may be used to balance the anode in two dimensions.

Abstract: An x-ray mirror provides focusing and monochromatization while maintaining a high degree of reflectivity. The mirror has at least two mirror portions, one with a multilayer surface that provides the desired monochromating, and the other with a total external reflection surface. The multiple surfaces combine to provide the desired focusing of the x-rays from a source to a focus point. A variety of configurations may be used, each of which does the desired focusing and monochromatization with minimal energy loss. Relative positioning of the mirror portions may also allow for adjustment of the focus length.

Abstract: In an X-ray source in which an electron beam spot is focused on a rotating anode, the height of the electron beam spot is reduced as much as practical, the width is increased so that the ratio of the height to the width of the electron beam spot is significantly smaller then the sine of the X-ray takeoff angle. The electron beam is generated by an electron optical configuration obtained by a process involving a combination of testing and simulations. An initial electron optics design is obtained by simulating the electron optics using conventional simulation software. This initial electron optical design is then built into hardware. Extensive measurements are then made on this hardware, and, based on the results of the measurements, new simulations are performed. This process is repeated until an optimum design is obtained.