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1.
Rev Sci Instrum ; 83(11): 113702, 2012 Nov.
Article in English | MEDLINE | ID: mdl-23206066

ABSTRACT

Several recent papers have shown the implementation of analyzer based X-ray phase contrast imaging (ABI) with conventional X-ray sources. The high flux is always a requirement to make the technique useful for bio-medical applications. Here, we present and discuss three important parameters, which need to be taken into account, when searching for the high flux ABI: anisotropic magnification, double image, and source size spread due to intrinsic dispersive diffraction by asymmetrically cut crystals. These parameters, if not well optimized, may cause important features in the acquired images which can mislead the interpretation. A few ways to minimize these effects are implemented and discussed, including some experimental results.

2.
Rev Sci Instrum ; 78(11): 113708, 2007 Nov.
Article in English | MEDLINE | ID: mdl-18052481

ABSTRACT

An analyzer-based x-ray phase-contrast microscopy (ABM) setup combining a standard analyzer-based x-ray phase-contrast imaging (ABI) setup [nondispersive 4-crystal setup (Bonse-Hart setup)] and diffraction by asymmetrically cut crystals is presented here. An attenuation-contrast microscopy setup with conventional x-ray source and asymmetrically cut crystals is first analyzed. Edge-enhanced effects attributed to phase jumps or refraction/total external reflection on the fiber borders were detected. However, the long exposure times and the possibility to achieve high contrast microscopies by using extremely low attenuation-contrast samples motivated us to assemble the ABM setup using a synchrotron source. This setup was found to be useful for low contrast attenuation samples due to the low exposure time, high contrast, and spatial resolution found. Moreover, thanks to the combination with the nondispersive ABI setup, the diffraction-enhanced x-ray imaging algorithm could be applied.


Subject(s)
Crystallization/instrumentation , Image Enhancement/instrumentation , Lenses , Microscopy, Phase-Contrast/instrumentation , X-Ray Diffraction/instrumentation , Equipment Design , Equipment Failure Analysis , Image Enhancement/methods , Microscopy, Phase-Contrast/methods , Reproducibility of Results , Sensitivity and Specificity , X-Ray Diffraction/methods
3.
J Synchrotron Radiat ; 11(Pt 4): 335-42, 2004 Jul 01.
Article in English | MEDLINE | ID: mdl-15211040

ABSTRACT

A high-resolution spectrometer aimed at performing experiments of inelastic X-ray scattering by electronic excitations is described. The spectrometer has been installed at the D12A-XRD1 beamline of the National Synchrotron Light Laboratory (LNLS), in Campinas, Brazil. Synchrotron radiation is monochromated to about 6 keV and focused horizontally onto the sample by a sagittally focusing Si(111) double-crystal monochromator in non-dispersive setting. The spectrometer operates in Rowland circle geometry and is based on a focusing Si(333) analyser in near-backdiffraction geometry for energy analysis of inelastically scattered photons. The analyser works at a fixed Bragg angle, so energy transfers are obtained by varying the incident photon energy. A relative energy resolution of the whole spectrometer of approximately 1.5 x 10(-4) at 5.93 keV has been achieved. As an example of application, inelastic X-ray scattering by plasmon excitation in polycrystalline Be was measured. Test results demonstrate that inelastic X-ray scattering experiments with eV energy resolution and an acceptable counting rate are feasible at the LNLS when focused on plasmon and particle-hole excitations.

4.
J Synchrotron Radiat ; 10(Pt 6): 421-3, 2003 Nov 01.
Article in English | MEDLINE | ID: mdl-14551441

ABSTRACT

Diffraction-enhanced images have been obtained using two silicon crystals in a non-dispersive set-up at the XRD2 beamline at the Brazilian Synchrotron Light Laboratory (LNLS). A first asymmetrically cut silicon crystal using the (333) reflection vertically expanded the monochromated beam from 1 mm to 20 mm allowing the imaging of the whole sample without movements. A symmetrically cut Si(333) second crystal was used as a Bragg analyzer. Images of biological samples including human tissue were recorded using a direct-conversion CCD detector resulting in enhancement of the contrast compared with absorption-contrast images.


Subject(s)
Cuspid/diagnostic imaging , Hysterosalpingography/methods , Radiographic Image Enhancement/instrumentation , Radiographic Image Enhancement/methods , Tuberculosis, Pulmonary/diagnostic imaging , X-Ray Diffraction/instrumentation , X-Ray Diffraction/methods , Brazil , Feasibility Studies , Humans , Lung/diagnostic imaging , Pilot Projects , Plant Leaves/anatomy & histology , Synchrotrons , Trees/anatomy & histology
5.
J Synchrotron Radiat ; 5(Pt 3): 491-3, 1998 May 01.
Article in English | MEDLINE | ID: mdl-15263555

ABSTRACT

Versatility was a major consideration in the project to provide an X-ray diffraction station at LNLS. At least two techniques are possible at the station: powder diffraction and multiple single-crystal diffraction. A two-crystal monochromator based on monolithic elastic translators, developed at LNLS, with sagittal focusing by the second crystal, allows 10 mrad of a >/=2 keV monochromatic beam to be used on the diffractometer. The station is equipped with a fast scintillation detector, imaging plates, a high-energy-resolution pin-diode detector, an ionization chamber and a high-angular-resolution soller slit. The data collection and control hardware and software were also developed at LNLS. The theta-2theta goniometry for powder diffraction on this 1 m-diameter diffractometer is based on commercial rotation tables. The multiple single-crystal goniometry is realized by an independent elastic axis driven by differential micrometers for both high- and low-resolution angular movements. At least four independent axes can be positioned as necessary on the diffractometer table. Powder diffractograms and double-crystal rocking curves collected with the synchrotron beam show the expected quality.

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