J Baumann

Publications (2)1.63 Total impact

• Article: The fractional Talbot effect in differential x-ray phase-contrast imaging for extended and polychromatic x-ray sources.

  M Engelhardt, C Kottler, O Bunk, C David, C Schroer, J Baumann, M Schuster, F Pfeiffer
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  ABSTRACT: The influence of different physical parameters, such as the source size and the energy spectrum, on the functional capability of a grating interferometer applied for phase-contrast imaging is discussed using numerical simulations based on Fresnel diffraction theory. The presented simulation results explain why the interferometer could be well combined with polychromatic laboratory x-ray sources in recent experiments. Furthermore, it is shown that the distance between the two gratings of the interferometer is not in general limited by the width of the photon energy spectrum. This implies that interferometers that give a further improved image quality for phase measurements can be designed, because the primary measurement signal for phase measurements can be increased by enlargement of this distance. Finally, the mathematical background and practical instructions for the quantitative evaluation of measurement data acquired with a polychromatic x-ray source are given.
  Journal of Microscopy 11/2008; 232(1):145-57. · 1.63 Impact Factor
• Source

  Available from: psi.ch

  Article: High-resolution differential phase contrast imaging using a magnifying projection geometry with a microfocus x-ray source

  M. Engelhardt, J Baumann, M Schuster, C. Kottler, F. Pfeiffer, O. Bunk, C David
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  ABSTRACT: Differential x-ray phase contrast imaging using a grating interferometer was combined with a magnifying cone beam geometry using a conventional microfocus x-ray tube. This brings the advantages of a magnifying cone beam setup, namely, a high spatial resolution in the micron range and the possibility of using an efficient, low resolution detector, into differential phase contrast imaging. The authors present methodical investigations which show how the primary measurement signal depends on the magnification factor. As an illustration of the potential of this quantitative imaging technique, a high-resolution x-ray phase contrast tomography of an insect is presented.