Two-Dimensional X-Ray Grating Interferometer
ABSTRACT We report on the design and experimental realization of a 2D x-ray grating interferometer. We describe how this interferometer has been practically implemented, discuss its performance, and present multidirectional scattering (dark-field) maps and quantitative phase images that have been retrieved using this device.
SourceAvailable from: Peter Modregger[Show abstract] [Hide abstract]
ABSTRACT: It was recently established that the pixel-wise ultra-small angle x-ray distribution can be retrieved with grating interferometry. However, in these one dimensional approaches the contrast was limited to the direction orthogonal to the structure of the line gratings. Here, we demonstrate that sensitivity in two contrast directions can be achieved by using two pairs of crossed line gratings and by adapting scan procedures and data analysis accordingly. We demonstrate the retrieval of two-dimensional scattering distributions with grating interferometry, thus overcoming the previously reported limit of seven obtainable, complementary contrasts. In addition, we give further evidence for the superiority of the signal-to-noise ratio for the dark-field contrast, if a deconvolution-based instead of the standard analysis is utilized.Applied Physics Letters 07/2014; 105(2):024102. DOI:10.1063/1.4890090 · 3.52 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The gold-coated cross-grating is investigated to simultaneously improve the diffraction efficiency, signal contrast and optical subdivision in heterodyne grating interferometer (HGI). Based on the theories of Fresnel-Kirchhoff diffraction integral and rigorous coupled wave analysis (RCWA), the diffractive characteristics related to diffraction efficiency, wavelength selectivity and polarization dependency are analyzed. The analysis reveals that grating pitch less than twice of the incident wavelength ought to be adopted here to avoid the second-orders, and longer wavelength is preferred to achieve high diffraction efficiency in the visible region. Meanwhile, the equivalent efficiency for TE and TM polarization, probably up to 18.32% at the wavelength of 632.8 nm, can be obtained with normal incidence which results in a signal contrast of 100% theoretically. Additionally, an eightfold optical subdivision method with cross-gratings is proposed for HGIs, and it is applicable to nearly all the existing two-dimensional (2D) optical configurations. The experimental tests on diffraction field, polarization dependency and signal contrast are performed. The results show reasonable consistency with the theoretical analysis, which validates the capability of cross-gratings for HGIs.Optics Communications 02/2015; 339. DOI:10.1016/j.optcom.2014.11.059 · 1.54 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Among X-ray phase-contrast techniques, grating-based X-ray differential phase contrast (DPC) imaging using conventional X-ray tube sources is the most prominent one for widespread applications in the case of acquisition of high-quality absorption gratings in mass production. In this letter, we report on a new type of absorption grating made from Bi and manufactured by a micro-casting process. We tested Bi absorption gratings with our X-ray DPC imaging system and obtained high-quality phase-contrast images. Our efforts towards the practical application of X-ray DPC imaging are briefly outlined. (C) 2013 The Japan Society of Applied PhysicsApplied Physics Express 11/2013; 6(11):117301. DOI:10.7567/APEX.6.117301 · 2.57 Impact Factor