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Figure 1
Schematic illustration of the principle of XGI in the moiré mode. The diffraction of an incident plane wave into positive and negative diffraction orders (propagating in the first order at an angle of [\lambda/p_1] with respect to the original propagation direction) by the diffraction grating gives rise to an interference pattern. The diffraction grating induces a phase shift of [h_1(2\pi\delta)/\lambda] where δ is the wavelength-dependent decrement in the real part of the refractive index of the grating material. The absorption grating acts as a transmission mask. For small rotation angles of one grating with respect to the other (3° with respect to the horizontal axis in the figure), the resulting moiré pattern can conveniently be imaged using an adequate camera system, whereas the spatial modulations with a high frequency cannot be resolved.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 24| Part 1| January 2017| Pages 150-162
https://doi.org/10.1107/S1600577516017562
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