A new X-ray optics for observing dark-field and bright-field refraction-contrast images is proposed. The optics consists of a collimator and an analyzer in the Bragg geometry with a sample between them. Phase gradients produced by the sample are resolved by the analyzer and the transmitted X-rays are recorded on an X-ray film. When the analyzer is tuned at an angle inside its selective reflection region, clear dark-field images are observed. On the other hand, when the analyzer is tuned in the vicinity of, but outside, the selective reflection region, bright-field images are observed. This optics was tested at a vertical wiggler beamline, BL-14B, at the Photon Factory. The analyzer images were taken at various points in the rocking curve. Both dark-field and bright-field images were successfully observed.
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Hirano et al. (2002) studied this question.
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