It has been shown in recent years that X-ray moir6 fringes are not given exactly as a projection of the intensity pattern on the exit surface of the crystal but oscillate spatially along the beam path behind the crystal. Experiments to reveal the real state of this moir6 image's nonprojectiveness have been conducted using synchrotron-radiation plane-wave topography, an Si bicrystal specimen and a simultaneous recording of moir6 topographic images onto a set of multilayered X-ray films. This paper reports the following experimental results: intensity prof'des revealing an unusual striking figure of the space wave field of moir6 fringes; qualitative analysis of the fringe profile change in its manner of occurrence and in the effect on the fringeposition variation; plots of oscillating fringe position and fringe direction. The amplitudes of the fringe oscillation determined over the whole field of the moir6 pattern exhibit a non-uniform characteristic distribution pattern that can be related to a specific feature of the intensity pattern on the specimen.

The rocking curve of monolithic bicrystals with a narrow gap is studied. The plane‐wave theory of X‐ray dynamical diffraction predicts that the rocking curve has an oscillatory structure caused by an interference between the two waves propagated in the transmitted‐ and diffracted‐beam directions in the gap. Experiments made with Si (220) and MoKα radiation verify that such oscillatory structure with a narrow peak interval (0.16 to 0.18″ of arc) appears in rocking curves in agreement with the theory.

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It has been experimentally found that X-ray moire  fringes are not exactly given as a projected ®gure from the specimen crystal as predicted by the standard theory of X-ray dynamical diffraction, but show a kind of spatial oscillation along the beam path out of the crystal. This paper reports that a similar spatial oscillation has been found for Pendello È sung fringes in a similar experiment recording plane-wave X-ray topographs of a silicon wedge crystal onto a set of multi-stacked ®lms. The oscillation of the Pendello È sung fringes was easily found among the simultaneous topographs on the multi-stacked ®lms by examining the fringe pro®les, and was also found in topographic images by somewhat careful inspection. It is noteworthy that a simple reciprocal correspondence was observed between the amplitude of fringe oscillation and the fringe contrast. This ®nding of nonprojectiveness, i.e. the fringe oscillation noted above, in Pendello È sung fringes as well as in moire  fringes suggests that the non-projectiveness occurs as a very basic property of X-ray interference fringes produced by crystal diffraction.