A Detailed Observation of the Nonprojectiveness of X-ray Moiré-Fringed Diffraction Images

It has been shown in recent years that X-ray moiré 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 moiré image's nonprojectiveness have been conducted using synchrotron-radiation plane-wave topography, an Si bicrystal specimen and a simultaneous recording of moiré topographic images onto a set of multilayered X-ray films. This paper reports the following experimental results: intensity profiles revealing an unusual striking figure of the space wave field of moiré fringes; qualitative analysis of the fringe profile change in its manner of occurrence and in the effect on the fringe-position variation; plots of oscillating fringe position and fringe direction. The amplitudes of the fringe oscillation determined over the whole field of the moiré pattern exhibit a non-uniform characteristic distribution pattern that can be related to a specific feature of the intensity pattern on the specimen.