(Colour online) (a) Schematics of the diffraction imaging experiment. The sample is illuminated by a parallel X-ray beam under an incident angle set to the Bragg angle (θBragg) of the Pt(111) buffer layer. The elevation angle (eulerian geometry) is ψ. The sample image is recorded by the high-resolution area detector (FReLoN). The part of the sample diffracting (Pt) is the part labelled as `electrode' [the inset shows the multi-layered structure of the sample (tunnel junction)]. (b) Optical microscopy image of the 120 µm-sized square junctions. (c) Radial scan (i.e. θ–2θ geometry) performed for a thick sample using a point detector (E = 15 keV; pink beam: ΔE/E = 10−2). (d) Images of the tunnel junction area taken for an incident angle of the sample set as the Bragg angle of the Pt peak; (1) mask alignment marks for lithography; (2) contact electrode; (3) junction area of the FReLoN chips; (4) square-shaped junctions (some of them with defects appearing as scratches).