Fig. 1: a) Experimental set-up. b) Interference pattern at 10 keV of a boron fibre with a tungsten core. c) and d) Intensity distributions in the horizontal and vertical directions.

The minimum detectable distance between fringes in the vertical scan is 1.8 µm. The fibre-to-film distance is

r1 = 1m, the source-to-fibre distance is r0 = 40 m.

With the demagnification factor r0/r1 = 40, the effective source size is about 80 µm.