A monochromatic X-ray imaging setup based on a combination of a
doubly curved crystal and a polycapillary focusing X-ray lens was designed. In
this setup, the bent crystal optic was used not only to monochromatize but also
to focus the divergent X-ray beam from a conventional X-ray source to form a
monochromatic X-ray focal spot with a size of 426 ×
467 μm
$^{2}$
at 17.5 keV. The beam
expanding from this focal point was focused by the polycapillary optic to
obtain a focal spot which was then used as the monochromatic X-ray imaging
virtual source. The output focal spot size of the focusing polycapillary optic
at 17.5 keV was 97 μm. Compared with the beam expansion
after the focal spot of the bent crystal optic, the beam expansion after the
focal spot of the focusing polycapillary optic was relatively large. This was
helpful for magnifying the X-ray image of the sample. The focused beam was
helpful to decrease the exposure time for imaging small samples.
