By
introducing an analyzer crystal between sample and detector it is possible
to convert into images the information on the sample carried by the phase
of the wave which traversed it.
When
aligned with the monochromator crystal placed upstream of the sample, the
analyzer crystal rejects all scattered photons, which blur the image and
reduce detail visibility.
A
slight misalignment angle between the two crystals transforms into different
shades of gray on the detector film the different scattering angles of
the photons which traversed the sample. These angles are, to first order
approximation, proportional to the gradient of the real part of the refractive
index, which is responsible for wave phase shifts. In this way one can
convert into image contrast the information on the sample internal structure
carried by the phase of the wave.
The
picture shows an image of a bee (which is practically transparent to X-rays
used in dagnostic practice) obtained with this technique.