Aiming at large-area phase-contrast x-ray imaging, a separated-type x-ray i
nterferometer system was designed and developed to produce 25 x 20 mm inter
ference patterns. The skew-symmetric optical system was adopted because of
the feasibility of alignment. The rotation between the separated crystal bl
ocks was controlled within a drift of 0.06 nrad using a feedback positionin
g system. This interferometer generated a 25 x 15 mm interference pattern w
ith 0.07 nm synchrotron x-rays. A slice of a rabbit's kidney was observed,
and its tubular structure could be revealed in a measured phase map. (C) 19
99 American Institute of Physics. [S0034-6748(99)05112-6].