X-ray phase imaging: Demonstration of extended conditions with homogeneous objects

We discuss contrast formation in a propagating x-ray beam. We consider the validity conditions for linear relations based on the transport-of-intensity equation ( IE) and on contrast transfer functions (CTFs). From a single diffracted image, we recover the thickness of a homogeneous object which has substantial absorption and a phase-shift of -0.37 radian. (C) 2004 Optical Society of America.