Differential interference contrast X-ray microscopy with twin zone plates at ESRF beamline ID21

We describe a novel approach for converting the specimens phase information into strong image contrast in the x-ray region, the differential interference contrast x-ray microscopy (X-DIC). In the used setup, X-DIC operation was accomplished by a twin zone plate (TZP), i.e. two zone plates on both sides of the same substrate, laterally shifted by about one outermost zone width. Once a TZP has been successfully produced by means of especially developed nanofabrication processes, it is as easy to use as a single zone plate, without any alignment difficulty or further requirements to the coherence of the illumination. The tremendous contrast enhancement was demonstrated at the microscopy beamline ID21 at ESRF in Grenoble for test objects and biological samples. TZPs allow for full field X-DIC imaging as well as for DIC scanning transmission x-ray microscopy. The first experiments were carried out at 0.31nm wavelength (4 keV photon energy), and features down to approx. 160 nm could be resolved in X-DIC.