Coherent diffractive imaging (CDI) is a means of overcoming the resolution and image contrast limitations of electron and x-ray lenses. The central tenet of the method is that the intensity of the diffraction pattern must be measured on a sufficiently fine pixel pitch, which is inversely related to the size of the illuminated region of the object. We show here that ptychography—a form of CDI that uses many diffraction patterns—is not subject to this constraint. Using a variant of the ePIE inversion algorithm, we demonstrate experimentally that the sampling requirement in ptychography is independent of illumination size.

• Received 28 March 2013

DOI:https://doi.org/10.1103/PhysRevA.87.053850