1. A focus/detector system of an X-ray apparatus for generating at least one of projective and tomographic phase contrast recordings, comprising: a beam source, including a focus and a focus-side source grating, arranged in the beam path to generate a field of ray-wise coherent X-rays; and a grating/detector arrangement including a phase grating with grating lines arranged parallel to the source grating for generating an interference pattern and a detector including a multiplicity of detector elements arranged in a plane for measuring the radiation intensity behind the phase grating, wherein the detector elements are formed by a multiplicity of elongate detection strips aligned parallel to the grating lines of the phase grating.