Building on the fact that x-ray illumination excites electrons that generate photochromic effects, a large photoconductivity and a bulk photovoltaic current, a research team at the University of Bonn in Germany designed an x-ray imaging system with relatively high resolution.In experiments that recorded an elementary holographic reflection grating in a photorefractive iron-doped lithium-niobate crystal, the group claims that the system easily resolved structures 25 µm in size with a radiation dose of 90 Gray and a signal-to-noise ratio of 6.The research detailing the holographic imaging x-ray sensor can be found in the Aug. 26 issue of Applied Physics Letters.