Virtual lens improves X-ray microscopy

With X-ray microscopes, researchers at PSI look inside computer chips, catalysts, small pieces of bone, or brain tissue. The short wavelength of the X-rays makes details visible that are a million times smaller than a grain of sand—structures in the nanometer range (millionths of a millimeter). As in a normal microscope, a lens is used to gather the light scattered by the sample and forms an enlarged image on the camera. Tiny structures, however, scatter light at very large angles. To obtain high resolution in the image, a correspondingly large lens is needed. "It remains extremely challenging to produce such large lenses," says PSI physicist Klaus Wakonig: "When working with visible light, there are lenses that can capture very large scattering angles. With X-rays, however, this is more complicated because of the weak interaction with the material of the lens. As a consequence, usually only very small angles can be captured, or the lenses are rather inefficient."