Keyhole coherent diffractive imaging

The availability of third-generation synchrotrons and ultimately X-ray free-electron lasers(1) is driving the development of many new methods of microscopy. Among these techniques, coherent diffractive imaging (CDI) is one of the most promising, offering nanometre-scale imaging of non-crystallographic samples. Image reconstruction from a single diffraction pattern has hitherto been possible only for small, isolated samples, presenting a fundamental limitation on the CDI method. Here we report on a form of imaging we term 'keyhole' CDI, which can reconstruct objects of arbitrary size. We demonstrate the technique using visible light and X-rays, with the latter producing images of part of an extended object with a detector-limited resolution of better than 20 nm. Combining the improved resolution of modern X-ray optics with the wavelength-limited resolution of CDI, the method paves the way for detailed imaging of a single quantum dot or of a small virus within a complex host environment.