  We demonstrate that in situ coherent diffractive imaging (CDI), which
harnesses the coherent interference between a strong and a weak beam
illuminating a static and dynamic structure, can be a very dose-efficient
imaging method. At low doses, in situ CDI can achieve higher resolution than
perfect lenses with the point spread function as a delta function. Both our
numerical simulation and experimental results show that the combination of in
situ CDI and ptychography can reduce the dose by two orders of magnitude over
ptychography. We expect that computational microscopy based on in situ CDI can
be implemented in different imaging modalities with photons and electrons for
low-dose imaging of radiation-sensitive materials and biological samples.
