  Modern microscopy techniques are developing towards high-resolution imaging,
and tremendous progress has been made in past decades; however, the imaging of
individual biological macromolecules at atomic resolution using
short-wavelength radiation such as electrons or X-rays has not yet been
achieved. The construction of free-electron lasers in many countries around the
world arises from the desire to develop new imaging techniques by employing
coherent radiation to image individual macromolecules. This work deals with
coherent imaging and related phase retrieval techniques, with an emphasis on
their application in the imaging of individual biological macromolecules.
