X-ray microscopy using FELs: possibilities and challenges

X-ray microscopy is often discussed as one of the experiments that would benefit from the development of x-ray free-electron lasers. We outline the source characteristics required for several different x-ray microscopy experiments, including possible approaches towards atomic resolution imaging. X-ray FELs would help many but not all of these experiments; those that would benefit the most include experiments that are extremely demanding of a high total flux of coherent x rays; experiments that require snapshot imaging at nanosecond or faster timescales; and pump-probe experiments that require synchronization of an x-ray and a UV laser pulse. In all of these experiments, caution must be taken with regard to radiation and thermal damage.