  We present feasibility study of an accelerator-based ultrafast transmission
electron microscope (u-TEM) capable of producing a full field image in a
single-shot with simultaneous picosecond temporal resolution and nanometer
spatial resolution. We study key physics related to performance of u-TEMs, and
discuss major challenges as well as possible solutions for practical
realization of u-TEMs. The feasibility of u-TEMs is confirmed through
simulations using realistic electron beam parameters. We anticipate that u-TEMs
with a product of temporal and spatial resolution beyond $10^{-19}~$m*s will
open up new opportunities in probing matter at ultrafast temporal and
ultrasmall spatial scales.
