Projected thickness reconstruction from a single defocused transmission electron microscope image of an amorphous object

► We reconstruct the projected thickness of a specimen using a phase retrieval technique. ► The technique requires a single out-of-focus phase contrast transmission electron micrograph. ► We demonstrate this technique is quantitative using simulation and experiment. ► We discuss the technique's realm of application and its nominal resolution. ► We employ this technique to measure the size of voids in latex sphere test objects.