Fig. 3

Simulated spatio-temporal response of the planar lens interacting with a 30 keV electron. a Snapshots of the z-component of the electric field amplitude at depicted times for the indicated electron positions, which demonstrate that the electromagnetic wave packet is focused into a 1.5 µm waist at 5.7 µm distance from the structure (see Supplementary Movie 1). Color bar is the electric field amplitude at the dimensions of V m⁻¹. Scale bar is 5 μm. b Temporal representation of the z-component of the electric field at the focal point. Fourier transform of the temporal data, giving the z-component of the electric field at the c E = 0.6 eV and d E = 1.4 eV. The white dashed line marks the focal plane. TR stands for transition radiation. Color bar is the averaged electric field magnitude at arbitrary units. Scale bar is 4 μm