Fig. 1. Schematic of the dynamic HEER experimental layout. High-brightness electron probes passing through the sample form a point-to-point magnified image of the sample with the magnetic imaging system. To image the irreversible laser ablation process, a specially designed sample holder containing numerous identical grids is mounted on a two-dimensional translation stage in the xy plane.

Fig. 2. (a) Simulated beam transverse envelope in the imaging section. (b) Simulated static image of a 200-mesh hexagonal TEM grid. (c) Experimental static image of a 200-mesh hexagonal TEM grid.

Fig. 3. (a) Image of the central part of a 200-mesh square TEM grid. (b) Beam intensity distribution in the x plane, i.e., the edge spread function (ESF) of the grid bar in the region of interest marked by the red box in (a). (c) The line spread function (i.e., the derivative of the ESF) of the grid bar and its Gaussian fit plot. The 1σ resolution is determined to be about 15 µm.

Fig. 4. (a) Electron deflection by transient electromagnetic fields at T = 4.8 ns. (b) Zoomed view of the areas illuminated by the laser.

Fig. 5. Typical images of the gold mesh during the melting process. The black squares in these images indicate the illuminating area.

Fig. 6. Measured intensity of illuminated area (a) and melting ratio (b) at different time delays.