Development of a real-time defocus-image modulation processing electron microscope. II. Dynamic observation of spherical aberration-free phase image of surface atoms

A real-time defocus-image modulation processing lectron microscope, which utilizes a custom designed, floating type, accelerating voltage generation system to modulate focus quickly and precisely, produced spherical aberration-free phase and amplitude images with a time resolution of 4/30ths of a second. The symmetric pattern of a Thon diagram, which was constructed by using through-focus images of an amorphous thin film under accelerating voltage modulation, revealed the successful correction of spherical aberration in real time. As a result of the modulation, the resolution of the microscope was improved a little higher than the Scherzer limit. The dynamic flip-flop motion of atoms on a Au (011) 2×1 reconstructed surface was clearly observed in the profile imaging mode by using this novel electron microscope, which demonstrates effectiveness of the developed high voltage modulation system for the real-time correction.