lattice image

HREM, which allows wave interference between transmitted and diffracted waves to be caused, enables us to obtain a lattice image of a thin crystalline specimen at an appropriate defocus of the objective lens. The lattice image (intensity distribution) does not always correspond to the electrostatic potential in the crystalline specimen projected along the direction of the incident electron beam (projected potential). However, the lattice image displays correctly the periodicity of a crystal. When the image is obtained at the defocus condition, which is determined by the spherical aberration of the objective lens and the accelerating voltage of the incident beam (Scherzer focus), it corresponds fairly well to the electrostatic potential (atomic arrangement) in the crystal. This image is called "crystal structure image."

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