The direct observation of the structure of real crystals by lattice imaging

The electron-microscope technique of lattice imaging can in favourable circumstances be used to observe the structure of materials directly. The technique is described, and examples of cases in which a direct correlation between image contrast and structural features has been established are given. Procedures for computing contrast in n-beam lattice images are outlined, and the important experimental parameters, thickness and orientation of the specimen, and spherical aberration and defocusing of the microscope objective, are discussed in some detail.