Patent ID: 7154092

Claim:
A method of three-dimensional image reconstruction for reconstructing a three-dimensional image of a specimen based on TEM (transmission electron microscope) images by tilting the specimen at plural tilt angles and obtaining the TEM images at these tilt angles, wherein (a) a positive focal point position of an objective lens incorporated in a transmission electron microscope is detected at each of the tilt angles of the specimen, (b) a focal point position of the objective lens is set to plural positions which are shifted from said positive focal point position by amounts of defocus Δf 1 , . . . , Δf n , respectively, at each of the tilt angles of the specimen and a TEM image is obtained at each of the set focal point positions, (c) a single optimum TEM image is selected at each of the tilt angles of the specimen from the TEM images obtained by the steps (a) and (b) above, and (d) a three-dimensional image of the specimen is reconstructed based on the selected TEM images.