Lawrence, M. C. Frank, J. (Ed.) Electron Tomography: Three Dimensional Imaging with the Transmission Electron Microscope. Least-squares method of alignment. Plenum, 1992, 197-204
An intermediate problem arises in the tomographic reconstruction of an object from a series of electron microscope exposures, namely that of determining the relationship between the axes of the individual digitized images, the tilt axis of the microscope, and a hypothetical internal coordinate system of the specimen. Accurate resampling of the tilt series images onto a common coordinate system is an essential prerequisite for any tomographic reconstruction algorithm. The lack of an immediately available common system of coordinates results from the microscope goniometer not being truly eucentric at high resolution. Thus, the goniometer control system is unable to provide the user with suffiicient control at a subpixel level as the specimen is tilted in the microscope, and the precise relationship between the microscope coordinate system and the specimen coordinate system is lost. In the case of photographic image recording, further inaccuracies can arise from the positioning of the plates in their holders or on the microdensitometer.