A study of O vacancies was carried out in a 300keV high-resolution electron microscope which was equipped with an imaging plate. Optimum imaging conditions were found under which O atoms and vacancies were seen as bright spots in a so-called dark-spot image. Under the optimum imaging conditions, a dependence of the image contrast upon the occupancy of the O sites, and the thickness of the samples, was explained in terms of dynamic diffraction theory. By using the imaging plate, the atomic occupancies were quantitatively estimated from the intensity distributions of the bright spots in the observed image contrast.

H.Shibahara, K.Numaguchi, M.Kawasaki, H.Takizawa, T.Oikawah, H.Taguchi: Journal of Electron Microscopy, 1995, 44[4], 174-81