Computer-aided reconstruction of the image contrast of atom clusters from diffractograms of electron micrographs

• Published in: Micron 1981, Vol.12 (4), p.353-364
• Main Authors: Kanaya, Koichi, Baba, Norio, Takamiya, Kengo
• Format: Article
• Language: English
• ISSN: 0047-7206; 1878-1152
• DOI: 10.1016/0047-7206(81)90004-2

By developing Lommel's Bessel integration with respect to the Gaussian scattering angular distribution, the Kirchhoff diffraction integrals indicating image profiles of atom clusters in high resolution electron microscopy, when taking account of the complex scattering amplitude and optical phase of the objective lens aberrations, can be performed as functions of the generalized spatial frequency, image distance and defocusing. The light optical diffractograms obtained by the Fourier-Bessel transformation; which involves the coherent wave consisting of both phase and amplitude contrast transfer functions, as well as the incoherent wave consisting of square terms; provide a useful method of measuring the aberration coefficients, scattering factor phase and the exact amount of defocus. It follows that the image contrast of clusters can be reconstructed from the diffractograms by evaluating the spatial frequencies and scattering factor phases of individual clusters with the aid of digital computer calculations in place of the previous Monte-Carlo method.