title: Analysis of nonlinear intensity attenuation in bright-field TEM images for correct 3D reconstruction of the density in micron-sized materials.
abstract: To obtain the correct tomographic reconstruction of micron-sized materials, the nonlinear intensity attenuation of bright-field transmission electron microscopy (BF-TEM) images was analyzed as a function of the sample thickness using a high-voltage electron microscope. The intensity attenuation was precisely measured relative to the projection thickness of carbon microcoils (CMCs) at acceleration voltages of 400-1000 kV using objective apertures (OAs) with radii of 2.1-28 nm(-1). The results show that the nonlinearity is strongly dependent on the OA size and the acceleration voltage. The influence of nonlinearity on tomographic reconstructions was also examined using a specially developed 360°-tilt sample holder. Sliced images of the reconstructed volumes indicated that an increase in the nonlinearity caused artificial fluctuations in the internal density of materials and inaccurate shapes of the objects in more significant cases. Conditions sufficient for reconstruction with the correct density have been estimated to be 0.67 of the minimum electron transmittance, and for reconstructions with correct shapes, 0.4. This information enables foreseeing the quality of the reconstruction from a single BF-TEM image prior to the tilt-series acquisition. As a result to demonstrate the appropriateness of these conditions, a CMC with a diameter of 3.7 µm was reconstructed successfully; i.e. not only the shape but also the internal density were correctly reproduced using electron tomography.
authors.affiliation: Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan yamasaki@uhvem.osaka-u.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Yamasaki
authors.affiliation: Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Mutoh
authors.affiliation: JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
authors.forename: Shigemasa
authors.initials: S
authors.lastname: Ohta
authors.affiliation: JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
authors.forename: Syuichi
authors.initials: S
authors.lastname: Yuasa
authors.affiliation: EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Arai
authors.affiliation: Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tanaka
keywords: 360°-tilt sample holder; HVEM; bright-field TEM; carbon microcoil; electron tomography; nonlinear intensity attenuation