Theoretical background of defocus image modulation processing (DIMP) based on three dimensional optical transfer functions (3D-OTFs)
Authors: Utsuro H.1; Ando T.1; Takai Y.1; Shimizu R.1; Ikuta T.2
Source: Optik – International Journal for Light and Electron Optics, Volume 112, Number 2, February 2001 , pp. 67-75(9)
Publisher: Urban & Fischer
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Abstract:
Defocus-image modulation processing (DIMP), where a bipolar weighted image integration of the observed defocus series is performed, is one of the most promising approaches for real-time observation of spherical-aberration-free phase and amplitude images with a transmission electron microscope. DIMP can be extended to hollow-cone illumination (HCI) to improve the resolution of the electron microscope significantly, which has been already confirmed in the experiment using an optical microscope. In this paper, the theoretical background of DIMP is investigated by using 3D-OTFs in 3D-Fourier space. First, 3D-OTFs are derived under coherent illumination and the filtering characteristics of the DIMP are interpreted using the 3D-OTFs. Then the bipolar weighting functions used in DIMP are obtained by inverse Fourier transform of the filter functions in 3D-Fourier space under axial and hollow-cone illuminations.
Keywords: Transmission electron microscope; defocus image modulation processing (DIMP); three-dimensional optical transfer function; hollow-cone illumination
Language: English
Document Type: Original article
DOI: 10.1078/0030-4026-00012
Affiliations: 1: Department of Material and Life Science, Osaka University, Yamada-oka 2-1, Suita, Osaka 565, Japan 2: Department of Lightwave Sciences, Osaka Electro-Communication University, 18-8 Hatsu-cho, Neyagawa, Osaka 572, Japan
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