Imaging properties of bright-field and annular-dark-field scanning confocal electron microscopy: II. Point spread function analysis

K. Mitsuishi, A. Hashimoto, M. Takeguchi, M. Shimojo, K. Ishizuka

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The imaging properties of bright field and annular dark field scanning confocal electron microscopy (BF-SCEM and ADF-SCEM) are discussed based on their point spread functions (PSFs) in comparison with multislice simulations. Although the PSFs of BF-SCEM and ADF-SCEM show similar hourglass shapes, their numerical distributions are quite different: BF-SCEM PSF is always positive and shows a center of symmetry whereas the ADF-SCEM PSF is complex and has Hermitian symmetry. These PSF properties explain the large elongation effect in BF-SCEM for laterally extended object and almost no-elongation in ADF-SCEM, illustrating the importance of the numerical analysis of PSFs. The Hermitian symmetry of the ADF-SCEM PSF results in an interesting "edge enhancement effect" at the interface. Simulation using the PSF and the multislice method verified this effect at GaAs surfaces and InAs interfaces embedded in GaAs. This unique feature of ADF-SCEM can potentially be useful for depth sectioning. It is also pointed out that a PSF imaging model cannot be applicable for BF-SCEM of a phase object, when the system is symmetric and aberration free.

Original languageEnglish
Pages (from-to)53-60
Number of pages8
JournalUltramicroscopy
Volume112
Issue number1
DOIs
Publication statusPublished - 2012 Jan

Keywords

  • CTF
  • Contrast transfer function
  • Image simulation
  • Multislice method
  • Optical sectioning
  • PSF
  • Point spread function
  • SCEM
  • Scanning confocal electron microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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