When structural noise is the signal

Speckle statistics in fluctuation electron microscopy

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

In a recent paper, Jungk et al. [Ultramicroscopy 104 (2005) 206-219] conclude that standard fluctuation electron microscopy speckle analysis, which examines the normalized variance of scattered intensity as a function of scattering angle, does not provide more information about disordered materials than does classical diffraction. In this letter, I point out flaws in both their experiments and their modeling that led them to this erroneous conclusion. In their experiments, they use resolutions that are excessively high relative to the length scale of the medium-range ordering in their samples, and consequently the diffraction fluctuations they seek are very weak. In their modeling, they attempt to correct this by applying low-pass image processing filters in order to broaden the effective point-spread function (i.e. to lower the image resolution after the experiment). Such filters, when applied to image intensities, do not emulate properly the evolution of coherent speckle as the point-spread function becomes wider. I affirm that fluctuation microscopy does indeed provide more information about disordered materials than classical diffraction when the experiments and modeling are conducted appropriately.

Original languageEnglish (US)
Pages (from-to)166-171
Number of pages6
JournalUltramicroscopy
Volume107
Issue number2-3
DOIs
StatePublished - Feb 2007

Fingerprint

Speckle
Electron microscopy
electron microscopy
Statistics
statistics
point spread functions
Diffraction
Optical transfer function
diffraction
filters
Experiments
image resolution
image processing
Image resolution
microscopy
Microscopic examination
Image processing
defects
Scattering
scattering

Keywords

  • Amorphous Ge
  • Amorphous Si
  • Dark-field speckle
  • Fluctuation electron microscopy
  • Medium-range order
  • Speckle

ASJC Scopus subject areas

  • Materials Science(all)
  • Instrumentation

Cite this

When structural noise is the signal : Speckle statistics in fluctuation electron microscopy. / Treacy, Michael.

In: Ultramicroscopy, Vol. 107, No. 2-3, 02.2007, p. 166-171.

Research output: Contribution to journalArticle

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