Estimation of defocus and astigmatism in transmission electron microscopy

Image formation in phase-contrast electron microscopy is governed by the contrast transfer function (CTF). The key parameter to tune the CTF is the defocus. A precise and unbiased estimate of the defocus is essential to determine the forward model and interpret high resolution images in cryo-TEM. We...

Full description

Saved in:
Bibliographic Details
Published in2010 IEEE International Symposium on Biomedical Imaging: From Nano to Macro pp. 1121 - 1124
Main Authors Vulović, M, Brandt, P L, Ravelli, R B G, Koster, A J, van Vliet, L J, Rieger, B
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.04.2010
Subjects
Amorphous materials
Approximation algorithms
astigmatism
cryo-TEM
CTF estimation
Electron microscopy
Image resolution
Lenses
phase contrast
Signal to noise ratio
Transfer functions
Transmission electron microscopy
Uncertainty
Vision defects
Online AccessGet full text

Cover

More Information
Summary:Image formation in phase-contrast electron microscopy is governed by the contrast transfer function (CTF). The key parameter to tune the CTF is the defocus. A precise and unbiased estimate of the defocus is essential to determine the forward model and interpret high resolution images in cryo-TEM. We present an algorithm based on the weak-phase approximation for determination of the defocus and astigmatism of the objective lens from recorded images of an amorphous sample. The algorithm identifies Thon rings in the power spectrum density (PSD) and uses them to estimate astigmatism and defocus together with their uncertainties. For the astigmatism estimation we use a transformation to polar coordinates to fit ellipses to the Thon rings. Averaging the PSD over these ellipses reduces CTF estimation to a 1D problem and enhances the signal-to-noise ratio.
ISBN:9781424441259
1424441250
ISSN:1945-7928
1945-8452
DOI:10.1109/ISBI.2010.5490190